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HCHS GCSE Science 3 - Biology > Section 7 - Animal Coordination, Control and Homeostasis > Flashcards

Section 7 - Animal Coordination, Control and Homeostasis Flashcards

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1
Q

What are hormones?

A

Chemicals released directly into the blood to affect specific cells and organs in order to perform vital bodily functions.

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2
Q

Where do hormones come from?

A

Hormones are produced in various glands throughout the body.

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3
Q

What is the endocrine system?

A 
The pituitary gland
The ovaries (females only)
The testes (male only)
The thyroid gland
The adrenal glands
The pancreas
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4
Q

What does the pituitary gland do?

A

It produces many different hormones that act on other glands, directing them to release their own hormones.

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5
Q

What do the ovaries do?

A

They produce oestrogen, which is used in the menstrual cycle.

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6
Q

What does the thyroid gland do?

A

It produces thyroxine, which is involved in the regulation of the rate of metabolism, heart rate and temperature.

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7
Q

What do the adrenal glands do?

A

They produce adrenaline which is used in preparation for the body’s “fight or flight” response

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8
Q

What does the pancreas do?

A

It produces insulin which is used to regulate blood glucose levels

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9
Q

What are the differences between sending signals with nerves and sending signals with hormones?

A 
Neurones:
Very fast action
Act for a very short time
Act on a very precise area
Hormones:
Slower action
Act for a longer time
Act in a more general area
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10
Q

What situations are nerves used in?

A

When the response must be quick, mostly pain responses, sight, heat, etcetera.

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11
Q

What situations are hormones used in?

A

When the response is long-term, like internal bodily cycles, the menstrual cycle, or resource distribution, “fight or flight” response and blood sugar regulation systems.

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12
Q

What is the “fight or flight” response?

A

A hormonal response in reaction to fear.

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13
Q

What happens in the “fight or flight” response?

A

Adrenaline is released into the bloodstream, where it binds to specific receptors in the heart, this causes the heart muscles to contract more frequently with more force, so heart rate and blood pressure increases.
The adrenaline also binds to the liver, which breaks down its glycogen stores, releasing more glucose for the cells.
It also constricts some of the arteries to prioritise blood flow to the brain and muscles

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14
Q

What is a negative feedback response?

A

Negative feedback ensures that, in any control system, changes are reversed and returned back to the set level.

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15
Q

How is metabolism regulated?

A

Thyroxine controls the body’s metabolic rate, a negative feedback system controls the levels of blood thyroxine so metabolic rate remains normal. When the blood thyroxin level is too low, the hypothalamus is stimulated to release thyrotropin-releasing hormone (TRH), which in turn stimulates the pituitary gland to release thyroid stimulating hormone, which causes the thyroid gland to release thyroxine.
When blood thyroxine is too high, the hypothalamus inhibits TRH secretion, which lowers the thyroxine levels.

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16
Q

What is the menstrual cycle?

A

The monthly series of events in which females release an egg and prepare the uterus for if the egg is fertilized.

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17
Q

What are the four stages of the menstrual cycle? When do they occur?

A

Stage 1, day 1-4: the lining of the uterus breaks down and is released.
Stage 2, day 4-14: The uterus lining is repaired until it becomes a spongy layer full of blood vessels ready for a fertilised egg to implant there.
Stage 3, day 14: An egg develops and is released from the ovary (ovulation).
Stage 4, day 14-28: The uterus lining is maintained until day 28, if no fertilised egg lands on the uterus by then, the lining breaks down and the cycle repeats.

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18
Q

What are the four hormones responsible for the menstrual cycle?

A

FSH (follicle stimulating hormone)
Oestrogen
LH (luteinising hormone)
Progesterone

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19
Q

Where is FSH produced? What is its job in the menstrual cycle?

A

Released by the pituitary gland, FSH causes a follicle (an egg and it’s surrounding cells) to mature in one of the ovaries. It also stimulates oestrogen production.

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20
Q

Where is oestrogen produced? What is its job in the menstrual cycle?

A

Released by the ovaries, oestrogen causes the uterus lining to thicken and grow. High levels of oestrogen can stimulate an LH surge.

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21
Q

Where is LH produced? What is its job in the menstrual cycle?

A

Released by the pituitary gland, LH stimulates ovulation at day 14 (The follicle ruptures and the egg is released). It also stimulates the follicle remains to develop into a structure called the corpus luteum, which secretes progesterone.

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22
Q

Where is progesterone produced? What is its job in the menstrual cycle?

A

Released by the corpus luteum after ovulation, progesterone maintains the lining of the uterus and inhibits the release of FSH and LH, once progesterone levels fall, the cycle can start over.

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23
Q

What is clomifene therapy?

A

Infertile women take a drug, called clomifene, which causes more FSH and LH to be released by the pituitary gland, stimulating egg maturation and ovulation. This means that by having intercourse whilst the woman is ovulating, there is a higher chance of fertilisation

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24
Q

What is IVF therapy?

