Chapter 22. The Lymphatic System And Immunity

Natural killer cells are a type of white blood cells that play a crucial role in the immune system's defense against infectious microbes and tumor cells. They are able to recognize and kill these abnormal cells through the release of cytotoxic substances, such as perforins, which create pores in the target cells' membrane, leading to their destruction. Unlike other immune cells, natural killer cells do not require prior activation and can quickly respond to infected or cancerous cells. Therefore, they are an important component of the body's innate immune response.

Mucus production is not a sign of inflammation because it is a normal bodily response to protect and lubricate the respiratory system. Inflammation is characterized by redness, pain, and heat, which are caused by increased blood flow and immune response to an injury or infection. Mucus production, on the other hand, is a natural defense mechanism that helps to trap and remove foreign particles, irritants, and pathogens from the respiratory tract.

The pancreas is not considered an organ of the immune system. While it does play a role in the digestive system by producing enzymes and hormones like insulin, it is not directly involved in the immune response. The immune system primarily consists of organs like the spleen, lymph nodes, and thymus, which are responsible for producing and storing immune cells, filtering out pathogens, and coordinating immune responses.

The thymus produces the hormone that promotes the maturation of T cells. T cells are a type of white blood cell that plays a crucial role in the immune system. The thymus is a gland located in the chest, near the heart, and is responsible for the development and maturation of T cells. It releases a hormone called thymosin, which helps in the maturation process of T cells. Therefore, the correct answer is the thymus.

Susceptibility refers to the lack of resistance or vulnerability to a particular disease or pathogen. It indicates that an individual or organism is more likely to be affected or infected by the pathogen due to a weakened immune system or other factors. Susceptibility can be innate, meaning it is present from birth, or it can be acquired due to various factors such as age, underlying health conditions, or exposure to certain environmental factors.

The spleen is responsible for removing worn-out blood cells from the body. It acts as a filter, identifying and eliminating old or damaged red blood cells. This process helps maintain the overall health and functionality of the blood by removing any cells that are no longer functioning properly.

The skeletal muscle and respiratory pumps are used in the lymphatic, cardiovascular, and immune systems. These pumps help to facilitate the movement of lymph fluid, blood, and immune cells throughout the body. The skeletal muscles contract and relax, creating pressure that helps to push lymph and blood through the vessels. The respiratory pumps work in conjunction with the skeletal muscles during breathing, as the movement of the diaphragm and ribcage helps to create pressure changes that assist in the circulation of lymph and blood. These pumps are essential for maintaining the proper functioning of these systems.

An antigen is a substance that induces the production of a specific antibody. When the immune system detects an antigen, it triggers the production of antibodies that are specifically designed to target and neutralize that particular antigen. This immune response helps to protect the body from harmful pathogens and foreign substances.

An acute allergic response can lead to anaphylactic shock. Anaphylactic shock is a severe and potentially life-threatening allergic reaction that occurs when the immune system overreacts to an allergen. It can cause a sudden drop in blood pressure, difficulty breathing, and swelling of the throat and tongue, which can lead to death if not treated immediately. Anaphylactic shock is a serious medical emergency that requires immediate medical attention and the use of epinephrine to reverse the symptoms.

The left subclavian vein receives lymph from the thoracic duct. The thoracic duct is the largest lymphatic vessel in the body and it drains lymph from the lower limbs, abdomen, left side of the thorax, left upper limb, and left side of the head and neck. Therefore, it is responsible for delivering lymph to the left subclavian vein, which then carries it back to the heart.

The lymphatic and immune system is responsible for various functions in the body. It helps in draining excess interstitial fluid, which prevents swelling and maintains tissue fluid balance. It also plays a crucial role in transporting dietary lipids, as it absorbs fats from the digestive system and transports them to the bloodstream. Additionally, the lymphatic and immune system carries out immune responses, defending the body against pathogens and foreign substances. However, maintaining water homeostasis in the body is primarily regulated by the kidneys and the endocrine system, not the lymphatic and immune system.

Lymphocytes are a type of white blood cells that play a crucial role in the immune system's response to foreign substances in the body. They are capable of recognizing and distinguishing between self cells and foreign cells. When lymphocytes encounter foreign cells, such as bacteria or viruses, they initiate an immune response to eliminate these invaders. Therefore, the correct answer is "foreign cells" as lymphocytes can specifically recognize and target them.

