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biology > homeostasis- b10 > Flashcards

homeostasis- b10 Flashcards

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1
Q

What is homeostasis?

A

Homeostasis is the regulation of the conditions inside your body to maintain a stable internal environment, in response to changes in both internal and external conditions.

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2
Q

What are internal conditions that are controlled by homeostasis?

A
  • body temperature
  • the water content of the body
  • blood glucose concentration
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3
Q

Why is homeostasis important?

A

It is important to respond to changes in the internal or external environment to maintain optimum conditions for cellular enzymes. Enzymes only work at their best in specific conditions of temperature and pH.

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4
Q

What are examples of automatic control systems?

A

Nervous and hormonal communication systems.

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5
Q

What three main components are automatic control systems made up of?

A

Receptors, coordination centres and effectors.

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6
Q

What does the nervous system do?

A

Detects and reacts to stimuli

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7
Q

What are receptors?

A

Receptors are cells that detect change in the internal or external environment. These changes are stimuli, so receptors detect stimuli.
Receptors are cells that detect stimuli

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8
Q

What are different examples of stimuli?

A

Change in temperature
Change in water content of blood
Change in blood glucose level
or external changes like loud sounds

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9
Q

What are examples of receptors?

A 
Taste receptors
Sound receptors in the ears 
Receptors in the eye 
Skin 
Can also sometimes be the brain or pancreas
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10
Q

What are coordination centres?

A

Coordination centres are areas that recieve and process the information from the receptors. They send out signals and coordinate the response of the body.

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11
Q

What are examples of coordination centres?

A

Brain
Spinal cord
Pancreas

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12
Q

What are effectors?

A

Bring about responses to bring the conditions in the body back to optimum levels.

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13
Q

What are examples of effectors?

A

Muscles and glands

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14
Q

How does the nervous system react to a stimulus?(explain in full)

A

When the receptor cells detect a stimulus, they convert the stimulus into an electrical impulse. The electrical impulse travels along the sensory neurones to the central nervous system(CNS). The impulse carries information about the change in the environment, once the impulse has reached the CNS, the CNS processes the information and coordinates a response, resulting in an electrical impulse being sent along motor neurones to the effectors. The effectors carry out the response, e.g muscles respond to the arrival of impulses by contracting. Your glands respond by secreting chemical substances.

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15
Q

What is the CNS?

A

The CNS is the central nervous system which is made up of the brain and spinal cord. It is a coordination centre and recieves information from the receptors and then coordinates a response.

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16
Q

What are sensory neurones?

A

Sensory neurones are the neurones that carry information as electrical impulses from the receptors to the CNS.

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17
Q

What are motor neurones?

A

Motor neurones are neurones that carry electrical impulses from the CNS to effectors.

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18
Q

What are neurones?

A

Special cells that carry electrical impulses, they are found in bundles of hundreds of neurones known as nerves.

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19
Q

What is a synapse?

A

The gap between neurones

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20
Q

How do synapses work?

A

When the impulse reaches the end of the first neuron, a chemical is released into the synapse. This chemical diffuses across the synapse. When the chemical reaches the second neuron, it triggers the impulse to begin again at the next neurone.

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21
Q

What is reaction time?

A

Your reaction time is how long you take to react to stimulus. It can be measured with the ruler drop test.

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22
Q

What are reflexes?

A

Reflexes are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain-they can reduce the chance of being injured

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23
Q

Why are reflexes important?

A

They help you to avoid danger or harm

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24
Q

What are examples of reflex actions?

A
  • If someone shines a bright light in your eyes, your pupils automatically get smaller so that less light gets into your eye-this stops it getting damaged
  • If you get a shock, your body releases the hormone adrealine automatically
  • If you touch something hot, or sharp, you pull your hand back quickly
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25
Q

What is a reflex arc?

A

It is the pathway that the information travels through in a reflex action(from receptor to effector)

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26
Q

What are relay neurones?

A

These connect a sensory neurone and a motor neurone, and are found in the CNS

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27
Q

How is a reflex arc different from usual respnoses?

A

The stimulus does not pass through the conscious areas of the brain which makes the reaction very quick.

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28
Q

How do reflexes work?(short)

A

An electrical impulse passes from the receptor along the sesnory neurone to the CNS. It then passes along a relay neurone and straight back along the motor neurone. From there the impulse arrives at the effector organ. The effector organ will be a muscle or a gland. This pathway is the reflex arc.

