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25.1: Anatomy of the Circulatory and Lymphatic Systems - Biology

25.1: Anatomy of the Circulatory and Lymphatic Systems - Biology



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Learning Objectives

  • Describe the major anatomical features of the circulatory and lymphatic systems
  • Explain why the circulatory and lymphatic systems lack normal microbiota
  • Explain how microorganisms overcome defenses of the circulatory and lymphatic systems to cause infection
  • Describe general signs and symptoms of disease associated with infections of the circulatory and lymphatic systems

clinical focus - part 1

Barbara is a 43-year-old patient who has been diagnosed with metastatic inflammatory breast cancer. To facilitate her ongoing chemotherapy, her physician implanted a port attached to a central venous catheter. At a recent checkup, she reported feeling restless and complained that the site of the catheter had become uncomfortable. After removing the dressing, the physician observed that the surgical site appeared red and was warm to the touch, suggesting a localized infection. Barbara’s was also running a fever of 38.2 °C (100.8 °F). Her physician treated the affected area with a topical antiseptic and applied a fresh dressing. She also prescribed a course of the antibiotic oxacillin.

Exercise (PageIndex{1})

  1. Based on this information, what factors likely contributed to Barbara’s condition?
  2. What is the most likely source of the microbes involved?

The circulatory and lymphatic systems are networks of vessels and a pump that transport blood and lymph, respectively, throughout the body. When these systems are infected with a microorganism, the network of vessels can facilitate the rapid dissemination of the microorganism to other regions of the body, sometimes with serious results. In this section, we will examine some of the key anatomical features of the circulatory and lymphatic systems, as well as general signs and symptoms of infection.

The Circulatory System

The circulatory (or cardiovascular) system is a closed network of organs and vessels that moves blood around the body (Figure (PageIndex{1})). The primary purposes of the circulatory system are to deliver nutrients, immune factors, and oxygen to tissues and to carry away waste products for elimination. The heart is a four-chambered pump that propels the blood throughout the body. Deoxygenated blood enters the right atrium through the superior vena cava and the inferior vena cava after returning from the body. The blood next passes through the tricuspid valve to enter the right ventricle. When the heart contracts, the blood from the right ventricle is pumped through the pulmonary arteries to the lungs. There, the blood is oxygenated at the alveoli and returns to the heart through the pulmonary veins. The oxygenated blood is received at the left atrium and proceeds through the mitral valve to the left ventricle. When the heart contracts, the oxygenated blood is pumped throughout the body via a series of thick-walled vessels called arteries. The first and largest artery is called the aorta. The arteries sequentially branch and decrease in size (and are called arterioles) until they end in a network of smaller vessels called capillaries. The capillary beds are located in the interstitial spaces within tissues and release nutrients, immune factors, and oxygen to those tissues. The capillaries connect to a series of vessels called venules, which increase in size to form the veins. The veins join together into larger vessels as they transfer blood back to the heart. The largest veins, the superior and inferior vena cava, return the blood to the right atrium.

Other organs play important roles in the circulatory system as well. The kidneys filter the blood, removing waste products and eliminating them in the urine. The liver also filters the blood and removes damaged or defective red blood cells. The spleen filters and stores blood, removes damaged red blood cells, and is a reservoir for immune factors. All of these filtering structures serve as sites for entrapment of microorganisms and help maintain an environment free of microorganisms in the blood.

The Lymphatic System

The lymphatic system is also a network of vessels that run throughout the body (Figure (PageIndex{2})). However, these vessels do not form a full circulating system and are not pressurized by the heart. Rather, the lymphatic system is an open system with the fluid moving in one direction from the extremities toward two drainage points into veins just above the heart. Lymphatic fluids move more slowly than blood because they are not pressurized. Small lymph capillaries interact with blood capillaries in the interstitial spaces in tissues. Fluids from the tissues enter the lymph capillaries and are drained away (Figure (PageIndex{3})). These fluids, termed lymph, also contain large numbers of white blood cells.

The lymphatic system contains two types of lymphoid tissues. The primary lymphoid tissue includes bone marrow and the thymus. Bone marrow contains the hematopoietic stem cells (HSC) that differentiate and mature into the various types of blood cells and lymphocytes (see [link]). The secondary lymphoid tissues include the spleen, lymph nodes, and several areas of diffuse lymphoid tissues underlying epithelial membranes. The spleen, an encapsulated structure, filters blood and captures pathogens and antigens that pass into it (Figure (PageIndex{4})). The spleen contains specialized macrophages and dendritic cells that are crucial for antigen presentation, a mechanism critical for activation of T lymphocytes and B lymphocytes (see Major Histocompatibility Complexes and Antigen-Presenting Cells). Lymph nodes are bean-shaped organs situated throughout the body. These structures contain areas called germinal centers that are rich in B and T lymphocytes. The lymph nodes also contain macrophages and dendritic cells for antigen presentation. Lymph from nearby tissues enters the lymph node through afferent lymphatic vessels and encounters these lymphocytes as it passes through; the lymph exits the lymph node through the efferent lymphatic vessels (Figure (PageIndex{4})).

The lymphatic system filters fluids that have accumulated in tissues before they are returned to the blood. A brief overview of this process is provided at this website.

Exercise (PageIndex{2})

What is the main function of the lymphatic system?

Infections of the Circulatory System

Under normal circumstances, the circulatory system and the blood should be sterile; the circulatory system has no normal microbiota. Because the system is closed, there are no easy portals of entry into the circulatory system for microbes. Those that are able to breach the body’s physical barriers and enter the bloodstream encounter a host of circulating immune defenses, such as antibodies, complement proteins, phagocytes, and other immune cells. Microbes often gain access to the circulatory system through a break in the skin (e.g., wounds, needles, intravenous catheters, insect bites) or spread to the circulatory system from infections in other body sites. For example, microorganisms causing pneumonia or renal infection may enter the local circulation of the lung or kidney and spread from there throughout the circulatory network.

If microbes in the bloodstream are not quickly eliminated, they can spread rapidly throughout the body, leading to serious, even life-threatening infections. Various terms are used to describe conditions involving microbes in the circulatory system. The term bacteremia refers to bacteria in the blood. If bacteria are reproducing in the blood as they spread, this condition is called septicemia. The presence of viruses in the blood is called viremia. Microbial toxins can also be spread through the circulatory system, causing a condition termed toxemia.

Microbes and microbial toxins in the blood can trigger an inflammatory response so severe that the inflammation damages host tissues and organs more than the infection itself. This counterproductive immune response is called systemic inflammatory response syndrome (SIRS), and it can lead to the life-threatening condition known as sepsis. Sepsis is characterized by the production of excess cytokines that leads to classic signs of inflammation such as fever, vasodilation, and edema (see Inflammation and Fever). In a patient with sepsis, the inflammatory response becomes dysregulated and disproportionate to the threat of infection. Critical organs such as the heart, lungs, liver, and kidneys become dysfunctional, resulting in increased heart and respiratory rates, and disorientation. If not treated promptly and effectively, patients with sepsis can go into shock and die.

