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The immune system is a collection of barriers, cells, and soluble proteins that interact and communicate with each other in extraordinarily complex ways. The modern model of immune function is organized into three phases based on the timing of their effects. The three temporal phases consist of the following:
- • **B... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**The Organization of Immune Function**",
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In the embryo, blood cells are made in the yolk sac. As development proceeds, this function is taken over by the spleen, lymph nodes, and liver. Later, the bone marrow takes over most hematopoietic functions, although the final stages of the differentiation of some cells may take place in other organs. The red **bone m... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Bone Marrow**",
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The **thymus** gland is a bilobed organ found in the space between the sternum and the aorta of the heart (**[Figure 21.7](#page-940-1)**). Connective tissue holds the lobes closely together but also separates them and forms a capsule.
**Figure 21.7 Location, Structure, and Histology of... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Thymus**",
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By the year 2050, 25 percent of the population of the United States will be 60 years of age or older. The CDC estimates that 80 percent of those 60 years and older have one or more chronic disease associated with deficiencies of the immune systems. This loss of immune function with age is called immunosenescence. To tr... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Immune System**",
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Lymphocytes develop and mature in the primary lymphoid organs, but they mount immune responses from the **secondary lymphoid organs**. A **naïve lymphocyte** is one that has left the primary organ and entered a secondary lymphoid organ. Naïve lymphocytes are fully functional immunologically, but have yet to encounter a... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Secondary Lymphoid Organs and their Roles in Active Immune Responses**",
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Lymph nodes function to remove debris and pathogens from the lymph, and are thus sometimes referred to as the "filters of the lymph" (**[Figure 21.8](#page-942-0)**). Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node. Dendritic cells and m... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Lymph Nodes**",
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In addition to the lymph nodes, the **spleen** is a major secondary lymphoid organ (**[Figure 21.9](#page-943-0)**). It is about 12 cm (5 in) long and is attached to the lateral border of the stomach via the gastrosplenic ligament. The spleen is a fragile organ without a strong capsule, and is dark red due to its exten... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Spleen**",
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The other lymphoid tissues, the **lymphoid nodules**, have a simpler architecture than the spleen and lymph nodes in that they consist of a dense cluster of lymphocytes without a surrounding fibrous capsule. These nodules are located in the respiratory and digestive tracts, areas routinely exposed to environmental path... | {
"Header 1": "**21.1 | Anatomy of the Lymphatic and Immune Systems**",
"Header 3": "**Lymphoid Nodules**",
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By the end of this section, you will be able to:
- Describe the barrier defenses of the body
- Show how the innate immune response is important and how it helps guide and prepare the body for adaptive immune responses
- Describe various soluble factors that are part of the innate immune response
- Explain the steps o... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
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Many of the cells of the immune system have a phagocytic ability, at least at some point during their life cycles. Phagocytosis is an important and effective mechanism of destroying pathogens during innate immune responses. The phagocyte takes the organism inside itself as a phagosome, which subsequently fuses with a l... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Phagocytes: Macrophages and Neutrophils**",
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NK cells are a type of lymphocyte that have the ability to induce apoptosis, that is, programmed cell death, in cells infected with intracellular pathogens such as obligate intracellular bacteria and viruses. NK cells recognize these cells by mechanisms that are still not well understood, but that presumably involve th... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Natural Killer Cells**",
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Cells of the innate immune response, the phagocytic cells, and the cytotoxic NK cells recognize patterns of pathogenspecific molecules, such as bacterial cell wall components or bacterial flagellar proteins, using pattern recognition receptors. A **pattern recognition receptor (PRR)** is a membrane-bound receptor that ... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Recognition of Pathogens**",
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A **cytokine** is signaling molecule that allows cells to communicate with each other over short distances. Cytokines are secreted into the intercellular space, and the action of the cytokine induces the receiving cell to change its physiology. A **chemokine** is a soluble chemical mediator similar to cytokines except ... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Cytokines and Chemokines**",
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Early induced proteins are those that are not constitutively present in the body, but are made as they are needed early during the innate immune response. **Interferons** are an example of early induced proteins. Cells infected with viruses secrete interferons that travel to adjacent cells and induce them to make antiv... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Early induced Proteins**",
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The **complement** system is a series of proteins constitutively found in the blood plasma. As such, these proteins are not considered part of the **early induced immune response**, even though they share features with some of the antibacterial proteins of this class. Made in the liver, they have a variety of functions... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Complement System**",
