kidney Flashcards
what is ultrafiltration
when the fluid part of the blood is filtered from the glomerulus into the renal tubule.
what is selective reabsorption
as fluid flows along tubules useful substances are reabsorbed back into the blood in amounts required by the body
what is secretion
unwanted substances, are actively secreted in to the tubules
what is need for ultrafiltration to take place ( 2 things)
- sufficient pressure, in order to force fluid through filter (3 layers)
- selective barrier, so molecules with an MR > 69,000 are retained in the blood stream, but it allows smaller molecules to pass through.
what is the hydrostatic pressure of the blood in glomerulus
7.8 KPa
what is the hydrostatic pressure of fluid in capsule
-2.3 KPa
what is the osmotic pressure of blood in glomerulus
- 4.2 KPa
what is the net filtration pressure
1.3 KPa
where is all of the glucose absorbed in the kidney?
the PCT (proximal convoluted tubule)
what does the renal artery do?
carries oxygenated blood to the kidney
what does the renal vein do
carries deoxygenated blood away from the kidney
which is smaller the afferent or efferent arteriole
efferent arteriole
why is the efferent arteriole smaller than the afferent arteriole
in order to cause a build up of hydrostatic pressure, in order create pressure in the glomerulus, in order to filter the waste materials.
what are podocytes and what is there role/function
- epithelium of the bowman’s capsule
- filter large molecules, to ensure red blood cells, plasma proteins do not enter filtrate.
what are the 3 layer of filtration between the glomerulus and bowman’s capsule
- capillary endothelium, contains fenestrations.
- basement membrane, mesh of collagen, that allows molecules with an Mr < 69,000 to pass
- podocytes, epithelium of the bowman’s capsule
filter large molecules, to ensure red blood cells, plasma proteins do not enter filtrate.
what is glomerular filtration rate?
rate at which fluid forms, in the bowman’s capsule, having been squeezed out of the blood plasma, during ultrafiltration.
what is absorbed in the PCT (proximal convoluted tubule)
all glucose reabsorbed in PCT + amino acids and vitamins
where does ultrafiltration take place
Bowman’s capsule
where does selective reabsorption take place
in the PCT (proximal convoluted tubule)
what does the PCT contain, in order to maximise SA
- it contains numerous microvilli to create a brush border thus increasing the surface area for transport proteins.
- folding’s in the basal membrane, to increase surface area for reabsorption
- capillaries close to PCT cells, in order to reduce diffusion, osmosis/active transport distance.
what is the purpose of the K+, NA+ pump in the PCT
to maintain a steep sodium concentration gradient.
summarise how selective reabsorption takes place in the PCT
- NA+, K+ pump, removes NA+ ions from cytoplasm of PCT cells, via active transport.
- NA + ions, cotransporter into cell along with glucose and some amino acids via facilitated diffusion
- glucose conc in the PCT cells increase, and then moves out of cells into capillaries by facilitated diffusion.
what has more mitochondria the DCT or PCT
the PCT.
what is the DCT
- cells are cuboidal epithelial cells
- small volume of water, are reabsorbed due to transport of NA+/ Cl - ions.
- aldosterone, acts on the DCT, to stimulate increased Na+ reabsorption into the blood.
what is the collecting duct
- where ADH acts
- creates a steep water concentration gradient between tubules and medulla using the loop of Henle.
- determines how much water, is reabsorbed back into the blood stream.
what does the loop of Henle act as?
a counter current multiplier.
what is ADH
regulates the volume of water that is reabsorbed into the kidney
what Aldosterone
Aldosterone is a steroid hormone secreted by adrenal glands. Its main role is to regulate salt and water in the body, thus having an effect on blood pressure
what does increasing the length of the loop of Henle do?
the longer the loop of Henle, the greater the solute potential and the lower the water potential is in the medulla, thus meaning, that greater water reabsorption occurs, in the collecting duct, thus meaning a greater concentration of urine (lower volume, (less water in urine))
what happens when blood pressure drops
the adrenal gland (zona glomerulosa) causes the release of ADH.
what diabetes
inability to control blood glucose levels
what is mellitus
a sweet taste - glucose in urine
what is insipidus
failure to respond to ADH (ADH, fails to bind to receptors, on collecting duct plasma membrane.