Certain infections can cause inflammation in the heart and blood vessels. Inflammation of the endocardium, the inner lining of the heart, is called endocarditis and can result in damage to the heart valves severe enough to require surgical replacement. Inflammation of the pericardium, the sac surrounding the heart, is called pericarditis. The term myocarditis refers to the inflammation of the heart’s muscle tissue. Pericarditis and myocarditis can cause fluid to accumulate around the heart, resulting in congestive heart failure. Inflammation of blood vessels is called vasculitis. Although somewhat rare, vasculitis can cause blood vessels to become damaged and rupture; as blood is released, small red or purple spots called petechiae appear on the skin. If the damage of tissues or blood vessels is severe, it can result in reduced blood flow to the surrounding tissues. This condition is called ischemia, and it can be very serious. In severe cases, the affected tissues can die and become necrotic; these situations may require surgical debridement or amputation.

Exercise (PageIndex{3})

  • Why does the circulatory system have no normal microbiota?
  • Explain why the presence of microbes in the circulatory system can lead to serious consequences.

Infections of the Lymphatic System

Like the circulatory system, the lymphatic system does not have a normal microbiota, and the large numbers of immune cells typically eliminate transient microbes before they can establish an infection. Only microbes with an array of virulence factors are able to overcome these defenses and establish infection in the lymphatic system. However, when a localized infection begins to spread, the lymphatic system is often the first place the invading microbes can be detected.

Infections in the lymphatic system also trigger an inflammatory response. Inflammation of lymphatic vessels, called lymphangitis, can produce visible red streaks under the skin. Inflammation in the lymph nodes can cause them to swell. A swollen lymph node is referred to as a bubo, and the condition is referred to as lymphadenitis.

Key Concepts and Summary

  • The circulatory system moves blood throughout the body and has no normal microbiota.
  • The lymphatic system moves fluids from the interstitial spaces of tissues toward the circulatory system and filters the lymph. It also has no normal microbiota.
  • The circulatory and lymphatic systems are home to many components of the host immune defenses.
  • Infections of the circulatory system may occur after a break in the skin barrier or they may enter the bloodstream at the site of a localized infection. Pathogens or toxins in the bloodstream can spread rapidly throughout the body and can provoke systemic and sometimes fatal inflammatory responses such as SIRS, sepsis, and endocarditis.
  • Infections of the lymphatic system can cause lymphangitis and lymphadenitis.

Multiple Choice

Which term refers to an inflammation of the blood vessels?

A. lymphangitis
B. endocarditis
C. pericarditis
D. vasculitis

D

Which of the following is located in the interstitial spaces within tissues and releases nutrients, immune factors, and oxygen to those tissues?

A. lymphatics
B. arterioles
C. capillaries
D. veins

C

Which of these conditions results in the formation of a bubo?

A. lymphadenitis
C. ischemia
D. vasculitis

B

Which of the following is where are most microbes filtered out of the fluids that accumulate in the body tissues?

A. spleen
B. lymph nodes
C. pericardium
D. blood capillaries

B

Fill in the Blank

Vasculitis can cause blood to leak from damaged vessels, forming purple spots called ________.

petechiae

The lymph reenters the vascular circulation at ________.

the subclavian veins

Short Answer

How do lymph nodes help to maintain a microbial-free circulatory and lymphatic system?

Critical Thinking

What term refers to the red streaks seen on this patient’s skin? What is likely causing this condition?

(credit: modification of work by Centers for Disease Control and Prevention)

Why would septicemia be considered a more serious condition than bacteremia?


Despite more than a century of intense research and clinical advancements, malaria remains one of the most important infectious diseases in the world today. Its widespread distribution places more than half of the world’s population in jeopardy. In 2015, the WHO estimated there were about 214 million cases of malaria worldwide, resulting in about 438,000 deaths about 88% of cases and 91% of deaths occurred in Africa. 1 Although malaria is not currently a major threat in the US, the possibility of its reintroduction is a concern. Malaria is caused by several protozoan parasites in the genus Plasmodium: P. falciparum, P. knowlesi, P. malariae, P. ovale, and P. vivax. Plasmodium primarily infect red blood cells and are transmitted through the bite of Anopheles mosquitoes.

Currently, P. falciparum is the most common and most lethal cause of malaria, often called falciparum malaria. Falciparum malaria is widespread in highly populated regions of Africa and Asia, putting many people at risk for the most severe form of the disease.

The classic signs and symptoms of malaria are cycles of extreme fever and chills. The sudden, violent symptoms of malaria start with malaise, abrupt chills, and fever (39–41° C [102.2–105.8 °F]), rapid and faint pulse, polyuria, headache, myalgia, nausea, and vomiting. After 2 to 6 hours of these symptoms, the fever falls, and profuse sweating occurs for 2 to 3 hours, followed by extreme fatigue. These symptoms are a result of Plasmodium emerging from red blood cells synchronously, leading to simultaneous rupture of a large number of red blood cells, resulting in damage to the spleen, liver, lymph nodes, and bone marrow. The organ damage resulting from hemolysis causes patients to develop sludge blood (i.e., blood in which the red blood cells agglutinate into clumps) that can lead to lack of oxygen, necrosis of blood vessels, organ failure, and death.

In established infections, malarial cycles of fever and chills typically occur every 2 days in the disease described as tertian malaria, which is caused by P. vivax and P. ovale. The cycles occur every 3 days in the disease described as quartan malaria, which is caused by P. malariae. These intervals may vary among cases.

Plasmodium has a complex life cycle that includes several developmental stages alternately produced in mosquitoes and humans (Figure 1). When an infected mosquito takes a blood meal, sporozoites in the mosquito salivary gland are injected into the host’s blood. These parasites circulate to the liver, where they develop into schizonts. The schizonts then undergo schizogony, resulting in the release of many merozoites at once. The merozoites move to the bloodstream and infect red blood cells. Inside red blood cells, merozoites develop into trophozoites that produce more merozoites. The synchronous release of merozoites from red blood cells in the evening leads to the symptoms of malaria.

In addition, some trophozoites alternatively develop into male and female gametocytes. The gametocytes are taken up when the mosquito takes a blood meal from an infected individual. Sexual sporogony occurs in the gut of the mosquito. The gametocytes fuse to form zygotes in the insect gut. The zygotes become motile and elongate into an ookinete. This form penetrates the midgut wall and develops into an oocyst. Finally, the oocyst releases new sporozoites that migrate to the mosquito salivary glands to complete the life cycle.

Diagnosis of malaria is by microscopic observation of developmental forms of Plasmodium in blood smears and rapid EIA assays that detect Plasmodium antigens or enzymes (Figure 2). Drugs such as chloroquine, atovaquone , artemether, and lumefantrine may be prescribed for both acute and prophylactic therapy, although some Plasmodium spp. have shown resistance to antimalarial drugs. Use of insecticides and insecticide-treated bed nets can limit the spread of malaria. Despite efforts to develop a vaccine for malaria, none is currently available.

Figure 1. The life cycle ofPlasmodium. (credit: modification of work by Centers for Disease Control and Prevention)​ Figure 2. A blood smear (human blood stage) shows an early trophozoite in a delicate ring form (upper left) and an early stage schizont form (center) ofPlasmodium falciparumfrom a patient with malaria. (credit: modification of work by Centers for Disease Control and Prevention)​

​Visit this site to learn how the parasite Plasmodium infects red blood cells.

The Nothing But Nets campaign, an initiative of the United Nations Foundation, has partnered with the Bill and Melinda Gates Foundation to make mosquito bed nets available in developing countries in Africa. Visit their website to learn more about their efforts to prevent malaria.


25.1: Anatomy of the Circulatory and Lymphatic Systems - Biology

In this section, you will explore the following questions:

  • What are the differences between digestion and absorption?
  • What are different types of digestive systems in invertebrates and vertebrates?
  • What are the specialized functions of the organs involved in processing food in the human body?
  • How do organs work together to digest food and absorb nutrients?

