Action Potential Conduction

Question 1

Leakiness

Answer 1

Membrane Resistance (Rm)

Question 2

Stickiness

Answer 2

Membrane Capacitance (Cm)

Question 3

Thickness

Answer 3

Axial Resistance (Ra)

Question 4

Oligodendrocyte

Answer 4

Glial cells responsible for forming the myelin sheath found in the CNS
Wrap segments of myelin around multiple different axons

Question 5

Schwann Cell

Answer 5

Glial cell which myelinates only one segment of a single axon in the PNS

Question 6

Resting Synapse

Answer 6

Voltage-gated Ca++ channels are closed
Low intracellular Ca++ concentration: Preventing fusion of synaptic vesicles (containing neurotransmitters)

Question 7

Active Synapse

Answer 7

Action potential reaches the axon terminal, causes the membrane to depolarize
Voltage-gate Ca++ channels in the presynaptic terminal membrane open due to depolarization
Ca++ influx:
[Ca++]out = 1mM
[Ca++]in = 0.0001mM
Ca++ binds to synaptotagmin (protein on the vesicle membrane) triggerinng the formation of SNARE complex
SNARE complexes form: allows the synaptic vesicles to be pulled down and fuse with the presynaptic membrane

Question 8

Synaptic Cleft

Answer 8

20-40 nm wide
Postsynaptic dendrite extending out receptors

Question 9

Ca++ Pump

Answer 9

Moving Ca++ ions out of the cell
Against its concentration gradient
Hydrolyzes ATP

Question 10

Na+/Ca++ Ion Exchanger

Answer 10

3 Na+ ions in for 1 Ca++ ion out
Driven on the concentration gradient of Na+ (higher outside), energy is released
Ca++ is carried out due to the power source created by Na+

Question 11

Antidromic

Answer 11

Propagation toward the cell body

Question 12

Orthodromic

Answer 12

Action potential propagating toward the axon terminal