B10

Question 1

What is the eye?

Answer 1

The eye is a sense organ containing receptors sensitive to light intensity and colour.

Question 2

What is the sclera? And what does it do ?

Answer 2

It is the tough outer layer of the eye and it protects and holds the eye in place.

Question 3

What is the retina?

Answer 3

It is the back of the eye and is made up of light-sensetive receptor cells. It contains rod and cone cells.

Question 4

What is the optic nerve?

Answer 4

It carries impulses from the retina to the brain

Question 5

What is the cornea?

Answer 5

It is the transparent region of the sclera at the front of the eye that refracts light - bends it as it enters the eye.

Question 6

What is the iris?

Answer 6

It has sets of muscles that control the size of the pupil and regulate the light reaching the retina

Question 7

What do the Cilary muscles and suspensory ligaments do?

Answer 7

They change the shape of the lens to focus light rays on the retina

Question 8

When reacting to light what does muscular iris do?

Answer 8

It controls the size of the pupil

Question 9

What happens when your eye reacts to bright light?

Answer 9

-The circular muscles contract
-The radial muscles relax
-Pupil constricts

Question 10

What is accommodation?

Answer 10

Accomodation is a reflex where your eye focuses on a near or distant object by changing the shape of the lens to focus the light onto the retina

Question 11

What happens when your short sighted?

Answer 11

When your short sighted, your cant focus on distant objects because either your lens is too fat (thickned) so it refracts the light too much and the light focuses in front of the retina or your eyeball is too long

Question 12

What is short sightedness caused by? (Myopia)

Answer 12

It is caused by the lens being too thick or by the eyeball being too long

Question 13

What happens when your long sighted? (Hyperopia)

Answer 13

It is when light rays focus behind their retina - they cant refract enough

Question 14

What is long sightedness caused by?

Answer 14

It is caused by the lens being too thin and the eyeball being too short

Question 15

How to fix long/short sightedness?

Answer 15

By wearing glasses or contacts to help focus light onto the retina. Or by getting eye surgery to change the shape of the cornea with a laser to help the eye focus the light correctly onto the retina. Or by getting replacment lens surgery - natural lense of eye is removed and an artificial lens is replaced - made of clear plastic

Question 16

What is homeostasis?

Answer 16

Homeostasis is all about the regulation of the conditions inside your body to maintain a stable internal environment in response to internal/external conditions

Question 17

What are the 2 types of automatic control systems inside your body that regulate your internal environment?

Answer 17

Nervous and hormonal communication systems

Question 18

What are your control systems made out of?

Answer 18

All your automatic control systems are made up of 3 main components which work together to maintain a steady condition (homeostasis) - cells called receptors, coordinations centres and effectors

Question 19

What is a negative feedback loop?

Answer 19

When the level of something gets too low or too high your body uses a negative feedback loop to bring it back to normal

Question 20

Explain a negative feedback loop

Answer 20

• Receptors detect a stimulus - level is too high
• The coordination centre recieves and processes the information, then organises a response
• Effector produces a response which counteracts the change and restores the optimum level - the level then decreases

This is also the same the other way around so when a level of something is too low your body counteracts it to make it come back to normal

Effectors will carry on producing the responses for as long as they’re stimulated by the coordination center.

This process happens automatically

Question 21

What is a stimulus?

Answer 21

It is a change in environment

Question 22

What is your nervous system made out of?

Answer 22

• CNS - consists of brain and spinal cord only, in mammals the CNS is connected to the body by sensory neurones and motor neurones
• Sensory Neurones - the neurones that carry information as electrical impulses from the receptors to the CNS
• Motor neurones - The neurones that carry electrical impulses from the CNS to effectors
• Effectors - All your muscles and glands which respond to the impulses

Question 23

What are the receptors and effectors?

Answer 23

Receptors are the cells that detect stimuli

Effectors respond to nervous impulses and bring about a change ( muscles and glands ). Muscles contract in response and glands secrete hormones in response

Question 24

What do relay neurones do?

