Neurology and Nerve Impulses

Question 1

Describe the 4 parts of a neuron.

Answer 1

Dendrites
Body
Axon
Terminal Buttons

Question 2

Identify the location within a neuron where an action potential occurs.

Answer 2

Axon.

Question 3

Define the terms Electrochemical Gradient and Equilibrium Potential.

Answer 3

Electrochemical Gradient – the sum of the concentration gradient (chemical force) and membrane potential (electrical gradient).
Equilibrium Potential – The membrane potential when there is no net movement of an ion. Nernst Equation.

Question 4

Describe physiological basis for graded potentials.

Answer 4

Small proportional changes from resting membrane potential due to a stimulus applied to the neuron.
If Na+ enters, membrane depolarizes (excitatory)
If K+ leaves, membrane hyperpolarizes (inhibitory)

Question 5

Define Subthreshold stimulus.

Answer 5

a graded potential is not strong enough to depolarize the axon hillock to threshold.

Question 6

Define Depolarization Phase

Answer 6

The result of a strong inward Na+ current that reuslts from the opening of a large number of voltage-gated Na+ channels once the axon membrane reaches threshold.

Question 7

Define repolarization Phase

Answer 7

The result of an outward K+ current that results from the opening of a large number of voltage-gated K+ channels.