Chapter 20 - Immune System Flashcards
Any Disease causing agent is called?
A Pathogen
Immune System
Theimmune systemis a host defense system. It comprises many biological structures—ranging from individual white blood cells to entire organs — as well as many complex biological processes. The function of the immune system is to protect the host from pathogens and other causes of disease such as tumor cells. To function properly, the immune system must be able to detect a wide variety of pathogens. It also must be able to distinguish the cells of pathogens from the host’s own cells and also to distinguish cancerous or damaged host cells from healthy cells.
Innate Immune System
The innate immune system provides very quick but non-specific response to pathogens. It responds the same way regardless of the type of pathogen that is attacking the host. It includes barriers — such as the skin and mucous membranes—that normally keep pathogens out of the body. It also includes general responses to pathogens that manage to breach these barriers, including chemicals and cells that attack the pathogens inside the human host.
Adaptive Imune System and Immunity
The adaptive immune system is activated if pathogens successfully enter the body and manage to evade the general defenses of the innate immune system. An adaptive response is specific to the particular type of pathogen that has invaded the body or to cancerous cells. It takes longer to launch a specific attack, but once it is underway, its specificity makes it very effective. An adaptive response also usually leads to immunity. This is a state of resistance to a specific pathogen due to the ability of the adaptive immune system to “remember” the pathogen and immediately mount a strong attack tailored to that particular pathogen if it invades again in the future.
Self, Nonself, and MHC
Virtually all body cells have surface proteins that are part of a complex calledmajor histocompatibility complex (MHC). These proteins are one way the immune system recognizes body cells as self. Non-self proteins, in contrast, are recognized as foreign because they are different from self proteins.
What do B cells do?
They respond to foreign antigens by producing antibodies.
What is an antigen and an antibody?
Many non-self molecules comprise a class of compounds called antigens. Antigens, which are usually proteins, bind to specific receptors on immune system cells and elicit an adaptive immune response.
An antibody is a molecule that precisely matches and binds to a specific antigen. This may target the antigen (and the pathogen displaying it) for destruction by other immune cells.
Immune Surveillance
Another important role of the immune system is to identify and eliminate tumor cells. This is calledimmune surveillance.The transformed cells of tumors express antigens that are not found on normal body cells. The main response of the immune system to tumor cells is to destroy them. This is carried out primarily by aptly named killer T cells of the adaptive immune system.
Lymphatic System
The lymphatic system is a human organ system that is a vital part of the adaptive immune system.
The lymphatic system consists of several lymphatic organs and a body-wide network of lymphatic vessels that transport the fluid called lymph. Lymph is essentially blood plasma that has leaked from capillaries into tissue spaces. It includes many leukocytes, especially lymphocytes, which are the major cells of the lymphatic system. Like other leukocytes, lymphocytes defend the body. There are several different types of lymphocytes that fight pathogens or cancer cells as part of the adaptive immune system.
Major organs in the lymphatic system?
Major lymphatic organs include the thymus and bone marrow. Their function is to form and/or mature lymphocytes. Other lymphatic organs include the spleen, tonsils, and lymph nodes, which are small clumps of lymphoid tissue clustered along lymphatic vessels. These other lymphatic organs harbor mature lymphocytes and filter lymph. They are sites where pathogens collect and adaptive immune responses generally begin.
Neuroimmine system:
Protects brain and spinal cord with blood-brain and blood-spinal cord barriers.
Neuroimmune system is generally considered to be ____ from the peripheral immune system which is the ___ immune system
distinct, main
Neuroimmine Cells
Unlike the peripheral system, in which leukocytes are the main cells, the main cells of the neuroimmune system are thought to be nervous system cells called glial cells. These cells are able to recognize and respond to pathogens, debris, and other potential dangers. Types of glial cells involved in neuroimmune responses include microglial cells and astrocytes.
Microglial cells are among the most prominent types of glial cells in the brain. One of their main functions is to phagocytize cellular debris that remains when neurons die. Microglial cells also “prune” obsolete synapses between neurons.
