tutorial one Flashcards
what is pus
a purulent exudate that is rich in neutrophils and the debris of dead cells and microbes
what are the 4 steps of the journey of white blood cells from the vessel lumen to the tissue
margination - when the dilation of the vessels causes more white blood cells to accumulate on the peripheries of the blood vessel
rolling - attachment of the leukocytes to the endothelium mediated by the weaker selectins before strongly binding to adhesins closer to the site of injury itself.
diapedesis - transmission of the cell across the endothelial membrane layer to the tissue site
chemotaxis - traveling through the tissue to the site of injury, following chemokine signals
why are interactions of cells with the selectins weak
the selectins are expressed all other the endothelium of the blood vessels. we want the white blood cell to be able to travel to the site its needed, so the bonds are easily broken up by the flow of blood inorder to carry the WBC to the site its needed.
these exist so that the WBC can be slowed so then it can bind more solidly to the integrins at the injured site.
whats the neutrophil extracellular trap
NETs are extracellular fibrillar networks that concentrate antimicrobial substances at sites of infection and trap the microbes thus helping prevent their spread. the trap is a viscous network of nuclear chromatin.
what is necrosis
it is a pathological process that is a consequence of severe tissue injury
what is coagulative necrosis
necrosis where the architecture of the dead tissue is well preserved. the necrotic debris are broken down by lysosomal enzymes
ishcemia will lead to this type of necrosis.
what is liquefactive necrosis
digestion of dead cells and tissue resulting in the formation of a viscous liquid. this happens during hypoxic death within the central nervous system
what is caseous necrosis
this is often in the foci of infection for Tuberculosis. it is cheese like in appearance. there are the lysed cells within a distinctive boarder of lymphocytes
