Nerve Cells

Question 1

Define neuron

Answer 1

Nerves cell; basic functional and structural unit of the NS

Question 2

What do all neurons consist of? (3) name and define

Answer 2

Cell body/soma: contain nerve cell nucleus
Axon: single long extensin of cytoplasm, carries nerve impulse away from cell body
Dendrites: branches of the cell body/soma, carries impulses towards cell body

Question 3

What is the myelin sheath?

What fibres does and doesn’t it cover? (2)

Answer 3

Layer of fatty material covering axons
Unmyelinated fibre: fibre without myelin sheath
Myelinated fibre: fibre with myelin sheath

Question 4

Define grey matter

Answer 4

Area with nerve cell bodies and unmyelinated fibres

Question 5

Define white matter

Answer 5

Myelinated fibres

Question 6

Define schwann cells?

Answer 6

Cells that wrap around the axon forming the myelin sheath

Question 7

Define node of ranvier

Answer 7

Gaps in the myelin sheath that allow for saltatory conduction

Question 8

Define neurilemma:

Answer 8

Outermost coil of schwann cell, helps in repair of damaged fibres

Question 9

Function of the myelin sheath?

Answer 9

Insulation
Protects axon from damage
Increases speed of nerve impulses across a fibre

Question 10

Define synapse

Answer 10

Junction between adjacent nerve fibres

Question 11

Where do most synapses occur?

Answer 11

Between the axon terminals of one neuron and the dendrites of another

Question 12

Name of the gap betweeen neuron and skeletal muscle?

Answer 12

Neuromuscular junction

Question 13

Define sensory neuron?

Answer 13

Neuron that receives nerve impulse from receptors

Question 14

Where does a sensory neuron carry an impulse?

Answer 14

Into the CNS spinal cord

Question 15

Where are interneurons found?

Answer 15

between sensory and motor neurons, often in spinal cord and brain

Question 16

Function of interneuron?

Answer 16

Process, store and retrieve information

Decides how we respond to a stimulus

Question 17

What percentage of our neurons are interneurons?

Answer 17

90%

Question 18

What do motor neurons do?

Answer 18

Carry impulses from CNS into the effectors

Question 19

What is a multipolar neuron?

Example?

Answer 19

Neuron with many dendrites and one axon
Motor neuron
Interneuron

Question 20

What is a unipolar neuron?

Example?

Answer 20

Contain ONE extension: the axon, cell body is to the side of an axon
Sensory neuron

Question 21

What is a bipolar neuron?

Answer 21

Contains one axon and one dendrite

Question 22

What is anaxonic neuron?

Answer 22

Contains no axon, many dendrites