Answer 24

They connect motor neurones and sensory neurones

Question 25

What are synapses and how do they work?

Answer 25

The connection between 2 neurones is called a synapse The nerve signal is transferred by chemicals which diffuse across the gap These chemical reactions then set off a new electrical signal in the next neurone

Question 26

What do reflexes do and what are they?

Answer 26

Reflexes are rapid, automatic responses to certain stimuli that don't involve the conscious part of the brain - they can reduce the chances of you getting injured

Question 27

Explain a reflex arc / action

Answer 27

Your receptors pick up a stimulus and send a electrical signal along a sensory neurone to a relay neurone in the CNS, then when the impulses reach a synapse between a sensory neurone and a relay neurone, they trigger chemicals to be released and these chemicals cause impulses to be sent along the relay neurone, then when the impulse reach another synapse, the same thing happens but this time the impulses are sent across a synapse to the motor neurone. Then the impulse travels along the motor neurone to the effector ( muscle or gland ) and this then causes the muscle to contract ( triggers a response )

Question 28

How can you measure reaction times? (Practical)

Answer 28

use the ruler drop test to see your reaction to a visual stimulus

Question 29

What is the celebral cortex?

Answer 29

This is the outer wrinkly bit. It's responsible for things like consciousness, intelligence, memory and language.

Question 30

What is the medulla?

Answer 30

Controls unconscious activities (things you don't have to think about doing) like breathing and your heartbeat.

Question 31

What is the Cerebellum?

Answer 31

Responsible for muscle coordination.

Question 32

Explain all the ways that you can study the brain

Answer 32

Studying patients with brain damage - If a small part of the brain has been damaged, the effect this has on the patient can tell you a lot about what the damaged part of the brain does. Electrically stimulating the brain - The brain can be stimulated electrically by pushing a tiny electrode into the tissue and giving it a small zap of electricity. By observing what stimulating different parts of the brain does, it's possible to get an idea of what those parts do. MRI scans - A magnetic resonance imaging (MRI) scanner is a big fancy tube-like machine that can produce a very detailed picture of the brain's structures. Scientists use it to find out what areas of the brain are active when people are doing things like listening to music or trying to recall a memory.

Question 33

What are the consequences of studying the brain?

Answer 33

1) Knowledge of how the brain works has led to the development of treatments for disorders of the nervous system. For example, electrical stimulation of the brain can help reduce muscle tremors caused by nervous system disorders such as Parkinson's disease. 2) However, the brain is incredibly complex and delicate - the investigation of brain function and any treatment of brain damage or disease is difficult. It also carries risks, such as physical damage to the brain or increased problems with brain function

Question 34

What happens to your eyes in dim light?

Answer 34

Radial muscles contract and the circular muscles relax, which makes the pupil wider

Question 35

What do automatic control systems do ?

Answer 35

They regulate your internal environment

Question 36

Why is treating the brain very difficult ?

Answer 36

-the brain is encased in a skull so its hard to get to -many things can go wrong when operating on a brain - physical damage, infection etc. -because its so complex - it's hard to target with medication

Question 37

What is the hypothalamus responsible for ?

Answer 37

It's responsible for regulating our body temperature

Question 38

Where is the medulla found ?

Answer 38

In the brain stem

Question 39

What is the pupil ?

Answer 39

It is the gap through which light passes through to get to the lens

Question 40

What are the two types of receptor cells in the retina ? And what do they do ?

Answer 40

Rod and cone cells Rod cells detect the presence of light or the absence of light Cone cells detect Colour

Question 41

What is the fovea ?

Answer 41

It is the place where light focuses on the retina - it contains the highest concentration if cone cells and gives the sharpest image

Question 42

Whats the iris reflex used for ?

Answer 42

To ensure that the optimum amount of light enters the eye and to prevent the eye from getting injured from lots of BRIGHT light entering the eye as bright light can damage the retina