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The hallmark of the innate immune response is **inflammation**. Inflammation is something everyone has experienced. Stub a toe, cut a finger, or do any activity that causes tissue damage and inflammation will result, with its four characteristics: heat, redness, pain, and swelling ("loss of function" is sometimes menti... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Inflammatory Response**",
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This reaction also brings in the cells of the innate immune system, allowing them to get rid of the sources of a possible infection. Inflammation is part of a very basic form of immune response. The process not only brings fluid and cells into the site to destroy the pathogen and remove it and debris from the site, but... | {
"Header 1": "**21.2 | Barrier Defenses and the Innate Immune Response**",
"Header 3": "**Figure 21.14**",
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The primary cells that control the adaptive immune response are the lymphocytes, the T and B cells. T cells are particularly important, as they not only control a multitude of immune responses directly, but also control B cell immune responses in many cases as well. Thus, many of the decisions about how to attack a pat... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**T Cell-Mediated Immune Responses**",
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Antigens on pathogens are usually large and complex, and consist of many antigenic determinants. An **antigenic determinant** (epitope) is one of the small regions within an antigen to which a receptor can bind, and antigenic determinants are limited by the size of the receptor itself. They usually consist of six or fe... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Antigens**",
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Although **[Figure 21.16](#page-954-0)** shows T cell receptors interacting with antigenic determinants directly, the mechanism that T cells use to recognize antigens is, in reality, much more complex. T cells do not recognize free-floating or cell-bound antigens as they appear on the surface of the pathogen. They only... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Antigen Processing and Presentation**",
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Two distinct types of MHC molecules, **MHC class I** and **MHC class II**, play roles in antigen presentation. Although produced from different genes, they both have similar functions. They bring processed antigen to the surface of the cell via a transport vesicle and present the antigen to the T cell and its receptor.... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Figure 21.17 Antigen Processing and Presentation**",
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Many cell types express class I molecules for the presentation of intracellular antigens. These MHC molecules may then stimulate a cytotoxic T cell immune response, eventually destroying the cell and the pathogen within. This is especially important when it comes to the most common class of intracellular pathogens, the... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Professional Antigen-presenting Cells**",
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The process of eliminating T cells that might attack the cells of one's own body is referred to as **T cell tolerance**. While thymocytes are in the cortex of the thymus, they are referred to as "double negatives," meaning that they do not bear the CD4 or CD8 molecules that you can use to follow their pathways of diffe... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**T Cell Development and Differentiation**",
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Mature T cells become activated by recognizing processed foreign antigen in association with a self-MHC molecule and begin dividing rapidly by mitosis. This proliferation of T cells is called **clonal expansion** and is necessary to make the immune response strong enough to effectively control a pathogen. How does the ... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Mechanisms of T Cell-mediated Immune Responses**",
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The clonal selection theory was proposed by Frank Burnet in the 1950s. However, the term clonal selection is not a complete description of the theory, as clonal expansion goes hand in glove with the selection process. The main tenet of the theory is that a typical individual has a multitude (1011) of different types of... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Clonal Selection and Expansion**",
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In the discussion of T cell development, you saw that mature T cells express either the CD4 marker or the CD8 marker, but not both. These markers are cell adhesion molecules that keep the T cell in close contact with the antigen-presenting cell by directly binding to the MHC molecule (to a different part of the molecul... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**T Cell Types and their Functions**",
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**Regulatory T cells (Treg)**, or suppressor T cells, are the most recently discovered of the types listed here, so less is understood about them. In addition to CD4, they bear the molecules CD25 and FOXP3. Exactly how they function is still under investigation, but it is known that they suppress other T cell immune re... | {
"Header 1": "**21.3 | The Adaptive Immune Response: T lymphocytes and Their Functional Types**",
"Header 3": "**Regulatory T Cells**",
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By the end of this section, you will be able to:
- Explain how B cells mature and how B cell tolerance develops
- Discuss how B cells are activated and differentiate into plasma cells
- Describe the structure of the antibody classes and their functions
Antibodies were the first component of the adaptive immune resp... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
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B cells differentiate in the bone marrow. During the process of maturation, up to 100 trillion different clones of B cells are generated, which is similar to the diversity of antigen receptors seen in T cells.
