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AQA GCSE Biology > GCSE Hormones and Metabolism > Flashcards

GCSE Hormones and Metabolism Flashcards

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1
Q

What is different about the endocrine system vs the nervous system?

A

Hormones are slower but last longer than nervous signals

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2
Q

What is thyroxine?

A

A hormone that controls metabolic rate. It is secreted by the thyroid, which is controlled by the secretion of TSH from the pituitary gland. It is made from iodine.

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3
Q

How does thyroxine link to temperature regulation?

A

As thyroxine controls metabolic rate, it’s release will be inhibited in extremely high temperatures to lower metabolic rate to conserve water and release less energy. The same happens for extremely low temperatures.

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4
Q

Give the negative feedback loop for thyroxine action

A

> Pituitary gland secreted TSH / TSH is detected by thyroid and secretes thyroxine / high thyroxine levels inhibit TSH secretion >

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5
Q

What is adrenaline?

A

A hormone secreted by the adrenal gland that prepares the body for fight or flight. It is stimulated by the nervous system in response to stress/excitement and targets vital organs like the heart, lungs and muscles.

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6
Q

What are the effects of adrenaline on the body?

A

Increased heart rate, dilated airways/pupils, increased breathing rate, increased blood glucose levels.

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7
Q

Why are the effects of adrenaline useful in dangerous situations?

A

Increased heart/breathing rate + dilated airways allows for more oxygen intake for aerobic respiration so we can run/fight. Dilated pupils improves vision, increased blood glucose levels gives more energy for muscle contraction

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8
Q

Describe the journey of glucose in the blood.

A

Glucose is consumed in various forms, carbohydrases break carbs into glucose, glucose is absorbed into the blood via villi in the SI.

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9
Q

Why is blood glucose regulation necessary?

A

High BG levels will cause the water concentration of the blood to fall, causing water to leave cells via osmosis and shrivel up. Low BG levels causes the excess water in the blood to enter the cells and burst.

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10
Q

Why might blood glucose levels peak at different rates?

A

Variation in food: simple vs complex carbs

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11
Q

What evidence might be in a graph to suggest that there is a mechanism that prevents blood glucose from becoming too low?

A

Blood glucose levels not falling below a certain point suggests that negative feedback activates a mechanism that raises BGL.

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12
Q

What is the pancreas’ role in the digestive system?

A

It is an endocrine gland that controls and monitors blood glucose levels using negative feedback.

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13
Q

What does the pancreas secrete when the blood glucose gets too high/low

A

insulin for high BGL, glucagon for low BGL.

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14
Q

How does insulin respond to high blood glucose levels?

A

It makes glycogen to be stored in the liver.

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15
Q

How does glucagon respond to low blood glucose levels?

A

It breaks down glycogen to be released into the blood as glucose.

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16
Q

How would the body regulate an athlete’s blood glucose levels when running a marathon?

A

Running a marathon would cause blood glucose levels to fall due to increased aerobic respiration in muscles using glucose for contraction. This fall in BGL is detected by the pancreas, which secretes glucagon, breaking down the glycogen in the liver into glucose to be released into the blood and return blood glucose levels to normal.

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17
Q

Why might athletes eat a carb-rich diet before a marathon?

A

To increase the glycogen stores in the liver, so when the marathon comes it can be broken into glucose by glucagon to be used for muscle contraction.

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18
Q

What is type 1 diabetes?

A

It’s an autoimmune disease that arises in young children and teenagers that means not enough insulin is produced to convert glucose into glycogen. There is no cure to T1D.

19
Q

What is type 2 diabetes?

A

A disease caused by obesity or a sedentary lifestyle that causes cells to stop responding to insulin.

20
Q

What are the treatment options for type 1 diabetes?

A

Insulin injections (tablets cannot be taken as insulin is a protein that would be digested), pancreas transplant in severe cases.

21
Q

What are the treatment options for type 2 diabetes?

