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Flashcards in Medical Phsiology Nerve Deck (18)
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Anatomy of a Neuron

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

1

Nuerons are special in that they are...

Electrically charged and can change their charge to produce impulses

2

Membrane potential

Inside of the cells negative with respect to the outside

3

Potential = voltage = push =

Ability to do electrical work

4

Cells are bag if sea water containing...

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

5

The resting potential is a result of these steps:

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

6

Passive K channels

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

7

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

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

8

Electrochemical equilibrium

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.

9

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

Polarized: -97mV

10

Na+ wants to go inside so because...

-concentration difference
-negative charge inside membrane

11

Potassium leaks out _____
more than Sodium

100X

12

Less negative than normal membrane potential

Depolarized

13

More negative than normal membrane potential

Hyperpolarized

14

Movement of sodium inside depolarizes membrane slightly to…

-86mV

15

Electrogenic pumping by Na/K ATPase pump causes ...

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

16

Action potential

Neurons send nerve impulses; is an electrical signal

17

Action potential works like this:

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)