3 Transmission Of Action Potentials

Question 1

Describe the cellular properties that determine the rate of electrical
depolarization and conduction.

Answer 1

Depolarization due to the AP’s decay rapidly from increase in stimulation.

Question 2

What’s a synapse?
What’re the two types?

_________ synapse: are ______ connections between cells which allows ions to flow between. Used in heart, smooth, muscle, bladder. ____ but NO integration, travels bilaterally. Uses gap junctions.

________ synapse: unidirectional flow, ____ but allows for integration! Allows multiple inputs and decide the best course of action. Via a neurotransmitter that must bind to receptor.

Answer 2

Synapse is a site of communication from one cell to another.

Electrical: are direct connections between cells which allows ions to flow between. Used in heart, smooth, muscle, bladder. FAST but NO integration, travels bilaterally. Gap junctions.

Chemical synapse: unidirectional flow, SLOW but allows for integration! Allows multiple inputs and decide the best course of action. Via a neurotransmitter that must bind to receptor.

Question 3

List and describe the steps in transmission on an action potential in a chemical synapse (Neuromuscular Junction). Include ionic flow in the pre and post-
synaptic cells.

Answer 3

Ach is broken down by AchE. Ach –> choline and acetate. Choline is taken up by pre and regenerates Ach.

Once Ach no longer bound, EPP’s stop, APs stop and contraction stops

Question 4

Because myelin moves ____, they control skeletal muscle and pain/touch receptors.

What’s a demyelinating disease that causes muscle weakness, loss of coordination, loss of sensation, paralysis and even death?

It _________ myelin to the point where AP’s might not be propagated .

Answer 4

Fast

Multiple sclerosis

Damages

Multiple sclerosis is damaging myelin. Decreases to the point where AP’s might not be propagated. Low number of ion channels under sheath so when they’re destroyed, can’t depolarize.

Question 5

What would give you the most rapid conduction? (Pick one)

Higher time constant, low length constant
Lower time constant, high length constant
Lower time constant, low length constant
Higher time constant, high length constant

Answer 5

Lower time constant, high length constant

Question 6

What would give you the slowest rate constant?

Higher time constant, high length constant
Higher time constant, low length constant
Lower time constant, high length constant
Lower time constant, low length constant

Answer 6

Higher time constant, low length constant

Question 7

Which nerve is likely the most heavily myelinated? (Pick one) Which is least myelinated? (Pick one)

Interneuron in CNS
Motor neuron
Sensory neuron from gut
Olfactory neuron

Answer 7

Motor

Interneuron CNS

Question 8

What is the effect of a calcium ionophore on NT release? What about the effect of hypocalcemia NT release?

Answer 8

MORE neurotransmitter released

LESS NT released

Question 9

What does neostigmine do?

Answer 9

Inhibits acetylcholine esterase