excretion Flashcards
excretion
-the removal of waste products of metabolism from the body
the structure of the liver
-made from lobules
-lobules are made up of:
-hepatic artery= supplies liver with oxygenated blood from the heart for respiration. (narrower+thicker than vein)
-hepatic vein= deoxygenated blood away from the liver
-hepatic portal vein= filters out harmful substances from the blood
-bile duct=takes bile to gall bladder to be stored. surrounded by hepatocytes
-kuffer cells= remove pathogens
sinusoid= where oxygenated and deoxygenated blood mixes
- central vein
-canalicus= speace in the bile duct
function of the liver cells
- storage of glycogen
-detoxification=e.g. uses ethanal dehydrogenase, NAD is also used therefore if too much alcohol is consumed there isn’t enough NAD to break down fatty acids therefore the fatty acids and stored as fats causing fatty liver disease
-formation of urea= - deamination= removes amino acid group from molecules and produces ammonina+keto acid
-ornithine cycle=ammonia is toxic so has to be converted to a less harmful substance
-ammonia is combines with carbon dioxide to produce urea in this process
the structure of the kidney
-outer =cortex
-inner=medulla
-centre=pelvis
-made up of many nephron
-blood enters from renal artery to the afferent arteriole also has a efferient arteriole
-glomrulus
-bowmans capsule
-basement membrane which have podocytes
-proximal convoluted tubule
-loop of henle
-distal convoluted tube
- collecting duct
ultrafiltation
-The afferent arteriole has a wider diameter than the efferent artiole therefore high hydrostatic pressure is generated
-blood is filtred by the gaps in the endothelium wall of the basemnt membrane which has small pores therefore larger molecules cannot pass through
filtate= glucose,water,salts and urea
-
selective reabsorbtion
- one hundred% useful solutes like glucose,amino acids, vitamins and salts are reabsorbed by the PCT.
- sodium ions are actively transported into the blood plasma from PCT walls decreasing the water potentional therefore water follows via osmosis
- because sodium has left the proximal convulted tubule walls it is replaced by more sodium ions this time co transporting glucose and amino acids via facillated diffusion which then move into th blood via facillated diffusion
- 50% of urea is reabsorbed
-water enters by osmosis due to lowered water potential
water is also reabsorbed at the loop of henle and DCT and collecting duct
osmoregulation
-changes are detected by the osmoreceptors in the hypothalamus
- if water levels are too high = pituitary gland releases less ADH. which is transported to the kidneys in the blood. kidney therefore absorbs less water. urin will be paler colour
- if water levels too low more ADH is released
- ADH binds to complementary receptors to collecting duct
- Therefore vesicles aquaporins fse to the membranes the therefore they are more permeable to water
-more water is therefore reabsorbed and the colour of the urine is darker
effects of kidney failure
-fluid and waste products such as urea build up
assessing kidney failure
- estimation of the glomerular filtration rate is taken (GFR) it would be lower in someone with kidney failure and analysing urine sample for substances
treatment of kidney failure
-haemodialysis= Blood is passed into a machine containing an artificial dialysis membrane
-heparin is added to avoid clotting
-dialysis fluid containing the correct concentration of substances e.g. urea and mineral ions is flowing in countercurrent direction from the blood to improve efficiency of exchange
- carried out two to three times a week
- airbubbles removed before entering the body
-peritoneal dialysis= dialysis membrane is the bodys own abdominal membrane
-dialysis fluid poured into implanted tube
- kidney transplant=risk of rejection and being on immunosuppresent drugs your whole life
pregnancy tests
-hCG is produced during pregnancy
-hCG is complemnatry to and binds to mobile antibodies attached to blue heads
-forms a HCG-antibody complex
-mobile antibodies move down test sticks
-bind to immbolisd antibodies holding the blue heads in place forming a blue line due to complementary shape
- two lines= pregnancy
drugs
-urine sample taken to test substances in the blood
different barriers prsent in thre kidney for ultrafiltration
-endothelium= fenstrations’
-basement membrane-= stops the removal of large substances from the blood
-podocytes=finger-like projections to ensure the passag of substances
water reabsorption at the loop of henly
-in the accending limb sodium ions and chlorine ions are actively pumped out. the accending limb is impermeable to water
-the movement of ions cause a decrease in water potential going down the meduula
-water is removed from the decending limb
-also the water potential of tisues surrounding the collecting duct is lower than the fluid therefore water is also removed from the collecting duct into themdulla and then into the blood
-water is also removed from the urine
