Lecture 23

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Name the four animal defence systems.
 Nonspecific Defences • Specific Defences: The Immune System • B Cells: The Humoral Immune Response • T Cells: The Cellular Immune Response
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Name the two general types of defence mechanisms.
 Nonspecific defences, or innate defenses, are inherited mechanisms that protect the body from many different pathogens. § Specific defences are adaptive mechanisms that protect against specific targets.
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Name components of the defence system.
• Lymphoid tissues (thymus, bone marrow, spleen, lymph nodes) are essential parts of the defence system.
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What is lymph?
• Lymph consists of fluids that accumulate outside of the bloodstream in the lymphatic system
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What is the lymph system?
• The lymphatic system is a branching system of tiny capillaries connecting larger vessels.
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Name and describe the two main groups of white bloods cells.
Phagocytes engulf and digest foreign materials. • Lymphocytes are most abundant. There are two types: B and T cells
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What are the two types of lymphocytes?
• T cells migrate from the circulation to the thymus, where they mature. • B cells circulate and also collect in lymph vessels, and make antibodies.
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Name of types of proteins that defend against disease.
Antibodies, Tcell receptores major histocompatibility complex and cytosines.
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What do antibodies and tcell receptors do?
Antibodies, secreted by B cells, bind specifically to certain substances. § T cell receptors are cell surface receptors that bind nonself substances on the surface of other cells.
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Descibe MHC and Cytokines.
Major histocompatibility complex (MHC) proteins are exposed outside cells of mammals. These proteins help to distinguish self from nonself. § Cytokines are soluble signal proteins released by T cells. bind/ alter the behavior of target cell
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List 6 no specific defences.
skin, flora on surface body (bacteria and fungi). lysozyme which attacs the cell walls of many bacteria. (in tears, nasal mucus saliva) Mucus and Cilia - repsiratory ystem Hydrochloric acid+protease in the stomach bile salts - small intestine
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What do antimicrobial complement proteins do and where are they found?
20 antimicrobial complement proteins in veterbrate blood.  They attach to microbes, helping phagocytes recognize and destroy them. § They activate the inflammation response, attract phagocytes to site of infection and lyse invading cells.
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What are interferons?
• Interferons are produced by cells that are infected by a virus. • They increase resistance of neighboring cells to infections by the same or other viruses.
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Describe four types of phagocytes.
§Neutrophils attack pathogens in infected tissue.Monocytes mature -->macrophages, live longer and consume larger numbers of pathogens than neutrophils.  Eosinophils kill parasites, i.e worms, that r coated with antibodieDendritic cells highly folded.
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Describe dentric cells?
Dendritic cells have highly folded plasma membranes that can capture invading pathogens.
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What are natural killer cells and what do they do?
 Natural killer cells are a class of nonphagocytic white blood cells They can initiate the lysis of virus-infected cells and some tumor cells.
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Describe first three points inflammatory response.
1. role dealing w/ infection + tissue damage. 2. mast cells+wbc's called basophills release histamine triggers inflamation (tissues leaky allowing plasma and phagocytes to escape tissue. complement protiens attract phagocytes Neutrophills > monocytes
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Describe last three points.
monocytes > macroThe macrophages engulf invaders and debris and are responsible for most of the healing. • They produce several cytokines, which may signal the brain to produce a fever. • Pus, composed of dead cells and leaked fluid, may accumulate.
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Describe first characteristics of the immune system.
Specificity: Antigens are organisms/molecules that are specifically recognized by T cell receptors+antibodies. sites on antigens that immune system recognizes are 'antigenic determinants /epititopes' - antigen sev dif ones.host cell> tcells specific
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Describe the second characteristic.
2. Diversity: q It is estimated that the human immune system can distinguish and respond to 10 million different antigenic determinants.
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Describe the third.
 3. Distinguishing self from nonself: q Each normal cell in the body bears a tremendous number of antigenic determinants. It is crucial that the immune system leave these alone.
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Describe the fourth
§ 4. Immunological memory: q Once exposed to a pathogen, the immune system remembers it and mounts future responses much more rapidl
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Describe the two repsonses against inavders.
The immune system has two responses against invaders: The humoral immune response and the cellular immune response. • The two responses operate in concert and share mechanisms.
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Describe the humoral immune reponse.
involves antibodies that recognize antigenic determinants by shape and composition. • Some antibodies are soluble proteins that travel free in blood and lymph. Others are integral membrane proteins on B cells. •
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Describe the first two stages of humoral reponse.
pathogen invades body, may be detected by + bound by a B cell whose membrane antibody fits 1 of its potential antigenic determinants.  This binding activates B cell, - makes multiple soluble copies of an antibody with same specificty as membraneAB.
