B3.1

Question 1

What is the nervous system?

Answer 1

Where a stimulus is detected by the body and send this as an impulse to the brain
The brain decides the appropriate response and tells the body how to respond

Question 2

What are the stages of a reflex arc? (non specific)

Answer 2

1) A stimulus is detected by receptors
2) The impulse travels along the sensory neurone and reaches the CNS
3) The impulse synapses with the relay neurone
4) Then it synapses with the motor neurone which takes the impulse to an effector (muscle/gland)
5) Then there is a response

Question 3

What is the CNS?

Answer 3

Made up of the brain and spinal cord
Made of delicate tissue so protected by bones (skull & backbone)

Question 4

What receptor cells would the skin have?

Answer 4

Pressure and Temperature (change in heat)

Question 5

What does a sensory neurone do?

Answer 5

Carries electrical impulses from receptor cells to the CNS

Question 6

What is the structure of a sensory neurone?

Answer 6

Receptors on one end
Nucleus in the middle of the structure inside cell body
Axon (after the cell body), dendron (before)
Myelin sheath - impulses travel between these

Question 7

What do relay neurones do?

Answer 7

Carry electrical impulses from sensory neurone to motor neurone

Question 8

What does a mitote neurone do?

Answer 8

Carries electrical impulses from the CNS to the effectors

Question 9

What is the structure of a motor neurone?

Answer 9

Same as sensory neurone but cell body is at the start
No dendron

Question 10

What are nerves?

Answer 10

Bundles (hundreds & thousands) of neurones

Question 11

What is a reflex?

Answer 11

Involuntary actions
Unconscious
Occur when in danger

Question 12

What are the structures & description in the eye?

Answer 12

Cornea - transparent coating in front of the eye
Pupil - central hole in the iris
Iris - coloured ring of muscle tissue
Lens - transparent biconvex lens
Ciliary body - ring of muscle tissue
Suspensory ligaments - ligament tissue
Optic nerve - nervous tissue

Question 13

What are their different functions?

Answer 13

Cornea - protects the eye, first point of refraction of light
Pupil - allows light to enter the eye
Iris - alters pupil size by contracting or relaxing
Lens - focuses light clearly onto the retina
Ciliary body - alters the shape of the lens
Suspensory ligaments - connects the ciliary muscle to the lens
Optic nerve - carries nervous impulses to the brain

Question 14

What is the retina?

Answer 14

Where the light is reflected from the eye onto so an image is formed

Question 15

How are images formed?

Answer 15

Photoreceptors (light sensitive cells) in the retina produce a nervous impulse when exposed to light
This impulse travels down the optic nerve to the brain where it is interpreted as an image

Question 16

What happens to the pupil in dim light?

Answer 16

The pupil dilates:
- radial muscles contract
- circular muscles relax

Question 17

What happens to the pupil in bright light?

Answer 17

Pupil constricts:
- radial muscles relax
- circular muscles contract

Question 18

What is accommodation?

Answer 18

The way the lens changes to focus on different objects

Question 19

How do you focus on a near object?

Answer 19

1) The ciliary muscle contracts
2) Causes the suspensory ligaments to slacken
3) Lens become thicker so light is refracted more

Question 20

How do you focus on distant objects?

Answer 20

1) Ciliary muscle relaxes
2) Suspensory ligaments taught
3) Lens becomes thinner so less light is refracted

Question 21

What is myopia?

Answer 21

Short sightedness
Lens is more curved or eyeball is too long (light is refracted too much)
Focal point is not on retina but infront

Question 22

How to treat myopia?

Answer 22

Concave lens
Diverges light rays before entering the eye

Question 23

What is hyperopia?

Answer 23

Long sightedness
Lens is less curved or eyeball is too short
Focal point is behind the eye

Question 24

How to treat hyperopia?

Answer 24

Convex lens
Converges the light rays before entering the eye

Question 25

What are the two photoreceptors?

Answer 25

Cones - respond to different colours
Rods - respond to different light levels

Question 26

What is the function of the brain?

Answer 26

Processes all the information from receptors & hormonal system

Question 27

What is the structure of the brain

Answer 27

Cerebrum - controls complex behaviour (memory, personality)
Cerebellum - controls posture, balance and involuntary actions
Medulla - controls automatic responses (heart rate)
Hypothalamus - regulates temperature and water balance
Pituitary gland - stores and release hormones that regulate the bidy

Question 28

What are the difficulties with investigating the brain?

Answer 28

• patients must give consent for information to be shared
• many believe animal testing is unethical

Question 29

What is the peripheral nervous system?

Answer 29

All the neurones that connect the CNS to the rest of the body

Question 30

How does damage to the nervous system occur?

Answer 30

Injury
Disease - diabetes, cancer
Genetic condition - Huntingtons
Ingesting toxic substances

Question 31

What are the effects of damage to the nervous system?

Answer 31

Inability to detect pain
Numbness
Loss of coordination

Question 32

Why is damage to the CNS more severe?

Answer 32

PNS has limited ability to regenerate
Minor damage self heals
damage to CNS means loss of control systems, paralysis, memory loss
CNS cannot regenerate

Question 33

Why is it difficult to repair CNS?

Answer 33

Many nerve fibres so identifying and repairing each fibre without damaging others is difficult
Difficult to diagnose damage to brain

Question 34

What treatments are for brain damage?

Answer 34

Radiotherapy & chemotherapy
Surgery
Deep brain stimulation (inserting and electrode to the brsin