A

In vitro fertilisation, or IVF, therapy allows infertile women to have children. This is because it takes the eggs directly from a woman’s ovaries, and fertilises them using a man’s sperm outside the body. The eggs are grown into embryos and then one or two of the healthiest embryos are implanted into the uterus, to increase the chance of pregnancy, FSH and LH are given before egg collection to stimulate egg production.

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25
Q

What is infertility?

A

Where someone is unable to have children due to biological factors.

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26
Q

What are contraceptives?

A

Contraceptives are methods of preventing fertilization.

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27
Q

How are hormones used in contraceptives?

A

Hormones like oestrogen can be used to prevent ovulation, this also inhibits FSH production and so egg development and production also stop.
Progesterone can reduce fertility by stimulating a thick layer of cervical mucus, which blocks sperm from passing. Examples include the mini-pill and the contraceptive injection.
Some contraceptives use both oestrogen and progesterone, like the combined pill and the contraceptive patch.

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28
Q

How do barrier contraceptives work?

A

Barrier contraceptives work by physically blocking sperm from reaching an egg, examples include the condom, both male and female, and diaphragms.

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29
Q

What are the benefits of hormonal contraceptives?

A

Hormonal methods are more effective than barrier methods, and couples don’t have to stop and think about contraception before intercourse.

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30
Q

What are the drawbacks of hormonal contraceptives?

A

Can cause headaches, acne, mood swings and they don’t protect against STDs and STIs.

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31
Q

What are the benefits of barrier contraceptives?

A

The condom protects against STIs.

32
Q

What are the drawbacks of barrier contraceptives?

A

Can be forgotten about.

33
Q

What is homeostasis?

A

The maintenance of a constant internal environment.

34
Q

Which hormones are involved in blood glucose regulation?

A

Insulin and Glucagon.

35
Q

Which organ monitors and controls blood glucose levels?

A

The pancreas.

36
Q

How and where is excess glucose stored?

A

As Glycogen in the liver and muscles.

37
Q

If all the excess glucose stores are full up how does the body store more excess glucose?

A

The glucose is stored as lipid in the tissues.

38
Q

How is glucose introduced into the body?

A

By eating foods containing carbohydrate.

39
Q

How is glucose removed from the body?

A

The normal metabolism of the body or exercise- which removes a lot more.

40
Q

How does the pancreas lower blood glucose?

A

The pancreas detects the excessive blood glucose and secretes the hormone insulin whilst inhibiting glucagon secretion. Insulin causes the liver and muscle cells to convert glucose into glycogen and store it. Lowering blood glucose levels.

41
Q

How does the pancreas raise blood glucose?

A

The pancreas detects too little blood glucose and secretes the hormone glucagon whilst inhibiting insulin secretion. Glucagon causes the liver and muscle cells to break down the stored glycogen back into glucose and release it into the blood. Raising blood glucose levels.

42
Q

What is Type 1 Diabetes?

A

A condition where the pancreas creates little or no insulin, meaning that the person’s blood glucose could rise to a lethal level.

43
Q

What is Type 2 Diabetes?

A

A condition where the pancreas doesn’t produce enough insulin or the person becomes insulin resistant, meaning that the person’s blood glucose could rise to a lethal level

44
Q

How is Type 1 Diabetes treated?

A

A person with Type 1 Diabetes is treated using insulin therapy - usually by injecting insulin into the blood. The insulin dosage varies depending on the person’s diet and how active they are.

45
Q

How is Type 2 Diabetes treated?

A

A person with Type 2 Diabetes is treated through a healthy diet, exercise and weight loss if needed, some also receive medication or insulin injections.

46
Q

Describe the link between obesity and the risk of developing Type 2 Diabetes.

A

There is a positive correlation between obesity and Type 2 Diabetes, meaning obese people have an increased risk of developing the condition.

47
Q

How are people classified as obese?

A

If they have a BMI, Body Mass Index, of over 30.

48
Q

How is BMI calculated?

A 
BMI = M/H²
M = Mass (Kg)
H = Height (m)
49
Q

How is where excess fat is stored in the body related to the risk of developing Type 2 Diabetes?

A

A lot of excess abdominal fat is associated with a higher risk of developing Type 2 Diabetes, meaning the more fat stored in the belly area means a higher risk of developing the condition.

50
Q

What measurement is used to give an indication of how fat is stored in the body?

A

Waist to Hip Ratio.

51
Q

How is Waist to Hip Ratio associated with increased chances of developing Type 2 Diabetes?

A

A ratio of 1.0 for men and 0.85 for women is associated with raised chances of developing Type 2 Diabetes as it indicates excessive abdominal fat.

52
Q

What is thermoregulation?

A

The body’s process to regulate internal temperature.

53
Q

Why does the body need to regulate its temperature?

