Biology edexcel 9-1 > Topic 7 > Flashcards

Topic 7 Flashcards

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1
Q

What are hormones?

A

Chemical messengers sent in the blood

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2
Q

Where are hormones produced?

A

endocrine glands

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3
Q

Where are hormones transported to?

A

To their target organs

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4
Q

Describe the function of the pituitary gland?

A

It produces many hormones that regulate body conditions. Sometimes called the master gland because these hormones act on other glands, directing them to release hormones that bring about change

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5
Q

Describe the function of the ovaries? (females)

A

Produces oestregen. which is involved in the menstrual cycle

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6
Q

Describe the function of the testes? (males)

A

Produces testosterone, which controls puberty and sperm production in males

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7
Q

Describe the function of the thyroid gland?

A

Produced thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature

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8
Q

Describe the function of the adrenal glands

A

Produces adrenaline, which is used to prepare the body for a ‘flight or fight’ response

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9
Q

Describe the function of the pancreas

A

Produces insulin, which is used to regulate the blood glucose level

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10
Q

What’s the different between neurones and hormones

A

For neurones: - very fast action
- act for a very short time
- act on a very precise area
For hormones: - slower action
- act for a long time
- act in a more general way

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11
Q

Describe how adrenaline prepares you for ‘fight or flight’

A
  1. Adrenaline binds to specific receptors in heart, causing heart muscle to contract more frequently & with more force, so heart rate and blood pressure increase
  2. This increases blood flow to muscles, so cells recieve more oxygen and glucose for increased respiration
  3. Adrenaline also binds to liver receptors, causing liver to break down glycogen stores to release glucose
  4. This increases blood glucose level, so theres more glucose in blood to be transported to the cells
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12
Q

Why is it important for adrenaline to increase the supply of oxygen and glucose to the cells?

A

This gets us ready for ‘fight or flight’

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13
Q

What is ‘preparing for fight or flight?’

A

Standing our ground in the face of a threat

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14
Q

Describe how thyroxine regulates metabolism

A
  1. When blood thyroxine level is lower than normal, hypothalamus(brain) is stimulated to release TRH
  2. TRH stimulates pituitary gland to release TSH
  3. TSH stimulates thyroid gland to release thyroxine so the blood thyroxine level rises back to normal
  4. When blood thyroxine level is higher than normal, release of TRH from hypothalamus in inhibited, which reduces the production of TSH, so blood throxine level falls
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15
Q

Describe the menstrual cycle (4 stages)

A

Stage 1 - menstruation starts: lining of uterus breaks down and is released
Stage 2 - Uterus lining is repaired, from day 4 to 14, until it becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there
Stage 3 - Egg develops and is released from the ovary (ovulation) at about day 14
Stage 4 - Lining is maintained for about 14 days, until day 28. If no fertilised egg has landed on the uterus wall by day 28, the cycle starts again

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16
Q

What four hormones control the menstrual cycle

A
  1. Oestregen
  2. Progesterone
  3. Follicle-stimulating hormone
  4. Luteinising hormone
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17
Q

State 3 facts about FSH

A
  1. Released by the pituitary gland
  2. Causes a follicle (an egg and its surrounding cells) to mature in one of the ovaries
  3. Stimulates oestrogen production
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18
Q

State 3 facts about Oestrogen

A
  1. Released by the ovaries
  2. Causes the lining of the the uterus to thicken and grow
  3. A high level stimulates an LH surge
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19
Q

State 3 facts about LH

A
  1. Released by the pituitary gland
  2. the LH surge stimulates ovulation at day 14 - the follicle ruptures and the egg is released
  3. Stimulates the remains of the follicle to develop into a structure called a corpus luteum - which secretes progesterone
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20
Q

State 5 facts about progesterone

A
  1. released by the corpus luteum after ovulation
  2. Maintains the lining of the uterus
  3. Inhibits the release of FSH and LH
  4. When the level of progesterone falls, and theres a low oestrogen level, the uterus lining breaks down
  5. A low progesterone level allows FSH to increase, and then the whole cycle starts over
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21
Q

How does clomifene therapy work?

A

Some women are infertile because they dont ovulate/ dont ovulate regularly. They can take a drug called clomifene, this causes more FSH and LH to be released in the body to stimulate egg maturation and ovulation. By knowing when the woman will be ovulating, couple can have intercouse during this time period to improve chance of being pregnant

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22
Q

How does IVF work?

A

Works by collecting eggs from a womans ovaries and fertilising them in a lab with a mans sperm till they grow into embryos. Once embryos are tiny balls of cells, they are transferred to womans uterus. FSH and LH are given before egg collection to stimulate egg production (so more than one egg can be collected)

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23
Q

How can oestrogen act as a contraceptive?

