Excretion Flashcards
What are the main 4 functions of the liver ?
- deamination (amino acid broken down to produce urea)
- stores glycogen
- detoxification (of alcohol)
- making bile
where does deamination occur ?
in the mitochondria of liver cells
The Ornithine cycle
produces urea and water
ammonia + co2 + ornihine = happens in mitochondira then citulline moves out of mitchondria into cytoplasm
what happens to urea produced by ornithine cycle
- urea transported to kidney to get removed
- high urea conc of blood = dec water pot of blood
- so increases water reabsorption of blood
role of hepatic artery
supplies liver with oxy blood from heart
function of hepatic vein
takes deoxy blood away from liver
what is sinusoid
where hepatic artery and hepatic portal vein join (flows towards central vein)
kupffer cells
in the sinusoids + break down bacteria
- have a larger nuclues than hepatocytes
function of hepatic portal vein
carries deoxyblood + nutrients from small intestine to liver
what is the differnece between efferent + afferent arteriole
efferent has a smaller lumen
How are Bowmans capsule and glomerulus adapted to aid ultrafiltration ? 3
- capillary endothelium has fenestrations allowing blood to flow through
- Basement membrane in BC = anything with mr greater than 69000 cannot pass through
- Podocytes in BC = contain slits
what are the 5 adaptations of PCT for selective reabsorption ?
- microvilli = to increase SA
- mitochondria = provide ATP for pumps
- Na/K pump
- folded membrane = increases SA
- co-transporter proteins for facilitated diffusion
What are the 5 stages of selective reabsorption ?
- Na+ ions actively pumped out so decreased conc inside PCT
- Na+ ions move back in down conc gradient through a co-transporter protein = carries glucose or aa as it goes through (secondary active transport)
- reduced water potential inside pct cell so water moves in by osmosis
- inc conc of glucose + aa inside pct cell so diffuses into blood in capillary down conc gradient
- larger molecules such as small proteins move in via endocytosis using ATP
what is the ascending loop of Henle impermeable to ?
- water
water reabsorption
- na+ + cl- actively trasported out of ascending limb
- ascending limb impermeable to water so it stays
- decreased water pot in medulla
- water pot in medulla lower than in descending limb so water moves out of d into m via osmosis
- bottom of ascending limb na+ + cl- diffuses out further lowering water pot in medulla
- so water from filtrate moves out of colleting duct via osmosis
- so filtrate becomes v concentrated
