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SB7 Flashcards

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1
Q

What is a hormone?

A

A chemical substance, produced by a gland and carried in the bloodstream, which alters the activity of specific target organs.

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2
Q

What are target organs?

A

The organ with receptor molecules on its cell surfaces which recognise a specific hormone.

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3
Q

What hormone is released by the adrenal glands?

A

Adrenaline.

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4
Q

What is one of the target organs of adrenaline?

A

The heart, which increases the heart rate.

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5
Q

What happens once a hormone has been used?

A

It is destroyed by the liver.

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6
Q

What are the effects of hormones?

A

The effects are much slower than the nervous system, but they last for longer.

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7
Q

Compare and contrast the nervous system and the hormonal system.

A

Nervous:
Type of signal- Electrical (chemical at synapses).
Transmission of signal- By nerve cells (neurones).
Effectors- muscles or glands.
Type of response- Muscle contraction or secretion.
Speed of response- Very rapid.
Duration of response- Short (until nerve impulses stop).

Hormonal:
Type of signal- Chemical.
Transmission of signal- By the bloodstream.
Effectors- Target cells in particular organs.
Type of response- Chemical change.
Speed of response- Slower.
Duration of response- Long (until hormone is broken down).

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8
Q

What hormone does the thyroid gland produce?

A

Thyroxine.

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9
Q

What hormone does the pancreas?

A

Insulin.

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10
Q

What hormone does the testes produce?

A

Testosterone.

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11
Q

What hormone do the ovaries produce?

A

Oestrogen.

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12
Q

What is the pituitary gland?

A

The ‘master gland’ situated at the base of the brain.

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13
Q

What hormone is produced at the pituitary gland?

A

ADH. Its target organ is the kidneys and its role is to control the water content of blood. Its effect is that it increases reabsorption of water by the collecting ducts.

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14
Q

What hormone is produced at the adrenal glands?

A

Adrenaline. It has several target organs including the respiratory and circulatory systems. Its role is preparation for ‘fight or flight’. It increases the breathing rate, heart rate, flow of blood to muscles and conversion of glycogen to glucose.

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15
Q

What hormone is produced in the pancreas?

A

Insulin. Its target organ is the liver. Its role is controlling blood glucose levels. It increases conversion of glucose into glycogen for storage.

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16
Q

What happens at the pituitary gland?

A

It secretes several hormones into the blood into the blood in response to the body’s condition, such as blood water levels. The hypothalamus detects changes in hormone levels and will release hormones which controls the pituitary gland or other organs. The hormones from the hypothalamus and pituitary can also act on other glands to stimulate the release of different types of hormones and bring about effects.

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17
Q

In animals, conditions such as what are kept constant as possible?

A

Water concentration, temperature, and glucose concentration.

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18
Q

Control systems that keep such conditions constant are examples of what?

A

Homeostasis; this is the maintenance of constant internal conditions in an organism.

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19
Q

What type of mechanism is an important type of control that it found in homeostasis?

A

Negative feedback mechanism.

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20
Q

When does a negative feedback control system respond?

A

When conditions change from the ideal or set point and returns conditions to this set point.

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21
Q

How does the negative feedback system work?

A
  • If the level of something rises, control systems reduce it again.
  • If the level of something falls, control systems reduce it again.
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22
Q

Give an example of negative feedback.

A

The control of body temperature. Body temperature is controlled by the hypothalamus in your brain. If your body gets too hot, your body begin to sweat, which reduces body temperature. In the opposite way, if the body gets too cold, your body begins to shiver to raise body temperature.

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23
Q

What does thyroxine do?

A

Stimulates the metabolic rate. It controls the speed at which oxygen and food products react to release energy for the body to use. Thyroxine also plays an important role in growth and development. Its levels are controlled by negative feedback.

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24
Q

What 2 things have important roles in detecting and controlling thyroxine levels?

