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Biology Michael > B1.2 Nerves and Hormones > Flashcards

B1.2 Nerves and Hormones Flashcards

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1
Q

What is the nervous system?

A

What allows you to respond to changes in environment

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2
Q

What is the nervous system made up of?

A

Neurones (nerve cells)

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3
Q

What is a stimulus? Can you name them? (8)

A

A change in environment e.g. Light, sound, touch, pressure, pain, chemical or a change in position or temperature

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4
Q

What are stimuli detected by?

A

Groups of cells called receptors - they change stimulus energy (e.g. light energy) into electrical impulses

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5
Q

Where are receptors found? Can you name the 5 different places?

A

Sense organs - the eyes, ears, nose, tongue and skin

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6
Q

What receptors do the eyes contain?

A

Light receptors which are sensitive to light - They have nuclei which contain their genetic material and are filled with cytoplasm and surrounded by a cell membrane

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7
Q

What receptors do the ears contain? (2)

A

Sound receptors which are sensitive to sound - they also contain balance receptors which are sensitive to a change in position

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8
Q

What receptors does the nose contain?

A

Smell receptors which are sensitive to chemical stimuli

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9
Q

What receptors does the tongue contain?

A

Taste receptors which are sensitive to chemical stimuli - They can detect bitter, salt, sweet and sour, plus the taste of savoury things like monosodium glutamate (MSG)

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10
Q

What receptors does the skin contain?

A

Receptors which are sensitive to touch, pressure, pain and temperature change

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11
Q

What happens at the central nervous system?

A

Where all the information from the receptors are sent to, and where actions and reflexes are coordinated

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12
Q

What does the CNS consist of?

A

The brain and spinal cord - Neurones transmit information as electrical impulses to and from the CNS

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13
Q

What are effectors?

A

Muscles or glands which respond to nervous impulses and bring about a response to a stimulus

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14
Q

How do effectors respond to nervous impulses?

A

Muscles contract and glands secrete chemical substances called hormones

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15
Q

What are the 3 different types of neurones?

A

Sensory, Relay and Motor

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16
Q

What do the sensory neurones do?

A

Carry electrical impulses from receptors in sense organs to the CNS

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17
Q

What do the relay neurones do?

A

Found in the CNS, they carry impulses from the sensory neurones to the motor neurones

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18
Q

What do the motor neurones do?

A

Carry impulses from the CNS to the effectors

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19
Q

What is a synapse?

A

The connection between two neurones

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20
Q

How do the nerve signals move across a synapse?

A

The nerve signals are transferred by chemicals which diffuse across the gap and cause new electrical signals to set off in the next neurone

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21
Q

How does the synapse affect how quickly information is delivered?

A

Although it is still very fast, it does slow it down

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22
Q

What is a reflex?

A

A fast, automatic response to certain stimuli which doesn’t require you to think consciously

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23
Q

Examples of reflexes?

A

Bright light in eye - pupil shrinks meaning less light enters the eye and stops them from getting damaged
Adrenaline production - your body is ready for action
Knee-jerk reflex - helps maintain posture and balance

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24
Q

What is a reflex arc?

A

The passage of information in a reflex from receptors to effectors, is called a reflex arc - the neurones in a reflex arc go through the spinal cord or through an unconscious part of the brain

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25
Q

What are the 5 main stages involved in a reflex arc?

A
  1. Stimulus is detected by receptors, impulses are sent along sensory neurones to the CNS
  2. The impulses reach a synapse between the sensory neurone and a relay neurone
  3. Impulses reach a synapse between the relay neurone and the motor neurone
  4. The impulses then travel along the motor neurone to the effector
  5. If the effector is a muscle, it will contract; if it’s a gland, it will secrete a hormone
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26
Q

What is homeostasis?

A

The maintenance of a constant internal environment

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27
Q

What bodily levels need to be controlled? (4)

A

Temperature, water content of the body, ion content of the body and blood glucose content

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28
Q

Why does the internal body temp need to be constant at around 37°C?

A

Because the metabolic reactions in our body are controlled by enzymes which work best at around 37°C

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29
Q

What controls the body temperature?

A

A part of the brain is sensitive to the blood flowing through the brain and it receives information from skin receptors which provide info on skin temperature

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30
Q

How do ions get into the blood?

