LECTURE 34 12/2/22 (LECTURE 18 SLIDES: RENAL PHYSIOLOGY CONT.) Flashcards
What receptors will ADH bind to in the kidney?
What receptors will ADH bind to in the systemic circulation?
V2 receptors on principal cells. (07:00)
V1 receptors (07:20)
What do V2 receptors do?
What do V1 receptors do?
V2 receptors help promote water reabsorption.
V1 receptors promote SVR in the systemic circulation (8:11)
Water reabsorption in the collecting duct are dependent on what factor?
Availability of aquaporins to establish water channels.
How many sets of aquaporins channels are there in the collecting ducts?
Three (AQP-2, AQP-3, AQP-4)
Describe the signal transduction cascade when ADH binds with it’s receptor on the kidney.
- ADH binds with V2 receptors on the principle cells.
- This will activate a Gs-GPCR that will activate adenylyl cyclase.
- Adenylyl Cyclase will cyclate ATP to cAMP.
- cAMP will activate Protein Kinase A
- PKA will phosphorylate AQP-2 vesicles that will release AQP-2 water channels to the apical side of the nephron for water reabsorption.
Why do we pee a lot with alcohol?
Ethanol interferes with the release of vasopressin (ADH) from the pituitary gland. (10:26)
What side of the cell will have AQP-2 Channels?
What side of the cell will have AQP-3 Channels?
What side of the cell will have AQP-4 Channels?
AQP-2 (Tubular Side, Apical Side, Luminal Side, or Side with the urine)
AQP-3 and AQP 4 will be on the Interstitial Side
Which AQP channels are not mediated by vasopressin?
AQP-3 and AQP-4
What two neurons does the osmoreceptor communicate with to release ADH?
What other sensor also communicate with these two neurons?
- Supraoptic Neuron
located near the optic nerves - Paraventricular Neuron
located near the 3rd ventricles
The baroreceptors will also communicate with the supraoptic neuron and paraventricular neuron.
(14:30)
The supraoptic neuron is responsible for ________ (fraction) of ADH release.
The Paraventricular neuron is responsible for _________ (fraction) of ADH release.
5/6 of the ADH release for the supraoptic neuron
1/6 of the ADH release for the paraventricular neuron
Where will the supraoptic and paraventricular nuclei send their signal?
What is an alternate name for this structure?
Posterior lobe of the pituitary gland.
Neurohypophysis
What is another name for the anterior lobe of the pituitary gland?
Adenohypophysis (17:40)
What are the names for the urea transporters?
What is the effect of ADH on urea transporters?
UT-A1 and UT-A3
Increase permeability for urea, increasing urea reabsorption.
What are the two reasons to reabsorb urea?
- Reabsorbing urea will increase water reabsorption
- Reabsorbing urea will increase osmolarity of the renal interstitium (21:00)
What happens to the brain as a result of hyponatremia?
Increase brain swelling, due to movement of water into the cell in order to increase osmolarity.
This will also result in increase ICP, decreasing perfusion in the brain.
Will there be a high or low urine osmolarity with less water and urea reabsorption?
There will be a low urine osmolarity (more diluted urine).
In this graph, how many mL of filtrate is reabsorbed in the proximal tubule?
81 mL
(125-44)
In this graph, how many mL of filtrate is reabsorbed with high levels of ADH?
In this graph, how many mL of urine is excreted with low levels of ADH?
124.8 mL of filtrate reabsorbed with high levels of AHD
20 mL of urine excreted with low levels of ADH.
Which of the nephron will have the least ADH effect?
Proximal Tubule
What is the condition where we have too much ADH?
What are the causes of this (4 possibilities) ?
Syndrome of Inappropriate AntiDiuretic Hormone Secretion
(SIADH) - Reduction in urine volume.
- Short response to a brain injury/emergent trauma.
- NSAIDs and pain drugs.
- Antidepressants - SSRIs, SNRIs
- Lung Cancer
(38:00)
If there is a traumatic brain injury with damaged pituitary tissues. What will be the result of ADH?
Decrease ADH and a large amount of urine production.
How does ethanol reduce ADH release from the pituitary gland?
Ethanol reduces calcium influx that generate a current that is required for ADH release at the pituitary gland.
Ethanol will cause a sharp reduction in ADH
(40:00)
How much urine output, would you expect someone to produce if they are on Lithium?
Will the pituitary gland still produce ADH with lithium therapy?
20 L/day
There will still be ADH production, but the kidneys will not respond the hormone.