A

Hypothalamus and pituitary gland:
1. Low thyroxine levels in the bloodstream stimulate the hypothalamus to release TRH and this causes the pituitary to release TSH so the thyroid releases more thyroxine. So the blood levels return to normal.
2. Normal thyroxine levels in the bloodstream inhibit TRH release from the hypothalamus and the production of TSH by the pituitary, so normal blood levels are maintained.
This is an example of negative feedback.

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25
Q

What happens when adrenaline is released into the bloodstream?

A

It creates multiple effects:
1. increases breathing rate, heart rate (therefore blood flow) and blood pressure.
2. conversion of glycogen to glucose in liver cells, increasing blood glucose.
These effects result in more glucose being delivered to the muscles and more energy being released by respiration in the muscles.

The effects of adrenaline allow the body to prepare for action in situation where a quick response may be needed.

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26
Q

Glucose is needed by cells for what?

A

Respiration.

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27
Q

What is insulin?

A

A hormone produced by the pancreas which regulates glucose concentration in the blood.

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28
Q

What happens if the blood glucose concentration is too high?

A

The pancreas produces the hormone insulin, which causes glucose to move from the blood into the cells. In liver and muscle cells excess glucose is converted to glycogen for storage and will be used at a later date.

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29
Q

What happens if there is low glucose?

A

Insulin is not secreted into the blood, the liver doesn’t convert glucose into glycogen and the blood glucose level increases.

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30
Q

What is diabetes?

A

A condition where the blood glucose levels cannot be controlled by the body. There are 2 types of diabetes- type 1 and type 2.

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31
Q

What is type 1 diabetes?

A

A disorder in which the pancreas fails to produce enough insulin. This can be detected from an early age. It is characterised by uncontrolled high blood glucose levels and it can be controlled by injecting insulin.

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32
Q

How can people with type 1 diabetes help to control their blood glucose level?

A

By being careful with their diet, and eat foods that will not cause large increases in blood sugar levels due to increased respiration in the muscles.

33
Q

What is type 2 diabetes?

A

When a person’s body cells no longer respond to insulin produced by the pancreas. It is more common in older people. It can be controlled by a carbohydrate controlled diet and an exercise regime. Carbohydrate is digested into glucose, which raises the overall blood glucose level. There is a correlation between rising levels of body mass in the general population and increasing levels of type 2 diabetes.

34
Q

How do you calculate Body Mass Index (BMI)?

A

Mass/ (height)2

People who are overweight or obese have an increased risk of developing type 2 diabetes.

35
Q

How do you calculate waist:hip ration?

A

Waist measurement/hip measurement.

36
Q

Describe the negative feedback response in blood glucose regulation.

A

In blood glucose regulation, the hormone insulin plays a key role. When blood sugar rises in the blood, insulin sends a signal to the liver, muscles and other cells to store the excess glucose. Some is stored as body fat and other is stored as glycogen in the liver and muscles. If the blood glucose level is too low, the pancreas releases the hormone glucagon. This travels to the liver in the blood and causes the break-down of glycogen into glucose. The glucose enters the blood stream and glucose levels increase back to normal.

37
Q

What is the menstrual cycle?

A

A recurring process that takes around 28 days. During the process, the lining of the uterus is prepared for pregnancy. If implantation of the fertilised egg into the uterus lining does not happen, the lining is then shed. This is known as menstruation.

38
Q

What hormones are involved in the menstrual cycle for a woman?

A
  • Follicle stimulation hormone (FSH) causes the maturation of an egg in the ovary.
  • Luteinising hormone (LH) stimulates the release of the egg.
  • Oestrogen is involved in repairing and thickening the uterus lining, progesterone maintains the uterine lining.
39
Q

Describe the interaction of oestrogen, progesterone, FSH and LH in the control of the menstrual cycle.

