Control Of Plasma Osmolairty

Question 1

Where are your osmoreceptors located in your body?

Answer 1

In the hypothalus, specificly in the organsusm vasoculum of the lmaina terminals

Question 2

How do the osmoreceptros wprl?

Answer 2

They have. Afenstrated leaky endothelium that can allow water in and out and therefore can sesne changes in the plasma osmolarity

Question 3

What are the conditions that cause ADH realeas?

Answer 3

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

Question 4

What is more important if the volume crashes?

Answer 4

The volume is more important than the osmolarirty if the volume crashes,

Question 5

What is the importance of thirst?

Answer 5

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

Question 6

What are some of the features of ADH?

Answer 6

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.

Question 7

What are some of the actions of ADH?

Answer 7

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

Question 8

What are some of the features of central diabetes inspidius?

Answer 8

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

Question 9

What are some of the features of nephrogenic diabetes inspidisu?

Answer 9

Occurs from an auired senstivity of the kidney to ADH,

Question 10

What is SIADH?

Answer 10

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

Question 11

What are the aquaporin channels in the proximal tubule?

Answer 11

AQP1 abd AQP7

Question 12

What are the aquaporin channels found in the cortex?

Answer 12

AQP1, AQP3 and AQP4

Question 13

What does ADH do if the plasma osmolarity decreases?

Answer 13

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

Question 14

What does ADH do if the plasma osmolarity increase?

Answer 14

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

Question 15

What are the key features of the concentration of urine?

Answer 15

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

Question 16

What happens in the descending limb of the loop of henle with regards to concentration gradients?

Answer 16

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

Question 17

What is the osmotlarity at the bottom of the loop of henle?

Answer 17

1200 mOsm/kg

Question 18

What happens with regards to concentration gradients in the ascending limb of the loop of Henl?

Answer 18

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

Question 19

What is the osmolarity of fluid entering the loop of henle?

Answer 19

100 mOsm/L

Question 20

What is an effective osmole?

Answer 20

If a membrane allows certain solutes to freely cross it, these solutes are ineffective at producing an osmotic force acorss a membrane

Question 21

Is urea an effective osmole in the kidney?

Answer 21

Yes as it is hydrophilic and therefore does not easily cross the membranes

Question 22

What is the proccess of the recycling of urea?

Answer 22

Urea is reabsorbed from the medullary collecting duct, and there is movement into the intersitium and diffusion back into the loop.

Question 23

What is the influence of ADH on the reycling of urea?

Answer 23

Fractional excreation of urea decreases and therefore the urea recylcin increases

Question 24

What is the role of the vasa recta?

Answer 24

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

Question 25

What happens in the descending limb of the vasa recta?

Answer 25

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,

Question 26

What happens in the ascending limb of the vasa recta?

Answer 26

Blood ascending towards the cortex will have a higher solute concentration than the intersitium and therefore water moves in form the desceding limb of the loop of Henle, and the vasa recta presevers the hypersosmolarity of the renal medualla