B10 - The human nervous system 2️⃣✅

Question 1

What is the function of the nervous system?

Answer 1

It enables organisms to react to their surroundings and coordinates behaviour

Question 2

What are the 2 parts of the central nervous system?

Answer 2

The brain and spinal cord

Question 3

Why are reflex actions described as rapid and automatic?

Answer 3

They do not involve the conscious part of the brain to happen almost automatically

Question 4

Why are reflex actions important?

Answer 4

For survival value and to prevent damage to the body

Question 5

Give the pathway of a nervous response

Answer 5

Stimulus → receptor → coordinator → effector → response

Question 6

Give the function of the cerebral cortex

Answer 6

The frontal area of the brain associated with consciousness, memory and language

Question 7

Give the function of the medulla

Answer 7

The region of the brain concerned with unconscious activities such as breathing and heart rate

Question 8

Give the function of the cerebellum

Answer 8

Region of the brain concerned with balance and coordination of muscular activity

Question 9

Why is it so difficult to treat brain disorders?

Answer 9

Because the brain is so very complex and delicate, one wrong move could cause permanent or fatal damage

Question 10

What is a synapse?

Answer 10

A synapse is a ‘junction’ between 2 neurones (where they connect and transmit information/ electrical impulses)

Question 11

What is the function of a neurone?

Answer 11

To carry electrical impulses around the body

Question 12

What is homeostasis?

Answer 12

The maintenance of a constant internal environment

Question 13

Give 3 internal conditions controlled by homeostasis

Answer 13

Body temperature, blood glucose concentration and water levels

Question 14

What is eye accomodation?

Answer 14

How the eye lens has to adjust its shape to be able to look at both near and distant objects so they are in sharp focus. For this to work light rays need to converge onto the focal point

Question 15

Give two common defects of the eye

Answer 15

Myopia (short-sightedness) and Hyperopia (long-sightedness)

Question 16

Give 3 ways eyes can be treated

Answer 16

Glasses, contact lenses & laser surgery

Question 17

What happens if body temperature is too high?

Answer 17

Blood vessels dilate and sweat is produced

Question 18

What happens if body temperature is too low?

Answer 18

Blood vessels constrict, sweating stops and shivering takes place

Question 19

How do you treated myopia (short-sightedness)?

Answer 19

concave spectacle lenses

Question 20

How do you treated hyperopia (long-sightedness)?

Answer 20

convex spectacle lenses

Question 21

Explain a reflex arc

Answer 21

1. Stimulus - e.g. hot surface
2. sensory receptor - detects change
   ↓ sensory neurone
3. coordinator - CNS (central nervous system)
   synapse
   ↓ relay neurone - ‘relays’ information between synapses
   synapse
   ↓ motor neurone - delivers electrical impulse to effector
4. Effector (e.g. muscle)
5. response (e.g. move arm away from hot surface)

Question 22

What is a nerve?

Answer 22

A bundle of neurones

Question 23

What is a neurone?

Answer 23

A single nerve cell

Question 24

How do synapses work?

Answer 24

1. electrical impulse arrives at the nerve ending in ‘neurone 1’
2. the electrical impulse causes sacs inside the synapse to fill with neurotransmitter chemicals
3. once enough sacs are full they will release the chemicals into the synaptic gap and the chemicals will diffuse across the gap, down the concentration gradient until they reach the complementary receptors on the other side of the gap
4. The neurotransmitter chemicals easily bind to the complementary receptor, if enough receptors are triggered then it will trigger another electrical impulse to remain its journey, but now in ‘neurone 2’

Question 25

How do stimulant drugs affect a response?

Answer 25

A stimulant drugs shape is similar to the neurotransmitter chemicals so can bind to receptor & increase the chances of an impulse so overall decreases reaction time

Question 26

How do depressant drugs affect a response?

Answer 26

A depressant drug may have a complementary shape to the receptor, but block them, preventing electrical impulses from being released at the usual speed so overall increases reaction time

Question 27

What is the cornea?

Answer 27

Transparent tough outer coat that refracts light as it enters the eye

Question 28

What is the iris?

Answer 28

Its pigmented (colour of your eyes) so light cannot pass through. Its muscles contract and relax to alter the size of the pupil. It controls how much light enters the pupil

Question 29

What is the lens?

Answer 29

Transparent flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles

Question 30

What is the retina?

Answer 30

The lining of the back of the eye containing to types of photoreceptor cells, rods and cones. The retina contains the light receptors in the eye

Question 31

What is the optic nerve?

Answer 31

A bundle of sensory neurones at the back of the eye that carries impulses from the eye to the brain

Question 32

What are rods?

Answer 32

Photoreceptor cells that are sensitive to dim light and black and white

Question 33

What are cones?

Answer 33

Photoreceptor cells that are sensitive to colour

Question 34

In dim light the radial muscles _________ and the circular muscles _________ therefore the pupil diameter _______ to let ________ light in.

Answer 34

In dim light the radial muscles contract and the circular muscles relax therefore the pupil diameter widens to let more light in.

Question 35

In bright light the radial muscles _________ and the circular muscles _________ therefore the pupil diameter _______ to let ________ light in.

Answer 35

In bright light the radial muscles relax and the circular muscles contract therefore the pupil diameter shrinks to let less light in.

Question 36

**Label this eye**

Answer 36

Question 37

**Label this brain**

Answer 37

Question 38

When seeing a near object, the lens shape becomes ________________________ in order to be able to ________ light more so it converges on the focal point to form a clear image

Answer 38

When seeing a near object, the lens shape becomes short and fat in order to be able to refract light more so it converges on the focal point to form a clear image

Question 39

When seeing a distant object, the lens shape becomes ________________________ in order to be able to ________ light less as ________ does most of the refraction; this is so it converges on the focal point to form a clear image

Answer 39

When seeing a distant object, the lens shape becomes long and thin in order to be able to refract light less as cornea does most of the refraction; this is so it converges on the focal point to form a clear image

Question 40

What are the structures associated with eye accomodation/ change of shape of the lens?

Answer 40

suspensory ligaments and cilliary muscles

Question 41

What are the structures assosciated with eye relfex in dim/ bright light?

Answer 41

radial muscles and circular muscles

Question 42

In order for lens shape to become short and fat the suspensory ligaments are ________ as the cilliary muscles have ___________

Answer 42

In order for lens shape to become short and fat the suspensory ligaments are slacken as the cilliary muscles have contracted

Question 43

In order for lens shape to become long and thin the suspensory ligaments are ________ as the cilliary muscles have ___________

Answer 43

In order for lens shape to become short and fat the suspensory ligaments are taught as the cilliary muscles have relaxed