Regulation of Body Fluid: Regulation of Water Balance (L) Flashcards
What condition describes fluid leaving the loop of henle?
Hypotonic
What is the maximum osmolarity of the interstitium?
1200-1400 mOsm
What condition describes tubular fluid entering the Proximal convoluted tubule?
Isotonic
What is the concentration difference always between the ascending loop of henle and the interstitium?
200 mOsm
What are the functions of the vasa recta?
- Supply blood, oxygen, and nutrients to the Medulla.
2. Remove water and solutes that get added to the interstitium
What is the effect of an increase in blood flow through the vasa recta?
Decrease in medullary gradient
- Decreases salt and solute transport by nephrons
(“medullary washout”)
Where are UT-A1 and UT-A3 located in the nephron?
Inner medullary Collecting Duct
UT-A1 is on the apical side
UT-A3 is on the basolateral side
Where is the UT-A2 receptor located?
Thin Ascending Loop of Henle
How is urea recycled throughout the nephron?
Urea can be reabsorbed through the collecting duct via UT-A1 and UT-A3 receptors. It is then taken back up into the ascending loop of henle via UT-A2.
In which part of the nephron does ADH influence the permeability of water
Collecting duct
Where is ADH produced?
Hypothalamus
Supraoptic Nuclei and Paraventricular nuclei
Where is ADH secreted?
Posterior pituitary
What two responses are initiated by osmoreceptors?
- ADH release (happens quicker than #2)
2. Increased thirst
What is the net effect of ADH on principle cells?
Reabsorption of water, Cl-, and Na+
Secretion of K+
What receptors does ADH have an effect on?
Na-K ATPase: Reabsorption of Na and secretion of K
Aquaporin 2 channels: Reabsorption of water
Where are AQ-2 channels located?
Apical side of principle cells
What is the net effect of ADH on Intercalated cells?
Increase K+ reabsorption
H+ secretion
What effect does Aldosterone have on intercalated cells?
Increases H+ secretion via H-ATPase
Where is Aldosterone secreted?
Adrenal cortex
What is aldosterone secreted in response to?
AGT II
Increased plasma K+ concentration
Decreased Na+ plasma concentration
What happens during Neurogenic Diabetes Insipidus?
Pt can’t produce ADH
**Buzzword = head injury
What happens during Nephrogenic Diabetes Insipidus
Kidneys fail to respond to ADH, OR Countercurrent multiplier fails to establish a osmotic gradient
Tx for Neurogenic Diabetes Insipidus
Desmopression
(ADH analog, acts on V2 receptors) –> results in rapid response
How do you distinguish between Neurogenic and Nephrogenic DI in a patient?
Administer Desmopression:
If there is a rapid response: Neurogenic
If there is no rapid response: Nephrogenic
