Keef 5 Flashcards
(52 cards)
How does insulin help w/ K uptake & the avoidance of the dangerous hyperkalemia?
Insulin prompts Na+ to be taken into the cells via Na/H exchanger. With more Na+ inside the cell, the sodium potassium pump is stimulated. This pushes more sodium outside of the cell & pushes more potassium inside the cell.
How does epinephrine help w/ K uptake & the avoidance of the dangerous hyperkalemia?
Epinephrine stimulates the sodium potassium pump.
Which part of the nephron is capable of giving you isotonic urine?
The PCT! The osmolarity is 300 entering it & 300 leaving it! All that happens is that 67% of the salt & water are taken out.
Urine: 300
Which part of the nephron is capable of giving you a hypotonic urine?
The thick ascending limb of the loop of Henle. Here: the H2O permeability is crazy low. However, the Na/K/Cl transporter is working like crazy.
Urine: 150-250
What is the osmolarity of our urine usually? Why?
Hypertonic
B/c of the whole nephron & b/c of the ADH effects in the DCT & the osmotic gradient formed by the loop of Henle. The osmotic gradient pulls water out of the collecting ducts so that by the time you get to the renal papilla the urine is concentrated.
What is the osmolarity in the cortex? At the entrance to the minor calyx?
Cortex: 300
Entrance: 1200
What are the steps to forming the osmotic gradient in the interstitial space of the loop of Henle?
Pump: the salt out of the ascending limb
Equilibrate: passive movement of salt into descending limb & water into interstitial space
Shift: put more water in!
What is the max osmolarity that you can get in the interstitial space from the movement of salt?
600mOsm
How do you get to an osmolarity of 1200 in the interstitial space?
from the movement of urea out of the loop of Henle
T/F as a part of the counter current multiplier…sodium is actively secreted into the descending limb of the loop of Henle
False.
It is passively secreted into the descending limb of the loop of Henle as a part of equilibration.
What is the osmolarity of the blood in the vasa recta that comes from the glomerulus? That goes to the vena cava? That is at the base of the loop?
From glomerulus: 300
To vena cava: 325
Bottom of Loop: 1200
In order to achieve the concentrations of blood it does at each section of the vasa recta:
what happens @ the descending limb?
The ascending limb?
Descending limb: get rid of water & absorb salt
Ascending Limb: absorb water & get rid of salt.
B/c of equilibration: what is the concentration at the bottom of the vasa recta, the loop of Henle & the interstitial space?
1200
Plasma flow exiting the vasa recta is ____ that entering the vasa recta.
2X. B/c of water reabsorption.
T/F Plasma exiting the glomerular capillaries is approximately 20% less than that entering the glomerular capillaries.
true.
20% filtered
What percentage of the renal blood flow goes to the cortex? What percentage goes to the medullary region?
90% goes to the cortex.
10% goes to the medullary region.
After the PCT…what is the concentration of urea?
50% of the original concentration…it is reabsorbed here along w/ sodium & water.
In the DCT…what is the concentration of urea?
110% b/c it is secreted along the loop of Henle.
What part of the nephron is impermeable to urea?
The DCT…this is why the urea becomes super concentrated here.
What is the concentration of urea leaving the collecting tubule? How is this possible?
40%. This is possible b/c of the reabsorption of urea in the collecting duct
How is urea reabsorbed in the collecting duct?
This process is considered facilitated diffusion. It is prompted in the presence of ADH. Remember…this is important in the formation of the conc’n gradient–get to that 1200!!
What ultimately stimulates the synthesis of ADH? What senses this?
An increase in plasma osmolarity.
Sensed by osmoreceptors.
Where is ADH synthesized?
In the supraoptic nuclei & the paraventricular nuclei.
Where is ADH released from?
The posterior pituitary
