Regions of the brain and why treating it is difficult, the structure of the eye, accommodation, long and short sightedness, and how body temperature is controlled. Biology only content.
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1.What is the brain made of, and what does it do?
Billions of interconnected neurones. It controls complex behaviour.
2.What does the cerebral cortex do?
It is responsible for consciousness, intelligence, memory and language.
3.What does the cerebellum do?
It coordinates muscular activity and balance.
4.What does the medulla do?
It controls unconscious activities such as heart rate and breathing rate.
5.Give three ways neuroscientists map the brain.
Studying patients with brain damage, electrically stimulating parts of the brain, and using MRI scans.
6.Why is treating brain disorders so difficult?
The brain is extremely complex and delicate, it is encased in the skull so hard to access, and damage during treatment can be permanent.
7.What is the function of the eye?
It is a sense organ containing receptors sensitive to light intensity and colour.
8.What does the cornea do?
It is the transparent front of the eye that refracts light as it enters.
9.What does the iris do?
It controls the size of the pupil, and so how much light enters the eye.
10.What is the pupil?
The hole in the middle of the iris that light passes through.
11.What does the lens do?
It focuses light onto the retina, and can change shape to focus on near or distant objects.
12.What does the retina contain?
Light receptor cells, sensitive to light intensity and colour.
13.What does the optic nerve do?
It carries impulses from the retina to the brain.
14.What happens to the pupil in bright light?
The circular muscles of the iris contract and the radial muscles relax, so the pupil gets smaller and less light enters.
15.What happens to the pupil in dim light?
The radial muscles contract and the circular muscles relax, so the pupil widens and more light enters.
16.What is accommodation?
The process of changing the shape of the lens to focus on near or distant objects.
17.Describe accommodation for a near object.
The ciliary muscles contract, the suspensory ligaments loosen, and the lens becomes thicker and more curved, refracting light strongly.
18.Describe accommodation for a distant object.
The ciliary muscles relax, the suspensory ligaments are pulled tight, and the lens is pulled thin so it refracts light only slightly.
19.What is myopia?
Short sightedness. Distant objects cannot be focused because rays are brought to a focus in front of the retina.
20.What is hyperopia?
Long sightedness. Near objects cannot be focused because rays are brought to a focus behind the retina.
21.How is short sightedness corrected?
With a concave lens, which spreads the light rays out before they enter the eye.
22.How is long sightedness corrected?
With a convex lens, which brings the light rays together before they enter the eye.
23.Give two treatments for eye defects other than spectacles.
Contact lenses, laser surgery to change the shape of the cornea, or a replacement lens implanted in the eye.
24.Where is body temperature monitored?
By the thermoregulatory centre in the brain, which contains receptors sensitive to the temperature of the blood.
25.Why must body temperature be controlled?
Enzymes work best at about 37 degrees Celsius and denature if the temperature rises too far above it.
26.Give three responses when body temperature is too high.
Sweat is produced from sweat glands, blood vessels near the skin dilate, and hairs lie flat.
27.How does sweating cool the body?
The sweat evaporates from the skin, and the energy needed for evaporation is taken from the body surface.
28.What is vasodilation?
Blood vessels supplying the skin capillaries dilate, so more blood flows near the surface and more energy is transferred to the environment.
29.Give three responses when body temperature is too low.
Shivering, vasoconstriction, and sweating stops. Hairs also stand up to trap an insulating layer of air.
30.Why does shivering warm you up?
Muscles contract rapidly, which requires respiration, and respiration is exothermic so it transfers energy that warms the body.
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