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Describe the cellular immune reponse.
able to detect antigens that reside within cells. • It destroys virus-infected or mutated cells. • Its main component consists of T cells. • T cells have T cell receptors that can recognize and bind specific antigenic determinants.
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Is the nmber of any b cell high or low?
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What happens when a b cell binds to an antigen?
the B cell divides and differentiates into plasma cells (which produce antibodies) and memory cells. • Thus, the antigen “selects” and activates a particular antibody-producing cell.
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What does activated lymphocytes (Bcell or tcell produce?)
two types of daughter cells. Effector B cells, called plasma cells, produce antibodies. • Effector T cells release cytokines. • Memory cells live longer and retain the ability to divide quickly to produce more effector and more memory cells.
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What the repsonse called when body encontours an antigen for the first time?
a primary immune response is activated
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What happends when it appears again?
a secondary immune response occurs. This response is much more rapid, because of immunological memory.
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What is artifical immunity?
acquired by the introduction of antigenic determinants into the body. • Vaccination - inoculation w/ whole pathogens that have been modified so they cannot cause disease. Immunization is inoculation w/ antigenic proteins, pathogen fragments/ antigen
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What do both immunization and vaccination require?
 Immunization and vaccination initiate a primary immune response that generates memory cells without making the person ill. The body is tolerant of its own molecules, even those that would cause an immune response in other individuals of the same spe
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What does failure to tolerate molecules that cause immune response in other species cause?
• Failure to do so results in autoimmune disease.
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What are B cells a basic commponent of and how does it differentaite?
cells are the basic component of the humoral immune system. • For a B cell to differentiate into a plasma cell, it must bind an antigenic determinant. •
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what is cellular divisom amd differentiation of the B cell triggered by?
 Cellular division and differentiation of the B cell is stimulated by a signal from the activated helper T cell (TH). • Activated B cells become plasma cells and memory cells.
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What are immunoglobins.
• Antibody molecules . • All are composed of one or more tetramers consisting of four polypeptide chains. • Two identical light chains and two identical heavy chains make up the tetrameric units.Disulfide bonds hold together
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What do light and heavy chains on each pepetide have?
variable + Constant regions which are similar amoung immun immunoglobulins and determine the class of the antibody.
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Describe the variable regions
regions thatdiffer in the amino acid sequences at the antigen-binding site and are responsible for the diversity of antibody specificity
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whats the bivalent
Each tetramer has two identical antigen-binding sites, making the antibody bivalent. • The enormous range of antibody specificities is made possible by the recombination of numerous versions of coding regions for the variable regions
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What are the five immunoglobin classes based on?
The five immunoglobulin classes are based on differences in the constant regions of the heavy chain.
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What is the similarities between t-cell and b-cell receptors.
 T cells, like B cells, possess specific surface receptors. • The genes that code for T cell receptors are similar to those for immunoglobulins. • T cell receptors also have constant and variable regions.
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Whats a difference between antibodies and tcell receptors?
• A major difference between antibodies and T cell receptors is that T cell receptors bind only to an antigenic determinant that is displayed on the surface of an antigen-presenting cell.
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what is the display of antigens on antigen presenting cells
major histocompatibility complex (MHC) gene products. • Also known as human leukocyte antigens (HLA) in humans and H-2 proteins in mice.
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What protein is present on the surface of every nucleated cell?
• Class I MHC proteins are present on the surface of every nucleated cell in animals and present antigens from intracellular pathogens such as viruses.
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What proteins are present on antigen presenting cells?
 Class II MHC proteins are present on Antigen Presenting Cells and present antigens processed in the phagocytic pathway
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what do class I and class || T cells present to tcells?
Processed antigen
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what happens to foreign protien molecules detected by tcell.
are bound by class I MHC molecules and carried to the plasma membrane, where TC cells can check them. • If a cell has been infected by a virus, or has mutated, it may present protein fragments that are not normally found in the body. • If a TC cell
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Card 2


Name the two general types of defence mechanisms.


 Nonspecific defences, or innate defenses, are inherited mechanisms that protect the body from many different pathogens. § Specific defences are adaptive mechanisms that protect against specific targets.

Card 3


Name components of the defence system.


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Card 4


What is lymph?


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Card 5


What is the lymph system?


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