Medical Phsiology Nerve

Question 0

Nuerons are special in that they are…

Answer 0

Electrically charged and can change their charge to produce impulses

Question 1

Anatomy of a Neuron

Answer 1

• body
• axonal hillock
• axon
• synaptic butons
• mylenated axons
• dentrites

Question 2

Membrane potential

Answer 2

Inside of the cells negative with respect to the outside

Question 3

Potential = voltage = push =

Answer 3

Ability to do electrical work

Question 4

Cells are bag if sea water containing…

Answer 4

Na+, Cl-, K+, Ca++

Question 5

The resting potential is a result of these steps:

Answer 5

1) Diffusion of K+ across the membrane
2) Diffusion of Na+ across the membrane passive Na+ channels
3) Na/K ATPase pump

Question 6

Passive K channels

Answer 6

• open all the time (not voltage-gated)
• protein channels made membrane permeable to K but not to Na
• K diffuses out along concentration gradient

Question 7

The diffusion of K+ out of the cell leaves behind…

Answer 7

Negatively charged anionic proteins [A-], creating a cloud of negative charge on inside of membrane.

Question 8

Electrochemical equilibrium

Answer 8

Force of the fusion pushing K out equals the negative attraction that pulls K back in, resulting in a cloud of K outside the membrane but no further net movement of K.

Question 9

Membrane is _______, inside ___ when potassium alone defuses out of the membrane

Answer 9

Polarized: -97mV

Question 10

Na+ wants to go inside so because…

Answer 10

• concentration difference

- negative charge inside membrane

Question 11

Potassium leaks out _____

more than Sodium

Answer 11

100X

Question 12

Less negative than normal membrane potential

Answer 12

Depolarized

Question 13

More negative than normal membrane potential

Answer 13

Hyperpolarized

Question 14

Movement of sodium inside depolarizes membrane slightly to…

Answer 14

-86mV

Question 15

Electrogenic pumping by Na/K ATPase pump causes …

Answer 15

Polarizes membrane -4mV, bringing membrane potential back to -90mV

Question 16

Action potential

Answer 16

Neurons send nerve impulses; is an electrical signal

Question 17

Action potential works like this:

Answer 17

1) neurons start at rest with membrane potential at -90mV. Both Na+/ K+ gated channels closed.
2) depolarization to -70mV to -50mV causes opening of voltage gated Na channels (activation gate)
3) Na+ rushes in because of electrochemical gradient causing the membrane interior to become more positive with respect to the exterior (overshoot)
3) slowly beginning with depolarization, Na+ gate closes and K+ gates open, stopping inward positive current and allowing K+ to diffuse out. (Repolarization)