A

All enzymes have an optimum temperature, where it works most effectively, in the human body this is 37°C. If it was too cool, the body’s chemical reactions would slow down and if it was too hot they enzymes would denature and stop, becoming useless. This would lead, eventually, to death in both circumstances.

54
Q

What part of the body is responsible for thermoregulation?

A

The hypothalamus, in the brain.

55
Q

How does the body detect temperature?

A

The hypothalamus itself contains receptors that monitor the blood temperature and it receives impulses from receptors in the epidermis that provide information on the external temperatures.

56
Q

How does the body respond when you’re too hot?

A

Erector muscles in the skin relax so that the hair lies flat.
Large amounts of sweat are released onto the surface of the skin through pores in the epidermis to transfer energy from the skin to the sweat as it evaporates.
Blood vessels near the surface of the skin dilate, widen, to allow more blood to flow close to the surface of the skin to transfer heat from the blood into the air.

57
Q

How does the body respond when you’re too cold?

A

Erector muscles in the skin contract so that the hair stands on end, creating an insulating layer of air near the surface of the skin.
Very little sweat is produced.
Blood vessels near the surface of the skin constrict, so less blood flows near the surface of the skin, so less energy is transferred into the air.
You shiver, increasing the rate of respiration, producing heat.

58
Q

What is osmoregulation?

A

The regulation of water content in the body.

59
Q

Why does the body need to regulate its water content?

A

If the water content in the blood is too high, water will move from the blood into the body cells, If too much water moves into the cells then they may burst, known as cytolysis.
If the water content in the blood is too low, water will move from the body cells into the blood, if too much water moves from the cells they will dry up and die.

60
Q

What do the kidneys do? How?

A

They remove urea from the blood, adjust the ion levels in the blood as well as the water content of the blood. This is done by filtering stuff out of the blood at high pressure and then reabsorbing the useful things, leaving urine as an end product.

61
Q

How do the kidneys help regulate water content?

A

By controlling how much water is reabsorbed into the blood, and how much is lost in urine.

62
Q

What is a nephron?

A

A filtration unit in the kidneys.

63
Q

Describe the path taken by substances in the nephron.

A

The liquids in the blood are forced out of the glomerulus and into the Bowman’s capsule at high pressure, larger molecules, such as proteins, and blood cells are too large and aren’t forced out.
After the Bowmans capsule, the liquid flows through the proximal convoluted tubule, then the loop of Henle, followed by the distal convoluted tubule and finally the collection duct before whatever wasn’t reabsorbed is carried to the ureter and into the bladder as urine before being released through the urethra.

64
Q

What molecules are reabsorbed from the nephrons?

A

All glucose, which is selectively reabsorbed.
Sufficient ions.
Sufficient water.

65
Q

What bodily system are the kidneys part of?

A

The urinary system.

66
Q

How is the amount of water reabsorbed by the nephrons controlled? How does it work?

A

Anti-diuretic hormone. It controls water reabsorption by controlling how permeable the collecting ducts are to water, more ADH allows more water to be reabsorbed.

67
Q

How does the body detect the water content of the blood?

A

Osmoreceptors in the brain monitor the water content in the blood.

68
Q

Where is ADH produced?

A

In the pituitary gland.

69
Q

How does the body respond when the water content in the blood is too low?

A

The brain detects the low levels of water and instructs the pituitary gland to release more ADH, which causes the kidneys to reabsorb more water, concentrating the urine and keeping the body hydrated. at sufficient levels

70
Q

How does the body respond when the water content in the blood is too high?

A

The brain detects the high levels of water and instructs the pituitary gland to release less ADH, which causes the kidneys to reabsorb less water, diluting the urine and keeping the body hydrated at sufficient levels.

71
Q

How are people with kidney failure treated?

A

Dialysis and kidney transplants.

72
Q

How does dialysis work?

A

Dialysis machines filter the blood mechanically, as the blood is pumped through the dialysis machine, the waste products naturally diffuse through a selectively permeable barrier into the dialysis fluid, large molecules like proteins and cells are too large to diffuse through the barrier and so they stay in the blood.

73
Q

Why does dialysis work?

A

The dialysis fluid has the same concentration of salts and glucose as blood plasma, so they aren’t removed from the blood, however, waste substances like urea as well as excess ions and water move across the membrane into the dialysis fluid.

74
Q

What are the benefits of dialysis?

A

It removes waste substances from the blood.

75
Q

What are the drawbacks of dialysis?

A

It has to be done regularly and can interfere with a patient’s everyday life.

76
Q

What are the benefits of kidney transplants?

A

They are more permanent than dialysis.

77
Q

What are the drawbacks of kidney transplants?

A

The donor kidney may be rejected by the patient’s immune system so the donor kidney must have a tissue type that closely matches the patient’s and the patient must take immune system-suppressing drugs to prevent rejection. The kidney must be replaced once every few years, a transplant can last as long as 15 years.

HCHS GCSE Science 3 - Biology (9 decks)

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