what are the nephrons?
structures in the kidney where blood is filtered
- waste removal and selective reabsorbance
define ultrafiltration
filtering of substances out of the blood at molecular level
where is the blood filtered from and to?
- from glomerulus
- to filtrate in the Bowmans capsule
where does blood enter the nephron?
through renal artery (wide vessel)
where does blood go when it enters the nephron?
through capillaries and out of the narrow blood vessel to leave the glomerulus
describe the pressure in the glomerulus
high
what happens to the small molecules in the blood at high pressure in the glomerulus?
forced out of capillaries
describe the layers that molecules have to pass through to move from the blood into the filtrate in the Bowmans capsule
- endothelium in capillary walls in glomerulus which are porous
- basement membrane
- specialist cells called podocytes
describe the basement membrane
- made of collagen and glycoproteins
- molecules in blood plasma are mostly small enough to pass through
describe the podocytes
- additional filter
- extensions called pedicels wrap around capillary, forming slits
- ensures that any blood cells or large proteins which didn’t get across basement membrane don’t enter filtrate
what is GFR?
- glomerular filtration rate
- volume of blood filtered through kidneys in a given time
- suggests how well the kidneys are working
give 2 examples of molecules which remain in the blood
- proteins
- red blood cells
give 4 examples of molecules which move to the filtrate
- water
- CO2
- amino acids
- inorganic ions
describe the water potential of the blood in the glomerulus
low due to the presence of plasma proteins
why is low water potential in the glomerulus important?
for reabsorption of water bu osmosis from the high water potential in the proximal convoluted tubule, loop of henle & collecting duct
explain why blood cells should not enter the urine and suggest a possible cause for this symptom
- should not enter due to being too large to leave capillaries
- possible cause is high blood pressure forcing large molecules out
how does the structure of the glomerulus allow the kidney to form its function?
wide entrance for large amounts of blood and narrow exit to give high blood pressure
how does the Bowmans capsule allow the kidney to perform its function?
- 3 layers (capillary, basement membrane and podocytes)
- large surface area