Astrocytes are glial cells that have a different immune function. They allow certain immune cells from the peripheral immune system to cross the blood-brain barrier into the brain to target both pathogens and damaged nervous tissue.
What do Killer T cells do?
Tumor surveillance.
Then DESTROY THEM.
What is the lymphatic system?
Thelymphatic systemis a collection of organs involved in the production, maturation, and harboring of white blood cells called lymphocytes. It also includes a network of vessels that transport or filter the fluid known aslymphin which lymphocytes circulate.
Lacteals, Villus, and Chyle
Lymphatic vessels called lacteals are present in the lining of the gastrointestinal tract, mainly in the small intestine. Each tiny villus in the lining of the small intestine has an internal bed of capillaries and lacteals. The capillaries absorb most nutrients from the digestion of food into the blood. The lacteals absorb mainly fatty acids from lipid digestion into the lymph, forming a fatty-acid-enriched fluid called chyle. Vessels of the lymphatic network then transport chyle from the small intestine to the main lymphatic ducts in the chest from which it drains into the blood circulation. The nutrients in chyle then circulate in the blood to the liver, where they are processed along with the other nutrients that reach the liver directly via the bloodstream.
What are Lymphocytes?
Lymphocytesare leukocytes that are involved in the adaptive immune system. They are responsible for the recognition of, and tailored defense against, specific pathogens or tumor cells. Lymphocytes may also create a lasting memory of pathogens so they can be attacked quickly and strongly if they ever invade the body again. In this way, lymphocytes bring about long-lasting immunity to specific pathogens.
What is the primary function of the lymphatic system?
The primary function of the lymphatic system is host defense as part of the immune system. This function of the lymphatic system is centered on the production, maturation, and circulation of lymphocytes.
What are the 2 types of lymphocytes and what do they do?
B (cells) Lympocytes - B cells mature in the bone marrow, which is why they are called B cells. After they mature and leave the bone marrow, they travel first to the circulatory system and then enter the lymphatic system to search for pathogens.
T (cells) Lymphocytes - T cells, on the other hand, mature in the thymus, which is why they are called T cells. The Thymus is a small lymphatic organ in the chest that consists of an outer cortex and inner medulla, all surrounded by a fibrous capsule. After maturing in the thymus, T cells enter the rest of the lymphatic system to join B cells in the hunt for pathogens.
The bone marrow and thymus are called primary organs because of their role in the production and/or maturation of lymphocytes.
lymphoid
The tonsils, spleen, and lymph nodes are referred to as ____ ____organs. These organs do not produce or mature lymphocytes. Instead, they filter lymph and store lymphocytes.
secondary lymphoid
TONSILS?!!?!!
There are actually four pairs of human tonsils. The fourth pair, called tubal tonsils, is located at the back of the nasopharynx. The palatine tonsils are the tonsils that are visible on either side of the throat. All four pairs of tonsils encircle a part of the anatomy where the respiratory and gastrointestinal tracts intersect and where pathogens have ready access to the body. This ring of tonsils is called Waldeyer’s ring.
SPLEEN
Oh my SPLEEEENNN!!!
Thespleen(pictured below) is the largest of the secondary lymphoid organs and is centrally located in the body. Besides harboring lymphocytes and filtering lymph, the spleen also filters blood. Most dead or aged red blood cells are removed from the blood in the red pulp of the spleen. Lymph is filtered in the white pulp of the spleen. In the fetus, the spleen has the additional function of producing red blood cells. This function is taken over by bone marrow after birth.
Lymph Nodes
Eachlymph nodeis a small but organized collection of lymphoid tissue that contains many lymphocytes. Lymph nodes are located at intervals along the lymphatic vessels, and lymph passes through them on its way back to the blood.
Lymphocyte Training Program
All lymphocytes are produced in bone marrow and then go through a process of maturation in which they “learn” to distinguish self from non-self.
Something to know about the Innate Immune System
Although the innate immune system provides immediate and rapid defenses against pathogens, it does not confer long-lasting immunity to them. In most organisms, the innate immune system is the dominant system of host defense.
