ch 21 the immune system part 1 Flashcards
immunity
the ability of the body to defend itself against unfamiliar microorganisms
immune cells use what to distinguish between cells as self or non self
antigens
immunity has 2 systems
innate and adaptive
innate defenses
nonspecific defense mechanism that is initiated very quickly in the body (does not search stuff out) it is built in when anything enters
how do the physical barriers and certain cells initially encounter pathogens
they prevent pathogen entry both physically and cellularly
2 defense lines of innate defenses
surface barriers and cells/chemicals
surface barriers
physically prevent pathogens from entering body, skin and mucous membranes
skin as a surface barrier
keratin- tough protein resistant to weak acids and bases and enzymes, it is tough and dry so bacteria cannot survive and reproduce
acid mantle- sweat and sebum on skin surface is a little acidic, bactericidal in nature inhibits growth of bacteria
mucous membranes as a surface barrier
line all body cavities that open to exterior, such as repsirotry digestive and reproductive tracts
the 6 mucous membranes
mucus- traps microorganisms and is thicker
nasal hairs- traps micro organisms in nasal cavity
cilia- takes mucus with the microorganisms and propels it away from nasal and respiratory
acid mantle- stomach secretes 1.3-3 pH level and vagina also prevents bacteria and fungal growth
tears/saliva- cleanses eyes and mouth with lysozyme (which destroys bacteria)
urine- acidic in nature, physically removes bacteria with pee
cellular and chemical defenses
used when the surface barriers are breached, sometimes the surface gets damaged. have pattern recognition receptors, which are proteins found on cells of innate immune system
pattern recognition receptors
proteins found on innate immune system cells, recognize harmful substance say presence of a shape of a molecule on pathogen but not on normal human cells.
natural killer cells (NK)
target cancerous and virus infected cells, non specific, do not phagocytize, rather induce apoptosis, release perforin and creates pores
non specific means
does not look for a specific cell, destroys anything not recognized
how is apoptosis dif from lysis and why does that help prevent viral infection
apoptosis is programmed cell death, lysis is a cell with so much water it bursts. viruses infected body cells by hijacking cell machinery to reproduce and spread, lysis helps virus spread rather than apoptosis. apoptosis makes Sure nothing reproduces
phagocytes
neutrophils and macrophages example, these cells engulf and destroy pathogenic cells or substances
neutrophils vs macrophages on phagocytosis
neutrophils- become phagocytic upon encountering pathogen, can use defenses to pierce through pathogen membrane and induce lysis
macrophages- large and voracious, with free and fixed to get rid of pathogens
free vs fixed macrophages
free- capable of travel through tissue tp search for pathogens, active
fixed- permanent location in tissue of a particular organ, waits for substances to flow past until something won’t belong
why is phagocytosis not always successful
pathogens may be resistant to phagocytosis lysosomes, or bacteria surrounded by a capsule, or pathogens can be too large for phagocyte to ingest.
if pathogen is resistant to phagocytic lysosome…
causes release of large free radicals, produces oxidizing chemicals
if some bacteria is surrounded by a capsule…
phagocyte cannot recognize Infectious organism, so opsonins occur. they bind to pathogen surface and allow phagocytes to recognize and bind pathogen easily ex- antiobodies and complement
pathogens can be too large for phagocyte to ingest …
phagocytes will release toxic chemicals to surrounding ECF fluid, however this has. downside… all digestive enzymes go to ECF, causing toxins to be in healthy body cells not just viral but better than nothing
inflammation
nonspecific localized response to tissue injury, uses cells and chemicals . symptoms- redness, heat, swelling, pain, impaired function only around the injury
benefits of inflammation
prevents spread of pathogens to the non damaged tissue, disposes of cell debris and pathogens, alerts immune System, allows repair to occur
inflammatory chemicals released at injury site
histamine- release by basophils locally, causes vasodilation and increases capillary permeability
kinins- derived from plasma protein kininogen, causes vasodilation and attracts leukocytes while inducing pain
prostaglanins- generated by neutrophils, basophils, mast cells causing vasodilation and neutrophil chemotaxis while inducing pain
4 step mobilization process of inflammation before beginning to defend the body undergone by neutrophils and macrophages
leukocytosis, margination, diapedesis, chemotaxis
leukocytosis in inflammation
step 1, increase in number of WBC to blood, has leukocytosis inducing factors which attracts more
margination in inflammation
phagocytes cling to inside of endothelial wall of capillaries, preventing phagocyte from being washed away
diapedesis in inflammation
cells clling too wall will squeeze between cells of endothelial wall. important for immune system functioning and body defense because the phagocyte will flatten itself and squeeze through, allowing WBC to actually leave and go. if WBC was restricted, alll pathogens would have to go into blood supply so this is great, prevents closer pathogens to blood
chemotaxis in inflammation
inflammatory chemicals are chemotactic agents, phagocytes and WBCs use positive chemotaxis to locate injury site.