Connection for AP ® Courses

Much information in this chapter is not within the scope of AP ® . However, the chapter provides us with the opportunity to review concepts we’ve explored previously, including structure and function, macromolecules, energy production, transport of substances across membranes, and enzyme activity. All living organisms require a source of energy and molecules needed to build cells, tissues, and organs. During digestion, food is broken down into smaller molecules for absorption and distribution to all cells of the body. Nutrients are required to carry out cellular processes and maintain homeostasis, and digestion and absorption require the participation of several organs. Different animals have evolved different types of digestive systems specialized to meet their dietary needs. You do not need to memorize details about the different types of animal digestive systems, but you might find it interesting to explore the evolution of the system through a few groups of animals, from intracellular digestion in simple invertebrates to a digestive tract and accessory organs in complex vertebrates. Using a human eating a turkey sandwich as an example, food is ingested through the mouth. The mouth is the location where both mechanical (chewing) and chemical breakdown of food begins via the enzyme amylase, which breaks down carbohydrates into simpler sugars. The food bolus then travels by peristalsis (alternating waves of contraction) down the pharynx and esophagus to the stomach. In the stomach, pepsinogen mixes with hydrochloric acid to form pepsin, which begins digesting proteins, such as turkey, into smaller chains of amino acids. Mucus in the stomach protects its lining from damage by acidity, and the tightening of a sphincter prevents stomach contents from regurgitating into the esophagus. Further digestion of the ingredients of the sandwich occurs in the small intestine aided by a variety of enzymes for example, bile salts and pancreatic amylase dumped into the small intestine from the gallbladder and pancreas, respectively, help emulsify fats. Once the ingredients of the sandwich have been broken down into smaller nutrient molecules, including amino acids, glucose, and fatty acids, they are absorbed from the small intestine into the circulatory and lymphatic systems. The walls of the small intestine contain small, finger-like projections called villi and microvilli that increase surface area for absorption of nutrients by diffusion. The large intestine or colon does not produce digestive enzymes but functions to absorb water, salts, and some vitamins. Any nutrients from the sandwich are stored in the liver, and wastes are eliminated.

Information presented and the examples highlighted in the section support concepts outlined in Big Idea 2 and Big Idea 4 of the AP ® Biology Curriculum Framework. The AP ® Learning Objectives listed in the Curriculum Framework provide a transparent foundation for the AP ® Biology course, an inquiry-based laboratory experience, instructional activities, and AP ® exam questions. A Learning Objective merges required content with one or more of the seven Science Practices.

Big Idea 2 Biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis.
Enduring Understanding 2.A Growth, reproduction and maintenance of living systems require free energy and matter.
Essential Knowledge 2.A.3 Organisms must exchange matter with the environment to grow, reproduce and maintain organization.
Science Practice 2.2 The student can apply mathematical routines to quantities that describe natural phenomena.
Learning Objective 2.6 The student is able to use calculated surface area-to-volume ratios to predict which cell(s) might eliminate wastes or procure nutrients faster by diffusion.
Essential Knowledge 2.A.3 Organisms must exchange matter with the environment to grow, reproduce and maintain organization.
Science Practice 6.2 The student can construct explanations of phenomena based on evidence produced through scientific practices.
Learning Objective 2.7 The student will be able to explain how cell size and shape affects the overall rate of nutrient intake and the rate of waste elimination.
Big Idea 4 Biological systems interact, and these systems and their interactions possess complex properties.
Enduring Understanding 4.A Interactions within biological systems lead to complex properties.
Essential Knowledge 4.A.4 Organisms exhibit complex properties due to interactions between their constituent parts.
Science Practice 3.3 The student can evaluate scientific questions.
Learning Objective 4.8 The student is able to evaluate scientific questions concerning organisms that exhibit complex properties due to the interaction of their constituent parts.
Essential Knowledge 4.A.4 Organisms exhibit complex properties due to interactions between their constituent parts.
Science Practice 6.4 The student can make claims and predictions about natural phenomena based on scientific theories and models.
Learning Objective 4.9 The student is able to predict the effects of a change in a component(s) of a biological system on the functionality of an organism(s).
Essential Knowledge 4.A.4 Organisms exhibit complex properties due to interactions between their constituent parts.
Science Practice 1.3 The student can refine representations and models of natural or man-made phenomena and systems in the domain.
Learning Objective 4.10 The student is able to refine representations and models to illustrate biocomplexity due to interactions of the constituent parts.
Enduring Understanding 4.B Competition and cooperation are important aspects of biological systems.
Essential Knowledge 4.B.2 Cooperative interactions within organisms promote efficiency in the use of energy and matter.
Science Practice 1.4 The student can use representations and models to analyze situations or solve problems qualitatively and quantitatively.
Learning Objective 4.18 The student is able to use representations and models to analyze how cooperative interactions within organisms promote efficiency in the use of matter and energy.

Animals obtain their nutrition by consuming other organisms. Depending on their diet, animals can be classified into the following categories: plant eaters (herbivores), meat eaters (carnivores), and those that eat both plants and animals (omnivores). The nutrients and macromolecules present in food are not immediately accessible to the cells. There are a number of processes that modify food within the animal body to make the nutrients and organic molecules accessible for cellular function. As animals evolved in complexity of form and function, their digestive systems have also evolved to accommodate their various dietary needs.

Herbivores, Omnivores, and Carnivores

Herbivores are animals whose primary food source is plant-based. Examples of herbivores, as shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_01">Figure 25.2 include vertebrates like deer, koalas, and some bird species, as well as invertebrates such as crickets and caterpillars. These animals have evolved digestive systems capable of handling large amounts of plant material. Herbivores can be further classified into frugivores (fruit-eaters), granivores (seed eaters), nectivores (nectar feeders), and folivores (leaf eaters).

Carnivores are animals that eat other animals. The word carnivore is derived from Latin and literally means “meat eater.” Wild cats such as lions, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_02">Figure 25.3a and tigers are examples of vertebrate carnivores, as are snakes and sharks, while invertebrate carnivores include sea stars, spiders, and ladybugs, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_02">Figure 25.3b. Obligate carnivores are those that rely entirely on animal flesh to obtain their nutrients examples of obligate carnivores are members of the cat family, such as lions and cheetahs. Facultative carnivores are those that also eat non-animal food in addition to animal food. Note that there is no clear line that differentiates facultative carnivores from omnivores dogs would be considered facultative carnivores.

Omnivores are animals that eat both plant- and animal-derived food. In Latin, omnivore means to eat everything. Humans, bears (shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_03">Figure 25.4a), and chickens are example of vertebrate omnivores invertebrate omnivores include cockroaches and crayfish (shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_03">Figure 25.4b).

Invertebrate Digestive Systems

Animals have evolved different types of digestive systems to aid in the digestion of the various foods they consume. The simplest example is that of a gastrovascular cavity and is found in organisms with only one opening for digestion. Platyhelminthes (flatworms), Ctenophora (comb jellies), and Cnidaria (coral, jelly fish, and sea anemones) use this type of digestion. Gastrovascular cavities, as shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_04">Figure 25.5a, are typically a blind tube or cavity with only one opening, the “mouth”, which also serves as an “anus”. Ingested material enters the mouth and passes through a hollow, tubular cavity. Cells within the cavity secrete digestive enzymes that break down the food. The food particles are engulfed by the cells lining the gastrovascular cavity.

