The thin descending part of the loop of henle is permeable to —— but the thick ascending part is not
The thin descending part of the loop of henle is permeable to water but the thick ascending part is not
The thick ascending limb of the loop of Henle
The remaining —– is reabsorbed and the excess —— is reabsorbed via the ——-
The remaining potassium is reabsorbed and the excess Cl is reabsorbed via the sodium, potassium, chloride co transporter.
Counter current mechanism
- There is no initial ——— gradient in the kidney’s interstitial fluid, the osmolarity is —– mOsm/L throughout the interstitium. This is the —– as the osmolarity of normal body fluids, including the fluid moving inside the —- of ——.
- ——- is transported out of the ———- limb of the loop of Henle and accumulates in the ——— interstitium. —— exits the —— ascending limb by ——- ——–, and is pumped out of the ——– ascending limb by the ———- cotransporter. The ——— ascending limb is ———- to water, so water stays ——- the loop of henle and the osmolarity of the —— ascending fluid ——-. The —– is added to the interstitial fluid, ———— its osmolarity. This creates a —– mOsm/L difference in the osmolarities of the ——— fluid and the fluid in the —— ascending limb.
- ——- then diffuses out of the — ——— limb until the fluid there has equilibrated with the ——– fluid at ——- mOsm/L.
- Once the ————- limb has equilibrated, —— mOsm/L fluid from the proximal tubule enters the top of the ———– limb. This pushes the ——- osmolarity fluid below it down towards the hairpin curve in the loop of Henle.
- The osmolarities of the fluids in the ———– limb and the interstitium are once again mismatched due to —– leaving the —— limb and the movement of fluid in the tube. This causes ——- to leave the ——- limb until the two fluids have re-equilibrated.
- You can see a corticopapillary gradient starting to appear. Interstitial fluid in the cortex has an osmolarity of —— mOsm/L, while the papillary interstitial fluid is —— mOsm/L
- Steps __-__ are repeated, with each cycle enhancing the ———. At its maximum, the gradient reaches —— mOsm/L between the —— and the inner ——-.
- There is no initial ——— gradient in the kidney’s interstitial fluid, the osmolarity is —– mOsm/L throughout the interstitium. This is the —– as the osmolarity of normal body fluids, including the fluid moving inside the —- of ——.
- ——- is transported out of the ———- limb of the loop of Henle and accumulates in the ——— interstitium. —— exits the —— ascending limb by ——- ——–, and is pumped out of the ——– ascending limb by the ———- cotransporter. The ——— ascending limb is ———- to water, so water stays ——- the loop of henle and the osmolarity of the —— ascending fluid ——-. The —– is added to the interstitial fluid, ———— its osmolarity. This creates a —– mOsm/L difference in the osmolarities of the ——— fluid and the fluid in the —— ascending limb.
- ——- then diffuses out of the — ——— limb until the fluid there has equilibrated with the ——– fluid at ——- mOsm/L.
- Once the ————- limb has equilibrated, —— mOsm/L fluid from the proximal tubule enters the top of the ———– limb. This pushes the ——- osmolarity fluid below it down towards the hairpin curve in the loop of Henle.
- The osmolarities of the fluids in the ———– limb and the interstitium are once again mismatched due to —– leaving the —— limb and the movement of fluid in the tube. This causes ——- to leave the ——- limb until the two fluids have re-equilibrated.
- You can see a corticopapillary gradient starting to appear. Interstitial fluid in the cortex has an osmolarity of —— mOsm/L, while the papillary interstitial fluid is —— mOsm/L
- Steps __-__ are repeated, with each cycle enhancing the ———. At its maximum, the gradient reaches —— mOsm/L between the —— and the inner ——-.
The longer the loop of henle you have the greater the —– gradient you will achieve, so the ——- the concentration of the —–.
The longer the loop of henle you have the greater the osmotic gradient you will achieve, so the higher the concentration of the urine.
What can you change to allow more fluid to be retained/ less urine?
The longer the loop of henle, the higher the concentration
Change how well or how much the sodium potassium chloride cotransporter there is in the thick ascending limb
What are some signs of dehydration?
Thirst
Fatigue
Dry mouth
Concentrated urine
Osmoreceptors
Monitor —– deficit
These are specialised cells that sit in the —— —– of the ———, in close contact with ——– that run through the ———. In response to changes in ——– they can —— or ——–, which changes the ——- activity of these cells which signal the supraoptic neurons to release —–.
Monitor water deficit
These are specialised cells that sit in the posterior pituitary of the hypothalamus, in close contact with capillaries that run through the hypothalamus. In response to changes in osmolarity they can expand or shrink, which changes the electrical activity of these cells which signal the supraoptic neurons to release ADH.
Antidiuretic hormone (ADH)/Vassopression (AVP)
ADH is manufactured and secreted from the ——- —– of the ——–.
ADH travels down to the —— and binds to — receptors which cause insertions of ——- on the —— —— side, allowing —— to move along its concentration gradient and into the —— interstitial fluid to be absorbed into the ———.
If actions of ADH are impaired (low ADH) it can result in either —— or ——– diabetes insipidus.
——– diabetes insipidus - the pituitary is unable to ——- ADH
———- diabetes insipidus - have the ——– amounts of ADH but the ——— in the kidney do not work.
ADH is manufactured and secreted from the posterior pituitary of the hypothalamus.
ADH travels down to the kidney and binds to V2 receptors which cause insertions of aquaporens on the tubular lumen side, allowing water to move along its concentration gradient and into the interstitial fluid to be absorbed into the capillaries.
If actions of ADH are impaired (low ADH) it can result in either central or nephrogenic diabetes insipidus.
Central diabetes insipidus - the pituitary is unable to secrete ADH
Nephrogenic diabetes insipidus - have the right amounts of ADH but the receptors in the kidney do not work.
Why are there high levels of ADH in heart failure?
The heart isn’t beating well, so isn’t perfusing blood to all of its organs, forcing the body to vasoconstrict and keep pressure up and retain as much water as it can.
The high levels of ADH are in response to trying to retain water
Does an increase in osmolarity increase ADH levels?
Yes
Does a decrease in blood volume increase ADH levels?
Yes
Does an increase in ADH levels result in dilute urine?
No
