Lecture 3 - Tubular Function (PCT)

Question 1

What are the 4 basic renal processes?

Also how do you calculate the amount of urine produced?

Answer 1

Question 2

What occurs during Filtration?

Answer 2

• Plasma is filtered from glomerulus into the Bowaman’s capsule.
• Large molecules are filtered out of the glomerulus, leaving an ultrafiltrate that similar to plasma(without proteins)
• Driven by starling forces.

Question 3

What occurs during reabsorption?

Answer 3

Question 4

What occurs during secretion?

Answer 4

Question 5

Where does 65-67% of reabsorption take place?

Answer 5

Proximal Convoluted Tubule

Question 6

What is an example of passive reabsooption?

Answer 6

Osmosis

Question 7

What is clearance?

Answer 7

The volume of blood cleared of drug per unit of time.

Question 8

What is excretion?

Answer 8

The amountof drug excreted over period of time.

Question 9

How much of ions,H20, glucose, animo acids and vitamins are reabsorbed from the PCT?

Answer 9

ions-65-67%

H20 - 65-67%

Glucose,amino acids and Vitamins- ALL

Question 10

What is required for active reabsorption?

Answer 10

Uses energy (ATP)

Question 11

What happens to the clearance and plasma half-life when renal function is decreased?

Answer 11

Clearance decreased and and hlaf life of plasma increases

Question 12

How are you able to tell the difference between PCT and DCT using an electron microscope?

Answer 12

PCT has a brush border which increases its absorptive capacity.

PCT will look darker due to it contaianing high content of organelle.

DCT seen to have a larger lumen as it doesnt contain a brush border.

Question 13

What is transcellular movement?

Answer 13

• Transport across apical membrane
• Diffusion through tubular cell cytosol
• Transport across the basolateral membrane
• Movement through the insteritium into the blood vessel

Question 14

What is paracellular movement?

Answer 14

Movement through leaky ‘tight’ junctions.

Question 15

What happens to ions that enter the interstitium that make it easy to passively diffuse into the capillaries?

Answer 15

Once something enter the interstitium, its conc increases higher than peri-tubular capillaries.

Question 16

Describe Sodium reabsorption coupled with glucose uptake.

Answer 16

Question 17

Describe how energy is invested to get sodium out of filtrate and create a sdoium electrochemical gradient.

Answer 17

Question 18

Describe how sodium reabsorption coupled with HCO3 uptake takes place.

Answer 18

H+ is secreted out of the tubullar cell into the PCT. Carbonic Anhydrase is found in abundance in the microvilli. the reaction of H+ with carbonate to make carbonic acid. Carbonic anhydrase aids this breakdown of the acid into CO2 + H20.

Then it goes into the cell and then CA helps it recombine into Carbonic acid and then into H+ and carbonate and then the carbonate is reabsorbed and the H+ is pumped out again to reabsorb more carbonate.

Question 19

How does water reabsorption in the PCT take place?

Answer 19

Paracellular route

Transcellular route, through aquaporine 1

Question 20

Describe how sdoium reabsorption aids reabsorption of water and many other solutes.

Answer 20

Question 21

What is the fate of molecules as they pass down the PCT?

Water

sodium

potassium

chlorine

HCO3

Glucose

Amino Acid

Urea

Answer 21

Question 22

What occurs in Iso-osmotic reabsorption in the PCT?

Answer 22

• Reabsorption of solutes is follwed by the obilidatory osmosis of H2O.
• Filtrate is neither diluted of reabsorbed
• At the end of PCT filtration, remains isotonic with respect to Plasma.