excretion Flashcards
(23 cards)
excretion
removal of excess metabolic waste from the body
products that need to be excreted
CO2, nitrogen and urea, bile pigments
why does waste need to be excreted
-metabolic products can act as inhibitors
- build up of toxins can be fatal
structure of liver
Made of hepatocytes
-hepatic artery (oxygenated blood to liver)
-hepatic vein (deoxygenated blood back to heart)
-hepatic portal vein (nutrients from food)
-bile duct (runs out of liver, bile to gall bladder)
sinusoid
where hepatic artery and portal vein mix
metabolic functions of liver
-storage of glycagon
-synthesis of bile
-synthesis of RBC in fetus
-storage of vitamins
-detoxification of alcohol/drugs
detoxification of alcohol
ethanol (ethanol dehydrogenase) —–> ethanal ethanal dehydrogenase)—–> ethanoic acid —-> acetyl CoA
-at each stage NAD is being reduced to NADH
Ornithine cycle
ornithine + NH3 & CO2 (water out)–> citruline + NH3 (water out) —> arginine + water to make UREA ,cycle continues back to ornithine
Deamination
amino acid +O2 —> keto acid + ammonia
osmoregulation
hypothalamus (gland)
-osmoreceptor cells crenate if water is lost
-activates neurosecretory cells
-causing ADH to be released
-aquaporins form on collecting duct (kidney)
-water therefore reabsorbed back into blood
-(ADH then broken down as wp would be too high in blood)
glomerulus
network of blood vessels in the kidney
-glomerular filtrate happens
3 layers endothelial cells, basement membrane, podocytes
proximal convoluted tubule
reabsorbing most of the glucose, amino acids back into blood from the ultrafiltrate
loop of henle
descending limb- absorbing water back into blood
-as medulla is salty
ascending limb- absorbing NaCl back into blood
-impermeable to water
distal convoluted tubule
more sodium and chloride ions reabsorbed into blood
-whereas H+ and K+ ions are secreted into DCT
collecting duct
aquaporins form to allow reabsorbtion back into blood if water potential is low
kidney failure
failure if filtration rate is below 15cm3min-1
-proteins in urine indicate filtration is damaged
treatments to kidney failure
kidney transplant, renal dialysis
renal dialysis
-haemodialysis
-peritoneal
haemodialysis
blood from artery or vein is passed into a machine containing an artificial dialysis membrane
-waste removed
-bubbles removed before blood is returned to body as bubbles can cause stroke
-happens 2/3 times a week
peritoneal dialysis
dialysis membrane is bodys own abdominal membrane (peritoneum)
-implant a permanent tube
-solution poured through tube and solution collects waste and is drained
-can do at home
kidney transplant
+improved quality of life
+cheaper
-risk of rejection
-long wait for donor
-succeptible to infections
causes of kidney failure
-infection
-heart disease
-hypertension
-diabetes ( too much salt)
Urine can be tested for :
pregnancy (hcg)
diabetes (glucose)
alcohol
