excretion Flashcards
what are the main metabolic waste products in mammals
carbon dioxide - respiration
bile pigments - formed from breakdown of haemoglobin excreted in the bile to the s.intesine
nitrogenous waste products - breakdown of excess AA
what are the adaptations of the liver
rich blood supply
blood is supplied by two blood vessels
(hepatic artery + hepatic portal vein)
where does the hepatic portal vein carry blood from
contains products of digestion from intestines
what is the structure of a hepatocyte
large nucleus
prominent golgi body
lots of mitochondria
where is blood from the hepatic artery and hepatic portal vein mixed
what does this do
sinusoids
increases oxygen content
what do sinusoids contain
what is their function
kupffer cells
act as resident macrophages, ingesting foreign particles
where do hepatocytes secrete bile into
spaces called canaliculi
from there, biles drains into bile ductules carrying it to the gall bladder
describe the function of carbohydrate metabolism in the liver
insulin stimulates glycogenesis
adrenaline stimulates gluconeogenesis or glycogenolysis
describe the function of deamination of excess amino acids in the liver
deaminate AA and => ammonia (toxic) => urea
urea excreted by kidneys
remainder AA is used in respiration
what is transamination
conversion of an AA into another
describe the function of detoxification in the liver
> liver contains catalase (for hydrogen peroxide)
> and alcohol dehydrogenase
to ethanol => ethanal => ethanoate used to build fatty acids or used in respiration
what are the kidneys involved in
excretion
osmoregulation
what is the kidney’s function
filter nitrogenous waste products out the blood
maintain water balance
what vein carries blood coming out the kidney
renal vein
what is the kidney made up of
what do they act
nephrons
as filtering units
where does urine leave the kidneys
ureter
how much urine can be stored in the bladder
400-600 cm^3
where does the urine leave the body from
urethra
give the structure of the kidney
cortex (dark outer layer)
filtering of blood takes place
dense capillary network
medulla (lighter inner layer)
contains tubules of nephrons that forms the pyramids and the collecting ducts
pelvis
where urine collects before leaving
how long is a nephron
how many nephrons in a kidney
3cm
1.5 million nephrons
give the structure and function of the bowman’s capsule
cup-shaped containing the glomerulus
blood goes into the glomerulus to go into ultrafiltration
give the structure and function of the proximal convoluted tubules
coiled region of the tubule
in the cortex
where substances needed are reabsorbed into the blood
what does the loop of henle do
tubule that creates a [high solute] in the medulla as tissue fluid
give the structure and function of the distal convoluted tubule
second twisted tubule where water balance maintenance takes place
ADH action is here
further ion + blood regulation is here too
what is the structure and function of the collecting duct
urine passes down the collecting duct in the medulla to the pelvis
fine tuning of water balance takes place here
(ADH action here)
what should the concentration of urea, glucose and amino acids be like when the blood leaves the kidney
urea = greatly reduced
glucose + AA = the same
describe ultrafiltration
process that results in the formation of tissue fluid in the capillary beds of the body
which arteriole is wider in the kidney
what does it cause
afferent
pressure builds up forcing blood through capillary wall
describe the basement membrane
made up of network of collagen fibres + other fibres
blood cells and proteins are retained in the capillary
describe podocytes
form pedicels that wrap around capillaries forming slits and make sure large substances go through epithelial cells
what is the ultrafiltrate
hypotonic (less conc. than) to blood plasma
what happens in the PCT
large substances are moved back into the blood by active transport
85% of NACl + water reabsorbed
what are the adaptations of the PCT
covered with microvilli
many mitochondria
what is the filtrate reaching the loop of henle
isotonic (same conc) with tissue fluid and blood
what happens at the loop of henle
different areas of the loop have different permeabilities to water
acts as a countercurrent multiplier
what happens in the descending limb
water moves out filtrate down gradient
(lower part)
conc of ions increases due to activity of ascending limb
filtrate entering descending limb is isotonic with blood
as it travels down, water passes out the loop by osmosis into the blood
descending limb impermeable to ions, so no active transport
fluid reaching the bend is hypertonic to blood
what happens in the ascending limb
the 1st section is permeable to ions and they move out by diffusion
in the 2nd section, ions are actively pumped into medulla tissue fluid
producing high [ion] in medulla
ascending limb is impermeable to water
so fluid in the limb is dilute while tissue fluid is very conc.
by the time the fluid reaches the top of the ascending limb, it is hypotonic to blood, and enters the distal convoluted tubule
what happens at the distal convoluted tubule
water balance takes place
contains many mitochondria
if the body lacks salt, ions are pumped out the DCL
what do desert animals have more of in the kidneys
longer
