excretion Flashcards
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