B cell differentiation and the development of tolerance are not quite as well understood as it is in T cells... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**B Cell Differentiation and Activation**",
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All antibody molecules have two identical heavy chains and two identical light chains. (Some antibodies contain multiple units of this four-chain structure.) The **Fc region** of the antibody is formed by the two heavy chains coming together, usually linked by disulfide bonds (**[Figure 21.21](#page-961-0)**). The Fc p... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**Four-chain Models of Antibody Structures**",
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**IgM** consists of five four-chain structures (20 total chains with 10 identical antigen-binding sites) and is thus the largest of the antibody molecules. IgM is usually the first antibody made during a primary response. Its 10 antigen-binding sites and large shape allow it to bind well to many bacterial surfaces. It ... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**Figure 21.22 Five Classes of Antibodies**",
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Primary and secondary responses as they relate to T cells were discussed earlier. This section will look at these responses with B cells and antibody production. Because antibodies are easily obtained from blood samples, they are easy to follow and graph (**[Figure 21.24](#page-964-0)**). As you will see from the figur... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**Primary versus Secondary B Cell Responses**",
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Immunity to pathogens, and the ability to control pathogen growth so that damage to the tissues of the body is limited, can be acquired by (1) the active development of an immune response in the infected individual or (2) the passive transfer of immune components from an immune individual to a nonimmune one. Both activ... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**Active versus Passive Immunity**",
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As discussed previously, Th2 cells secrete cytokines that drive the production of antibodies in a B cell, responding to complex antigens such as those made by proteins. On the other hand, some antigens are T cell independent. A **T cellindependent antigen** usually is in the form of repeated carbohydrate moieties found... | {
"Header 1": "**21.4** The Adaptive Immune Response: B-lymphocytes and Antibodies",
"Header 3": "**T cell-dependent versus T cell-independent Antigens**",
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By the end of this section, you will be able to:
- Explain the development of immunological competence
- Describe the mucosal immune response
- Discuss immune responses against bacterial, viral, fungal, and animal pathogens
- Describe different ways pathogens evade immune responses
Now that you understand the devel... | {
"Header 1": "**21.5 | The Immune Response against Pathogens**",
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"Wash your hands!" Parents have been telling their children this for generations. Dirty hands can spread disease. But is it possible to get rid of enough pathogens that children will never get sick? Are children who avoid exposure to pathogens better off? The answers to both these questions appears to be no.
Antibact... | {
"Header 1": "**21.5 | The Immune Response against Pathogens**",
"Header 2": "**Disinfectants: Fighting the Good Fight?**",
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Mucosal tissues are major barriers to the entry of pathogens into the body. The IgA (and sometimes IgM) antibodies in mucus and other secretions can bind to the pathogen, and in the cases of many viruses and bacteria, neutralize them. **Neutralization** is the process of coating a pathogen with antibodies, making it ph... | {
"Header 1": "**21.5 | The Immune Response against Pathogens**",
"Header 2": "**Disinfectants: Fighting the Good Fight?**",
"Header 3": "**The Mucosal Immune Response**",
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The primary mechanisms against viruses are NK cells, interferons, and cytotoxic T cells. Antibodies are effective against viruses mostly during protection, where an immune individual can neutralize them based on a previous exposure. Antibodies have no effect on viruses or other intracellular pathogens once they enter t... | {
"Header 1": "**21.5 | The Immune Response against Pathogens**",
"Header 2": "**Disinfectants: Fighting the Good Fight?**",
"Header 3": "**Defenses against Viruses**",
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It is important to keep in mind that although the immune system has evolved to be able to control many pathogens, pathogens themselves have evolved ways to evade the immune response. An example already mentioned is in *Mycobactrium tuberculosis*, which has evolved a complex cell wall that is resistant to the digestive ... | {
"Header 1": "**21.5 | The Immune Response against Pathogens**",
"Header 2": "**Disinfectants: Fighting the Good Fight?**",
"Header 3": "**Evasion of the Immune System by Pathogens**",
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A list of all inherited immunodeficiencies is well beyond the scope of this book. The list is almost as long as the list of cells, proteins, and signaling molecules of the immune system itself. Some deficiencies, such as those for complement, cause only a higher susceptibility to some Gram-negative bacteria. Others are... | {
"Header 1": "**21.6 | Diseases Associated with Depressed or Overactive Immune Responses**",
"Header 3": "**Inherited Immunodeficiencies**",
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Although many viruses cause suppression of the immune system, only one wipes it out completely, and that is the previously mentioned HIV. It is worth discussing the biology of this virus, which can lead to the well-known AIDS, so that its full effects on the immune system can be understood. The virus is transmitted thr... | {
"Header 1": "**21.6 | Diseases Associated with Depressed or Overactive Immune Responses**",
"Header 3": "**Human Immunodeficiency Virus/AIDS**",
