RESPONSE TO INFECTION Flashcards
NON-SPECIFIC (14 cards)
What are the types of response to infection? (2)
-non-specific inflammatory response
-specific inflammatory response
what is a non-specific inflammatory response? (1)
this infection response is the same for all pathogens
what is inflammation? (1)
the rapid, localised response of our tissues to damage.h
how is inflammation triggered? (1)
it is triggered when damaged cells release ‘alarm’ chemicals, including histamine and prostaglandins.
what effect don chemical released from damaged cells have on the wounded area? (3)
-the smooth muscles of arterioles relaxes, increasing blood flow to that area
-cells in the walls of capillaries draw away from one another (diapedesis) so that the capillaries become ‘leaky’, forming more tissue fluid than usual. this extra tissue fluid causes local swelling of the infected area.
-sensory neurones become more sensitive
what is diapedesis? (1)
a localised response to damage in which cells lining capillaries move apart creating gaps, through which plasma can leave the capillaries. this leads to the local production of increased volumes of tissue fluid (oedema). it also allows phagocytes to leave the capillaries.
what is the initial outcome to the chemicals released by damaged cells in the wounded are? (1)
the volume of blood in the damaged area is increased and we suffer local oedema.
what does the increased blood flow in the wounded area cause? (1)
results in more leucocytes being brought to the infected area, some of these are macrophages and neutrophils which are phagocytic leucocytes. These engulf and destroy foreign cells.
what are phagocytes aided by in order to distinguish foreign cells(1)
a group called complement proteins
what effect doe complement proteins have? (3)
-attracting more phagocytes to the site of infection
-binding to, and forming pores in, the surface membrane of foreign cells, leading to the lysis of these cells
-binding to surface membrane of a phagocyte to a foreign cell.
what are complement proteins called? (1)
these proteins are called opsonin’s and the process they invoke is opsonisation
what are the stages of phagocytosis of a bacterium? (1)
1) phagocytic leucocyte detects presence of bacterium
2) bacterium becomes attached to receptor molecules on the cell surface membrane of leucocyte
3) trapped bacterium engulfed into a food vacuole in the cytoplasm of leucocyte
4) lysosomes in the cytoplasm fuse with the vacuole and discharge hydrolytic enzymes
5) bacterium is broken up into its constituent molecules, and these are dispersed into the cytoplasm
6) ‘rubbish collecting’ leucocytes are distributed widely in the body
what is triggered by cells when they are infected by a virus? (1)
a group of cytokines, called interferons are released by cells infected by viruses.
what are the function of interferons? (1)
they bind to neighbouring healthy cells and trigger synthesis of antiviral proteins, as a result viral replication is slowed or haltered.
