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A&P EXAM 2 - CH 21
Terms in this set (29)
what is the difference between innate and adaptive immunity?
innate: you are born with it. It includes certain physical, cellular, and chemical barriers throughout the body. It is NONSPECIFIC
active: acquired immunity that develops in response to antigens. It is SPECIFIC to the antigen. Specificity is determined by B-cells and T-cells.
what are the first and second line of defense mechanisms that are generally associated with the innate immune system?
first: external body membranes
second: antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders)
describe the first line of defense against pathogens
surface barriers -- skin & mucous membranes
what distinguishes the second line of defense from the first line?
the first line is surface barriers and the second line is internal defenses
what are the importance of cells like phagocytes (macrophages & neutrophils), natural killer cells and dendritic cells?
neutrophils are most abundant phagocytes - become phagocytic on exposure to infectious material.
macrophages are chief phagocytic cells - most robust. uses its cytoplasmic extensions to pull rod-shaped bacteria toward it.
nk cells kill cancer & virus-infected cells before adaptive immune system is activated. attack cells that lack "self" cell-surface receptors. kill by inducing apoptosis in cancer cells & virus-infected cells. secrete potent chemicals that enhance inflammatory response.
dendritic cells act as messengers between the innate and the adaptive immune systems.
steps of phagocytosis
1. adherence - phagocyte recognizes & adheres to pathogen's carbohydrate "signature"
2. engulfment - pseudopods bind to & engulf particle in phagosomes
3. phagolysosome is acidified, and lysosomal enzymes digest particles
4. indigestible & residual waste is exocystosed
what happens in the end of phagocytosis?
sometimes exocytosis of the vesicle removes indigestible & residual material
according to the video that you watched, are all macrophages successful? what is an opsonin? how does it help macrophages fighting off pathogens?
not all macrophages are successful. an opsonsin is a complement protein that binds to foreign microbes. the phagocytic activity of macrophages is regulated by opsonins on pathogenic materials.
what are natural killer cells? how do they differ from lymphocytes?
natural killer cells are lymphocytes that rapidly defend against abnormal (cancer) or virus-infected cells.
describe the inflammatory response
it prevents the spread of pathogens and dead tissue, while promoting healing. macrophages, neutrophils, and dendritic cells enter the damaged area, and fibrin threads enclose the area while promoting tissue recover and circulation.
what are the 4 cardinal signs of inflammation?
redness, heat, swelling, pain
describe the 4 steps of phagocytic mobilization
1. leukocytosis - neutrophils enter blood from bone marrow.
2. margination - neutrophils cling to capillary wall.
3. diapedesis - neutrophils flatten and squeeze out of capillaries.
4. chemotaxis - neutrophils follow chemical trail
what are interferons? how are they able to prevent the spread of viruses from one cell to another?
secreted by cells infected with viruses, "warn" healthy neighboring cells
complement antimicrobial proteins
group of plasma proteins that become activated when under attack by foreign entities that enter the body
what do complement antimicrobial proteins specifically attack?
the membrane of a microbe & punch holes into to cause the cell to lysis.
what are the 3 main methods of fighting off pathogens using the complement system?
classical, lectin, alternative
stimulated by antibodies that are surrounding the target cell (either as a result of pathogen itself or due to the actions of B cells)
activated by special proteins called lectins that bind to carbohydrates on the surface of a microbe
result of spontaneous interactions between any of the complement proteins and the pathogen
why are there so many different pathways of complement system?
all three pathways converge on complement component 3 (C3). its inhibition leads to complete blockade of complement activation.
what are the 3 key characteristics of adaptive immunity?
specific - recognizes & targets specific antigens
systemic - not restricted to initial site
memory - mounts an even stronger attack to "known" antigens
portion of an antigen that is recognized as foreign
what is the difference between complete and incomplete antigens?
complete antigens have both immunogenicity and reactivity. incomplete antigens (haptens) must combine with a protein before becoming immunogenic.
what are major histocompatibility complexes? (MHC) why are they important to adaptive immunity?
group of genes that code for proteins found on the surfaces of cells that help the immune system recognize foreign substances. important because T lymphocytes can recognize only antigens that are presented on MHC proteins.
compare and contrast B and T lymphocytes
- both B and T come from red bone marrow.
- T cells mature in thymus.
- B cells mature in bone marrow.
- T cells are involved in cell-mediated immunity, whereas B cells are primarily responsible for humoral immunity (relating to antibodies)
fundamental importance of adaptive immunity
system is capable of recognizing what is self and what is foreign.
ability of the body to produce a normal immune response following exposure to an antigen
lymphocytes unresponsive to own antigens
what is the selection process that lymphocytes undergo best in?
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