The alimentary canal, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_04">Figure 25.5b, is a more advanced system: it consists of one tube with a mouth at one end and an anus at the other. Earthworms are an example of an animal with an alimentary canal. Once the food is ingested through the mouth, it passes through the esophagus and is stored in an organ called the crop then it passes into the gizzard where it is churned and digested. From the gizzard, the food passes through the intestine, the nutrients are absorbed, and the waste is eliminated as feces, called castings, through the anus.

Vertebrate Digestive Systems

Through evolution, vertebrate digestive systems have adapted to different diets. Some animals have a single stomach, while others have multi-chambered stomachs. Birds have developed a digestive system adapted to eating unmasticated food.

Monogastric: Single-chambered Stomach

As the word monogastric suggests, this type of digestive system consists of one (“mono”) stomach chamber (“gastric”). Humans and many animals have a monogastric digestive system as illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_05">Figure 25.6ab. The process of digestion begins with the mouth and the intake of food. The teeth play an important role in masticating (chewing) or physically breaking down food into smaller particles. The enzymes present in saliva also begin to chemically break down food. The esophagus is a long tube that connects the mouth to the stomach. Using peristalsis, or wave-like smooth muscle contractions, the muscles of the esophagus push the food towards the stomach. In order to speed up the actions of enzymes in the stomach, the stomach is an extremely acidic environment, with a pH between 1.5 and 2.5. The gastric juices, which include enzymes in the stomach, act on the food particles and continue the process of digestion. Further breakdown of food takes place in the small intestine where enzymes produced by the liver, the small intestine, and the pancreas continue the process of digestion. The nutrients are absorbed into the blood stream across the epithelial cells lining the walls of the small intestines. The waste material travels on to the large intestine where water is absorbed and the drier waste material is compacted into feces it is stored until it is excreted through the rectum.

Avian

Birds face special challenges when it comes to obtaining nutrition from food. They do not have teeth and so their digestive system, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_06">Figure 25.7, must be able to process un-masticated food. Birds have evolved a variety of beak types that reflect the vast variety in their diet, ranging from seeds and insects to fruits and nuts. Because most birds fly, their metabolic rates are high in order to efficiently process food and keep their body weight low. The stomach of birds has two chambers: the proventriculus, where gastric juices are produced to digest the food before it enters the stomach, and the gizzard, where the food is stored, soaked, and mechanically ground. The undigested material forms food pellets that are sometimes regurgitated. Most of the chemical digestion and absorption happens in the intestine and the waste is excreted through the cloaca.

EVOLUTION CONNECTION

Avian Adaptations

Birds have a highly efficient, simplified digestive system. Recent fossil evidence has shown that the evolutionary divergence of birds from other land animals was characterized by streamlining and simplifying the digestive system. Unlike many other animals, birds do not have teeth to chew their food. In place of lips, they have sharp pointy beaks. The horny beak, lack of jaws, and the smaller tongue of the birds can be traced back to their dinosaur ancestors. The emergence of these changes seems to coincide with the inclusion of seeds in the bird diet. Seed-eating birds have beaks that are shaped for grabbing seeds and the two-compartment stomach allows for delegation of tasks. Since birds need to remain light in order to fly, their metabolic rates are very high, which means they digest their food very quickly and need to eat often. Contrast this with the ruminants, where the digestion of plant matter takes a very long time.

  1. a. Birds have smaller surfaces to lose heat than humans, so their metabolic rate must be higher.
    b. Birds need to eat greater amounts of food since they digest food quickly.
  2. a. Birds need to be light to fly, so they need to digest their food faster than humans.
    b. Birds need to eat greater amounts of food since they digest food quickly.
  3. a. Birds have smaller surfaces to lose heat than humans, so their metabolic rate must be higher.
    b. Birds need to eat often to maintain energy since they digest food quickly.
  4. a. Birds need to be light to fly, so they need to digest their food faster than humans.
    b. Birds need to eat often to maintain energy since they digest food quickly.

Ruminants

Ruminants are mainly herbivores like cows, sheep, and goats, whose entire diet consists of eating large amounts of roughage or fiber. They have evolved digestive systems that help them digest vast amounts of cellulose. An interesting feature of the ruminants’ mouth is that they do not have upper incisor teeth. They use their lower teeth, tongue and lips to tear and chew their food. From the mouth, the food travels to the esophagus and on to the stomach.

To help digest the large amount of plant material, the stomach of the ruminants is a multi-chambered organ, as illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_07">Figure 25.8. The four compartments of the stomach are called the rumen, reticulum, omasum, and abomasum. These chambers contain many microbes that break down cellulose and ferment ingested food. The abomasum is the “true” stomach and is the equivalent of the monogastric stomach chamber where gastric juices are secreted. The four-compartment gastric chamber provides larger space and the microbial support necessary to digest plant material in ruminants. The fermentation process produces large amounts of gas in the stomach chamber, which must be eliminated. As in other animals, the small intestine plays an important role in nutrient absorption, and the large intestine helps in the elimination of waste.

Pseudo-ruminants

Some animals, such as camels and alpacas, are pseudo-ruminants. They eat a lot of plant material and roughage. Digesting plant material is not easy because plant cell walls contain the polymeric sugar molecule cellulose. The digestive enzymes of these animals cannot break down cellulose, but microorganisms present in the digestive system can. Therefore, the digestive system must be able to handle large amounts of roughage and break down the cellulose. Pseudo-ruminants have a three-chamber stomach in the digestive system. However, their cecum—a pouched organ at the beginning of the large intestine containing many microorganisms that are necessary for the digestion of plant materials—is large and is the site where the roughage is fermented and digested. These animals do not have a rumen but have an omasum, abomasum, and reticulum.

Parts of the Digestive System

The vertebrate digestive system is designed to facilitate the transformation of food matter into the nutrient components that sustain organisms.

Oral Cavity

The oral cavity, or mouth, is the point of entry of food into the digestive system, illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_08">Figure 25.9. The food consumed is broken into smaller particles by mastication, the chewing action of the teeth. All mammals have teeth and can chew their food.

The extensive chemical process of digestion begins in the mouth. As food is being chewed, saliva, produced by the salivary glands, mixes with the food. Saliva is a watery substance produced in the mouths of many animals. There are three major glands that secrete saliva—the parotid, the submandibular, and the sublingual. Saliva contains mucus that moistens food and buffers the pH of the food. Saliva also contains immunoglobulins and lysozymes, which have antibacterial action to reduce tooth decay by inhibiting growth of some bacteria. Saliva also contains an enzyme called salivary amylase that begins the process of converting starches in the food into a disaccharide called maltose. Another enzyme called lipase is produced by the cells in the tongue. Lipases are a class of enzymes that can break down triglycerides. The lingual lipase begins the breakdown of fat components in the food. The chewing and wetting action provided by the teeth and saliva prepare the food into a mass called the bolus for swallowing. The tongue helps in swallowing—moving the bolus from the mouth into the pharynx. The pharynx opens to two passageways: the trachea, which leads to the lungs, and the esophagus, which leads to the stomach. The trachea has an opening called the glottis, which is covered by a cartilaginous flap called the epiglottis. When swallowing, the epiglottis closes the glottis and food passes into the esophagus and not the trachea. This arrangement allows food to be kept out of the trachea.

