The Human Nervous System

Question 1

Homeostasis

Answer 1

the regulation of the internal conditions of cells to maintain optimum conditions for functioning, in response to internal and external changes.

Question 2

Internal conditions that are controlled:

Answer 2

. body temperature
. the water content of the body
. blood glucose concentration

Question 3

Receptors

Answer 3

cells that detect changes in the internal and external environment

Question 4

Stimuli

Answer 4

changes in the internal and external environment

Question 5

Coordination centres

Answer 5

areas that receive and process the information from the receptors.
they send out signals and coordinate the response of the body

Question 6

Effectors

Answer 6

muscles or gland that bring about responses to the stimulus that has been received

Question 7

Neurones

Answer 7

special cells which has electrical impulses pass along them

Question 8

Nerve

Answer 8

a bundle of neurones

Question 9

Central Nervous System

Answer 9

made up of the brain and spinal cord

Question 10

Sensory neurones

Answer 10

cells that carry impulses from your sense organs to your CNS

Question 11

Motor neurones

Answer 11

cells that carry information from the CNS to the rest of the body

Question 12

Nervous system

Answer 12

stimulus –> receptor –> CNS –> effector

Question 13

Reflexes

Answer 13

Automatic responses

Question 14

Reflexes in the body

Answer 14

. breathing
. moving food through your digestive system

Question 15

Relay neurones

Answer 15

they connect a sensory neurone and a motor neurone, and are found in the CNS

Question 16

Synapse

Answer 16

junctions between neurones

Question 17

Cerebral cortex

Answer 17

concerned with consciousness, intelligence, memory and language

Question 18

Cerebellum

Answer 18

concerned mainly with coordinating muscular activity and balance

Question 19

Medulla

Answer 19

concerned with unconscious activities e.g. controlling the heartbeat, breathing, the movement of the gut

Question 20

Hypothalamus

Answer 20

involved in controlling body temperatures

Question 21

Pituitary Gland

Answer 21

produces many different hormones which play a big part in coordinating and controlling body systems

Question 22

Studying people with brain damage

Answer 22

Matching changes in behaviour or memory with the damaged area has helped scientists map the functions of some parts of the brain

Question 23

Ways of studying the brain

Answer 23

. Electrically stimulating different parts of the brain
. MRI scans

Question 24

Retina

Answer 24

a special light-sensitive layer in the back of the eye

Question 25

Sclera

Answer 25

White outer layer of the eye which is relatively tough and strong so it is not easy to damage

Question 26

Cornea

Answer 26

a transparent area at the front of the eye in the sclera and it allows light into the eye
it also changes the direction of light as it passes into the eye

Question 27

Iris

Answer 27

controls the size of the pupil and it is made of muscles that contract and relax

Question 28

Pupil

Answer 28

the hole through which light enters the eye

Question 29

The eye in dim light:

Answer 29

The pupil is enlarged so as much light as possible enters the eye
. circular muscles relax
. radial muscles contract
. pupil dilates

Question 30

The eye in bright light:

Answer 30

The iris makes the pupil very small which reduces the amount light that goes inside the eye, so that too much bright light won’t damage the delicate, light sensitive cells
. circular muscles contract
. radial muscles relax
. pupil constricts

Question 31

Lens

Answer 31

a clear disc through which light passes
It is held together by suspensory ligaments and ciliary muscles

Question 32

Focus on a distant object:

Answer 32

. Ciliary muscles relax
. Suspensory ligaments are pulled tight
. Lens is pulled flat and thin
. It only refracts light slightly so they are focused on the retina

Question 33

Focus on a near object:

Answer 33

. Ciliary muscles contract
. Suspensory ligaments loosen
. Lens is thicker and more curved
. It refracts light strongly so they are focused on the retina

Question 34

Myopia ( short sightedness )

Answer 34

. you can see objects near clearly, but distant objects look blurred
. light is focused on the front of the retina so images that land on the retina are blurry
. result of lens being too curved or a particularly long eyeball

Question 35

Hyperopia ( long sightedness )

Answer 35

. you can see distant objects clearly, but close objects look blurred
. light is focused behind the retina so images that land on the retina are out of focus
. result of lens being too flat and thin or a particularly short eyeball

Question 36

Glasses for Myopia

Answer 36

glasses with concave lenses spread out the light from distant objects before it reaches the eye.
. The thicker the lens can bring it into perfect focus on the retina

Question 37

Glasses for Hyperopia

Answer 37

glasses with a convex lens bring the light rays together before they reach the eye itself.
. The thinner lens can bring the rays of light into perfect focus on the retina

Question 38

New Technology for the Eyes

Answer 38

. Contact lenses
. Laser eye surgery - myopia - lasers are used to reduce the thickness of the cornea so it
refracts less light
hyperopia - lasers are used to change the curve of the cornea so it
refracts light from close objects more effectively
. Replacement lenses
Risks : cataracts developing, infections, damage to the retina