Dr. Stevens - Transporters, channels, voltage and concentration

Question 1

What is the concentration of electrolytes in the cell?

Answer 1

Na+ and Cl- outside the cell

K+ and A- inside the cell

Question 2

What is the normal osmolarity of Na+ outside the cell?

Answer 2

145 mEq/L

Question 3

What is the normal osmolarity if K+ inside the cell?

Answer 3

120 mEq/L

Question 4

What is the normal osmolarity of Cl- in the ECF?

Answer 4

105 mEq/L

Question 5

What is the primary contributor of the electrical gradient across the cell membrane?

Answer 5

K+ leakage back across the cell membrane from the gradient created by Na+ / K+ pump.

Question 6

Where are AA anions (-) most prevalent?

Answer 6

Outside the cell in the cytoplasm.

Question 7

What are the components of the cell membrane?

Answer 7

lipid bilayer

cholesterol

proteins

lipids

Question 8

What are the two general ways that ions

Answer 8

passively without any kind of transporter

by way of a transporter

Question 9

Of membrane transporter what are the catagories?

Answer 9

Channels

Transporters

Question 10

How is a channel different than a transporter?

Answer 10

Channels are just proteins that allows ions and water to flow with the concentration gradient.

Question 11

What two types of transporters?

Answer 11

Solute Carrier and Pumps

Question 12

What is the key characteristics of pumps?

Answer 12

They use ATP to pump against gradient.

Question 13

What is a secondary active transport?

Answer 13

They use the concentration gradient created by a pump to move another ion / molecule against the concentration gradient without ATP.

Question 14

What are the characteristics of passive diffusion?

Answer 14

Goes with concentration gradient.

small polar molecules pass through

Large polar and ions don’t

Question 15

What are the types of channels? against / with gradient?

Answer 15

1. Ligand-Gated
2. Voltage-Gated
3. Leak
4. Stretch-Activated

It moves things with concentration gradient.

Question 16

Solute Carriers do?

Answer 16

The use a concentration gradient created with a Na/K ATPase pump to move other molecules (glucose) against the concentration gradient without ATP.

Question 17

What are the purposes of primary active transporters?

Answer 17

Maintain bioelectrical gradient

Provide gradient for secondary active transport

pump electrolytes

Create solute concentrations that support osmosis

Question 18

What is the pump leak model?

Answer 18

That leaking via a channel and pumping via and ATPase happen simultaneously but separatly.

Question 19

How is cell membrane potential maintained?

Answer 19

degree of ion permeability and ion concentration.

Question 20

What is the physiology of metabolic acidosis hyperkalemia?

Answer 20

High H+ concentration in the ECF leads to a slient exchange across the membrane with K+ as H+ flows in and K+ flows out. This is clinically represented as hyperkalemia.

Question 21

Why does Rhabdomyolysis cause cardiac arrest?

Answer 21

The muscle cell crush causes a flood of K+ into the ECF. This initial hyperkalemia results in an influx of K+ into the cell and the resulting depolarization of the cell. This can cause caridac arrest by depolarization.