Esophagus

The esophagus is a tubular organ that connects the mouth to the stomach. The chewed and softened food passes through the esophagus after being swallowed. The smooth muscles of the esophagus undergo a series of wave like movements called peristalsisthat push the food toward the stomach, as illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_09">Figure 25.10. The peristalsis wave is unidirectional—it moves food from the mouth to the stomach, and reverse movement is not possible. The peristaltic movement of the esophagus is an involuntary reflex it takes place in response to the act of swallowing.

A ring-like muscle called a sphincter forms valves in the digestive system. The gastro-esophageal sphincter is located at the stomach end of the esophagus. In response to swallowing and the pressure exerted by the bolus of food, this sphincter opens, and the bolus enters the stomach. When there is no swallowing action, this sphincter is shut and prevents the contents of the stomach from traveling up the esophagus. Many animals have a true sphincter however, in humans, there is no true sphincter, but the esophagus remains closed when there is no swallowing action. Acid reflux or “heartburn” occurs when the acidic digestive juices escape into the esophagus.

Stomach

A large part of digestion occurs in the stomach, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_10">Figure 25.11. The stomach is a saclike organ that secretes gastric digestive juices. The pH in the stomach is between 1.5 and 2.5. This highly acidic environment is required for the chemical breakdown of food and the extraction of nutrients. When empty, the stomach is a rather small organ however, it can expand to up to 20 times its resting size when filled with food. This characteristic is particularly useful for animals that need to eat when food is available.

VISUAL CONNECTION

  1. Bile is a mixture of food and digestive juices that is produced in the stomach.
  2. Food enters the large intestine before the small intestine.
  3. In the small intestine, chyme mixes with bile, which emulsifies fats.
  4. The large intestines are separated from the small intestines by the pyloric sphincter.

The stomach is the major site for protein digestion in animals other than ruminants. Protein digestion is mediated by an enzyme called pepsin in the stomach chamber. Pepsin is secreted by the chief cells in the stomach in an inactive form called pepsinogen. Pepsin breaks peptide bonds and cleaves proteins into smaller polypeptides it also helps activate more pepsinogen, starting a positive feedback mechanism that generates more pepsin. Another cell type—parietal cells—secretes hydrogen and chloride ions, which combine in the lumen to form hydrochloric acid, the primary acidic component of the stomach juices. Hydrochloric acid helps to convert the inactive pepsinogen to pepsin. The highly acidic environment also kills many microorganisms in the food and, combined with the action of the enzyme pepsin, results in the hydrolysis of protein in the food. Chemical digestion is facilitated by the churning action of the stomach. Contraction and relaxation of smooth muscles mixes the stomach contents about every 20 minutes. The partially digested food and gastric juice mixture is called chyme. Chyme passes from the stomach to the small intestine. Further protein digestion takes place in the small intestine. Gastric emptying occurs within two to six hours after a meal. Only a small amount of chyme is released into the small intestine at a time. The movement of chyme from the stomach into the small intestine is regulated by the pyloric sphincter.

When digesting protein and some fats, the stomach lining must be protected from getting digested by pepsin. There are two points to consider when describing how the stomach lining is protected. First, as previously mentioned, the enzyme pepsin is synthesized in the inactive form. This protects the chief cells, because pepsinogen does not have the same enzyme functionality of pepsin. Second, the stomach has a thick mucus lining that protects the underlying tissue from the action of the digestive juices. When this mucus lining is ruptured, ulcers can form in the stomach. Ulcers are open wounds in or on an organ caused by bacteria (Helicobacter pylori) when the mucus lining is ruptured and fails to reform.

Small Intestine

Chyme moves from the stomach to the small intestine. The small intestine is the organ where the digestion of protein, fats, and carbohydrates is completed. The small intestine is a long tube-like organ with a highly folded surface containing finger-like projections called the villi. The apical surface of each villus has many microscopic projections called microvilli. These structures, illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_11">Figure 25.12, are lined with epithelial cells on the luminal side and allow for the nutrients to be absorbed from the digested food and absorbed into the blood stream on the other side. The villi and microvilli, with their many folds, increase the surface area of the intestine and increase absorption efficiency of the nutrients. Absorbed nutrients in the blood are carried into the hepatic portal vein, which leads to the liver. There, the liver regulates the distribution of nutrients to the rest of the body and removes toxic substances, including drugs, alcohol, and some pathogens.

VISUAL CONNECTION

  1. Absorptive cells that line the small intestine have small projections that increase surface area and aid in the absorption of food.
  2. The outside of the small intestine has many folds, called villi.
  3. Microvilli are lined with blood vessels as well as lymphatic vessels.
  4. The inside of the small intestine is called the lymphatic vessel.

The human small intestine is over 6m long and is divided into three parts: the duodenum, the jejunum, and the ileum. The “C-shaped,” fixed part of the small intestine is called the duodenum and is shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_10">Figure 25.11. The duodenum is separated from the stomach by the pyloric sphincter which opens to allow chyme to move from the stomach to the duodenum. In the duodenum, chyme is mixed with pancreatic juices in an alkaline solution rich in bicarbonate that neutralizes the acidity of chyme and acts as a buffer. Pancreatic juices also contain several digestive enzymes. Digestive juices from the pancreas, liver, and gallbladder, as well as from gland cells of the intestinal wall itself, enter the duodenum. Bile is produced in the liver and stored and concentrated in the gallbladder. Bile contains bile salts which emulsify lipids while the pancreas produces enzymes that catabolize starches, disaccharides, proteins, and fats. These digestive juices break down the food particles in the chyme into glucose, triglycerides, and amino acids. Some chemical digestion of food takes place in the duodenum. Absorption of fatty acids also takes place in the duodenum.

The second part of the small intestine is called the jejunum, shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_10">Figure 25.11. Here, hydrolysis of nutrients is continued while most of the carbohydrates and amino acids are absorbed through the intestinal lining. The bulk of chemical digestion and nutrient absorption occurs in the jejunum.

The ileum, also illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#CNX_AP_Bio_34_01_10">Figure 25.11 is the last part of the small intestine and here the bile salts and vitamins are absorbed into blood stream. The undigested food is sent to the colon from the ileum via peristaltic movements of the muscle. The ileum ends and the large intestine begins at the ileocecal valve. The vermiform, “worm-like,” appendix is located at the ileocecal valve. The appendix of humans secretes no enzymes and has an insignificant role in immunity.

EVERYDAY CONNECTION FOR AP® COURSES

  1. Microvilli form the inner layer of epithelial tissue in the small intestine and increase the absorption of nutrients from chyme.
  2. Microvilli are projections of absorptive cells that are involved in the absorption of bile salts and vitamin B12.
  3. Microvilli increase the surface area of absorptive cells, and therefore increase the amount of nutrients that can be absorbed.
  4. Microvilli use smooth muscle contractions to move the chyme, which contains nutrients, thereby increasing the rate of absorption.

Large Intestine

The large intestine, illustrated in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_12">Figure 25.14, reabsorbs the water from the undigested food material and processes the waste material. The human large intestine is much smaller in length compared to the small intestine but larger in diameter. It has three parts: the cecum, the colon, and the rectum. The cecum joins the ileum to the colon and is the receiving pouch for the waste matter. The colon is home to many bacteria or “intestinal flora” that aid in the digestive processes. The colon can be divided into four regions, the ascending colon, the transverse colon, the descending colon and the sigmoid colon. The main functions of the colon are to extract the water and mineral salts from undigested food, and to store waste material. Carnivorous mammals have a shorter large intestine compared to herbivorous mammals due to their diet.