positive chemotaxis
WBC senses inflammatory chemical, travels, stronger concentration of that chemical then closer WBC will get
which cell arrives first to the site of inflammation
neutrophils, then monocytes bc they will take a bit to form macrophages. macrophages will replace the neutrophils that are worn out, and dispose of cellular debris
antimicrobial proteins
proteins that can attack microorganisms,s directly or interfere with their reproduction
interferons, a type of microbial protein
released by cells infected by a virus to protect surrounding non infected cells. diffuse into cell and noninflected cells will synthesize proteins to degrade viral DNA. OVERALL warn the healthy cells there is an impostor.
complement ,a type of microbial protein
group of 20 plasma proteins synthesized by liver. normally inactive in healthy blood, it amplifies immune system response. activates massive release of inflammatory chemicals, which complements innate defenses. stimulates phagocytes to clear debris and damaged stuff, and can lyse and kill several bacteria and other cell types.
fever
body wide systemic response to pathogens, abnormally high body temp. normal body temp is 98.6, low grade fever 99-100.4 and fever of 103 plus is very concerning
pyrogens
circulate up to hypothalamus, reset it to higher temperature.
benefits of fever
causes spleen and liver to store more iron, bacteria cannot use it for growth. fever also increases metabolic rate of tissue cells, speeding up repair.
adaptive defenses
slower than innate, but more specific. gets rid of what does not belong. cells here must be exposed to an antigen before they can react, 1 lymphocyte looks for 1 antigen
humoral immunity
antibodies present in body fluids, humors. circulate freely after release, mark and temporarily inactivate target cells for destruction. B CELLS
cellular immunity
when lymphocytes directly defend the body, can either kill target cels directly or release chemicals that increase inflammatory response and activative macrophages T CELLS
adaptive defenses differ from innate defenses with these 4 things
adaptive uses lymphocytes, more specific bc identifies pathogens, systemic and not restricted to infection site, and adaptive has memory previously identified pathogens can be identified fast before infection can even get the chance to occur
antigens
any substance that can mobilize the adaptive defense system
immune system recognizes self vs non self by binding to what
antigens
complete antigens are
immunogenic, stimulates lymphocyte proliferation and generates immune response. reacts with lymphocytes and antibodies. any foreign molecule can react as a complete antigen (protein, polysach, lipid, nucleic acid)
hapten or incomplete antigens are
can only carry immune response when attached to protein carrier. if it was bound to a carrier protein, immune system may recognize it as non self. if no protein carrier attached, no immune response. ex, poison ivy and pet dander or detergents.
how do antigens begin their adaptive defenses
lymphocytes and antibodies must bind to antigenic determinants on antigen surface. one antigen can have many determinants on its surface, so many antibodies can interact with one antigen. determinants may have ,many shapes n forms, body antibodies and lymphocytes can only recognize one antigenic determinant
self antigens (MHC proteins)
self antigens that belong to your own body, on individual basis. we produce it ourself.
major histocompatability complex (MHC) proteins
class of glycoprotein on cell surface, must be there for self antigen to work. genes code for this class of proteins, unlikely that 2 indivudals have same gene set. MHC protein + self antigen = no immune response.
why are the MHC proteins necessary for immune system function
T lymphocytes can’t interact with any antigen unless it is bound to MHC protein.
