Phagocytosis, Complement, Oedema Flashcards
Name phagocytic cells
neutrophils, macrophages, dendritic cells, B lymphocytes
What are the 6 main types of lysosomes?
nucleases, proteases, glycosidases, lipases, phosphatases, sulphatases
Explain how oxygen dependent killing works
phagocyte oxidase in membrane of phagolysosome generates oxygen radicals. 1 electron is taken from NADPH, added to oxygen, partially reducing it. This oxygen radical generates hydroxyl radicles + H peroxide. This generates hypochlorite which is the active ingredient of bleach.
What is opsonisation?
Labelling of cell for more efficient destruction by the immune system
How is the classical complement pathway activated?
C1 activated when binding to Ab-Ag complex
How is the alternative complement pathway activated?
C3b activated when it binds to Ag such as a bacterial cell wall
Explain how a membrane attack complex is formed
C3 cleaved to C3b + C3a. C3b remains bound to complex at surface of microorganism. C3b activates next step + is a good opsonin. C3a diffuses away + acts as chemotactic factor + inflam paracrine. C5 cleaved to C5b + C5a. C5b remains bound to complex on surface. C5a diffuses away and acts much like C3a. C6, C7, C8 bind to growing complex. C9 bind complex, elongated molecules = circle with large hole in middle = membrane attack complex (MAC), pierces membrane = lysis (microbe) or apoptosis.
What is oedema?
accumulation of excessive amount of watery fluid in cells, tissue, serous cavities, can pit
How do you define lymphoedema?
swelling (especially in subcutaneous tissues) from obstruction of lymphatic vessels or lymph nodes and accumulation of large amounts of lymph in the affected region, does not pit due to fibroblast formation that gives structure
How can heart failure result in oedema?
Pooling blood in R ventricle due to ventricle not pumping properly will then go back into circulation, pooling in the L ventricle can cause pulmonary oedema, more fluid in the veins = increased pressure = fluid moves out of veins = oedema
What is the arteriolar capillary hydrostatic pressure, venular capillary hydrostatic pressure and blood colloid oncotic pressure?
35, 15, 25 mm Hg respectively
What could cause swelling down one side?
obstruction of lymph, DVT, osteoarthrosis so not using muscle so not pumping lymph
What causes skin staining?
Venous hypertension = Capillaries under high pressure, rip open, RBC seep out, phagocytosed = ROS and lysosomes, iron in the haemoglobin oxidised to ferric oxide = rust = colouring of leg
Explain starling forces
govern passive exchange of water between capillary microcirculation + interstitial fluid. Forces determine direction of net water movement between 2 diff compartments + determines rate of water exchange. Depends on hydrostatic pressure gradient (higher = arteriolar, lower = venular), oncotic pressure gradient, vascular permeability