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Antigens that cause allergic responses are often referred to as allergens. The specificity of the **immediate hypersensitivity** response is predicated on the binding of allergen-specific IgE to the mast cell surface. The process of producing allergenspecific IgE is called sensitization, and is a necessary prerequisite... | {
"Header 1": "**21.6 | Diseases Associated with Depressed or Overactive Immune Responses**",
"Header 3": "**Immediate (Type I) Hypersensitivity**",
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**Delayed hypersensitivity**, or type IV hypersensitivity, is basically a standard cellular immune response. In delayed hypersensitivity, the first exposure to an antigen is called **sensitization**, such that on re-exposure, a secondary cellular response results, secreting cytokines that recruit macrophages and other ... | {
"Header 1": "**21.6 | Diseases Associated with Depressed or Overactive Immune Responses**",
"Header 3": "**Delayed (Type IV) Hypersensitivity**",
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The worst cases of the immune system over-reacting are autoimmune diseases. Somehow, tolerance breaks down and the immune systems in individuals with these diseases begin to attack their own bodies, causing significant damage. The trigger for these diseases is, more often than not, unknown, and the treatments are usual... | {
"Header 1": "**21.6 | Diseases Associated with Depressed or Overactive Immune Responses**",
"Header 3": "**Autoimmune Responses**",
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By the end of this section, you will be able to:
- Explain why blood typing is important and what happens when mismatched blood is used in a transfusion
- Describe how tissue typing is done during organ transplantation and the role of transplant anti-rejection drugs
- Show how the immune response is able to control s... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
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Red blood cells can be typed based on their surface antigens. ABO blood type, in which individuals are type A, B, AB, or O according to their genetics, is one example. A separate antigen system seen on red blood cells is the Rh antigen. When someone is "A positive" for example, the positive refers to the presence of th... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 3": "**The Rh Factor**",
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Tissue transplantation is more complicated than blood transfusions because of two characteristics of MHC molecules. These molecules are the major cause of transplant rejection (hence the name "histocompatibility"). **MHC polygeny** refers to the multiple MHC proteins on cells, and **MHC polymorphism** refers to the mul... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 3": "**Tissue Transplantation**",
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**Table 21.8**
| | | Partial Table of Alleles of the Human MHC (Class I) | | | |
|--|--|-----------------------------------------------------|--|--|--|
|--|--|-----------------------------------------------------|--|--|--|
| Gene | # of alleles | # of possible MHC I protein components |
|------|--------------|... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 3": "**Partial Table of Alleles of the Human MHC (Class I)**",
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On the other hand, as cancer cells are often able to divide and mutate rapidly, they may escape the immune response, just as certain pathogens such as HIV do. There are three stages in the immune response to many cancers: elimination, equilibrium, and escape. Elimination occurs when the immune response first develops t... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 3": "**Figure 21.31 Karposi's Sarcoma Lesions** (credit: National Cancer Institute)",
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The immune system cannot exist in isolation. After all, it has to protect the entire body from infection. Therefore, the immune system is required to interact with other organ systems, sometimes in complex ways. Thirty years of research focusing on the connections between the immune system, the central nervous system, ... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 2": "**How Stress Affects the Immune Response: The Connections between the Immune, Nervous, and Endocrine Systems of the Body**",
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**Table 21.10**
At one time, it was assumed that all types of stress reduced all aspects of the immune response, but the last few decades of research have painted a different picture. First, most short-term stress does not impair the immune system in healthy individuals enough to lead to a greater incidence of diseas... | {
"Header 1": "**21.7** | Transplantation and Cancer Immunology",
"Header 2": "**How Stress Affects the Immune Response: The Connections between the Immune, Nervous, and Endocrine Systems of the Body**",
"Header 3": "**Effects of Stress on Body Systems**",
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After studying this chapter, you will be able to:
- List the structures of the respiratory system
- List the major functions of the respiratory system
- Outline the forces that allow for air movement into and out of the lungs
- Outline the process of gas exchange
- Summarize the process of oxygen and carbon dioxide t... | {
"Header 1": "**Introduction**",
"Header 2": "**Chapter Objectives**",
"token_count": 389,
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By the end of this section, you will be able to:
- List the structures that make up the respiratory system
- Describe how the respiratory system processes oxygen and CO2
- Compare and contrast the functions of upper respiratory tract with the lower respiratory tract
The major organs of the respiratory system functi... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"token_count": 238,
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The major entrance and exit for the respiratory system is through the nose. When discussing the nose, it is helpful to divide it into two major sections: the external nose, and the nasal cavity or internal nose.
