15) Excretion Flashcards
How and why does liver breakdown excess amino acids
Nitrogenous sub cannot be stored
Removed to form ammonia in deamination.
Organic acids respired to give ATP or converted to carb + glycogen
Through ornithine cycle, create urea.( ammonia + co2)
How and why does liver break down other substances in the blood
via detoxification
alcohol - damage cells , into ethanal. excess lead to cirrhosis
paracetamol - kidney and liver failure
insulin - prob ww sugar levels
What are the different vessels in the liver and role
Hepatic aertery Oxygenated blood to liver
Hepatic vein takes deoxygenated blood away from liver
Hepatic portal veinblood from duodenum in small intestine
Describe the structure of the liver
Rows of hepatocytes
Hepatic artery and hepatic portal vein connect to central vein by sinusoids.
Blood run thru sinusoid with harmful sub
Kupffer cells remove bacteria and break down old rbc
Hepatocytes produce bile and screte into bile canaliculi drains into bile duct
Describe the structure of the kidneys
renal cavity to capillaries in cortex , long tubules , medula ,ereter to urethra
How does ultrafiltration occur
Blood from renal artery enter afferent arterioles in cortex
Split into glomerulus - bundle of capillaries in a bowman’d capsule
Filtered blood away in efferent arteriole
create high pressure so small molecules and liquid pass into capsule
Describe selective reabsorption and its adaptations of the kidney
Along proximal convoluted tubule and through loop of henle and distal convoluted tubule
microvilli-provide large surface area
useful subs - glucose,amino acids , vitamins ,sald by active transport or facilitated diffusion
urea via diffucsion
WHat does urine not contain why?
Proteins blood cells - too big to be filtered out of blood
Glucose,amino acids and vitamins - actively reabsorbed back into the blood.
Explain Countercurrent Multiplier Mechanism in the loop of henle
1) Top of ascending limb , NA+ and Cl- ions pumped out into medulla. Creates low water potential in the medulla.
2) Loweer water potential in the medula than the descending limb , water moves out of the DLimb so filtrate is more concentrated. Water is reabsorbed into the blood through capillary network
3) At bottom of the ascending limb, ions diffue out into the medulla , further decreasing the water potential.
4) Low water potential in medula cause water to move out of collecting duct by osmosis, water reabsorbed into the blood
Longer ascending linb , more ions pumped out , low water potential , more water moves out.
In hot areas, longer loops , save as much water
How is water reabsorption controlled by hormones
Monitored by osmoreceptors
Stimulate low water potential , posterior pituitary gland release ADH .
DCT and collecting type is more permeablt to water.
Water is reabsorbed
What can cause kindey failure
Rate lower than avg GFR
Kidney infection - inflammation , damage cells , interfere filteing or reabsorption
High blood pressure- Damage glomeruli, Damage capilaries , allow large molecules to get into the uring
What problems can kidney failure lead to
Waste product build up - weighloss + vomiting
Fluid accumilate - partsof body swells
Imbalance of electrolutes - too acidic , brittle bones , water retention
Long term - anaemia
Describe Haemodialysis
Pass dialysis machine
Across partially permeable memberane and dialysis fluid..
sesions 3-5 hours.
sessions every week
-waste products can build up in blood
Describe peritoneal dialysis
Dialysis fluid through a tube into their abdominal cavity.
Waste products diffuse across peritoneum .Fluid is drained out
-Either at home or several times throughout the dayor overnight
-Risk of infectionand doesn’t have any dialysus-free days.
Less risky than major surgery.
Describe Kidney Transplant
Neww kidney replace damged kindey
-Person with the same blood and tissue type.
-CHeaper to give , more convenient
-Undergo major operation , risky , immune system may also reject transplant , drugs to supress it
