Plasma Volume Flashcards
What is the major osmotically effective solute in the effective circulating volume?
Na+
What happens when blood pressure in the renal atery increases?
There is a reduced activity of Na-H antiporter and reduced Na-K atpase activity in the proximal tubule, and the reduction in sodium reabosportion the proximal tubule and this causes a reduction in the water reabsoption- this process is known as pressure naturesis
What happens to pressure naterisus and diresusis when the ECF volume is high?
Increase in the renal atery pressure means that there is large pressure increase in naturesis and diresusis
What happens to pressure naturesis and direusis when the ECF volume is low?
There is an decrease in renal artery pressure, and there is a small pressure naturesis and direusis
What are some of the features of sodium reabosrbtion?
A mostly active proccess that is faciliated by 3Na -2K- ATPase pumps on the basolateral membrane,
What are some of the features of chloride reabsorption?
Is dependant on the proccess of sodium reabsorption, and it is important to remeber the proccess of electorneutraility,
What are the sodium transporters found in the proximal tubule?
Na-H antipoter, the Na Glucose symporter, Na-AA co transporter and the Na-Pi
What are the sodium transporters that are found in the loop of Henle?
NaKCC- which is a symporter
What are the sodium transporters found in the early DT?
The NaCl symporter
What are the sodium transporters found in the late DT and the collecting duct?
ENaC
What are the features of the S1 segment of the proximal convultued tubule?
Its main job is Na+ reabsorption, with the basolateral 3Na-2k-ATPase, also NaHCO3_ co transporter that is seen more in acids and bases, and on the apical you see a Na H exchange, co transport with AA or carboxylic acids, and there is also co transport what’s phosphate, and the aquaproin/.
What are some of the features of the S2-S3 segments of the proximal convulted tubule?
There is still the basolateral 3na-2K-ATPase, the apical membrane has a Na H exchanger, a paracellular Cl- gradient as it is moving between the cells, aquaporing, and faciliates the movement of Na and water
What are the two forms of autoregulation of the GFR?
Myogenic action and tubuloglomeular feedback
What are the features of the permability of the loop of henle?
The thin ascending limb is permeable to water, but the thick ascending limb is not
What are some of the features of the thin ascending limb of the loop of henle?
Sodium ion reabsorption is passive in the thin ascending limb, water reabsorption in the descending limb creates a gradient for passive Na+ ion reabsorption, and the epithelium allows this passive reabsorption through the paracellular route
What are some of the features of the thick ascending limb of the loop of henle?
From the lumen to cells via the NKCC2 transporter, Na= moves in the intersitium via the action of the 3Na- 2K- ATPase, and K+ ions diffuse back into the lumen via ROMK and CL- ions move into the intersitium, in the filitrate at this point there are less K ions so they need to come back in to maintain the activity of the NKCC2 transporter
What are some of the feautres of fluid reabsoption in the distal tubule?
Hyposomotic fluid enters, and there is active transport of about 5-8% of Na, and the water permeability of this segment is fairly low.
What diuretics is the NCCT transporter senstive too?
Thiazide diuretics
What direutics is ENaC senstive too?
Amiloride diuretics
How is calcium reabsoped in the DCT?
There is apical calcium transport, where cytosolic calcium is boun by calbin which shuttles calcium to the basolateral aspect, and is transported out by NCX.
What are the hormones that regulate calcium reabsorption?
Tightly regulated by the hormones parathyroid hormone and 1, 25 di- hydroxyvitamin D
What are the two cell types found in the collecting duct?
Principal cells (70% of the cells are principle, and these facilitate the reabsorption of Na+ via ENaC) and type B intercalated cells, which are involved in the active reabsorption of chloride, and the intercalated cells secrete H+ ions and HCO3- ions)
What are some of the features of the principle cells of the collecting duct?
Reabsorption of na+ ions via ENaC on the transapical membtane, and 3Na+- 2K+ atapse is the driving force, and active Na+ ion uptake is through a channel and not a cotransported.
What are the difference between the AC-IC cells and the BC-IC cells?
One is the acid secreting type and the other is the bicarbonate secreting type