Macrophages are immune cells that play a crucial role in the body's defense against pathogens. They are responsible for engulfing and destroying foreign substances, such as bacteria and viruses. Unlike saliva, urine, and mucus, which all provide physical or chemical barriers to protect the body, macrophages do not act as a physical or chemical barrier. Instead, they are part of the immune system's response to pathogens, working to eliminate them once they have breached the body's barriers.

When B and T cells are fully developed and mature, they are known to be immunocompetent. This means that they are capable of recognizing and responding to specific antigens in the body, thus playing a crucial role in the immune response. Immunocompetent cells are able to differentiate between self and non-self antigens, and they can effectively mount an immune response against pathogens or foreign substances. This ability is essential for the proper functioning of the immune system in defending the body against infections and diseases.

The correct answer is NONSPECIFIC. Non-specific immunity refers to the immune response that defends against any type of invader, regardless of its specific characteristics. This type of immunity includes physical barriers like the skin, as well as general immune responses such as inflammation and the activation of phagocytes. It is called non-specific because it does not target a specific pathogen, but rather provides a generalized defense mechanism against a wide range of invaders.

Lymph from the small intestine appears white due to the presence of lipids. Lymph is a fluid that contains various substances, including fats and fat-soluble vitamins, which are absorbed from the small intestine. These lipids give the lymph a milky appearance, causing it to appear white. This is because lipids are not soluble in water and form small droplets in the lymph, scattering light and giving it a white color.

Interferons are a group of proteins that are released by infected cells as a response to viral infection. They play a crucial role in the immune response by inhibiting the replication of viruses and reducing the production of viral proteins in uninfected cells. This helps to limit the spread of the virus and prevent further infection. Therefore, the statement "These antimicrobial substances will diffuse to uninfected cells and reduce production of viral proteins" accurately describes the function of interferons.

The major difference between lymph and interstitial fluid is their location. Lymph is found in the lymphatic vessels and lymph nodes, while interstitial fluid is found in the spaces between cells and tissues.

Immunodeficiency diseases are characterized by the inability of the immune system to protect the body from a pathogen. This means that individuals with immunodeficiency diseases have a weakened or compromised immune system, making them more susceptible to infections and diseases. These conditions can be inherited or acquired, and can range from mild to severe. Immunodeficiency diseases can be caused by genetic mutations, certain medications, chemotherapy, radiation therapy, or diseases such as HIV/AIDS. Treatment for immunodeficiency diseases may involve medications, immune globulin therapy, and in some cases, stem cell or bone marrow transplantation.

IgA antibodies are mainly found in sweat, tears, breast milk, and GI secretions. IgA is the predominant antibody class in mucosal tissues and plays a crucial role in immune defense at mucosal surfaces. It helps prevent pathogens from entering the body through mucosal membranes, such as the respiratory and gastrointestinal tracts. IgA antibodies are also transferred from mother to child through breast milk, providing passive immunity to the infant.

The correct answer is the thoracic duct. The thoracic duct is the largest lymphatic vessel in the body and is responsible for draining lymph from the lower limbs, abdomen, left side of the thorax, left upper limb, and left side of the head and neck. It empties into the left subclavian vein, which is located in the left axillary region. This allows the lymph from the right foot to eventually enter the bloodstream and be returned to circulation.

Macrophages provide a non-specific cellular disease resistance mechanism. Macrophages are a type of white blood cell that play a crucial role in the immune response by engulfing and destroying foreign substances, such as bacteria and viruses. They also release chemical signals that attract other immune cells to the site of infection and help coordinate the overall immune response. Unlike T lymphocytes, B lymphocytes, and memory B cells, which are all involved in specific immune responses targeted against specific pathogens, macrophages provide a general defense mechanism against a wide range of pathogens.

Helper T cells display CD4 in their membrane and are associated with MHC class II molecules. CD4 is a co-receptor protein that binds to MHC class II molecules on antigen-presenting cells, allowing helper T cells to recognize and interact with these cells. Helper T cells play a crucial role in the immune response by activating other immune cells, such as B cells and cytotoxic T cells, and helping to coordinate the immune response against pathogens. Therefore, helper T cells are the correct answer in this case.

Cytokines are small signaling molecules that can stimulate or inhibit various normal cell functions. They play a crucial role in regulating the immune response and inflammation. They can act as mediators between cells, influencing cell growth, differentiation, and activation. Cytokines are involved in many physiological processes, including the immune response, hematopoiesis, and wound healing. Therefore, the given statement aligns with the function of cytokines, making it the correct answer.