A

The food we eat contains ions (e.g. sodium) which are absorbed into the blood stream - excess ions need to be removed

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31
Q

How are excess ions removed from the body?

A

Some is lost through sweat, but is mainly removed by the kidney and then got rid of in urine

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32
Q

How does water get into the body?

A

Through the food we eat and what we drink

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33
Q

How is water removed from the body?

A

Through the skin as sweat, via the lungs in breath and via the kidney in urine

34
Q

How does the balance of sweat and urine change on a cold day when you’re not exercising?

A

You will sweat less and will produce more urine which is pale because the urea is diluted

35
Q

How does the balance of sweat and urine change on a hot day when you’re exercising?

A

You will sweat a lot and produce less urine which will be more concentrated and is a darker colour - you will also lose more water through breath because you breathe faster when you exercise

36
Q

How does glucose get into the blood?

A

Eating food containing carbs puts glucose into the blood from the gut

37
Q

How is glucose removed and how does this change when you exercise?

A

The normal metabolism of cells removes glucose from the blood but a lot of exercise means that more glucose is removed as it fuels body cells as a source of energy

38
Q

What maintains the right levels of glucose in the blood so your cells get a constant supply of energy?

A

A hormone called insulin

39
Q

What are hormones?

A

Chemical messengers which travel in the blood to activate target cells

40
Q

Give 3 examples of hormones

A

Follicle stimulating hormone, luteinising hormone and oestrogen - all hormones involved in the menstrual cycle

41
Q

Where hormones produced?

A

In glans e.g. the pituitary gland and the ovaries

42
Q

What are hormones like in the blood?

A

They are carried by blood plasma and travel around the body relatively slowly - they also tend to have long-lasting effects

43
Q

What’s the difference between nerves and hormones?

A

Although they do similar jobs -
Nerves: Fast action, act for a short time and acts on a precise area
Hormones: Slower action, act for a long time and acts in a more general way

44
Q

Name 2 examples of a nervous and hormonal action

A

Nervous: information is passed to effectors quickly e.g. pain signals
Hormonal: response lasts for a longer time e.g. adrenaline released into the body

45
Q

What is the menstrual cycle?

A

The monthly sequence in which the female body releases an egg and prepares the uterus in case it receives a fertilised eggs

46
Q

What events are in involved in the menstrual cycle?

A

The build-up of the protective lining in the uterus ready for the implantation of a fertilised egg, the release of an egg from the woman’s ovaries and the breakdown of the uterus lining if a fertilised egg is not implanted - this results in bleeding (a period)

47
Q

What happens in stage 1 of the menstrual cycle?

A

Day 1 - bleeding starts and the uterus lining breaks down for about 4 days

48
Q

What happens in stage 2 of the menstrual cycle?

A

Day 4 to day 14 - the uterus builds up again into a spongy layer full of blood vessels ready to receive a fertilised egg

49
Q

What happens in stage 3 of the menstrual cycle?

A

Day 14 - an egg is released into the ovary

50
Q

What happens in stage 4 of the menstrual cycle?

A

Day 14 to day 28 - the wall is maintained, if no fertilised egg was implanted by day 28, the spongy lining breaks down again and the cycle starts again

51
Q

Where is FSH produced and what is it’s role in the menstrual cycle?

A

Produced by the pituitary gland, it causes an egg to mature in one of the ovaries and stimulates the ovaries to produce oestrogen

52
Q

Where is Oestrogen produced and what is it’s role in the menstrual cycle?

A

Produced in the ovaries, causes the pituitary gland to produce LH and inhibits further release of FSH

53
Q

Where is LH produced and what is it’s role in the menstrual cycle?

A

Produced by the pituitary gland, it stimulates the release of an egg at around the middle (14 days) of the menstrual cycle

54
Q

How do the levels of hormones in the menstrual cycle change throughout the menstrual cycle?

A

Levels of one hormone can predict the level of another hormone e.g. FSH stimulates the ovaries to produce oestrogen so if FSH levels rise, so would oestrogen

55
Q

How can you reduce chances of pregnancy?

A

Contraception and taking hormones like oestrogen and progesterone from a woman

56
Q

What happens when a woman takes oestrogen everyday?