The **external nose** consists of the surface and skeletal structures that result in the outward appearanc... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**The Nose and its Adjacent Structures**",
"token_count": 756,
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Several bones that help form the walls of the nasal cavity have air-containing spaces called the paranasal sinuses, which serve to warm and humidify incoming air. Sinuses are lined with a mucosa. Each **paranasal sinus** is named for its associated bone: frontal sinus, maxillary sinus, sphenoidal sinus, and ethmoidal s... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Figure 22.4 Upper Airway**",
"token_count": 616,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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The **pharynx** is a tube formed by skeletal muscle and lined by mucous membrane that is continuous with that of the nasal cavities (see **[Figure 22.4](#page-991-0)**). The pharynx is divided into three major regions: the nasopharynx, the oropharynx, and the laryngopharynx (**[Figure 22.6](#page-993-0)**).
![](_page... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Pharynx**",
"token_count": 741,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The **larynx** is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs (**[Figure 22.7](#page-994-0)**). The structure of the larynx is formed by several pieces of cartilage. Three large cartilage pieces—t... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Larynx**",
"token_count": 780,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The trachea (windpipe) extends from the larynx toward the lungs (**[Figure 22.9](#page-996-0)a**). The **trachea** is formed by 16 to 20 stacked, C-shaped pieces of hyaline cartilage that are connected by dense connective tissue. The **trachealis muscle** and elastic connective tissue together form the **fibroelastic m... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Trachea**",
"token_count": 357,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The trachea branches into the right and left primary **bronchi** at the carina. These bronchi are also lined by pseudostratified ciliated columnar epithelium containing mucus-producing goblet cells (**[Figure 22.9b](#page-996-0)**). The carina is a raised structure that contains specialized nervous tissue that induces ... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Bronchial Tree**",
"token_count": 338,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
An **alveolar duct** is a tube composed of smooth muscle and connective tissue, which opens into a cluster of alveoli. An **alveolus** is one of the many small, grape-like sacs that are attached to the alveolar ducts.
An **alveolar sac** is a cluster of many individual alveoli that are responsible for gas exchange. A... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Alveoli**",
"token_count": 566,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Asthma is common condition that affects the lungs in both adults and children. Approximately 8.2 percent of adults (18.7 million) and 9.4 percent of children (7 million) in the United States suffer from asthma. In addition, asthma is the most frequent cause of hospitalization in children.