Rectum and Anus

The rectum is the terminal end of the large intestine, as shown in //cnx.org/contents/ This email address is being protected from spambots. You need JavaScript enabled to view it. :[email protected]/25-1-Digestive-Systems#fig-ch34_01_12">Figure 25.14. The primary role of the rectum is to store the feces until defecation. The feces are propelled using peristaltic movements during elimination. The anus is an opening at the far-end of the digestive tract and is the exit point for the waste material. Two sphincters between the rectum and anus control elimination: the inner sphincter is involuntary and the outer sphincter is voluntary.

Accessory Organs

The organs discussed above are the organs of the digestive tract through which food passes. Accessory organs are organs that add secretions (enzymes) that catabolize food into nutrients. Accessory organs include salivary glands, the liver, the pancreas, and the gallbladder. The liver, pancreas, and gallbladder are regulated by hormones in response to the food consumed.

The liver is the largest internal organ in humans and it plays a very important role in digestion of fats and detoxifying blood. The liver produces bile, a digestive juice that is required for the breakdown of fatty components of the food in the duodenum. The liver also processes the vitamins and fats and synthesizes many plasma proteins.

The pancreas is another important gland that secretes digestive juices. The chyme produced from the stomach is highly acidic in nature the pancreatic juices contain high levels of bicarbonate, an alkali that neutralizes the acidic chyme. Additionally, the pancreatic juices contain a large variety of enzymes that are required for the digestion of protein and carbohydrates.

The gallbladder is a small organ that aids the liver by storing bile and concentrating bile salts. When chyme containing fatty acids enters the duodenum, the bile is secreted from the gallbladder into the duodenum.

SCIENCE PRACTICE CONNECTION FOR AP® COURSES

ACTIVITY

Create a mini-poster that shows the procurement, digestion, absorption, and distribution of nutrients through the digestive systems of one invertebrate animal and one vertebrate animal. Explain how the organs of the system promote efficiency in the use of matter and energy.

THINK ABOUT IT

Explain how the villi and microvilli aid in absorption of nutrients from the small intestine into the circulatory system.


25.1: Anatomy of the Circulatory and Lymphatic Systems - Biology

Chapter 45-Skeletal , Muscular , and Integumentary Systems

Section 45-1 Human Body Plan

1. What are the different types of human tissue?

2. What is the hierarchal order from cells?

3. What are the major structures in the systems of human body?

5. How do the organ systems function together in the human body?

Section 45-2 Skeletal System

1. Know the names and location of the major bones of the body.

2. What are the five functions of bones?

3. What are the major types of joints and what is an example of each?

4. What is the general structure of long bone?

5. What is the function of bone marrow?

6. What is the function of ligaments?

7. What is the function of synovial fluid?

Section 45-3 Muscular System

1. Know the names and location of the major muscles of the body.

2. What do myofibrils, myosin, actin,Z line, sarcomere have to do with contraction of a muscle?

3. What is the function of tendons?

4. What is meant by origin and insertion of a muscle?

5. What is meant by flexor and extensor?

6. What causes muscles to be fatigued?

Section 45-4 Integumentary System

1. Know the location and names of the parts of our skin.

2. What are the functions of our skin?

3. What glands are located in our skin and what are their functions?

Chapter 46 Circulatory and Respiratory Systems

Section 46-1 Circulatory System

1. Know the names and location of the parts of the human heart.

2. Know the flow of blood through the human heart.

3. How is the heart stimulated to contract?

4. What is meant by the diastole and systole?

5. What are the blood vessels of the body and how do their structures differ?

6. What is the difference between pulmonary and systemic circulation?

7. What is the function of the lymphatic system?

1. What are the main components of blood.

2. What are the functions of those main components of blood?

3. What are the main blood types?

4. Know what blood types are compatible when getting a transfusion?

5. What is the universal recipient and universal donor types?

6. What would happen if a Rh- person received Rh+ blood ?

Section 46-3 Respiratory System

1. Know the names and location of the parts of our respiratory system.

2. What is the difference between external and internal respiration?

3. What is the path that air will take as we inhale?

4. Explain the process of gas exchange in the lungs.

5. Differentiate between oxygen transport and carbon dioxide transport in the bloodstream.

6. What factors regulate the rate of breathing?

7. Describe the movement of the diaphragm and the rib muscles during inspiration and expiration.

Chapter 48 Digestive and Excretory Systems

1. What is the major role of each of the organic nutrients in the body?

2. What are the six basic nutrients?

3. What is the role of minerals in maintaining a healthy body?

4. What is the importance of water in our diet?

Section 48-2 Digestive System

1. Know the name and location of the parts of the digestive system.

2. What are the processes involved with mechanical digestion?

3. What is the sequence of organs that are involved in each step of digestion?

Section 48-3 Urinary System

1. Know the names and location of the parts of the urinary system.

2. How does the structure of a nephron relate to its function?

3. Be able to describe 3 processes carried out in the kidney that help maintain homeostasis.

Final Exam will have 110 questions.The first part will have some multiple choice , matching and identification of skeletal structure, muscular structure, parts of the heart, parts of the skin,parts of the respiratory and digestive system.The last part will have essay questions dealing with topic such as function of skeletal system, function of skin. types of joints, sequence blood flow, how to use AED, sequence flow of oxygen in respiratory system. There will also be a few questions dealing with some basic first aid. The total point of final will be 200.

Assignments Week of April 29-May3, 2019.4/29-Finish EKG website. Assign-Handout Go with the Flow. 4/30-Review HMWK. Blood Vessels. Assign-Arteries/Veins Hdt and Lymphatic System Handout. 5/1-Review HMWK. Assign-Circulatory Disorder Ppts. 5/2-Present C.Disorder Ppts. Assign-Handout 75/76. 5/3-Finish C.Disorders Assign-Circulatory Review Handout and Section Review. Review/Quiz on Monday.

Assignments Week of April 22-26, 2019. 4/23-Finish Integumentary Ppts. Fingerprint Lab. Assign-45-4 Review Handout and Section Review. 4/24-Review HMWK. Quiz 45-4. Assign-Power point 46-1. 4/25-Review Circulatory System Assign-Sketch/label both 46-1 and 46-2. 4/26-Discuss 933-34. Assign-Go with Flow 172 Handout.

Assignments Week of April 1-5,2019. 4/1-Workout PPts Assign-Muscle Injury Ppts. 4/2-ACT 4/3-Workouts and MUscle Injury Ppts. Assign-Hdt. pgs. 23/26 4/4-Muscle Injury Ppts. Review HMWK. Muscle Fatigue Lab Assign-Hdt.22/25. 4/5-Review HMWK. Muscle Injury PPts Assign-45-3 Review Handout and section review. Review/Quiz Monday.

Assignments Week of March 25-29,2019. 3/25-Scans Muscles contractions and Stimuli Lab. 3/26-Finish Stimuli Lab Joint critique. 3/27-Joint critique, Origin and insertion handout and Workout power point. 3/28-Joint critique,Present workouts power points and review origin/insertion handouts. 2/29-Muscle ID quiz, Workouts, Assign-Work those Muscles.

Assignments Week of March18-22, 2019. 3/18-Skeletal Injury Ppts. Review Head/Brain Handouts. Assign-Vertebrae Handout. 3/19-Review HMWK. Skeletal Injury Ppts. Assign-Arms/Leg Handouts. 3/20-Review HMWK. Finish 45-2 discussion Assign-45-2 Review Handout and section Review. Quiz over 45-2 tomorrow. 3/21-Review HMWK. Quiz 45-2 Assign-Sketch fig. 45-9 Posterior and Anterior. 3/22- Muscles add to skeleton and Muscle Handout-label the muscles.

