Neurobiology (C7)

Question 1

Neuron Structure

Answer 1

dendrites: send impulses toward axon
soma: body
axon hillock: most voltage gated, Na+ channels here
nodes of Ranvier
axon: send impulse away from soma
myelin: insulator, increase speed of impulse transmission
axon terminal

Question 2

PNS myelinated neurons

Answer 2

Schwann cells

Question 3

CNS myelinated neurons

Answer 3

oligodendrocytes

Question 4

Types of Neurons

Answer 4

multipolar - most neurons in our bodies
unipoalr
bipolar

Question 5

Resting potential

Answer 5

3Na+ out, 2K+ in - Na+/K+ ATPase
K+ leak channels
-70mV
Na+ voltage-gated channels open at -50mV

Na/K ATPase pumps out 1 net + ion
Na/K ATPase establishes Na+ and K+ [ ] gradients
many + ions are lost through K+ leak channels
end result = cell more neg inside than outside

Question 6

Depolarization

Answer 6

move away from resting potential in + direction

Question 7

Hyperpolarization

Answer 7

move away from resting potential in - direction

Question 8

Repolarization

Answer 8

return to resting potential

Question 9

Equilibrium potential

Answer 9

potential at which there is no driving force on an ion
Na = +50
K = -90

Question 10

Action potential

Answer 10

rest - depo - repo - hyper - repo
unidirectional, all-or-none events
2-3msec
-50 = threshold potential 
-50: vg Na+ channels open --> +35: vg K+ channels fully open, vg Na+ channels inactivate --> (around -40: Na+ vg channels close) -90: vg K+ channels close

Question 11

Refractory period

Answer 11

impossible/very difficult to fire another action potential

Question 12

Absolute refractory period

Answer 12

absolutely impossible to fire a 2nd AP
- Na+ channels inactivated
- cell is too +
near Na+ equilibrium potential

Question 13

Relative refractory period

Answer 13

possible but difficult to fire a 2nd AP
- Na+ channels are now reset to "closed"
- cell is too -
further from threshold
near K+ equilibrium potential