topic 11. powerpoint 11.1 Flashcards
What are the 3 parts of a nephron?
cortex- outer medulla- inner medulla
3 parts of nephron are
Where do we find..
Afferent arteriole
glomerulus
proximal tube
distal tube
loop of henle
collecting duct
Afferent arteriole- cortex
glomerulus- cortex
proximal tube-cortex
distal tube-cortex
loop of henle- outer medulla
collecting duct- inner medulla
filtration occurs in what of the three parts of the nephron
cortex
at the proximal end the nephrons forms
bowman capsule, which is around a ball of capillaries
The fluid in the bowman capsule is called what
filtrate,
Filtrate travels through the nephron, whatoccurs?
reabsorbtion and secretion
explain process filtrate travels through in nephron
drains into the collecting ducts
and renal pelvis- ureter-urinary bladder-urethra
Explain the process of filtration
we know filtration occurs in glomerulus but to be more specific…
There are spaces between endothelial cells of glomerular capillaries and Bownman capsule, very small. So proteins and blood can’t pass through but other can
How does pressure relate to filtration?
capsule because the large diameter and less resistance, retain pressure to drive filtration into bowman
What is the important of efferent arterioles and filtration?
Efferent arterioles: receives blood from the glomerulus; has smaller diameter, blood “backs up” (dam) in the glomerulus, keeping pressure high
What substances enter through high pressure filtration?
water,
glucose, amino acids, sodium chloride and urea
ultrafiltration
type of high pressure filtration
filtrate that accumulates things like water, glucose, amino acids due to ultrafiltration, are called what?
fluid formed in this way is called glomerular filtrate
What is the main function of the proximal tube?
By what mechanism?
Main function: reabsorption of water, ions and nutrients back into the interstitial fluid
Na+/+ exchanger and Na+/K+ pumps
positive ions creates a voltage gradient, causing absorption of cl-
proximal tube secretes and absorbs what
secretes H+ into filtrate
absorbs: na+, cl-,k+, hco3
in proximal tube, cl- flows out causing
water follows salt, filtrate is hypoosmotic
during reabsorption , what transports big things like glucose or amino acids?
membrane proteins actively transport it
Explain descending and ascending in loop of henle
Descending limb, water reabsorbed passively[water/membrane permeable/osmosis/psotive feedback] to interstual fluid because Na+ and Cl- is reabsorbed, falliated by thin walls of vasa recta. As it goes downward towards medulla, osmolarity increases. At bottom, isomotic. Ascending , active transport of Na+/Cl-, [membrane impermeable to water]creating urine that is hyperosmotic to blood.
What mechanism helps maintain concentrated urine?
Loop of Henle and Vasa recta facilitates
counter-current multiplierwhich helps retain concentration gradient
vasa recta is located
The vasa recta is located around the Loop of Henle in the medulla region of the kidney.
In the counter-current multiplier: Flow of filtrate through the LoH is in the ___direction from the flow of blood
through the vasa recta.
opposite
why doesn’t the water that moves out of the descending LoH dilute the concentration of
the interstitial fluid?
Because the vasa recta is reabsorbing the water (due to oncotic pressure
of blood).
vasa recta capillaries have fenestrae (pores) that makes them highly permeable to water
and solutes, allowing for equilibration.
How is Urea important to counter current multiplier?
Urea plays a role in this process by diffusing out of the collecting duct and into the interstitial fluid of the medulla. This increases the osmolarity of the medulla, further enhancing the concentration gradient. The high concentration of urea in the medulla helps to maintain the high osmolarity needed for water reabsorption in the loop of Henle.
distal convuluted tube, what is reabsorbed and secreted?
reabsorbed: Na+, cl-, h20, hco3
secreted: K= andH+
What is the role of the duct?
function: to concentrate urine
duct descends, there is
an increasing solute
gradient in the medulla
H2O moves out of the duct
Some urea is passively
transported out of the duct,
which adds to the
increasing solute gradient in
the medulla
H+ is secreted into the
duct