Asthma is a chronic disease ... | {
"Header 1": "**22.1 | Organs and Structures of the Respiratory System**",
"Header 3": "**Respiratory System: Asthma**",
"token_count": 643,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the diaphragm. The diaphragm is the flat, dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by the pleurae, which ... | {
"Header 1": "**22.2 | The Lungs**",
"Header 3": "**Gross Anatomy of the Lungs**",
"token_count": 211,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Each lung is composed of smaller units called lobes. Fissures separate these lobes from each other. The right lung consists of three lobes: the superior, middle, and inferior lobes. The left lung consists of two lobes: the superior and inferior lobes. A bronchopulmonary segment is a division of a lobe, and each lobe ho... | {
"Header 1": "**22.2 | The Lungs**",
"Header 3": "**Figure 22.13 Gross Anatomy of the Lungs**",
"token_count": 201,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The major function of the lungs is to perform gas exchange, which requires blood from the pulmonary circulation. This blood supply contains deoxygenated blood and travels to the lungs where erythrocytes, also known as red blood cells, pick up oxygen to be transported to tissues throughout the body. The **pulmonary arte... | {
"Header 1": "**22.2 | The Lungs**",
"Header 3": "**Blood Supply**",
"token_count": 239,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Each lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum. The pleurae consist of two layers. The **visceral pleura... | {
"Header 1": "**22.2 | The Lungs**",
"Header 3": "**Pleura of the Lungs**",
"token_count": 207,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The burning of a tobacco cigarette creates multiple chemical compounds that are released through mainstream smoke, which is inhaled by the smoker, and through sidestream smoke, which is the smoke that is given off by the burning cigarette. Second-hand smoke, which is a combination of sidestream smoke and the mainstream... | {
"Header 1": "**22.2 | The Lungs**",
"Header 3": "**The Effects of Second-Hand Tobacco Smoke**",
"token_count": 365,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Inspiration (or inhalation) and expiration (or exhalation) are dependent on the differences in pressure between the atmosphere and the lungs. In a gas, pressure is a force created by the movement of gas molecules that are confined. For example, a certain number of gas molecules in a two-liter container has more room th... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Pressure Relationships**",
"token_count": 1141,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
In addition to the differences in pressures, breathing is also dependent upon the contraction and relaxation of muscle fibers of both the diaphragm and thorax. The lungs themselves are passive during breathing, meaning they are not involved in creating the movement that helps inspiration and expiration. This is because... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Physical Factors Affecting Ventilation**",
"token_count": 241,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The difference in pressures drives pulmonary ventilation because air flows down a pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure. Air flows into the lungs largely due to a difference in pressure; atmospheric pressure is greater than intra-alveolar pressure, and intra-... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Pulmonary Ventilation**",
"token_count": 802,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Respiratory volume** is the term used for various volumes of air moved by or associated with the lungs at a given point in the respiratory cycle. There are four major types of respiratory volumes: tidal, residual, inspiratory reserve, and expiratory reserve (**[Figure 22.18](#page-1007-0)**). **Tidal volume (TV)** is... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Respiratory Volumes and Capacities**",
"token_count": 695,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Respiratory capacity is the combination of two or more selected volumes, which further describes the amount of air in the lungs during a given time. For example, **total lung capacity (TLC)** is the sum of all of the lung volumes (TV, ERV, IRV, and RV), which represents the total amount of air a person can hold in the ... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Figure 22.19 Pulmonary Function Testing**",
"token_count": 478,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Breathing usually occurs without thought, although at times you can consciously control it, such as when you swim under water, sing a song, or blow bubbles. The **respiratory rate** is the total number of breaths, or respiratory cycles, that occur each minute. Respiratory rate can be an important indicator of disease, ... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Respiratory Rate and Control of Ventilation**",
"token_count": 216,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The medulla oblongata contains the **dorsal respiratory group (DRG)** and the **ventral respiratory group (VRG)**. The DRG is involved in maintaining a constant breathing rhythm by stimulating the diaphragm and intercostal muscles to contract, resulting in inspiration. When activity in the DRG ceases, it no longer stim... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Figure 22.20 Respiratory Centers of the Brain**",
"token_count": 250,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The respiratory rate and the depth of inspiration are regulated by the medulla oblongata and pons; however, these regions of the brain do so in response to systemic stimuli. It is a dose-response, positive-feedback relationship in which the greater the stimulus, the greater the response. Thus, increasing stimuli result... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Factors That Affect the Rate and Depth of Respiration**",
"token_count": 790,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
