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2nd line of defence
Question | Answer |
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4 main categries | phagocytosis. inflammation. fever. defensive moluecules |
phagocytes | white blood cells (leukocytes) that move throughout the tissue. no fixed shape, can squeeze thru tissue spaces, consume pathoogens, alert other immune cells thru cytokines |
types of phagocytes | neutrophils - circulate thru the blood macrophages - reside in tissue dendritic cell |
how do phagocytes work | engluf pathogens via endocytosis, then destryed by enzyme action macroophagees/monocytes are large phagocytic cells that engluf & destroy microbes, cell debris & dying cells. important activate lymphocyte - apcs |
neutrophil role in inflammation | - first to move to tissue to destroy pathogen phagocytosis - chemically attracted to the area very important in killing pathogens inside cells |
dendritic cells | highly spcialised to take up pathoogens at infection site & transfer to lymph organs to present antigen to t lymphocytes dedicated apcs |
inflammation symptoms | redness, swelling, pain & heat |
mast cells | least abundant & smallest WBC found in tissue nuclus is u/s shaped few coarse granules - contain histamine & heparin |
2 initiating inflammation | - mast cells detect damaged tissue and secret histamines - histamines increase capillary permeability - increase blood flow to the area - also release heparin - reduces clotting in underlying tissue to enhance blood flow |
3 phagocytosis - swelling | phagocytes (neutrophils) attracted to area enter damaged tissue thru spaces in capillary wall phagocytes & macrophages consume pathogens fluid also leaks causing swelling |
4 chemical signaling | phagocytes and other cells secrete cytokines these speed up tissue repair |
cytokine | protein that signal local immune responses. 1 specific form is interferons - released by infected cell(virus) increase resistance of surrounding cells |
clotting & repair | platelets secrete proteins that aid in clotting at wound site |
redness | caused by increased blood flow due to vasodilation blood flow slows at wound site |
swelling | fluid from blood leaks out of capillaries swelling the area |
heat | additional blood flow to the area makes it fl warmer radiates heat |
pain | extra fluid and build up of cellular material stimulates pain receptors chemicals also stimulate receptors induce protective mechanism |
fever | increase in body temperature designed to speed up body's cellular responses & inhibit pathogenic reproduction or functioning if it gets too high, body proteins affected (denature) and can lead to death |
fever - chemically | tissue & some pathogens release pyrogens - eg interleukin 1 these are detected by the hypothalamus which responds by increasing heat production & retention |
fever 'feedback loop' | pyrogen released, detected by hypothalamus, set point raised, shivering to generate more heat, feel cold & adjust behaviours, body temp rises. pyrogen reduced feel too hot & sweat |
complement proteins | plasma proteins that when activated can cause cellular lysis in pathogenic cells and enhance the activity of antibodies boost inflammatory response |