The Nervous System

Question 1

Neuron

Answer 1

A neuron (or neurone) is a nerve cell

Question 2

Sensory Neuron

Answer 2

A sensory (or afferent) neuron takes a message from a sense organ to the CNS

Question 3

Motor Neuron

Answer 3

A motor (or efferent) neuron takes a message from the CNS to a muscle or a gland

Question 4

Ganglion

Answer 4

A ganglion (plural: ganglia) is a group of cell bodies located outside the CNS

Question 5

Interneuron

Answer 5

An interneuron carries information between sensory and motor neurons

Question 6

Threshold

Answer 6

The threshold is the minimum stimulus needed to cause an impulse to be carried in a neuron

Question 7

The All or Nothing Law

Answer 7

The ‘all or nothing’ law states that if the threshold is reached an impulse is carried, but if the threshold is not reached no impulse is carried

Question 8

Refractory Period

Answer 8

The refractory period is a short time span after a neuron has carried an impulse during which a stimulus fails to cause a response

Question 9

Synapse

Answer 9

A synapse is a region where two neurons come into close contact

Question 10

Synaptic Cleft

Answer 10

A synaptic cleft is the tiny gap between the two neurons at a synapse

Question 11

Reflex Action

Answer 11

A reflex action is an autmatic, involuntary, unthinking response to a stimulus

Question 12

Reflex Arc

Answer 12

A reflex arc is the pathway taken by a nerve impulse in a reflex action