A
  • The pituitary gland produces FSH which causes the development of a follicle in the ovary.
  • As the egg develops inside the follicle, the follicle produces the hormone oestrogen.
  • The oestrogen causes growth and repair of the lining of the uterus wall. Oestrogen inhibits FSH.
  • When oestrogen rises to a high enough level it causes a surge in LH from the pituitary which causes ovulation where an egg is released from the follicle (day 14 of the cycle).
  • The follicle become the corpus luteum and this produces oestrogen and progesterone which inhibit FSH and LH production by the pituitary. This is an example of negative feedback.
  • Progesterone maintains the uterus lining (the thickness of the uterus wall).
  • If the egg has not been fertilised, the corpus luteum dies and progesterone levels drop. This cause menstruation, where the uterus lining breaks down-n this is known as having a period.
40
Q

What happens if a woman becomes pregnant?

A

The placenta produces progesterone. This maintains the lining of the uterus during pregnancy and means that menstruation does not happen.

41
Q

What is human fertility controlled by?

A

Hormones, so fertility can be controlled using hormonal forms of contraception.

42
Q

What does the oral contraceptive contain?

A

Oestrogen or progesterone or a combination of both hormones. These hormones inhibit the production of FSH, and eggs cannot mature.

43
Q

What does oestrogen at low levels do?

A

Stimulates the release of eggs. However at high doses, oestrogen will inhibit FSH production.

44
Q

What are the benefits of oral contraceptives?

A

They are more than 99% effective if taken correctly and can reduce the risk of certain cancers.

45
Q

What are the side-effects of oral contraceptives?

A

Changes in weight, mood and blood pressure due to high levels of oestrogen. Modern pills contain much less oestrogen.

46
Q

What do contraceptive injections, implants or skin patches contain?

A

Slow release progesterone to inhibit maturation and release of eggs.

47
Q

What are some non-hormonal methods of contraception?

A
  • Physical barrier methods such as condoms, which prevent the sperm reaching an egg.
  • Intrauterine devices (IUD) also known as a coil, prevent the implantation of an embryo or release of a hormone.
  • Spermicidal agents which kill or disable sperm.
  • Abstaining from intercourse when an egg may be in the oviduct.
  • Surgical methods of male and female sterilisation- an example is a vasectomy, where the sperm ducts are cut and tied.
48
Q

What are the benefits and risks of these methods?

A
  • Condoms are easy and quick to use, but sometimes they can tear or rip.
  • Diaphragms needs to be put in just before sex and left in several hours afterwards.
  • IUDs need to be fitted by a health professional- IUD can remain in position for up to 10 years, however there is a small risk of causing an ectopic pregnancy.
  • Spermicidal agents can be added to other physical barriers such as condoms, but some people can have allergic reactions to these.
  • Abstaining can be used successfully but if the timings are not accurate the chance of pregnancy is high.
  • Surgical methods cannot be reversed, and is considered permanent.
49
Q

Assisted Reproduction Technology (ART) is the use of what?

A

Hormones and procedures, as fertility treatments, to help achieve pregnancy. The include in vitro fertilisation (IVF) and a fertility drug, clomifene.

50
Q

If a couple are having difficulty conceiving a child because there are issues with the quality of the man’s sperm, or a woman has blocked oviducts, then what can be used?

A

IVF:

  • IVF involves giving a mother FSH and LH, to stimulate the maturation of several eggs in the ovary.
  • The eggs are collected from the mother and fertilised by sperm from the father in a dish in the laboratory.
  • The fertilised eggs develop into embryos.
  • At the stage when they are tiny balls of cells one or two embryos are inserted into the mother’s uterus (womb).
51
Q

What drug can be used as a fertility drug to stimulate ovulation, the release of eggs?

A

Clamifene. It works by blocking the action of oestrogen-s negative feedback on LH. Therefore more LH is released in a surge. This mimics the LH surge which occurs just before ovulation.

52
Q

Why must conditions in our body must be carefully controlled?

A

To allow it to function properly.