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29
Q

How do reflexes work?(long) ugh ik but its not very hard dont worry :)

A

When you touch an object, a receptor in your skin is stimulated. An electrical impulse from a receptor passes along a sensory neurone to the CNS(usually the spinal cord)
When an impulse from the sensory neurone arrives at the synapse with a relay neurone, a chemical is released. The chemical diffuses across the synapse to the relay neurone where it sets off a new electrical impulse that travels along the relay neurone.
When the impulse reaches the synapse between the relay neurone and a motor neurone, another chemical is released. Again, the chemical diffuses across the synpase and starts a new electrical impulse travellling down the motor neurone to the effector.
When the impulse reaches the effector organ, it is stimulated to respond.
An impulse also travels up to the spinal cord to the conscious areas of the brain, so you will know about the relfex action after its happened.

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30
Q

What are the main stages of a reflex arc?

A

Stimulus-receptor-sensory neurone-relay neurone-motor neurone-effector-response

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31
Q

What can reaction time be affected by?

A

Age, drugs, amount of sleep, tiredness, distractions

32
Q

How can you measure reaction time experiment?(effect of caffeine)

A

Caffeine is a drug that can speed up a persons reaction time. The effect of caffeine on reaction time can be measured like this…
-The person being tested should sit still with their arm resting on the edge of a table(this should stop them moving their arm up and down)
Hold a ruler vertically between their thumb and forefinger. Make sure the zero end of the ruler is level with their thumb and finger. Then let go without any warning.
The person being tested should try to catch the ruler as quicly as they can
Reaction time is measured by the number on the ruler where it is caught-the higher the number, the slower their reaction time
Repeat the test several times then calculate the mean distance that the ruler fell
The person being tested should then have a caffeniate drink and after 10 minutes repeat the steps

33
Q

What should you do to make the reaction time experiment a fair test?

A

You should use the same person to catch the ruler each time, and that person should always use the same hand to catch the ruler. Also the ruler should always be dropped from the same height.

34
Q

How can reaction time be measured using a computer?

A

The person being tested has to click the mouse as soon as they see a stimulus on the scrren eg a box change colour

35
Q

Why can computer be better for measuring reaction time?

A

Computers can give a more precise reaction time because they remove the possibility of human error from the measurement.
As the computer can record the reaction time in milliseconds it can also give a more accurate measurement
Using a computer can also remove the possibility that the person can predict when to respond-using the ruler test, the catcher may learn to anticipate the drop by reading the testers body language.

36
Q

Brief explanation of brain?

A

The brain is made up of many connected neurons and controls complex behavior. It is part of the central nervous system, along with the spinal cord. Different regions control different functions.

37
Q

What are the main regions of the brain?

A
  • Ceberal cortex
  • Medulla
  • Cerebellum
38
Q

What does the cerebral cortex do?

A

It is the outer part of the brain and it controls consciousness, intelligence, memory and language

39
Q

What does the medulla do?

A

Found in the brain stem, in front of the cerebellum. Controls unconscious activities such as breathing and heart rate

40
Q

What does cerebellum do>

A

It is a rounded structure towards the back/bottom of the brain. It controls muscle coordination

41
Q

why is investigating brain function and treating brain damage/disease difficult?

A

The brain is complex and delicate, it carries risks becuase the brain is easily damaged.
Drugs given to treat disease cannot always reach the brain becuase of the membranes surrounding it
It is not fully understood which part if the brain does what

42
Q

What methods can neuroscientists use to study the brain?

A
  • Studying patients with brain damage
  • Electrically stimulating the brain
  • MRI scans
43
Q

How can studying patients with brain damage tell us more about the brain?

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, e.g if the area at the back the brain was damaged by stroke and the patient went blind, you know that the area has something to do with vision.

44
Q

How can electrically stimulating the brain tell us more about the brain?

A

The brain can be stimulated electrically be pushing a tiny electride into the tissue and giving it a zap of electricty. By observing what stimulating different parts of the brain does, it is possible to get an idea of what those parts do e.g when a certain part of the brain is stimulated, it causes muscle coordination and movement.

45
Q

How can MRI scans tell us more about the brain?

A

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, it can also show a tumor.

46
Q

How has knowledge of the brain helped scientists?

A

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 Parkinsons disease.

47
Q

What is the eye?

A

The eye is a sense organ, containing receptors sensitive to light intensity and colour. It has many different structures within which are adapted to allow the eye to change its shape in order to focus on near or distant objects.