Fever intensifies the effect of interferons and promotes the rate of repair. Fever is a natural response of the body to infection or inflammation, and it helps to enhance the immune response. When the body temperature rises, it creates an unfavorable environment for the growth and replication of pathogens, while also stimulating the production and activity of immune cells like macrophages. Interferons are proteins released by infected cells to prevent the spread of viruses, and fever can enhance their effectiveness by increasing their production and activity. Additionally, fever can also promote tissue repair by increasing blood flow and metabolic rate.

Complement proteins are a group of proteins that play a crucial role in the immune system. They promote sytolysis, which is the destruction of bacteria and other pathogens, by forming a membrane attack complex that punches holes in the pathogens' cell membranes. They also enhance phagocytosis, the process by which immune cells engulf and destroy pathogens. Additionally, complement proteins contribute to inflammation, a key immune response that helps recruit immune cells to the site of infection. Therefore, complement proteins are the correct answer as they promote sytolysis, phagocytosis, and inflammation.

The correct answer is "Antigen Presenting Cells." This class of cells, which includes macrophages, B cells, and dendritic cells, plays a crucial role in the immune response by capturing, processing, and presenting antigens to activate other immune cells, such as T cells. Antigen presenting cells are essential for initiating and coordinating immune responses against pathogens and foreign substances. They help in recognizing and presenting antigens to activate the adaptive immune response, making them an important component of the immune system.

Natural exposure to an infectious agent leads to active immunity. When a person is exposed to a pathogen, their immune system recognizes it as foreign and mounts a response to eliminate it. This response includes the production of specific antibodies and the activation of immune cells, such as T cells and B cells. Active immunity provides long-term protection against future infections by the same pathogen, as the immune system "remembers" the pathogen and can mount a rapid and effective response if re-exposed. Passive immunity, on the other hand, is acquired through the transfer of pre-formed antibodies from another individual and provides only temporary protection.

IgM is the correct answer because it is the class of antibodies that is produced after an initial exposure to antigens. IgM is the first antibody produced by the immune system in response to an infection or antigen exposure. It is considered the primary immune response and helps to activate other components of the immune system. IgA, IgE, and IgD are not produced after an initial exposure to antigens.

Opsonization is a process in which microbes are coated with antibodies or complement proteins, making them more recognizable and easier for phagocytes to engulf and destroy. This process enhances the immune response by marking the microbes for destruction and promoting their uptake by phagocytic cells. It increases the efficiency of phagocytosis and ultimately makes the microbes more susceptible to being eliminated by the immune system.

Pluripotent stem cells come from B. The diagram suggests that B is the source of pluripotent stem cells. This could be due to the specific characteristics or properties of B that allow it to generate pluripotent stem cells. However, without further information or context, it is difficult to provide a more detailed explanation.

Lymphotoxin is the correct answer because T cells secrete this toxin to fragment DNA. Lymphotoxin is a protein that is released by T cells upon activation and it plays a role in immune responses. It has cytotoxic effects on target cells, including the ability to induce DNA fragmentation, which ultimately leads to cell death. Therefore, lymphotoxin fits the description given in the question.

In the given diagram, the white and red pulp is comprised in option C.

Epithelial cells are speculated to be the site where T cells die in the thymus. This is because the thymus is composed of a network of epithelial cells that provide a specialized microenvironment for the maturation and selection of T cells. These epithelial cells play a crucial role in the process of negative selection, where T cells that recognize self-antigens are eliminated to prevent autoimmune responses. Therefore, it is speculated that T cells undergo cell death in close proximity to the epithelial cells in the thymus.

An anergy cell refers to a type of immune cell that is in a state of inactivity or unresponsiveness. This can occur when the cell encounters an antigen but fails to mount a proper immune response. Anergy cells are characterized by their inability to proliferate and produce cytokines, which are essential for immune responses. This state of anergy can be induced by various mechanisms, such as chronic antigen exposure or dysfunctional signaling pathways. Anergy cells play a role in immune tolerance and preventing excessive immune reactions.

T cells are a type of white blood cells that play a crucial role in the immune response. They can only become activated when they are bound to a foreign antigen, which is a substance that triggers an immune response. Additionally, T cells require a costimulatory signal to be activated. This means that they need an additional signal, usually from another immune cell, to fully activate and carry out their immune functions. Therefore, the given statement accurately describes the activation process of T cells.

