2. Permeability Barriers & ATP Pumps/Ion Gates

Question 0

In a normal cell what is the extracellular concentration of Na+?

Answer 0

145mM

Question 1

In a normal cell what is the intracellular concentration of Na+?

Answer 1

12mM

Question 2

In a normal cell what is the intracellular concentration of K+?

Answer 2

155mM

Question 3

In a normal cell what is the extracellular concentration of K+?

Answer 3

4mM

Question 4

In a normal cell what is the intracellular concentration of Cl-?

Answer 4

4.2mM

Question 5

In a normal cell what is the extracellular concentration of Cl-?

Answer 5

123mM

Question 6

In a normal cell what is the distribution of Ca2+ intracellularly and extracellularly?

Answer 6

Intracellular 100nM

Extracellular 1.5mM

Question 7

In the small intestine, name a protein that allows the entry of glucose and explain how it works?

Answer 7

Na+glucose co transporter, the energy from sodium moving in is used to allow the uptake of glucose also.

Question 8

Name a protein that involves Ca2+ and Na+ movement?

Answer 8

Na+Ca2+ exchanger. Inward flow of 3 Na+ drives outward flow of 1 Ca2+. (This is electrogenic)

Question 9

Name a protein that leads to internal alkalinisation of the cell.

Answer 9

Na+H+ exchange, inward flow of Na+, outward flow of H+

Question 10

How many subunits make up the Na+K+ATPase and what are their functions?

Answer 10

2, alpha unit is phosphorylated and allows the movement of the ions, beta directs the protein into the membrane

Question 11

Name four proteins that control resting Ca2+ concentration.

Answer 11

PMCA - Plasma Membrane Calcium ATPase
SERCA - Sarco Endoplasmic Reticulum Calcium ATPase
NCX - Na+Ca2+exchanger
Ca2+ uniports - in mitochondria, remove H+ take in Ca2+

Question 12

Explain the significance that the NCX protein is membrane potential dependant?

Answer 12

When polarised (negative inside) the protein removes a calcium ion for every 3 sodium ions that enter
When depolarised (positive inside) the protein reverses and removes 3 sodium ions for every calcium ion that enters

Question 13

In ischaemia why does the membrane become more permeable to calcium ions?

Answer 13

No oxygen therefore ATP depleted, the Na+K+ATPase therefore doesn’t transport any Na+ out of the cell, the NCX then reverses, removing Na+ but causing an influx of Ca2+

Question 14

How would a decrease in intracellular pH be corrected?

Answer 14

Increase activity of NHE

Question 15

How would an increase in intracellular pH be corrected?

Answer 15

Increased activity of AE, anion exchange, (Cl- in, HCO3- out)

Question 16

How does a cell resist swelling?

Answer 16

Removes ions (K+/Na+/Cl-), water follows

Question 17

How does a cell resist shrinking?

Answer 17

Ions taken in, water follows

Question 18

How much of bicarbonate does the kidney reabsorb and what does it use it for?

Answer 18

Under normal circumstances, all of it, it is retained for use in pH buffers.

Question 19

Name the part of the kidney that loop diuretics work on?

Answer 19

Thick ascending limb

Question 20

What part of the kidney do Thiazides work at?

Answer 20

Distal convoluted tubule

Question 21

What part of the kidney does ADH work at?

Answer 21

Cortical collecting duct

Question 22

What part of the kidney does amiloride work at?

Answer 22

Distal convoluted tubule

Question 23

What part of the kidney does aldosterone work at?

Answer 23

Cortical collecting duct

Question 24

What part of the kidney does spirondactone work at?

Answer 24

Cortical collecting duct

Question 25

What protein do loop diuretics inhibit?

Answer 25

NKCC2 Transporter in the proximal

Question 26

What protein do thiazides inhibit?

Answer 26

NCCT Transporter in the distal convoluted tubule

Question 27

What protein does amiloride inhibit?

Answer 27

ENaC in the distal convoluted tubule and cortical collecting duct

Question 28

What protein does ADH insert?

Answer 28

Aquaporin in the cortical collecting duct