A

Although oestrogen helps to stimulate the release of an egg, if it is taken everyday, oestrogen levels are permanently high which inhibits FSH production and stops eggs from being released

57
Q

What happens when a woman takes progesterone everyday?

A

It increases the production of a thick cervical mucus which prevents sperm from reaching the egg

58
Q

What is an example of an oral contraceptive?

A

The pill

59
Q

The pill was first introduced in the 1950s, what were the issues related to this early version of the pill?

A

This pill contained high levels of oestrogen and progesterone - the high levels of oestrogen was linked to blood clots so nowadays the pill contains lower levels of oestrogen

60
Q

What alternatives are there to the OG pill?

A

Progesterone-only pills, but they’re not as effective

61
Q

What benefits are there of the combined oral contraceptive?

A

The pill’s over 99% effective at preventing pregnancy and it also is thought to reduce the risk of getting some types of cancer

62
Q

What drawbacks are there of the combined oral contraceptive?

A

It isn’t 100% effective, it can cause side effects like: headaches, nausea, irregular menstrual bleeding and fluid retention, and it also doesn’t protect against STDs

63
Q

Some women have low amounts of ____ so their eggs don’t mature, what is ____? And how is it resolved?

A

FSH - FSH and LH can be injected by women to stimulate egg maturation and release in their ovaries (these are fertility drugs)

64
Q

What problems are there with fertility drugs?

A

They don’t always work, some women need them several times which is expensive, and too many eggs could be stimulated resulting in multiple pregnancies

65
Q

How is IVF carried out?

A
  1. FSH and LH are given to the woman to stimulate the maturation of multiple eggs
  2. Eggs are then collected from the woman’s ovaries
  3. The eggs are fertilised in the lab using the man’s sperm
  4. The fertilised eggs then grow into embryos
  5. Once the embryos have formed 1 or 2 are transferred to the woman’s uterus - transferring more than 1 improves chance of pregnancy
66
Q

What are the drawbacks of IVF?

A

Some women react to the hormones e.g. abdominal pain, vomiting and dehydration, also there have been reports of an increase in cancer due to the hormones and multiple births can happen

67
Q

What is the main benefit of IVF?

A

It gives an infertile couple a child

68
Q

What do plants need to do in order to survive?

A

They need to be able to detect and respond to stimuli

69
Q

What is auxin?

A

A plant hormone that controls growth near the tips of shoots and roots

70
Q

What does auxin control? (3)

A

Phototropism, gravitropism and a plants growth in response to moisture

71
Q

What is phototropism?

A

Plant growth in response to light

72
Q

What is gravitropism?

A

Plant growth in response to gravity

73
Q

Where is auxin produced? And where does it work?

A

In the tips of shoots and roots and movies backwards to stimulate cell elongation which occurs in cells just behind the tips

74
Q

What happens if the tip of a plant is removed?

A

No auxin is available and the shoot may stop growing

75
Q

What does extra auxin do to the plant’s shoots/roots?

A

It promotes growth in the shoot, but inhibits growth in the roots

76
Q

How do shoots grow towards the light?

A

When a shoot tip is exposed to light, more auxin is accumulated on the shaded side which makes the shaded side’s cells grow faster and thus makes the shoot bend towards the light as it grows

77
Q

How do shoots grow away from gravity?

A

When a shoot is growing sideways, more auxin is accumulated on the lower side, this causes the lower side to grow faster and makes the shoot bend upwards as it grows

78
Q

How do roots grow towards gravity?

A

When a root is growing sideways, more auxin is accumulated on the lower side, this causes the lower side to grow slower than the upper side and makes the root bend downwards as it grows (as extra auxin in roots inhibits growth)

79
Q

How do roots grow towards moisture?

A

An uneven amount of moisture on either side of the root causes the auxin to accumulate on the side with more moisture - this makes the other side grow faster and this grows the root towards the moisture

80
Q

What are selective weed killers made of? How do they work?

A

Weeds are broad-leaved, unlike grasses and cereals which have narrow leaves. SWK contain plant growth hormones which disrupt the broad-leaved weeds growth patterns, which soon kills them

81
Q

How do rooting powders help plants grow?

A

Plant cuttings won’t always grow in soil - adding rooting powder (containing auxin) produces roots for the cutting rapidly and starts growing it as a new plant. This helps growers produces clones very quickly

Biology Michael (18 decks)

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