A

A balanced diet with reduced carbs and increased exercise, sometimes drugs help the pancreas make more insulin and reduce glucose absorption from the gut, in rare cases insulin injections are used.

22
Q

Define excretion.

A

The removal of metabolic waste products from the body.

23
Q

Why is urination the best option for osmoregulation?

A

The body can control how much urine is produced and how much of different substances is in it. Breathing is necessary for respiration, and sweating is necessary for thermoregulation.

24
Q

What does urine contain?

A

Urea, excess water & excess salt ions

25
Q

What is the nephron?

A

The functional part of the kidney where blood is filtered into urine.

26
Q

What are the main three processes that take place in the nephron?

A

Filtration, reabsorption and urine production

27
Q

Describe filtration in the nephrons.

A

A partially permeable membrane is used to filter out excess glucose, water, salt and urea from the blood in the renal artery. WBCs, RBCs and proteins stay in the blood as they are too big to cross the partially permeable membrane.

28
Q

Describe reabsorption in the nephrons.

A

All glucose and some water is reabsorbed into the blood. This process is selective and uses diffusion, osmosis and active transport.

29
Q

Describe urine production in the kidneys.

A

Whatever is not reabsorbed (excess water, salt & urea) is sent to the collecting duct where it passes through the ureter to the bladder to be excreted. ADH controls the volume of urine produced.

30
Q

How are excess amino acids excreted?

A

Excess amino acids cannot be stored, so they are deaminated (amine group removed) in the liver to form ammonia, and then urea to be excreted via urination.

31
Q

How does ADH work?

A

ADH is released by the pituitary gland when the blood concentration is too high. ADH causes more water to be reabsorbed from the collecting duct in the nephron, resulting in a small volume of yellow urine being produced.

32
Q

What are the sex hormones for men and women?

A

Women: oestrogen and progesterone. Men: testosterone

33
Q

Give some secondary sex characteristics for women.

A

Breast growth, widened hips, facial, underarm and pubic hair, growth spurt

34
Q

Give some secondary sex characteristics for men.

A

Increased penis + testicle growth, increased muscle mass, deepening of voice, broadening of shoulders, growth spurt, growth of facial, underarm and pubic hair.

35
Q

What are the four stages of the menstrual cycle?

A

Menstruation, follicle growth, ovulation, lutenisation/fertilisation

36
Q

Describe the menstrual cycle.

A

Menstruation causes the uterus lining to break down for ~4 days. The lining of the uterus builds up again from days 1-14 to form a thick spongy layer full of blood vessels for the fertilised egg. An egg is released from the ovary at day 14. The wall is maintained until day 28, and breaks down if no fertilised egg implants.

37
Q

Describe FSH.

A

Produced by the pituitary gland, targets ovaries causing egg to mature + stimulates oestrogen production.

38
Q

Describe oestrogen.

A

Produced in the ovary, causes the lining of the uterus to thicken. High oestrogen levels tells the pituitary gland to stop producing FSH and start producing LH.

39
Q

Describe LH.

A

Produced by the pituitary gland, tells the ovary to release the egg.

40
Q

Describe progesterone.

A

Produced by the ovaries, maintains the thick uterus lining if fertilised egg implants. High progesterone levels during pregnancy stops the menstrual cycle.

41
Q

How is oestrogen used as a contraceptive?

A

It prevents egg release, and inhibits FSH production to stop egg maturation and release.

42
Q

How is progesterone used as a contraceptive?

A

It stimulates the production of cervical mucus to prevent sperm from entering the uterus. It also inhibits egg maturation and release.

43
Q

What are the advantages and disadvantages of the contraceptive pill?

A

Advantages: over 99% effective, reduces risk of certain cancers.

Disadvantages: not 100% effective, can cause side effects like headaches, nausea, irregular period etc. Doesn’t protect against STDs

44
Q

How is FSH and LH used to increase fertility?

A

FSH and LH can be injected to stimulate egg maturation and release.

AQA GCSE Biology (13 decks)

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