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The Immune System - Coggle Diagram
The Immune System
Adaptive Immunity
24.3
Adaptive immunity is a set of defenses found only in vertebrates that is activated in response to specific pathogens.
Any molecule that elicits an adaptive immune response is called an antigen. They are nonself molecules that protude from pathogens or other particles, such as viruses and bacteria
When the immune system detects an antigen, it responds with an increase in the number of cells that either attack the invader directly or produce antibodies.
An antibody is an immune protein found in blood plasma that attaches to one particular kind of antigen and helps counter its effect.
Adaptive immunity is usually obtained by natural exposure to antigens, but it can also be achieved by vaccination. The immune system is confronted with a vaccine composed of harmless variant or part of a disease-causing microbe.
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24.4
The lymphatic system is involved in both innate and adaptive immunity. It consists of a branching network of vessels, numerous lymph nodes
The lymphatic vessels carry a fluid called lymph, which is similar to the interstitial fluid that surrounds body cells but contains less oxygen and fewer nutrients.
24.5
Lymphocytes originate from stem cells in the bone marrow. Some immature lymphocytes continue developing in the bone marrow to become specialized as B lymphocytes
When a B cells and T cells develop, the cell differentiate from other cells by synthesizing many copies of a membrane. Antigen receptors stick out from the cell's surface, capable of binding one specific type of antigen.
One of the adaptive responses produced by B cells is the humoral immune response which defends primarily against bacteria and viruses present in body fluids. B cells secrete free-floating antibodies into the blood and lymph.
The type of adaptive immunity, produced by T cells is the cell-mediated immune response, which defends against infections inside body cells. It results from the action of defensive T cells, in contrast to the action of free-floating defensive antibody proteins produced by B cells, it destroy the body cells infected with bacteria or virus.
Other immature lymphocytes migrate to the thymus, a gland above the heart, to become specialized as T lymphocytes or T cells
24.6
Both the humoral and cell-mediated immune responses are initiated when lymphocytes recognize antigens. B cells bind antigens directly, while T cells require an additional step for recognition.
A small surface-exposed region of an antigen is called an epitope. Antigen receptors on B cells as well as antibodies recognize and bind to the epitope.
The specific region on an antigen receptors or antibody that recognizes an epitope is the antigen-binding site. The binding site and epitope have complementary shapes that fit together like a lock and key.
24.7
The humoral and cell-mediated immune response both defend against a wide variety of antigens through a process known as clonal selection.
When an antigen enters the body, it activates only a small subset of lymphocytes that have receptors specific for the antgen.
The selected cells multiply into clones of short-lived effector cells specialized for defending against that antigen and into memory cells, which confer long-term immunity.
Some of these cells, called effector cells, act immediately to combat infection, while others known as memory cells ready to help activate the immune system upon subsequent exposure to the antigen.
24.8
The primary immune response occurs the first time a particular antigen enters the body and selectively activates lymphocytes.
When memory cells produced during the primary response are activated by a second exposure to the same antigen. They initiate the secondary immune response.
The primary response does not start right away; it usually takes several days for the lymphocytes to become activated by antigen X and form clones of effector cells.
The second exposure to antigen X triggers the secondary immune response. The secondary immune response starts in a few day, produce higher levels of antibodies and is more prolonged.
24.9
When most people in a population are vaccinated, a disease cannot spread.
Community referred as herd immunity, is the rationale behind state-mandated vaccinations for children in public schools.
24.10
Antibodies do not kill pathogens. Instead, antibodies mark a pathogen by combining with it to form an antigen-antibody complex.
Weak chemical bonds between antigens and the antigen-binding sites on antibodies hold the complex together. Once an antigen is marked in this manner, other components of the immune system destroy it.
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24.11
Active adaptive immunity to s specific pathogen can be gained through a natural infection or through vaccination.
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24.12
The anti-body producing B cells or the humoral immune response make up one arm of the adaptive immune response network. It identifies and helps destroy invaders that are in our blood, lymph, or interstitial fluid.
It is the cell-mediated immune response produced by cytotoxic T cells that battles pathogens that have already entered the body.
A type of T cells called helper T cell triggers both the humoral and cell-mediated immune responses. Instead, signals from it initiate the production of antibodies that neutralize pathogens and activate the cytotoxic T cells that kill infected cells.
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24.13
Cytotoxic T cells recognize infected body cells through a self-nonself complex and then trigger the cell's death.
24.14
AIDS results from infection by HIV. Although HIV can infect a variety of cells, it most often attack helper T cells.
HIV destroys the helper T cells, compromising the body's defense
Immune system impariment makes AIDS patients susceptible to cancers and opportunistic infection, infections that can be normally be fought off by a person with health immune system.
24.15
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24.16
The ability of lymphocytes to recognize the body's own molecules to distinguish self from nonself- enables our adaptive immune response to battle foreign invaders without harming healthy cells.
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Innate Immunity
24.1
Pathogens - Bacteria, fungi,
viruses, and other disease-causing agents
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24.2
Inflammatory response, a major component of innate immunity. The main function of the inflammatory response is to disinfect and clean injured tissues.
- The bacteria activate macrophages, which produce signaling molecules that increase local blood flow
- Histamine was released to induces neighboring blood capillaries to dilate and become leaky. Fluid passes out of the leaky capillaries into the affected tissues
The neutrophils that migrate into the area engulf bacteria and the remains of any body cells killed by them or by the physical injury
Inflammation is a natural defense. However, chronic inflammation- the persistence of inflammatory components for abnormally long periods can be harnful.