B3.1 The Nervous System

Question 1

Nervous system

Answer 1

A network of nerve cells (neurones) that transmits nerve impulses (messages) between parts of the body

Question 2

Functions of the nervous systems (it enables humans to…)

Answer 2

React to their surroundings
Coordinate their behaviour

Question 3

A nerve

Answer 3

A nerve is a bundle of neurones

Question 4

Coordination

Answer 4

The ability to use different parts of the body together smoothly and efficiently

Question 5

Neurones (nerve cells)

Answer 5

Specialised to rapidly carry nerve impulses (electrical) from one part of the body to another

Question 6

Motor neurone

Answer 6

Connects the CNS to an effector organ

Question 7

Sensory neurone

Answer 7

Connects a receptor to the CNS

Question 8

Relay neurone

Answer 8

Transmits impulses within the CNS

Question 9

Cell body (soma)

Answer 9

Contains the nucleus, which controls the cell, also produces neurotransmitters

Question 10

Axon terminals

Answer 10

To transmit neurotransmitters from the presynaptic neurone into the synapse

Question 11

Myelin sheath

Answer 11

Insulated neurone speeding up impulse

Question 12

Nodes of ranvier

Answer 12

The ‘gaps’ between the Schwann cells (1um in size) Allow the speed of transmission to be further increased by allowing impulse to jump from node to node in a process called saltatory conduction.

Question 13

Dendrites

Answer 13

Branches endings connect with other neurones and carry nerve impulses towards cell body

Question 14

Schwann cells

Answer 14

Form myelin sheath

Question 15

Axon

Answer 15

Single long fibre that carries nerve impulses away from the cell body towards nerve endings

Question 16

Why is a reflex reaction quicker than the coordinated responses

Answer 16

Because it is involuntary
Conscious brain isn’t involved
These Reactions often have a protective role

Question 17

Cornea

Answer 17

Refracts light

Question 18

Lens

Answer 18

Fine focusing of light so that image forms on the retina

Question 19

Iris

Answer 19

Controls how much light enters the pupil

Question 20

Retina

Answer 20

Contains light receptors ( including specialised cells sensitive to colour)

Question 21

Optic nerve

Answer 21

Carries impulses to the brain

Question 22

Pupil

Answer 22

The hole in the centre of the iris that allows light to pass through

Question 23

Ciliary body

Answer 23

Contains ciliary muscles which are attached to suspensory ligaments

Question 24

Suspensory ligaments

Answer 24

Work alongside the collars muscles they work together to alter the shape of the lens