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Sleep apnea is a chronic disorder that can occur in children or adults, and is characterized by the cessation of breathing during sleep. These episodes may last for several seconds or several minutes, and may differ in the frequency with which they are experienced. Sleep apnea leads to poor sleep, which is reflected in... | {
"Header 1": "**22.3 | The Process of Breathing**",
"Header 3": "**Respiratory System: Sleep Apnea**",
"token_count": 582,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Gas molecules exert force on the surfaces with which they are in contact; this force is called pressure. In natural systems, gases are normally present as a mixture of different types of molecules. For example, the atmosphere consists of oxygen, nitrogen, carbon dioxide, and other gaseous molecules, and this gaseous mi... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Gas Laws and Air Composition**",
"token_count": 247,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
| Gas | Percent of total composition | Partial pressure<br>(mm Hg) |
|---------------------------------------------------|------------------------------|-----------------------------|
| Nitrogen (N2) | 78.6 | 597.4... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Partial Pressures of Atmospheric Gases**",
"token_count": 308,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Henry's law** describes the behavior of gases when they come into contact with a liquid, such as blood. Henry's law states that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas. The greater the partial pressure of the gas, the greater the number of gas m... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Solubility of Gases in Liquids**",
"token_count": 556,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Two important aspects of gas exchange in the lung are ventilation and perfusion. **Ventilation** is the movement of air into and out of the lungs, and perfusion is the flow of blood in the pulmonary capillaries. For gas exchange to be efficient, the volumes involved in ventilation and perfusion should be compatible. Ho... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Ventilation and Perfusion**",
"token_count": 474,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The pulmonary artery carries deoxygenated blood into the lungs from the heart, where it branches and eventually becomes the capillary network composed of pulmonary capillaries. These pulmonary capillaries create the respiratory membrane with the alveoli (**[Figure 22.22](#page-1015-0)**). As the blood is pumped through... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**External Respiration**",
"token_count": 585,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Internal respiration** is gas exchange that occurs at the level of body tissues (**[Figure 22.23](#page-1016-0)**). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the res... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Internal Respiration**",
"token_count": 376,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
A type of device used in some areas of medicine that exploits the behavior of gases is hyperbaric chamber treatment. A hyperbaric chamber is a unit that can be sealed and expose a patient to either 100 percent oxygen with increased pressure or a mixture of gases that includes a higher concentration of oxygen than norma... | {
"Header 1": "**22.4 | Gas Exchange**",
"Header 3": "**Hyperbaric Chamber Treatment**",
"token_count": 571,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Even though oxygen is transported via the blood, you may recall that oxygen is not very soluble in liquids. A small amount of oxygen does dissolve in the blood and is transported in the bloodstream, but it is only about 1.5% of the total amount. The majority of oxygen molecules are carried from the lungs to the body's ... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Oxygen Transport in the Blood**",
"token_count": 400,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Hemoglobin is composed of subunits, a protein structure that is referred to as a quaternary structure. Each of the four subunits that make up hemoglobin is arranged in a ring-like fashion, with an iron atom covalently bound to the heme in the center of each subunit. Binding of the first oxygen molecule causes a conform... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Function of Hemoglobin**",
"token_count": 279,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Partial pressure is an important aspect of the binding of oxygen to and disassociation from heme. An **oxygen–hemoglobin dissociation curve** is a graph that describes the relationship of partial pressure to the binding of oxygen to heme and its subsequent dissociation from heme (**[Figure 22.26](#page-1020-0)**). Reme... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Oxygen Dissociation from Hemoglobin**",
"token_count": 1086,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The fetus has its own circulation with its own erythrocytes; however, it is dependent on the mother for oxygen. Blood is supplied to the fetus by way of the umbilical cord, which is connected to the placenta and separated from maternal blood by the chorion. The mechanism of gas exchange at the chorion is similar to gas... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Hemoglobin of the Fetus**",
"token_count": 307,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
A large fraction—about 70 percent—of the carbon dioxide molecules that diffuse into the blood is transported to the lungs as bicarbonate. Most bicarbonate is produced in erythrocytes after carbon dioxide diffuses into the capillaries, and subsequently into red blood cells. **Carbonic anhydrase (CA)** causes carbon diox... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Bicarbonate Buffer**",
"token_count": 415,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
About 20 percent of carbon dioxide is bound by hemoglobin and is transported to the lungs. Carbon dioxide does not bind to iron as oxygen does; instead, carbon dioxide binds amino acid moieties on the globin portions of hemoglobin to form **carbaminohemoglobin**, which forms when hemoglobin and carbon dioxide bind. Whe... | {