48
Q

What is retina?

A

Layer of light sensitive cells found at the back of the eye. When light hits this, the cells are stimulated. Impulses are sent to the brain, which interprets the information to create an image.

49
Q

What is the optic nerve?

A

A nerve that leaves the eye and leads to the brain. It carries the impulses from the retina to the brain to create an image.

50
Q

What is the sclera?

A

White outer layer which supports the structures inside the eye. It is strong to prevent some damage to the eye.

51
Q

What is the cornea?

A

The see through layer at the front of the eye. It allows light through and curved surface bends and focuses light onto the retina.

52
Q

What is the Iris?

A

Muscles that surround the pupil. They contract or relax to alter the size of the pupil.

53
Q

What are cilliary muscles and suspensory ligaments?

A

Hold the lens in place and control its shape.

54
Q

What happens when there is a bright 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 and the radial muscles relax. This reduces the amount of light that can enter the eye.

55
Q

What happens to the eye in dim light?

A

The radial muscles contract and the circular muscles relax, which makes the pupil wider.

56
Q

Why is the Iris reflex important?

A

The Iris reflex protects the eye because very bright light can damage the retina.

57
Q

What is accommodation?

A

It is when the eye focuses light on the retina by changing the shape of the lens, it is a reflex.

58
Q

How does accommodation work when looking at near objects?

A

The ciliary muscles contract, which relaxes the suspensory ligaments. The lens becomes more curved and thicker, so more light is refracted.

59
Q

How does accommodation work when looking at distant objects?

A

The ciliary muscles relax which allows the suspensory ligaments to contract. This makes the lens thinner and less curved, so less light is refracted.

60
Q

Why do many older people use reading glasses?

A

As you get older, your eye’s lens loses flexibility, so it can’t easily spring back to a round shape. This means light can’t be focused well for near viewing, so older people often have to use reading glasses.

61
Q

Why are some people short or long sighted?

A

Becuase the lens cannot refract the light by the right amount so that it focuses on the retina.

62
Q

What does it mean when someone is long sighted?

A

Long sighted people are unable to focus on near objects.

63
Q

Why does long sightedness happen?

A

This occurs when the lens is the wrong shape and doesn’t refract the light enough or the eyeball is too short.

64
Q

What happens in the eye when a person is long sighted?

A

The images of near objects are brought into focus behind the retina.

65
Q

How can you fix long sightedness?

A

You can use glasses with a convex lens to correct it.

66
Q

How do glasses fix long sightedness?

A

The glasses lens refracts the light rays so they focus on the retina.

67
Q

What is the medical term for long sightedness?

A

Hyperopia

68
Q

What does it mean when people are short sighted?

A

Short sighted people are unable to focus on distant objects.

69
Q

Why does short sightness happen?

A

This occurs when the lens is the wrong shape and refracts the light too much or the eyball is too long.

70
Q

What happen in the eye when a person is short sighted?

A

The images of distant objects are brought into focus in front of the retina.

71
Q

How can you fix short sightedness?

A

You can use glasses with a concave lens to correct it, so that the light rays focus on the retina.

72
Q

What is the medical term for short sightedness?

A

Myopia

73
Q

What are contact lenses and what are the pros and cons of wearing contacts?

A

Contact lenses are thin lenses that sit on the surface of the eye and are shaped to compensate for the fault in focusing.
They are popular because they are lightweight and almost invisible. They are also more convinient than glasses for activities like sport.
The are two main types of contact lenses are hard lenses and soft lenses. Soft lenses are more comfotable but carry a higher risk of eye infections than hard lenses.

74
Q

What is laser eye surgery and what are the pros and cons?

A

A laser can be used to vapourise tissue, changing the shape of the cornea.
Slimming it down makes it less powerful and can improve short sight. Changing the shape so that it is more powerful will improve long sight.
The surgeon can precisly control how much tissue the laser takes off, completly correcting the vision.
However, like all surgical procedures, there is a risk of complications, such as infection or the eye reacting in a way that makes your vision worse than before.

75
Q

What is replcament lens surgery and what are the pros and cons?

A

Sometimes long sightedness can be more effectively treated by replacing the lens of the eye.
In replacement lens surgery, the natural lens of the eye is removed and replaced with a artificial one made with clear plastic.
As it involves work inside the eye, replacing the lens carries higher risks than laser eye surgery, including possible damage to the retina(which could lead to loss of sight)

biology (8 decks)

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