Assignments Week of March 11-15. 3/11-Review 45-1 HMWK/Handout & section review. Quiz 45-1. Assign-Sketch of skeleton use pg 911 and label. 3/12-Build larger skeleton with cut-outs. Assign-Power point 45-2. 3/13-Discuss pgs 911-914. Assign-Handout of Bone Structure pgs 15/86. 3/14-Review HMWK. Quiz Parts of Skeleton. Assign-Skeletal Injuries power point/Present tomorrow. 3/15-Present Injury Ppts. Assign-Handouts Id. Head/Brain pgs. 17/60 and 16/73.

Assignments Week of Feb.18-22, 2019. 2/19-Review 46-3 Review Hdt. and take 46-3 quiz. Assign-sketch Digestive System and label parts. 2/20-Make large model of Digestive System and Functions of each part.Assign-Digestive Handout. 2/21-Review HMWK. Ppts on Digestive Disorders and Digestive Handouts. 2/22-Begin PPts. Digestive Disorders Assign-Digestive System Review Handout and section review.

Assignments Week of Feb.11-14,2019. 2/11-Finish Powerpoints C.System Disorders. Review 46-1 Review and Section Handout. Quiz 46-1. Assign-46-2 Blood Power points. 2/12-Discuss Blood. Assign-46-2 R.Hdt. , Section Review and Blood Handout. Blood Quiz tomorrow. 2/13- Review Blood Handouts Quiz over Blood Info. Assign-46-3 Respiratory System Power point. 2/14- Discuss Respiratory System, Respiratory Lab and Respiratory System Handouts.

Assignments Week of Feb.4-8, 2019. 2/4-Discuss pg. 933-934 Assign-Go with the Flow 1 and 2. 2/5-Review HMWK. Pulse Lab. Assign-Hdt.pgs 75-76. 2/6-Review Hdt. Blood Vessels Assign-Lymphatic System Hdt.2/7- Review HMWK. Assign-C.Disorders Ppt. 2/8-Circulatory Disorders Presentations.

Assignments Week of January 28-February 1,2019.1/28-Present Ppts. Assign-Fingerprint Handout 1/29-Present Ppts. Assign-Integumentary System lab on line. 1/30-Pinish Ppts. Review Lab Assign-45-4 Review Handout and section review. 1/31-Review HMWK. Quiz 45-4 Assign-46-1 Power point. Review 46-1 info. Assign-sketch and label figures 46-1 and 46-2

Online Assignments for January 30/31,2019-work on the online lab, 45-4 Review Handout and section review. Also work on putting together a power point for 46-1 Circulatory System. We will have a review on 45-4 and take a Quiz over that information Friday. Stay Warm!

Online assignment for January 25,2019-work on finishing your powerpoint on integumentary system disorder. Those of you whose partner was absent e-mail them and let them know about the assignment so they can help.Looks like we will start on Monday! God Bless-Be Safe

Assignments Week of 1/21/19-1/22-Review HMWK 88/92 handout,Assign-skin lesion handout and handout pgs. 90/94 1/23-Review HMWK. Assign-Integumentary disorder Power point. 1/24-Present Power points Assign- Handout finger prints 1/25-Present Power points Assign-online lab

Assignments Week of 1/14/19-1/14-Review muscle connections and muscle fatigue. muscle fatigue lab Power points muscle injury. 1/15-Review muscle fatigue lab, power point muscle injury. 1/16-Finish muscle injury Ppts. Assign-45-3 Review Hdt. and section review pg. 922 1-10. 1/17-Review HMWK. Quiz 45-3 muscles Assign-Ppt.45-4 Integumentary System. 1/18-Discuss 445-4. Assign-sketch figs. 45-15/45-17 along with handout 88/92.

Assignments Week of Dec. 10-14,2018. 12/10-Review HMWK. Scans Injury Presentations Assign-ID Legs and Arms Hdt. 12/11-Review HMWK. Discuss 914 Injury Presentations Assign-Skeleton Hdt. 12/12-Review HMWK. Joint discuss Finish Injury Presentations?? Assign- Skeleton Handout. 12/13-Review HMWK. Assign-45-2 Review Handout and section review pg.916 #'s 1-9. 12/14 Review HMWK. Quiz 45-2 Assign-Sketch figure 45-9 Anterior and Posterior.

Assignments Week of Dec.3-7,2018. 12/3-Build large Skeleton/label Quiz over Skeleton 12/5 Skeleton Hdt. Assign-Ppt45-2 124-Discuss pgs.911-914 Assign-Structure of Bone Hdt. and Ppt. Injury. 12/5-Quiz-Skeleton Present Ppt. on Injury Assign-Handouts on Cranium/Brain Ears/Eyes. 12/6- Review HMWK.Present Ppt.Injury Assign-Vertebrae Handouts. 12/7-Review HMWK. Finish Injury Ppts. Assign-Arms/Legs Handouts.

Assignments Week of November 26-30, 2018. 11/26-Snow Day 11/27-Website,Questionaire,Assign- Powerpoint 45-1. 11/28-First Aid Kit,Review 45-1 Info. Assign-Handout pgs. 6/7. 11/19-Review HMWK. Shock? Assign-Review Handout 45-1 and section review pg. 910#'s 1-8. 11/30-Review HMWK. Good Samaritan Laws Quiz 45-1. Assign-sketch skeleton pg. 911 and label the bones.


Lymphoid organs

The lymphatic system is commonly divided into the primary lymphoid organs, which are the sites of B and T cell maturation, and the secondary lymphoid organs, in which further differentiation of lymphocytes occurs. Primary lymphoid organs include the thymus, bone marrow, fetal liver, and, in birds, a structure called the bursa of Fabricius. In humans the thymus and bone marrow are the key players in immune function. All lymphocytes derive from stem cells in the bone marrow. Stem cells destined to become B lymphocytes remain in the bone marrow as they mature, while prospective T cells migrate to the thymus to undergo further growth. Mature B and T lymphocytes exit the primary lymphoid organs and are transported via the bloodstream to the secondary lymphoid organs, where they become activated by contact with foreign materials, such as particulate matter and infectious agents, called antigens in this context.


New To This Edition

  • Improved accessibility standards: The new edition has designed with accessibility in mind regarding font size, color, and other accessibility standards,
  • Signature homeostatic feedback cycle illustrations: Many have been refined and several have been added to Chapter 18.
  • Clinical Connections: These well-received and timely features provide students with clinical, professional, and everyday relevance of anatomy and physiology. Each Clinical Connection directly follows the discussion to which it relates. This edition contains numerous new and updated Clinical Connections, many of which are now illustrated, dealing with topics such as tracheostomy, endotracheal intubations, and ventilators.
  • Focus on Homeostasis. Each full-page summary following a chapter or several chapters for each body system has been redesigned for this edition to help students better understand how each body system contributes to homeostasis by itself and through its interactions with other body systems.
  • Updated Terminology: The 16 th edition has been updated with the most current anatomical, histological, and cytological terminology. Virtually all eponyms have been eliminated and replaced with current terminology.

Lymphatic System

The lymphatic system plays a vital role as one of the organ systems of the body. This system functions with the digestive system to absorb dietary lipids , which enter lymphatic vessels rather than blood vessels for transport. It also acts with the cardiovascular system to control the body's fluid balance. This is accomplished by a series of interconnected thin-walled lymphatic vessels that permeate the body's tissues that collect substances lost through the walls of capillaries. These lymphatic vessels drain into lymphatic trunks and then into veins.

