Membrane proteins and resting membrane potential

Question 1

#PMT 
What are the differences bw spl diffu and facili diffu?

Answer 1

1, Nonpolar and lipids-soluble substances, directly through, cannot control speed.
2, facilited difu: THROUGH channel protein

Question 2

What substances can diffusion through protein channels? How?

Answer 2

Glucose, amino acids, ions

Transported Subs bind carries protes or pass through channels

Question 3

What is active transport?

Answer 3

1, Uses ATP to move solutes across a membrane

2, Requires carrier proteins

Question 4

Give an example of type of membrane pump that uses primary active transport? Describe?

Answer 4

Na-K pump.

Pumping 3 Na+ ions out and 2 K+ ions back into the cell (to maintain the resting membrane potential)

Question 5

What are ions?

Answer 5

Charged particles that have either gained or lost electrons

Question 6

Anion—–Cation
Note: Any particle or chemical wants to move from an area of higher concentration to an area of lower concentration, ions are no different

Answer 6

(-)———-(+)

Question 7

Distribution of sodium and potassium?

Answer 7

Sodium-(Na+) is the major extracellular ion

Potassium-(K+) is the major intracellular ion

Question 8

Which two types of membrane proteins are important in maintaining the resting membrane potential?

Answer 8

ion channels & ion transporters (channel và carrier protein)

Question 9

What is the resting membrane potential (voltage)? Why?

Answer 9

1, -70 mV(inside of the cell)
2, Protein anions (- charged) can not leave the cell. jush beneath the membrane, thus giving the inside of the cell a negative charge relative to the outside.

Question 10

Name 5 reasons why the resting membrane potential is important.

Answer 10

1, Propagation of electrical signals through the heart
2, Transmission of nerves impulses
3, Hormone secretion
4, Neurotransmitter release
5, Muscle contraction

Question 11

4 types of ion channels can exist on a membrane

Answer 11

1, Leakage: Usually ion specific, Are always open
2, Voltage-gated: - Open/close in response to changes in voltage across membrane (action potential happens)
3, Ligand-gated: Open/close in response to chemical messenger attaching to receptor on membrane
4, Mechanically-gated: Open/close in response to a mechanical event on the cell

Question 12

What is Resting membrane potential?

Answer 12

the ability of a cell to perform potential work, Is maintained by two ions (Na+ and K+)

Question 13

Explain how the cell maintains the high intracellular K and high extracellular Na concentrations?

Answer 13

1, Leakage channels allow for movement of K+ ions out and Na+ into cell.
2, Na-K ATPase compensates for the loss of ions via leakage channels and helps maintain the concentration gradients of Na+ and K+

Question 14

What causes changes in the membrane potential-Define stimulus?

Answer 14

1, Stimulus : any change in the environment of the cell
2, May cause ion channels to open/close
3, As a result ions will move in/out of the cell
4, Membrane potential changes

Question 15

Name two different types of membrane potentials.

Answer 15

1, Action potentials

2, resting Potentials

Question 16

What are the main differences between an action potential and a graded potential?

Answer 16

Action potential | Graded potential
Large change in membrane potential (to +30mV)><small>< Strength dissipates as it moves along cell membranes</small>

Our bodies version of a “message”>< Is not a “message”

How our cells communicate >< Multiple graded potentials can be added together (summed) to produce an action potential.</small>

Question 17

What is a depolarization?

Answer 17

Depolarization is when the membrane potential becomes less negative (more positive) (from -30mv → 70mV)

Question 18

What is repolarization?

Answer 18

repolarization refers to the change in membrane potential that returns it to a negative value just after the depolarization phase of an action potential has changed the membrane potential to a positive value. (30mV → -70mV)

Question 19

What is hyperpolarization?

Answer 19

Hyperpolarization is when the membrane potential becomes more negative at a particular spot on the neuron’s membrane

Question 20

Describe Action potential?

Answer 20

1, Stimulus causes alteration of RMP
2, If the GP strong enough to cause the RMP to reach Threshold then voltage gated Na+ Cs open and Na+ rushes into cell.
3, MP quickly climbs from -70 to +30 (AP is generated)
4) Na+ channels close, and K+ open
5) Repolarization due to K+ exiting cell
6) K+ channels close slowly and membrane becomes hyperpolarised for short duration.

Question 21

In a normal cell, what is the threshold membrane potential?

Answer 21

-55mv

Question 22

Once the threshold membrane potential has been reached, what happens next?

Answer 22

Once the charge reaches -55mv, MORE Na+ gates open, and more Na+ is added to the cell, until +30 mv is reached

Question 23

Dendrites -> Axon -> Nodes of Ranvier ->

Answer 23

Axon terminals

Question 24

What is Myelin and what is its function?

Answer 24

1, Whitish, fatty covering of axons
2, Associated with long, and large diameter nerve fibers.
3, Form Nodes of Ranvier

Question 25

What is the difference between a myelinated fiber and a non-myelinated fiber.

Answer 25

Myelin keeps current in axon, APs are generated only from nodes of Ranvier and apprear to jump rapidly

Question 26

What are the main differences between group a, b, and c nerve fibers?

Answer 26

A: sensory and motor fibers (skin, muscles)
Thick, myelinated, conduction velocity (120m/s)
B: Fibers serving visceral organs
Intermediate diameter, lightly myelinated, conduction velocity = 15m/s
C: Smallest diameter, unmyelinated
Fibers serving organs
Conduction velocity ˂ 1m/s