53
Q

What is homeostasis?

A

It is the maintenance of a constant internal environment in the body. The nervous system and hormones are responsible for controlling this.

54
Q

What are the body control systems all?

A

Automatic, and involve both nervous and chemical responses.

55
Q

What are the parts of the body control systems?

A
  • Receptors - detect a stimulus, which is a change in the environment, such as temperature change.
  • Coordination centres- in the brain, spinal cord and pancreas. They receive information from the receptors, process the information and instigate a response.
  • Effectors- such as muscles or glands create the response. Glands often release a hormone, which would restore the optimum condition again.
56
Q

Body temperature is one of the factors that is controlled during what?

A

Homeostasis.

57
Q

The human body maintains the temperature that enzymes work best, which is around what temperature?

A

37°C.

58
Q

What happens if body temperature increases over this temperature?

A

Enzymes will denature and become less effective at catalysing important reactions, such as respiration.

59
Q

What is body temperature regulation controlled by?

A

The thermoregulatory centre, which is contained in the hypothalamus in the brain, and it contains receptors sensitive to the temperature of the blood. The skin also has temperature receptors and sends nervous impulses back to the hypothalamus.

60
Q

How does the hypothalamus respond to this information?

A

By sending nerve impulses to effectors in the skin to maintain body temperature.

61
Q

What 3 layers does the skin contain?

A

The epidermis, dermis and fatty tissue.

62
Q

What happens when we get too hot?

A
  • Sweat glands in the dermis release more sweat onto the surface of the epidermis. The sweat evaporates, transferring heat energy from the skin to the environment.
63
Q

What happens when we get too cold?

A
  • Skeletal muscles contract rapidly and we shiver. These contractions need energy from respiration, and some of this is released as heat. Nerve impulses are sent to the hair erector muscles in the dermis, which contract. This raises the skin hairs and traps a layer of insulating air next to the skin.
64
Q

The amount of blood flowing through the skin capillaries is altered by what?

A

Vasoconstriction and vasodilation.

65
Q

What is vasoconstriction?

A

The process when you are too cold and the arterioles get narrower therefore blood flow in the skin capillaries decreases and so the heat loss from the skin decreases.

66
Q

What is vasodilation?

A

The process when you are too hot, so the arterioles get wides and blood flow in the skin capillaries increases therefore heat loss from the skin increases.

67
Q

What is osmoregulation?

A

The control of water levels and mineral ions (salt) in the blood.

68
Q

What happens if body cells lose or gain too much water?

A

They do not function properly.

69
Q

What does hypotonic mean?

A

More dilute solution outside the cell, normal turgid cell.

70
Q

What does hypertonic mean?

A

More concentrated solution outside the plant cell. The cytoplasm shrinks from cell wall.

71
Q

What happens if the water concentration is too high outside?

A

Water enters the cell by osmosis and they may burst.

72
Q

What happens if the water concentration is too low outside compared to the inside of the cells?

A

Water will leave by osmosis and the cells may shrivel. If body cells lose or gain too much water by osmosis they do not function efficiently.

73
Q

What are some organs of excretion in humans?

A

The skin, lungs and kidneys.

74
Q

Water is lost from the body as what?

A
  • Sweat from the skin
  • Water vapour, from the lungs when we exhale.
  • Urine from the kidneys.
75
Q

What do sweat glands in the skin produce?

A

Sweat. Water, ions and urea are lost from the skin as they are contained in sweat.

76
Q

Water leaves the body via the lungs when we do what?

A

Exhale.

77
Q

What can we not control the level of loss by the lungs or skin?

A

The level of water, ion or urea loss.

78
Q

What are kidneys organs of?

A

The urinary system.

79
Q

What does the urinary system do?

A

Removes excess water, mineral ions and urea. Our bodies CAN control the amount of water and ions removed by the kidneys. This is called osmoregulation.

Biology (3 decks)

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