If lymphatic drainage is temporarily or permanently blocked, the buildup of interstitial fluid creates a condition called lymphedema. In tropical areas of the world, a mosquito-borne roundworm can infect lymph nodes, blocking lymphatic drainage and thereby creating a condition called elephantiasis.

The lymphatic system also plays a vital role in immunity by providing a defensive network against pathogens . Multiple lymphatic organs, all with specialized functions, work together for this purpose. Lymph flowing along the lymphatic vessels passes periodically through lymph nodes, primarily in the neck, armpit, and groin regions. The nodes contain lymphocytes and macrophages that mount an immune response to any pathogen borne within this fluid. Lymphatic vessels also lead to lymph nodes near internal organs such as the heart, lungs, and alimentary canal (gut).

Lining the alimentary canal are collections of mucosa-associated lymphatic tissues (MALT) that form lymphatic nodules. Clusters of lymphatic nodules are also deep to the lining of the alimentary canal. These include Peyer patches of the ileum (lower small intestine) and appendix that guard the entry of pathogens into the internal environment. When the appendix becomes inflamed, appendicitis results.

Other lymphatic organs—the tonsils, thymus, and spleen𠅊lso play a critical role in immunity. The tonsils include the pharyngeal tonsil located in the rear of the nasopharynx, the palatine tonsils to the side of the tongue, and the lingual tonsils at the base of the tongue. Together, the tonsils form patches of lymphatic tissue that encircle the back of the oral and nasal cavities as a defense mechanism to detect pathogens before they enter the alimentary canal. If the tonsils become infected, a tonsillectomy may be necessary.

The thymus is found deep to the sternum (breastbone) and superficial to the pericardial sac surrounding the heart. The thymus contains lymphocytes that differentiate into T cells . These cells are vital to the proper function of the immune system.

Finally, the spleen is located in the left upper quadrant of the abdomen. It has several functions. Its red pulp stores erythrocytes (red blood cells) for use in cases of sudden blood loss, whereas the white pulp contains macrophages and other leukocytes (white blood cells) that break down old erythrocytes as they squeeze through splenic sinuses. Additionally, these leukocytes can mount an immune response and fight infections that enter this organ. As the spleen contains many vessels, it bleeds easily when ruptured. In such cases, removal of the spleen (splenectomy) may be required to prevent fatal hemorrhage.


The lymphatic system

The lymphatic system is also a network of vessels that run throughout the body ( [link] ). However, these vessels do not form a full circulating system and are not pressurized by the heart. Rather, the lymphatic system is an open system with the fluid moving in one direction from the extremities toward two drainage points into veins just above the heart. Lymphatic fluids move more slowly than blood because they are not pressurized. Small lymph capillaries interact with blood capillaries in the interstitial spaces in tissues. Fluids from the tissues enter the lymph capillaries and are drained away ( [link] ). These fluids, termed lymph , also contain large numbers of white blood cells.

The essential components of the human lymphatic system drain fluid away from tissues. Blood enters the capillaries from an arteriole (red) and leaves through venules (blue). Interstitial fluids may drain into the lymph capillaries (green) and proceed to lymph nodes. (credit: modification of work by National Cancer Institute, National Institutes of Health)

The lymphatic system contains two types of lymphoid tissues. The primary lymphoid tissue includes bone marrow and the thymus. Bone marrow contains the hematopoietic stem cells (HSC) that differentiate and mature into the various types of blood cells and lymphocytes (see [link] ). The secondary lymphoid tissue s include the spleen, lymph nodes, and several areas of diffuse lymphoid tissues underlying epithelial membranes. The spleen , an encapsulated structure, filters blood and captures pathogens and antigens that pass into it ( [link] ). The spleen contains specialized macrophages and dendritic cells that are crucial for antigen presentation, a mechanism critical for activation of T lymphocytes and B lymphocytes (see Major Histocompatibility Complexes and Antigen-Presenting Cells ). Lymph nodes are bean-shaped organs situated throughout the body. These structures contain areas called germinal centers that are rich in B and T lymphocytes. The lymph nodes also contain macrophages and dendritic cells for antigen presentation. Lymph from nearby tissues enters the lymph node through afferent lymphatic vessels and encounters these lymphocytes as it passes through the lymph exits the lymph node through the efferent lymphatic vessels ( [link] ).


34 Correctly Label The Following Anatomical Features Of The Lymph Node

Match the lymphatic trunk with the major body region that it drains. Vessels afferent vessel lymphatic efferent vein and artery sinus cord medullary artery and vein efferent lymphatic vessel afferent lymphatic vessels medullary cord medullary cord medullary sinus medulla artery and vein medullary.

Automatic Identification Of Iaslc Defined Mediastinal Lymph Node

There are neurolemmocytes or oligodendrocytes in unmyelinated areas of the neuron.

Correctly label the following anatomical features of the lymph node. During inspiration thoracic cavity volume increases. Answer to correctly label the following lymphatics of the thoracic cavity. Correctly label the following anatomical features of the lymph node.

Skip navigation chegg home. Answer to 3 correctly label the following anatomical features of the lymph node efterent lymphatic vessel ebook germinal center co. Left internal jugular vein right lymphatic duct lymphat.

As the lungs expand while breathing the pressure in the lungs decreases. Correctly label the following anatomical features of the lymph node. External respiration involves the exchange of gases between the atmosphere and the blood.

Answer to help save exit submit 6 correctly label the following anatomical features of the thymus left lobe ebook lobule copyrig. Correctly label the following meninges of the brain. Correctly label the following anatomical features of fluid exchange between lymphatic and circulatory systems superior vena cava ook arteries systemic capillaries lymphatic capillaries collecting duct lymphatic trunks lymph flow lymph nodes collecting vessels subclavian vein.

Correctly label the following anatomical features of a neuron. Which of the following is not found in high concentration outside. Some neurons are specialized to detect stimuli whereas neurons send signals to the effectors of the nervous system.

There are neurolemmocytes or oligodendrocytes at a node of ranvier. Adjust credit for all students. Label the structures of the spleen.

Correctly label the following anatomical features of the surface of the brain. Nodes of ranvier are gaps found in the plasma membrane of neurolemmocytes and oligodendrocytes. Correctly label the following anatomical features of the lymph node.

Correctly label the following parts of the brainstem.

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Life Span of Lake

Like other objects, lakes change over time. Even a human-like, lake has a lifespan such as immature lakes, middle-aged lakes and ancient lakes. Many lakes in British Columbia are still completely immature as they were formed during the last ice age. Many lakes are slowly shrinking. The lake gradually shrinks as there is natural land on the shores of the lake. Every year leaves fall from trees and shrubs on the shores of the lake and accumulate at the bottom of the lake. The debris of this herb gradually decomposes to create new habitats for grasses and hogla plants.

Grasses spread their roots quickly and create stable new fields for dry land species. In places where water lilies grow once, sometimes shrubs and small plants grow. If the lake is too small, it will not be able to provide enough oxygen and food for some fish. However, this happens so slowly that the fish have enough time to move to another lake. In this case, the lakes are connected to other lakes by small water flows. Succession of organisms did not occur in all types of lakes. In the case of steep and rocky arrows, the fish cannot crawl to the top in a short time.


Watch the video: Herz und Blutkreislauf - Zusammenschnitt von Volle Leistung für das Herz (August 2022).