Homeostasis and response Flashcards

1
Q

What is homeostasis?

A

Maintaining a stable internal environment controlled by automatic nervous and hormonal control systems.

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2
Q

What is negative feedback?

A

A mechanism that keeps internal conditions stable. When a level of something (eg. water, blood sugar, temperature) gets too high or too low, your body uses negative feedback to bring it back to the normal level.

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3
Q

What does the nervous system do?

A

Detects and reacts to stimuli

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4
Q

What are stimuli?

A

Changes in environment

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5
Q

What is the nervous system made up of?

A

Central Nervous System CNS (brain and spinal cord)
Sensory Neurones
Motor neurones
Effectors

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6
Q

What are receptors?

A

The cells that detect stimuli.

They can form part of larger organisms.

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7
Q

What are effectors?

A

Effectors respond to nervous impulses and bring about a change.
They’re either muscles or glands.

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8
Q

What are synapses?

A

The connection between two neurones.

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9
Q

What are reflexes?

A

Rapid, automatic responses to certain stimuli that do not require the conscious part of the brain.

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10
Q

What is the reflex arc?

A
Stimulus
Receptors
Sensory neurone
Relay neurone
Motor neurone
Effector
Response
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11
Q

What is the function of the cerebral cortex?

A

The part of the brain responsible for consciousness, memory, intelligence and language.

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12
Q

What is the function of the medulla?

A

The part of the brain that controls unconscious activities eg. breathing and heartbeat

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13
Q

What is the function of the cerebellum?

A

The part of the brain responsible for muscle coordination.

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14
Q

How do scientists study the brain?

A
  • Studying patients with brain damage
  • Electrically stimulating the brain
  • MRI scans
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15
Q

What are the disadvantages of studying the brain?

A

It is difficult.

There is a risk of physical damage or increased problems involving the brain.

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16
Q

What is the sclera?

A

Tough, supporting wall of the eye

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17
Q

What is the cornea?

A

The transparent outer layer at the front of the eye which refracts light into the eye.

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18
Q

What is the iris?

A

The coloured part of the eye that contains muscles which control the diameter of the pupil and therefore how much light enters the eye.

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19
Q

What is the pupil?

A

Hole in the middle of the eye which light enters through

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20
Q

What is the lens?

A

The part of the eye that focuses the light.

21
Q

What is the retina?

A

The part of the eye that contains receptor cells sensitive to light intensity and colour.

22
Q

What is the function of the ciliary muscles and suspensory muscles?

A

Control the shape of the lens

23
Q

What is the function of the optic nerve?

A

Carries impulses from the receptors on the retina of the eye to the brain

24
Q

What happens to the eye in bright light?

A

Pupil constricts (goes smaller)
Circular muscles contract
Radial muscles relax

25
Q

What happens to the eye in dim light?

A

Pupil dilates (gets bigger)
Circular muscles relax
Radial muscles contract

26
Q

What happens to the eye to look at near objects?

A

Ciliary muscles contract which slacken the suspensory ligaments
Lens becomes fat (more curved)
Increases amount by which it refracts light

27
Q

What happens to the eye to look at distant objects?

A

Ciliary muscles relax which allow the suspensory ligaments to pull tight
Lens becomes thins (less curved)
Refracts light by smaller amount

28
Q

What is hyperopia?

A

Long sightedness

Being unable to focus on near objects

29
Q

What is myopia?

A

Short sightedness

Being unable to focus on far objects

30
Q

What treatments are there for vision defects?

A

glasses
contact lenses
laser eye surgery
replacement lens surgery

31
Q

How does hyperopia happen?

A

Being long sighted happens when:
the lens is the wrong shape and doesn’t refract enough light
or
the eyeball is too short
images of near objects are brought to focus behind the retina instead of on it

32
Q

How does myopia happen?

A

Being short sighted happens when:
the lens is the wrong shape and refracts too much light
or
the eyeball is too long
images of far objects are brought to focus in front of the retina instead of on it

33
Q

Where is body temperature controlled?

A

thermoregulatory centre in the brain

contains receptors sensitive to blood temperature and receives impulses from receptors in the skin

34
Q

What are antagonistic effectors?

A

effectors that oppose each other’s actions

eg. one effector heats and the other cools at the same time so that together they reach the correct temperature

35
Q

What does your body do when you’re too hot?

A

hairs lie flat
sweat is produced (by sweat glands) and then evaporates from the skin, which transfers energy to the environment
vasodilation - blood vessels supplying the skin dilate so more blood flows closer to the skin so that more enegy transfers to the environment

36
Q

What does your body do when you’re too hot?

A

hairs stand up, which creates an insulating layer of air
vasoconstriction - bloos vessels supplying the skin capillaries constrict to cloe of the skin’s blood supply so that less heat is transferred to the surroundingd
shivering (muscles contract quickly), which needs respiration which transfers some energy to the body

37
Q

What are hormones?

A

Chemical molecules released directly into the blood, which are produced and secreted by endocrine glands (that make up the endocrine system)

38
Q

What is the role of the pituitary gland?

A

Produces many hormones that regulate body conditions

39
Q

What is the role of the thyroid?

A

Produces thyroxine, which regulates things like the rate of metabolism, heart rate and temperature

40
Q

What is the role of the adrenal gland?

A

Produces adrenaline, the hormone in control of the fight or flight response

41
Q

What is the role of the pancreas?

A

Produces insulin, which regulates the blood glucose level

42
Q

What is the role of the ovaries (in women)?

A

Produce oestrogen, which is involvd in the menstrual cycle

43
Q

What is the role of the testes (in men)?

A

Produce testosterone, which controls puberty and sperm production

44
Q

What are the differences between nerves and hormones?

A
NERVES:
-very fast action
-act for a very short time
-act on a very precise area
HORMONES:
-slower action
-act for a long time
-act in a more general way
45
Q

What happens when your blood glucose level is too high?

A

The pancreas secretes insulin into the blood
The insulin and glucose move into the liver
The insulin makes the liver turn glucose into glycogen so that it can be stored

46
Q

What happens when your blood glucose level is too low?

A

The pancreas secretes glucagon into the blood
The glucagon makes the liver turn glycogen into glucose
Glucose is released into the blood

47
Q

What is diabetes?

A

Condition where your body can’t control your blood sugar level

48
Q

What is type 1 diabetes?

A

Where the pancreas produces little or no insulin.
This means the person’s blood glucose levels can easily get to a dangerous level.
People with type 1 glucose need to have insulin therapy (eg. insulin injections)
Developed at young age/born with it

49
Q

What is type 2 diabetes?

A

Where someone’s body becomes resistant to their own insulin.
This means the person’s blood glucose levels can easily get to a dangerous level.
Can be controlled by eating a carbohydrate controlled diet or by regular exercise.
Being overweight and unfit can increase chances of developing type 2 diabetes.