Immune System Flashcards
Immune system
-Protects the body against invading pathogens including bacteria, viruses, fungi, and protists
-includes the lymphatic system (lymph, lymph capillaries, lymph vessels and lymph nodes) as well as the red bone marrow and numerous leukocytes, or white blood cells
-tissue fluid enters the lymph capillaries, which combine to form lymph vessels
-skeletal muscle contractions move the lymph one way through the lymphatic system to lymphatic ducts which dump back into the venous blood supply into the lymph nodes, which are situated on the lymph vessels and filter the lymph of pathogens and other matter
-the lymph nodes are concentrated in the neck, armpits, and groin areas
-outside the lymphatic vessel system lies the lymphatic tissue including the tonsils, adenoids, thymus, spleen, and Peyer’s patches
-the tonsils, located in the pharynx, protect against pathogens entering the body through the mouth and throat
-the thymus serves as maturation chamber for the immature T-cells that are formed in the bone marrow
-the spleen cleans the blood of dead cells and pathogens
-Peyer’s patches, which are located in the small intestine, protect the digestive system from pathogens
Body’s general immune defense
-Skin: an intact epidermis and dermis form a formidable barrier against bacteria
-ciliated mucus membranes: cilia sweep pathogens out of the respiratory tract
-Glandular secretions: secretions from exocrine glands destroy bacteria
-gastric secretions: gastric acid destroys pathogens
-normal bacteria populations: compete with pathogens in the gut and vagina
Three types of WBCs form the foundation of the body’s immune system
-Macrophages: phagocytes that alert T cells to the presence of foreign substances
-T Lymphocytes: these directly attack cells infected by viruses and bacteria
-B Lymphocytes: these cells target specific bacteria for destruction
Immune system
-Memory cells, suppressor T cells, and helper T cells also contribute to the bodies defense immune responses
-can be antibody mediated when the responses to an antigen or
-cell mediated when the response is to already infected cells
-these responses are controlled and measured counteracts that recede when the foreign agents are destroyed
-once an invader has attacked the body, if it returns it is immediately recognized and a secondary immune response occurs
-the secondary response is rapid and powerful, much more so than the original response is
-memory lymphocytes circulate throughout the body for years, alert to a possible new attack
Leukocytes or WBCs
-Leukocytes (white blood cells), are produced in the red bone marrow
-leukocytes can be classified as monocytes (macrophages and dendritic cells), granulocytes (neutrophils, eosinophils, and basophils), or lymphocytes (T lymphocytes, B lymphocytes, or natural killer cells)
[WBC]
Macrophages
-macrophages found traveling in the lymph or fixed in lymphatic tissue are the largest, long-living phagocytes that engulf and destroy pathogens
[WBC]
T Lymphocytes
-include helper T cells, killer T cells, suppressor T cells, and memory T cells
-helper T cells help the body fight infections by producing antibodies and other chemicals
-killer T cells destroy cells that are infected with a virus or pathogen and tumor cells
-suppressor T cells stop or suppress the other T cells when the battles over
-memory T cells remain in the body on alert in case the invader attacks again
-B lymphocytes, or B cells, produce antibodies
Antigen and Typical Immune Response
-Antigens are substances that stimulate the immune system
-antigens are typically proteins on the surfaces of bacteria, viruses, and fungi
-substances such as drugs, toxins, and foreign particles can also be antigens
-the human body recognizes the antigens of its own cells, but it will attack cells or substances with unfamiliar antigens
-specific antibodies are produced for each antigen that enters the body
-in a typical immune response, when a pathogen or foreign substance enters the body, it is engulfed by a macrophage, which presents fragments of the antigen on its surface
-helper T cell joins the macrophage, and the killer (cytotoxic) T cells and B cells are activated
-killer T cells search out and destroy cells presenting the same antigens
-B cells differentiate into plasma cells and memory cells
-plasma cells produce antibodies specific to the pathogen or foreign substance
-antibodies bind to antigens on the surface of pathogens and mark them for destruction by other phagocytes
-memory cells remain in the bloodstream to protect against future infections from the same pathogen
[active and passive immunity]
Innate immune system
-protects individual from pathogen
-when an individual encounters infection or has an immunization, the individual develops an adaptive immunity that reacts to pathogens
so this adaptive immunity is acquired
-active and passive immunities can be acquired naturally or artificially
[active and passive immunity]
Naturally acquired active immunity
-Natural because the individual is exposed and build immunity to a pathogen without an immunization
-an artificially acquired active immunity is artificial because the individual is exposed and builds immunity to a pathogen by a vaccine
[active and passive immunity]
Naturally acquired passive immunity
-Natural because it happens during pregnancy as antibodies move from the mothers bloodstream to the bloodstream of the fetus
-the antibodies can also be transferred from a mothers breastmilk
-during infancy, these antibodies provide temporary protection until childhood
[active and passive immunity]
Artificially acquired passive immunity
-an immunization that is given in recent outbreak for emergency situations
-this immunization provides quick and short-lived protection to disease by the use of antibodies that can come from another person or animal
[WBC]
Dendritic cells
-dendritic cells present antigens (foreign particles) to T cells
[WBC]
Neutrophils
-neutrophils are short-living phagocytes that respond quickly to invaders
[WBC]
Basophils
-basophils alert the body of invasion
