B1.6/7 - The Nervous System & The eye

Question 1

What detects light in our eyes?

Answer 1

Receptors

Question 2

How does our brain process what we see with our eyes?

Answer 2

Receptors detect light and change this light into electrical impulses. The impulses pass along the optic nerve into the brain.

Question 3

Animals with both eyes facing forwards have

_______ vision.

Answer 3

Binocular

Question 4

What is one disadvantage of binocular vision?

Answer 4

Animals with binocular vision do not have a very wide field of view.

Question 5

Why may binocular vision be good for predators when hunting?

Answer 5

Since both eyes focus on the same thing, this allows them to judge distance accurately and focus well.

Question 6

Animals with eyes on each side of their head have ________ vision.

Answer 6

Monocular

Question 7

State two advantages of animals with monocular vision

Answer 7

• They have a much wider field of view

- They can see all around and notice predators in time to run.

Question 8

What sort of vision do humans have? And what does this allow them to do well?

Answer 8

Binocular vision. This allows humans to judge distance accurately and focus on objects.

Question 9

How does the human brain judge distance?

Answer 9

To judge distance the brain compares the images from each eye. If the images are very similar the brain knows you are looking at something from distance and vice versa.

You can test this. Look at something from a close distance. Cover one eye and then the other. You can see the object from a different view.

Question 10

What is it called when the lens in the eye has to change shape when focusing on a near or distant object?

Answer 10

Accomodation

Question 11

What is a symptom of red-green colour blindness and how can someone get this? And why does this symptom occur?

Answer 11

Red-green colour blindness is an inherited condition. It is when someone cannot tell the difference between the colour red and green. This happens because they do not have certain specialised cells in the retina.

Question 12

What is the retina?

Answer 12

A layer at the back of the eyeball that contains cells sensitive to light, which trigger nerve impulses that pass via the optic nerve to the brain, where a visual image is formed.

Question 13

What are the impacts to people with long sight?

Answer 13

People with long sight can see things in the distance clearly, but cannot focus on thing close by clearly.

Question 14

What are the impacts to people with short sight?

Answer 14

People with short sight can see things close by clearly, but cannot focus on things in the distance clearly.

Question 15

In short sight the eyeball is too (i)_____. In long sight the eyeball is too (ii)____.

Answer 15

(i) long

(ii) short

Question 16

Why are distant objects blurred to people with short sight?

Answer 16

Distant objects are blurred to people with short sight because the light rays meet in front of the retina instead of on it. This causes the final image to become blurred.

Question 17

How do lenses in glasses correct short sight?

Answer 17

Lenses in glasses for a person with short sight are called diverging lenses. Lenses in glasses for a person with long sight are called converging lenses.

Diverging lenses in glasses for people with short sight correct an image as it bends light rays outwards before they enter the eye. This causes the light rays to meet on the retina instead of in front of it, meaning a clear final image can be seen,

Question 18

What is a stimuli?

Answer 18

A stimuli is a change in the environment or in your body.

Question 19

Why do we need to be able to respond to changes in the environment or our bodies?

Answer 19

If you could nor respond to or detect a stimuli you would not be able to find food or avoid danger. E.g withdrawing your hand from a hot object.

Question 20

What is the nervous system?

Answer 20

The network of nerve cells and fibres which transmits nerve impulses between parts of the body

Question 21

There are two main parts of the nervous system and what do these include?

Answer 21

• The Central Nervous System (CNS) - the spinal cord and brain
• The peripheral Nervous System - nerves taking information from sense organs into the CNS, and from the CNS to effectors (muscles or glands)

Question 22

What is an effector?

Answer 22

An effector is any part of the body that produces the response to a stimuli. These are usually glands or muscles.

Question 23

What are receptors cells?

Answer 23

Receptors cells are special cells adapted to detect stimuli. Like most animal cells, they have a nucleus, cell membrane and cytoplasm.

Question 24

Name the 5 human sense organs and what information do they detect?

Answer 24

Skin - pressure, temperature, touch and pain
Nose - chemicals in air (smell)
Tongue - chemicals in food (taste)
Eyes - light (sight)
Ears - sound (hearing), balance

Question 25

How does information from the receptors pass as electrical impulses to the brain?

Answer 25

They travel along nerve cells called neurones, to the brain. The brain then coordinates the response.

Question 26

What is a voluntary response?

Answer 26

A voluntary response is for example when you hear a song on the radio and decide whether to turn up the radio, turn it off or leave it as it is.

Question 27

Sometimes you need to respond to a potentially dangerous situation very quickly. For example, you may need to withdraw your hand from a hot object before you get burnt. There is no time to think so the brain is not involved. Instead the response is coordinated by another part of the CNS, the spinal cord. These responses are fast, automatic and protective. What are they called?

Answer 27

Reflex actions

Question 28

Describe the order of the reflex arc pathway

Answer 28

Stimulus -> receptor -> sensory neurone -> relay neurone -> motor neurone -> effector -> response

Question 29

What is a neurone?

Answer 29

A specialized cell transmitting nerve impulses; a nerve cell.

Question 30

In the situation of a pin prick, what would the effector be according to the reflex arc pathway?

Answer 30

The effector would be the finger muscle as this is what pulls your hand away from the prick.

Question 31

What is a synapse?

Answer 31

a junction between two nerve cells, consisting of a tiny gap across which information travels from neurone to another.

Question 32

In terms of a muscle and gland being an effector, how would they respond.

Answer 32

Muscle: A muscle responds by contracting.

Gland : A gland responds by secreting chemical substances.

Question 33

Name two example of a reflex action

Answer 33

• Withdrawing a hand from a hot plate

- Withdrawing a hand from a pin