Flashcards in Control Of Plasma Osmolairty Deck (26)
Where are your osmoreceptors located in your body?
In the hypothalus, specificly in the organsusm vasoculum of the lmaina terminals
How do the osmoreceptros wprl?
They have. Afenstrated leaky endothelium that can allow water in and out and therefore can sesne changes in the plasma osmolarity
What are the conditions that cause ADH realeas?
There is always a basal level of ADH, but is released under conditiosn of predominated loss of water, and an increase of 1% in osmolarity causes an increase by 1% of ADH, and there are negative feedback loops that regulate the release
What is more important if the volume crashes?
The volume is more important than the osmolarirty if the volume crashes,
What is the importance of thirst?
Large defecits in water can only be partially compensated for by the kidney, and therefore ingested water is the ultimate compensate, and is also stimualted by an increase in fluid osmolarity and by an reduced ECF volume
What are some of the features of ADH?
Is realeased from the posterior pitaurity gland, but is produced by the neruosecretory cells in the hypothalmus, ADH is a small peptide that is 9AA long.
What are some of the actions of ADH?
Acts on the kidney to regulate the volume and the osmolairty of the urine, increases the permeability of the collecting duct via water and urea, a low plasma ADH results in direusis whereas a high plasma ADH results in antidireusis
What are some of the features of central diabetes inspidius?
Results from when the plasma ADH levels are far to low, due to damage done to the hypothalmus or the pitaurity gland, a barin injury, a sacordosis or tubuleculosis and an anyersum
What are some of the features of nephrogenic diabetes inspidisu?
Occurs from an auired senstivity of the kidney to ADH,
What is SIADH?
The syndrome of inapproate anitdireutic hormone secretion, is characterised by an excessive realease of ADH from the posterior pituarity gland, and results in dilution hyponatiremia, in which the plasma sodium levels are lowered and the total body fluid volume is increased
What are the aquaporin channels in the proximal tubule?
AQP1 abd AQP7
What are the aquaporin channels found in the cortex?
AQP1, AQP3 and AQP4
What does ADH do if the plasma osmolarity decreases?
No ADH stimulation means that no aqaporin in the basolateral membrane of the late DCT and the collecting duct, therefore there is limited water uptake
What does ADH do if the plasma osmolarity increase?
Budy needs to produce an hypersomotic urine, and therefore there are insertion of aqaoprin in the kidney cells to make sure that as much water passes out of the bloodstream as possibl y
What are the key features of the concentration of urine?
Happens due juxtamedullary neprhons which produce the osmotic gradients, the vasa recta that help to maintian the osmotic graidetn and the collecting duct of all nephrons use this gradinet to help with the reabsoption of water
What happens in the descending limb of the loop of henle with regards to concentration gradients?
Descedning limb of the loop of henle is hihgly permeable to water due to the AQP-1 water channels which are always open, but is not peremable to Na= therefore it remains in the descending limb and the concentration or osmolarity increases
What is the osmotlarity at the bottom of the loop of henle?
What happens with regards to concentration gradients in the ascending limb of the loop of Henl?
The ascending limb actively transports NaCl out of the tubular lumen into the intersitila fluid, and this ascending limb is imperable to H20 and NaCl leaves and H20 remains, the osmolairt decreases in the ascending limb
What is the osmolarity of fluid entering the loop of henle?
What is an effective osmole?
If a membrane allows certain solutes to freely cross it, these solutes are ineffective at producing an osmotic force acorss a membrane
Is urea an effective osmole in the kidney?
Yes as it is hydrophilic and therefore does not easily cross the membranes
What is the proccess of the recycling of urea?
Urea is reabsorbed from the medullary collecting duct, and there is movement into the intersitium and diffusion back into the loop.
What is the influence of ADH on the reycling of urea?
Fractional excreation of urea decreases and therefore the urea recylcin increases
What is the role of the vasa recta?
The concentration gradient is produced by the loop of henle acting as a counter current mulitplier, but is maintained by the vasa recta acting as a counter current exchanger, as the osmotic gradient would not last long if the osmoles were washed out into the intersitium
What happens in the descending limb of the vasa recta?
Isomotic blood in the vasa recta enter the hyperosmotic mileu of the meduall, and therefore the Na+ and Cl- diffuse into the lumen of the vasa recta,