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B10 Flashcards

1
Q

What is the retina

A

Made up of light -sensitive receptor cells

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2
Q

What is the optic nerve?

A

Carries impulses from the retina to the brain

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3
Q

What is the sclera?

A

The tough outer layer of the eye

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4
Q

What is the cornea?

A

Transparent region of the sclera at the front of the eye. Refracts light - bends it as it enters the eye

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5
Q

What is the iris?

A

Has sets of muscles thst control the size of the pupil and regulate the light reaching the retina

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6
Q

What does the lens do on an eye?

A

The lens focuses the light onto the retina ( which contains receptor cells sensitive to light intensity and colour

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7
Q

Very bright light can damage the retina. Explain the reflex to protect it… and dim light…

A

When light receptors in the eye detect very bright light, a reflex is triggered that makes the pupil smaller. The circular muscles in the iris contract the radial miscles relax. This reduces the amount ofnoight that can enter the eye.

The opposite process happens in dim light. The radial muscles contract and the circular muscles relax, which makes the pupil wider.

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8
Q

What is accomodation?

A

The eye focuses light on the retina by changing the shape of the lens

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9
Q

What can short-sightedness be casued by?

A

The lens being too thick
The eyeball being too long

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10
Q

What is long-sightedness caused by?

A

The lens being too thin
The eyeball being too short

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11
Q

What is short-sightedness?

A

People with short-sight can focus clearly on objects that are close to them, by automatic accomodation.

However, they cannot focus clearly on distant objects. The image forms in front of their retina even when the lens is as thin as possible.

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12
Q

What is long-sightedness?

A

People with long-sight can focus clearly on objects that are in distance by automatic accomodation.

However they cannot focus clearly on objects that are close to them. The image is focused behind their retina, even when the lens is as thick as possible

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13
Q

Ways to correct sight problems?

A

Wearing glasses. The extra lens in front of the eye helps to focus light onto retina.

Wearing contact lenses. These work in the same way as glasses, but are a lot smaller and sit directly on top of the eye. They are barely visisble

Eye surgery - the shape of the cornea can be changed with a laser to help the eye focus the light correctly onto the retina. This is usually carried out under local anaesthetic

Replacement LENS SURGERY: Sometimes long-sightedness may be more effactively treated by
Replacing the lens of the eye (rather than altering the shape of the corner with laser eye surgery).
In replacement lens surgery, the natural lens of the eye is removed and an artificial lens, made of clear plastic, is inserted in its place.
As it involves work inside the eye, replacing a lens carries higher risk than laser eye surgery, including possible damage to the retina (which could lead to loss of sight).

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14
Q

Homeostasis

A

Maintaining a constant internal environment

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15
Q

Homeostasis maintains optimal conditions for

A

enzyme action and all cell functions

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16
Q

Homeostasis is all about

A

regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

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17
Q

Your cells rely heavily on homeostasis. Why?

A

As they need the right conditions to function properly

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18
Q

In the human body, homeostasis include control of:

A

• blood glucose concentration
• body temperature
• water levels.

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19
Q

What are the three components that work together to maintain a steady condition

A

Receptors, coordination centres and effectors

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20
Q

Sensory organ

A

An area of the body which can detect a simulus

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21
Q

Automatic control systems in your body that regulate your internal environment include

A

Nervous and hormonal communication systems

22
Q

Stimulus

A

A detectable change in an organisms environment

23
Q

What is your nervous system

A

Means that humans can react to their surroundings and coordinate their behaviour.

24
Q

The CNS consists of the ….. and is connected to the body by

A

Brain and spinal cord.
by sensory neurones and motor neurones

25
Q

Sensory neurones

A

Carry information as electrical impulses from receptors to the CNS

26
Q

Motor neurones

A

Neurones that carry electrical impulses from the CNS to effectors

27
Q

Effectors

A

All your muscles and glands, which respond go nervous impulses.

28
Q

Receptors

A

The cells that detect a stimulus

29
Q

coordination centres (such as the brain, spinal cord and pancreas)

A

that receive and process information from receptors

30
Q

The CNS Is a

A

Coordination centre

31
Q

Bottom of page 66 for example on CNS

A
32
Q

The connection between two neurones is

A

A synapse

33
Q

(Synapse between two neurones) The nerve signal is transferred by

A

Chemicals which diffuse across the gap

34
Q

Reflexes are

A

Rapid, automatic response to certain stimuli that don’t involve the conscious part of the brain

35
Q

A reflex arc is

A

The passage of information in a relflex (from receptor to effector)

36
Q

The two types of effectors and what they do

A

-Muscles contract in response
-Glands increase or decrease hormone secretion

37
Q

Explain the process of a reflex arc

A

-Neurones go through spinal cord of through an unconscious part of the brain.
- when a stimulus is detected by receptors, impulses are sent along a sensory neurone to a relay neurone in the CNS.
- when the impulses reach a synapse between the sensory neurone and the relay neurone, it triggers chemicals to be released. These chemicals cause impulses to be sent along the relay neurone.
- when the impulses reach a synapse between the relay neurone and a motor neurone, the same thing happens. Chemicals are released and cause impulses to be sent along the motor neurone.
- the impukses then travek along motor neurone to effector.
- the muscle then contracts and move quicker than normal responses

38
Q

Cerebal cortex

A

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

39
Q

Medulla

A

Controls unconscious activities like breathing and heartbeat

40
Q

Cerebellum

A

Responsible for muscle coordination

41
Q

Studying patients with brain damage

A

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

42
Q

What is the name of the chemical messenger that crosses the synapse

A

Neurotransmitter

43
Q

What specialised cell is found in the nervous system

A

Nerve cells/nuerons

44
Q

Examples of sensory organs-

A

Eyes- detect change in light intensity
Ears- detect sound waves
Nose- detects chemicals in air
Tongue- detects chemicals in food
Skin- detects pressure applied to body

45
Q

What is fhe order of how information goes through from a stimulus go response

A

Simulus —- receptor —– coordinator —- effector —– response

46
Q

Include info on CNS specific neurones

A

Simulus
Receptor
Sensory neurone
Relay neurone
Motor neurone
Effector
Response

47
Q

Electrically stimulating the brain

A

The brain can be simulated 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 go get an idea of what those parts do.

48
Q

MRI SCANS

A

a magnetic resonance imaging scanner is a big tube 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

49
Q

Why is it difficult to investigate brain function and treating it

A

The brain is incredibly complex and delicate - the investigation of brain function and any treatment of brain damage or disease is difficult. It carries risk, physicsl damage and increased problems with brain function.

50
Q

To focus on a near object:

A

• the ciliary muscles contract
• the suspensory ligaments loosen
• the lens is then thicker and refracts light rays strongly.

51
Q

To focus on a distant object:

A

• the ciliary muscles relax
• the suspensory ligaments are pulled tight
• the lens is then pulled thin and only slightly refracts light rays.

52
Q

Two common defects of the eyes are

A

myopia (short sightedness) and hyperopia (long sightedness) in which rays of light do not focus on the retina.

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