2. Homeostasis Pt2

Question 1

How did they used to map the brain?

Answer 1

• as the brain is protected by the skull

- early information on its functions only came from studying the effects of damage to different parts

Question 2

How do they map the brain now?

Answer 2

• modern techniques like ‘magnetic resonance imaging’ (MRI) can show us scans of patients brains to see the effects of tumours, strokes etc.
• you can also remove parts of the skull and electrically stimulate areas of the brain to map the areas, often before surgery

Question 3

What are the problems with MRI?

Answer 3

• MRI can only diagnose a problem not treat it

- it can only be used on patients that have no metal in there bodies due to prior surgeries

Question 4

What are the problems with opening the skull for brain surgery?

Answer 4

It risks damaging the very delicate neurones and synapses, especially when we don’t fully understand what each area does.
It’s delicacy & complexity makes it hard to investigate

Question 5

What are the problems with drugs to treat brain disorders?

Answer 5

• drugs can by used but many struggles to cross the membrane surrounding the brain so don’t reach it
• the range of chemicals released by synapses can be easily disrupted with serious side-effects

Question 6

What does the sclera in the eye do?

Answer 6

White outer layer of the eye

Providing protection

Question 7

What does the cornea in the eye do?

Answer 7

It’s the transparent front section of the sclera

It allows light into the eye and bends (refracts) the light to aid focus

Question 8

What does the iris in the eye do?

Answer 8

• a ring of muscle which can contract or relax to change the amount of light passing through to the retina
• it constricts in bright light to protect the retina from damage or dilates in low light to allow more light to reach the light-sensitive cells

Question 9

What does the retina in the eye do?

Answer 9

It’s a Layer of light-sensitive receptor cells

Question 10

What does the optic nerve do?

Answer 10

Carries impulses from the retina to the brain to be processed and interpreted as a visual image

Question 11

What’s our blind spot?

Answer 11

The point where the optic nerve leaves the eye so there’s no retina to detect light

Question 12

Explain accommodation

Answer 12

-the process of changing the shape of the lens to focus on near or distant objects

Question 13

Explain what happens to the eye when it tries to focus on something in the distance?

Answer 13

• the ciliary muscles relax, allowing the suspensory ligaments to pull the lens tight
• this pulls the lens flat and thin, and only slightly refracts light rays

Question 14

Explain what happens to the eye when it tries to focus on something close up

Answer 14

• the ciliary muscles contract, loosening the suspensory ligaments
• the lens is then thicker and refracts light rays more strongly

Question 15

What’s the scientific word for shortsightedness?

Answer 15

Myopia

Rays of light don’t focus on the retina

Question 16

Explain how myopia/shortsightedness works?

Answer 16

• if your lens is too curved or your eyeball is too long the light is refracted too much and the light rays focus in front of the retina
• this causes the rays that reach the retina from distant objects to be out of focus and blurry

Question 17

If your short sight you can’t see objects which are ………. ……….

Answer 17

Far away

Question 18

How do contacts/glasses work for people with myopia/short-sightedness?

Answer 18

Glasses/contacts which are concave spread out the light before it reaches the eye so the lens can then focuses the rays correctly

Question 19

Explain how hyperopia/longsightedness works?

Answer 19

• if your lens is too flat and thin, or your eyeball is too short your lens can’t refait the light rays enough so they focus behind the retina
• this causes objects to become blurry
• it often gets worse with age as the ciliary muscles get weaker

Question 20

What’s the scientific word for longsightedness?

Answer 20

Hyperopia

Question 21

What kind of glasses do you use for longsightedness and explain how they work?

Answer 21

• convex glasses/contact lenses

- they refract the light before it reaches the eye so the lens doesn’t have to

Question 22

What are 3 new types of technology to improve eyesight? And how are they dangerous?

Answer 22

1. laser eye surgery
2. Lens replacement
3. Permanent contact lenses
   These surgeries are new and carry risks of damage to retina, infection or possible cataract formation in lens replacement

Question 23

Explain how laser eye surgery works?

Answer 23

-once your eye has stopped growing, a laser can be used to change the shape of the cornea

Question 24

Explain how laser eye surgery works to tread myopia

Answer 24

-the thickness of the cornea is decreased to reduce refraction

Question 25

Explain how laser eye surgery works to treat hyperopia

Answer 25

The curvature of the cornea is changed to increase refraction

Question 26

Explain how lens replacement works?

Answer 26

Surgery can replace a faulty lens with an artificial one that refracts the light the correct amount

Question 27

Explain how a permanent contact lens works

Answer 27

A permanent contact lens can be implanted into the eye to aid the natural lens

Question 28

How would you carry out an investigation to test if practise improved reaction speed?

Answer 28

- sit on a stool and rest your non-dominate arm on the desk - your patterned hold one end of the ruler level with index finger and thumb then drops it - catch the ruler as quickly as possible - repeat 10 times and plot a graph