Natural Killer (NK) cells are involved in the body's second line of defense. NK cells are a type of lymphocyte that plays a crucial role in the immune response against viral infections and cancer. They are able to recognize and directly kill infected or abnormal cells without prior activation, making them an important component of the innate immune system. NK cells are part of the body's second line of defense because they provide a rapid response to pathogens, complementing the slower adaptive immune response mediated by lymphocytes.

The inner cortex of the lymph node does not contain any lymphatic nodules. Lymphatic nodules are small structures composed of lymphocytes that play a crucial role in the immune response. They are mainly found in the outer cortex and medulla of the lymph node. The sinuses, on the other hand, are spaces within the lymph node that allow the flow of lymphatic fluid. Therefore, the correct answer is the inner cortex, as it lacks lymphatic nodules.

A hapten is a small molecule that can only stimulate an immune response if it is attached to a larger carrier molecule. This is because the immune system recognizes antigens based on their size and complexity. Haptens alone are too small to be recognized, but when they bind to a larger carrier molecule, the immune system can detect the complex and mount an immune response. Therefore, a hapten can only stimulate an immune response if attached to a large carrier molecule.

The given correct answer is "CLASSICAL AND ALTERNATIVE COMPLEMENT SYSTEM". The classical complement system and alternative complement system are two pathways of the complement system, which is a part of the immune system. Both pathways can lead to inflammation, enhancement of phagocytosis, and bursting of microbes. The classical pathway is activated by the binding of antibodies to pathogens, while the alternative pathway is activated by the presence of certain molecules on the surface of pathogens. Therefore, the combined action of both pathways is responsible for the mentioned effects.

B cell receptors consist of two main regions, the variable region and the constant region. The variable region is responsible for binding to specific antigens, while the constant region is involved in signaling and immune response activation. Therefore, it is incorrect to say that there is no variable region on a B cell receptor.

Perforins do not induce vasodilation and permeability to an infection site. Perforins are proteins that are released by cytotoxic T cells and natural killer cells as a defense mechanism against infected or abnormal cells. They form pores in the cell membrane of the target cells, leading to their destruction. However, they do not directly cause vasodilation or increase permeability at the infection site, which are functions typically associated with histamines, kinins, and complement proteins.

The correct answer is C because the question asks for the cells found in the region described in the diagram. The diagram shows B cells, follicular dendritic cells, and macrophages, and option C corresponds to macrophages.

Lymphocytes are the most polymorphic molecules in the immune system. They are a type of white blood cell that plays a crucial role in the adaptive immune response. Lymphocytes are highly diverse and can recognize and respond to a wide range of antigens. This diversity is achieved through the expression of different cell surface receptors, such as T cell receptors (TCRs) and B cell receptors (BCRs). The ability of lymphocytes to recognize and respond to a diverse array of antigens makes them the most polymorphic molecules in the immune system.

The primary response will peak 10-17 days after an exposure. This means that the body's immune response to the exposure will reach its highest level during this time period. After being exposed to a pathogen or antigen, the immune system takes time to recognize and respond to it. The initial response is usually slower, but it gradually increases over time until it reaches its peak. This peak represents the maximum level of immune activity against the specific pathogen or antigen.

In this diagram, the correct answer is A. T cells mature in the thymus gland, which is represented by option A in the diagram. The thymus gland is an organ located in the chest, just above the heart. It is responsible for the maturation and development of T cells, which are a type of white blood cell involved in the immune response. The thymus gland plays a crucial role in the immune system by ensuring that T cells are able to recognize and respond to foreign antigens appropriately.

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The vessel that drains lymph from the upper right side of the body into venous blood is represented by option C in the diagram.

Reactivity refers to the ability of an antigen to react specifically with the antibodies or cells it has provoked. This means that when an antigen encounters the specific antibodies or cells that it has provoked, it will bind to them and trigger an immune response. Reactivity is an important characteristic of antigens as it allows the immune system to specifically target and eliminate foreign substances.

MHC (major histocompatibility complex) is responsible for diversity in the immune system. MHC molecules present antigens to T cells, allowing the immune system to recognize and respond to a wide range of pathogens. The MHC genes are highly polymorphic, meaning they have many different alleles, which contributes to the diversity of the immune system. Additionally, MHC molecules can bind to a variety of antigens, further increasing the diversity of the immune response. Therefore, MHC plays a crucial role in the ability of the immune system to recognize and respond to diverse pathogens.