"Header 1": "**22.5 | Transport of Gases**",
"Header 3": "**Carbaminohemoglobin**",
"token_count": 470,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**Hyperpnea** is an increased depth and rate of ventilation to meet an increase in oxygen demand as might be seen in exercise or disease, particularly diseases that target the respiratory or digestive tracts. This does not significantly alter blood oxygen or carbon dioxide levels, but merely increases the depth and rat... | {
"Header 1": "**22.6 | Modifications in Respiratory Functions**",
"Header 3": "**Hyperpnea**",
"token_count": 444,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
An increase in altitude results in a decrease in atmospheric pressure. Although the proportion of oxygen relative to gases in the atmosphere remains at 21 percent, its partial pressure decreases (**[Table 22.4](#page-1024-1)**). As a result, it is more difficult for a body to achieve the same level of oxygen saturation... | {
"Header 1": "**22.6 | Modifications in Respiratory Functions**",
"Header 3": "**High Altitude Effects**",
"token_count": 276,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
As you recall, partial pressure is extremely important in determining how much gas can cross the respiratory membrane and enter the blood of the pulmonary capillaries. A lower partial pressure of oxygen means that there is a smaller difference in partial pressures between the alveoli and the blood, so less oxygen cross... | {
"Header 1": "**22.6 | Modifications in Respiratory Functions**",
"Header 3": "**Table 22.4**",
"token_count": 587,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Especially in situations where the ascent occurs too quickly, traveling to areas of high altitude can cause AMS. **Acclimatization** is the process of adjustment that the respiratory system makes due to chronic exposure to a high altitude. Over a period of time, the body adjusts to accommodate the lower partial pressur... | {
"Header 1": "**22.6 | Modifications in Respiratory Functions**",
"Header 3": "**Acclimatization**",
"token_count": 218,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Respiratory development in the embryo begins around week 4. Ectodermal tissue from the anterior head region invaginates posteriorly to form olfactory pits, which fuse with endodermal tissue of the developing pharynx. An **olfactory pit** is one of a pair of structures that will enlarge to become the nasal cavity. At ab... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**Weeks 4–7**",
"token_count": 248,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Respiratory distress syndrome (RDS) primarily occurs in infants born prematurely. Up to 50 percent of infants born between 26 and 28 weeks and fewer than 30 percent of infants born between 30 and 31 weeks develop RDS. RDS results from insufficient production of pulmonary surfactant, thereby preventing the lungs from pr... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**Respiratory System: Respiratory Distress Syndrome**",
"token_count": 412,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
**acclimatization** process of adjustment that the respiratory system makes due to chronic exposure to high altitudes - **acute mountain sickness (AMS)** condition that occurs a result of acute exposure to high altitude due to a low partial pressure of oxygen - **ala** (plural = alae) small, flaring structure of a nost... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**KEY TERMS**",
"token_count": 1820,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The respiratory system is responsible for obtaining oxygen and getting rid of carbon dioxide, and aiding in speech production and in sensing odors. From a functional perspective, the respiratory system can be divided into two major areas: the conducting zone and the respiratory zone. The conducting zone consists of all... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**[22.1 Organs and](#page-988-1) [Structures of the Respiratory System](#page-989-0)**",
"token_count": 361,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The lungs are the major organs of the respiratory system and are responsible for performing gas exchange. The lungs are paired and separated into lobes; The left lung consists of two lobes, whereas the right lung consists of three lobes. Blood circulation is very important, as blood is required to transport oxygen from... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**[22.2 The Lungs](#page-1000-0)**",
"token_count": 249,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Pulmonary ventilation is the process of breathing, which is driven by pressure differences between the lungs and the atmosphere. Atmospheric pressure is the force exerted by gases present in the atmosphere. The force exerted by gases within the alveoli is called intra-alveolar (intrapulmonary) pressure, whereas the for... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**[22.3 The Process of Breathing](#page-1003-0)**",
"token_count": 810,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
The behavior of gases can be explained by the principles of Dalton's law and Henry's law, both of which describe aspects of gas exchange. Dalton's law states that each specific gas in a mixture of gases exerts force (its partial pressure) independently of the other gases in the mixture. Henry's law states that the amou... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**[22.4 Gas Exchange](#page-1012-0)**",
"token_count": 374,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
Oxygen is primarily transported through the blood by erythrocytes. These cells contain a metalloprotein called hemoglobin, which is composed of four subunits with a ring-like structure. Each subunit contains one atom of iron bound to a molecule of heme. Heme binds oxygen so that each hemoglobin molecule can bind up to ... | {
"Header 1": "**22.7 | Embryonic Development of the Respiratory System**",
"Header 3": "**[22.5 Transport of Gases](#page-1018-0)**",
"token_count": 549,
"source_pdf": "datasets/websources/Med_v1/med_textbook/AnatomyAndPhysiology-LR.pdf"
} |
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