Collecting Duct! Flashcards
(32 cards)
Principal Cell
Cells that maintain mineral and water balance
Intercalated A and intercalated B cells
Control Acid base balance
Intercalated A cell-what does the A stand for?
A is for acidosis type of conditions
metabolic acidosis
respiratory acidosis
Intercalated Bcell-what does the B stand for?
B is for basic conditions
Alkalosis
Metabolic alkalosis
respiratory alkalosis
What happens when blood levels are high in CO2
CO2 goes into intercalated cells, combine with water to form carbonic acid —> dissociates into protons and bicarbonate
enzyme that does this is carbonic anhydrase
What is the pH is acidosis?
Low pH
What does the body do?
Bicarbonate is a good base that dissociate into bicarbonate ions and protons
Channel protein has some potassiums enter the cell. from low to high
Protons move from low conc. to high conc,
Needs ATP dependent
Protons excreted
What happens if ammonia is in high concentration?
Enters intercalated cell A, excreted out through the transporters into collecting duct
What happens to the protons in the collecting duct and the now excreted ammonia?
They can combine to form ammonium (weak acid)
Buffer system within the body
What happens to the bicarbonate ions?
Channels in the basolateral membrane for bicarb can be pumped out into the blood stream
Increased bicarb= will tie up some of the protons in the blood= decrease pH (towards basic)
What is transported with bicarbonate ions and how
Transporter
Bicarb goes out, chlorine goes in
Chlorine maintains charge inside cell
What happens in the B cell?
pH too high
Same process as acidic
h2O +CO2=H2CO3—> H+ and HCO3-
We want to get rid of the negative ion bicarbonate, so bicarb is excreted and Cl- comes into cell and then through channel into the blood
More bicarb less proton
We want to increase the protons in the blood-how?
Basolateral membrane channel brings potassium in and pushes H+ out of the cell
needs ATP as they are going against conc. gradient
What does the proton do?
pH goes back down.
What else could the collecting duct do?
Have cells that are secreting drugs and toxins, creatinine
How is ADH released?
Hypothalamus cell bodies (supraoptic nucleus) axons that moved through to the posterior pituitary to release ADH
Why is ADH released?
When plasma osmolality is changing
Pulls water into the blood
Blood was Hypertonic
Angiotensin II can also stimulate ADH
High plasma osmolality (high solute, low water)
ADH receptor is…
G protein coupled receptor
How does G coupled proteins work
G stimulatory protein
Binds to GTP becoming active
Activates another effector enzyme called Adenyl cyclase
Active Adenyl Cyclase stimulates conversion of ATP to cAMP
Activates Protein Kinase A
What does activation of protein kinase A do?
Vesicles with specialised channels that are aquaporins II and snare proteins
PKA phosphorylates the snare proteins to fuse with the cell membrane
Aquaporin II are now in the cell membrane
Where does water go
Through aquaporin II into cell
Then through aquaporin 3 and 4 in the basolateral membrane into the blood
Principal cells…
Control water balance, is what ADH acts on
Aquaporin 3 or 4 are found…
Basolateral membrane
What effect does water have on the blood volume and pressure?
Increases blood pressure and volume
