Topic 10 - The Human Nervous System

Question 1

What is homeostasis?

Answer 1

Keeping the body in a steady state.

Question 2

What is the advantage of homeostasis?

Answer 2

The body is kept at optimum conditions so that the metabolism is the most effective as possible.

Question 3

What internal conditions need to be kept the same in the body?

Answer 3

1) Temperature - (37 degrees) so that enzymes don’t denature but work at optimum temperature.
2) pH - So enzymes don’t denature but work at optimum.
3) Water concentration - to keep an osmotic balance, so cells won’t burst or shrink.
4) Sugar + salt concentration - to maintain an osmotic balance.

Question 4

What are the five stages of a reflex action?

Answer 4

1) Stimulus
2) Sensory Receptor
3) Co-ordinator (nervous system)
4) Effector
5) Response

Question 5

Which neurones link the different stages of the reflex action?

Answer 5

1) The sensory neurone links the sensory receptor and the relay neurone in the central nervous system.
2) The relay neurone links the sensory neurone and the motor neurone in the central nervous system.
3) The motor neurone links the relay neurone with the effector (muscle or gland).

Question 6

What two parts consist the nervous system?

Answer 6

1) Central Nervous System - brain + spinal cord (co-ordinators).
2) Peripheral Nervous System - goes to the furthest parts of the body (sensory + motor neurones).

Question 7

What are neurones?

Answer 7

Long specialised cells that are normally found in bundles of hundreds or thousands of neurones called nerves.

Question 8

What are receptors?

Answer 8

Cells that detect stimuli.

Question 9

What are effectors?

Answer 9

Areas (muscles or glands normally) that bring about a response from the body.

Question 10

What are coordination centres?

Answer 10

Areas that receive and process information from receptors.

Question 11

What are reflex arcs?

Answer 11

They bring about a reflex action. They involve the sense organ, sensory, relay and motor neurones.

Question 12

What are reflexes?

Answer 12

Rapid automatic responses of the nervous system that do not involve conscious thought.

Question 13

What does the cerebral cortex do?

Answer 13

This is the region of the brain associated with consciousness, memory and language.

Question 14

What does the medulla do?

Answer 14

This is the region of the brain concerned with unconscious activities like controlling heart or breathing rate. Additionally, the medulla controls long term memory storage.

Question 15

What does the cerebellum do?

Answer 15

This is the region of the brain concerned with coordinating muscular activity and balance.

Question 16

What does the hypothalamus control?

Answer 16

This is the region of the brain that controls body temperature.

Question 17

What does the temporal lobe do?

Answer 17

Processing auditory information and with the encoding of memory.

Question 18

What do the meninges do?

Answer 18

They are semi-permeable and prevent diseases from entering the brain.

Question 19

What does the brain stem do?

Answer 19

Sends signals to the rest of the body.

Question 20

What do MRI scans do?

Answer 20

They use magnetic resonance to scan different areas of brain for the different levels of activity.

Question 21

What does electrically stimulating the brain do?

Answer 21

It can contract and relax muscles due to stimulating parts of the brain via electrodes.

Question 22

What does the pituitary gland do?

Answer 22

Controls the release of hormones.

Question 23

What does the cornea do?

Answer 23

Refracts light - bends it as it enters the eye.

Question 24

What does the iris do?

Answer 24

Controls how much light enters the pupil of the eye.

Question 25

What does the lens do?

Answer 25

Due to it ps transparency and bi-convex shape, it focuses light onto the retina.

Question 26

What does the retina do?

Answer 26

It contains the light receptors at the back of the eye, allowing the light to be sent to the brain via the optic nerve.

Question 27

What does the optic nerve do?

Answer 27

Carries impulses from the retina at the back of the eye to the brain.

Question 28

How does the pupil change in dark conditions?

Answer 28

The circular muscles relax, the radial muscles of the iris contact and thus pupil diameter increases, so more light enters the eye.

Question 29

How does the pupil change in bright conditions?

Answer 29

The circular muscles contract, radial muscles of the iris relax and thus pupil diameter decreases, so less light enters the eye.

Question 30

What happens to the eye when it focuses on an object that is close up?

Answer 30

The ciliary muscle contracts, suspensory ligaments slack and thus a fat lens is made, bending light rays more.

Question 31

What happens when the eye focuses on an object far away?

Answer 31

The ciliary muscles relax, suspensory ligaments are pulled tight and the lens is pulled long and thin and thus light isn’t bent as much.

Question 32

What is myopia?

Answer 32

Near objects are clear, far objects are blurred. light rays are bent too much and the focal point is in front of the retina.

Question 33

What is hypermetropia?

Answer 33

Where far objects are clear, near objects are blurred as light rays are not refracted enough, the focal point is behind the retina.