Lecture 7, Nerve/Muscle 3

Question 1

What is a synapse?

Answer 1

The junction between the pre-synaptic and post-synaptic neuron.

Question 2

The post-synaptic neuron receives input (at the dendrites and cell body) from the axon terminals of the pre-synaptic neuron. What does this input create?

Answer 2

A local potential

Question 3

Why does the neurotransmitter bind to receptors on the post-synaptic cell?

Answer 3

Chemically gated ion channels require a neurotransmitter to bind to the receptor for it to be opened.

Question 4

Where are all of the excitatory inputs from the pre-synaptic neuron summated and what happens to them?

Answer 4

Axon hillock, if it reaches a threshold (-60 mV) the neuron will fire an action potential down its axon.

Question 5

What are the four stages of neuronal communication called in order from the dendrites to the axon terminals?

Answer 5

Input → Integration → Action Potential → Output

Question 6

What is the difference between action potential and local potential?

Answer 6

An action potential opens voltage-gated ion channels as they shoot down the axon, local potentials are a small graded response in membrane potential at the cell body/dendrites.

Question 7

Schwann cells wrap a myelin sheath around axons, why do they do this?

Answer 7

The action potential regenerates at each gap between the myelin sheath, increasing the speed of action potentials down the axon.

Question 8

What triggers the neurotransmitter to be released from vesicles into the synaptic cleft?

Answer 8

Ca(2+)

Question 9

What happens after the neurotransmitter diffuses across the synaptic cleft?

Answer 9

The neurotransmitter binds to its receptor (chemically gated ion channel) on the post-synaptic membrane.