B3.1 - The Brain

Question 1

What is the function of the nervous system?

Answer 1

The nervous system works by detecting changes in your external environment, and deciding on an appropriate response.

Question 2

What are the three main stages to a nervous response?

Answer 2

• The change in the environment (stimulus)
• Group of cells detecting the stimuli (sensory receptors)
• A response from the effector (muscle or gland).

Question 3

Define the term stimuli.

Answer 3

A change in the environment which you need to react to.

Question 4

List the different kinds of stimuli.

Answer 4

• Light
• Chemical
• Heat
• Pressure
• Change in position
• Sound

Question 5

Define sensory receptor.

Answer 5

Receptor cells found in your sense organs which detect a change in the environment (stimulus).

Question 6

What do sensory receptors do?

Answer 6

They detect stimuli and change it into electrical impulses that travel along neurones (nerve cells) to your CNS.

Question 7

What receptor cells do you find in the eye? What stimuli do they detect?

Answer 7

Photoreceptors -light.

Question 8

What receptor cells do you find in the tongue? What stimuli do they detect?

Answer 8

Taste receptors - chemical

Question 9

What receptor cells do you find in the nose? What stimuli do they detect?

Answer 9

Olfactory receptors (taste and smell) - chemical and chemical.

Question 10

What receptor cells do you find in the skin? What stimuli do they detect?

Answer 10

Pressure and temperature receptors - pressure and heat.

Question 11

Define the term ‘effector’.

Answer 11

A muscle or gland that responds to a stimulus by contracting (causing movement) or secreting hormones respectively.

Question 12

What is the Central Nervous System comprised of?

Answer 12

The brain and spinal cord.

Question 13

What is the Peripheral Nervous system comprised of?

Answer 13

All the sensory and motor neurones in the body.

Question 14

What are the 3 types of neurones, and what do they do?

Answer 14

1) Sensory neurones
- Carry electrical impulses from receptor cells to the CNS
2) Relay neurones
- Carry electrical impulses from sensory neurones to motor neurones
3) Motor neurones
- Carry electrical impulses from the CNS to effectors.

Question 15

What is a synapse? Explain the function and how it works.

Answer 15

‘A synapse is the ‘junction’ or gap between neurones. When an electrical impulse hits the end of a nerve, it causes the release of chemical which diffuse across the gap to the next neurone, where the chemicals will trigger another electrical impulse.

Question 16

what are neurones also known as, and what is a bundle of lots of neurones called?

Answer 16

nerve cells, nerve.

Question 17

summarise the steps in a coordinated response (nervous reaction).

Answer 17

Stimulus -> Receptor cells -> Sensory neurones -> spinal cord -> brain -> spinal cord -> motor neurone -> effector -> response.

Question 18

how long does a coordinated response take?

Answer 18

about 0.2 seconds.

Question 19

What is a reflex action?

Answer 19

A reflex action is an automatic (involuntary) reaction which occurs without thinking. They take around 0.2 seconds.

Question 20

What type of action do breathing, heart rate and digestion fall under?

Answer 20

reflex action

Question 21

summarise the steps in a reflex arc.

Answer 21

Stimulus -> Receptor cells -> Sensory neurones -> spinal cord -> motor neurone -> effector -> response.

Question 22

Describe and state the function of the cornea.

Answer 22

The Cornea is a transparent coating on the front of the eye. It protects the eye, and refracts light entering the eye.

Question 23

Describe and state the function of the iris.

Answer 23

The iris is a coloured ring of muscle tissue and alters the pupil size by contracting or relaxing.

Question 23

Describe and state the function of the pupil.

Answer 23

The pupil is the central in the iris, and it allows light to enter the eye.

Question 24

Describe and state the function of the lens.

Answer 24

The lens is a transparent biconvex lens and focusses light onto the retina.

Question 25

Describe and state the function of the ciliary body.

Answer 25

The ciliary body is a ring of muscle tissue that alters the shape of the lens.

Question 26

Describe and state the function of the suspensory ligaments.

Answer 26

The suspensory ligaments are ligament tissue that connects the ciliary body to the lens.

Question 27

Describe and state the function of the optic nerve.

Answer 27

The optic nerve is nervous tissue that carries nerve impulses to the brain.

Question 28

Describe the path light takes when entering the eye.

Answer 28

As light enters the eye, the cornea refracts the light rays and provides most of the focus to the incoming light. The light then passes through the pupil and is further refracted by the lens, creating a sharp image on the retina.

The photoreceptors in the retina produce a nervous impulse when exposed to light, and the impulse travels down the optic nerve to the brain, where the impulses are interpreted as a visual image.

Question 29

What happens in your eye when you focus on nearby objects.

Answer 29

When focussing on nearby objects, your ciliary muscles contract, and lens becomes more convex (fatter).

Question 30

What happens in your eye when you focus on distant objects.

Answer 30

When focussing on distant objects, your ciliary muscles relax, and lens becomes less convex (thinner).

Question 31

What are the causes of myopia (short-sightedness)?

Answer 31

The lens in the eye is too strong, or the eyeball is too long.

Question 32

What are the causes of hyperopia (long-sightedness)?

Answer 32

The lens in the eye is too weak, or the eyeball is too short.

Question 33

How can you correct short-sightedness?

Answer 33

Myopia can be corrected with concave (diverging) lens, which bends the light outwards. Visualise this.

Question 34

How can you correct long-sightedness?

Answer 34

Hyperopia can be correct with convex (converging) lens, which bends the light inwards. Visualise this.

Question 35

What are the 2 types of photoreceptors in the eye, and what are their functions?

Answer 35

1) Rods. Rods respond to light, and allows you to see in low levels of lighting.
2) Cones. Cones responds to colours, and there are different cones for red, green, and blue.

Question 36

What does your brain do?

Answer 36

Your brain processes all the information collected from receptor cells about your external and internal environment and processes information from your hormonal system, to produce coordinated responses.

Question 37

Why is having a brain useful?

Answer 37

It acts as the central control centre, and allows for fast neuronal communication.

Question 38

What are the main 5 components of your brain?

Answer 38

Cerebrum
Cerebellum
Medulla Oblongata
Hypothalamus
Pituitary Gland

Question 39

Describe the function of the cerebellum.

Answer 39

The cerebellum controls posture, balance, and involuntary movements.

Question 40

Describe the function of the cerebrum.

Answer 40

The cerebrum controls complex behaviours such as learning, memory, personality and conscious thought.

Question 41

Describe the function of the medulla.

Answer 41

The medulla oblongata controls automatic actions such as heart rate and breathing rate.

Question 42

Describe the function of the hypothalamus.

Answer 42

The hypothalamus regulates temperature and water balance.

Question 43

Describe the function of the pituitary gland.

Answer 43

The pituitary gland stores and releases hormones that regulate many bodily functions.

Question 44

List the 4 parts of the cerebrum.

Answer 44

1) Frontal lobe - decision making, reasoning, planning, emotions.
2) Parietal Lobe (top right) - orientation, movement, memory.
3) Occipital lobe (bottom right) - visual cortex
4) Temporal lobe - auditory information.