A

If oestrogen is taken every day to keep the level of it permanently high, it inhibits the production of FSH, and after a while egg development and production stop and stay stopped

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24
Q

How can progesterone be used as a contraceptive?

A

It can stimulate the production of thick cervical mucus, which prevents any sperm getting through the entrance to the uterus (the cervix) and reaching an egg

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25
How can the combined pill/contraceptive patch and the mini pill/contraceptive injection be used as a contraceptive?
The combined pill/contraceptive patch both contain oestrogen and progesterone. The mini pill/contraceptive injection both contain progesterone
26
What are barrier methods and give 2 examples?
These are methods to stop the sperm from getting to the egg. e.g. condoms and diaphragms
27
What are pros of hormonal contraceptive methods as opposed to barrier methods?
1. They are more effective in preventing pregnancy | 2. A couple doesnt have to stop and think about contraception each time they have intercourse (like barrier methods)
28
What are cons of hormonal contraceptive methods as opposed to barrier methods?
1. They can have unpleasant side effects, such as headaches, acne, and mood changes. 2. They dont protect against STI's whilst condoms (barrier method) do
29
Define homeostasis
Maintaining a constant internal environment
30
Why is it important to maintain a constant internal environment?
Conditions in the body need to be kept steady as cells/ enzymes in the body need the right conditions in order to function properly
31
What does the body need to do to maintain a constant internal environment in terms of internal and external changes
The body needs to respond to both internal and external changes, whilst balancing inputs with outputs
32
Define thermoregulation
Keeping internal temperature steady
33
What happens to enzymes if body temperature increases?
enzymes may denature due to the shape of the active site changing
34
What happens to enzymes if body temperature decreases?
enzyme activity slows down
35
How does homeostasis keep our internal temperature steady?
Homeostasis maintains out core body temperature at a steady 37 degrees. Any change in body temperature triggers a response that counteracts it
36
How does the thermoregulatory centre in the hypothalamus detect external temperature?
It contains receptors that are sensitive to the blood temperature in the brain. It also receives impulses from receptors in the skin (nerve endings) that provide info about the external temperature
37
Where are the external temperature receptors located?
In the epidermis (outer layer of the skin) and in the dermis. (a deeper layer of skin just below the epidermis)
38
What happens when the hypothalamus detects a change?
It causes a response in the skin
39
Describe what happens in thermoregulation when we're too hot
1) Erector muscles relax, so hairs lie flat 2) Lots of sweat is produced in sweat glands in the dermis. The sweat is released onto the surface of the skin through pores in the epidermis. When the sweat evaporates, it transfers energy from your skin to the environment, cooling you down 3) Blood vessels close to the surface of the skin dilate (widen). This is called vasodilation. It allwos more blood to flow near the surface, so it can transfer more energy into the surroundings, which cools you down.
40
Describe what happens in thermoregulation when youre too cold
1) Erector muscles contract. Hairs stand on end to trap an insulating layer of air near the surface of the skin, which helps keep you warm 2) Very little sweat is produced 3) Blood vessels near the surface of the skin constrict (vasoconstriction). This means less blood flows near the surface, so less energy is transferred to the surroundings 4) When you're cold, you shiver (your muscles contract automatically). This increases your rate of respiration, which transfers more energy to warm the body
41
How does insulin controls blood glucose concentration?
1. When blood has too much glucose, insulin is secreted by pancreas 2. There would be too much glucose, but also insulin along with it 3. Glucose moves from blood into liver and muscle cells 4. Insulin makes liver turn glucose into glycogen 5. Blood glucose is reduced
42
How does glucagon control blood glucose concentration
1. When blood has too little glucose, glucagon is secreted by pancreas 2. There would be too little glucose but glucagon as well 3, Glucose enters the liver and glucagon makes liver turn glycagon into glucose 4. Glucose released into blood by liver 5. Blood glucose is increased
43
What puts glucose into the blood
Food containing carbs put glucose into blood from the small intestine
44
What 3 things can remove glucose from the blood (other than insulin)
1. The normal metabolism of cells removes glucose from the blood 2. Vigorous exercise removes much more glucose from the blood 3. Excess glucose can be stored as glycogen in the liver and the muscles `
45
What causes type 1 diabetes?
a lack of insulin
46
Why is type 1 diabetes dangerous?
A person's blood glucose could rise to a level that can kill them
47
How can diabetes type 1 be treated with insulin therapy
They can inject insulin into the blood often at mealtimes to remove glucose from the blood quickly once it had been digested. Amount of insulin that needs to be injected depends on persons diet and how active they are
48
What 2 other things can people with diabetes type 1 do to control their blood glucose level
1. Take regular exercise | 2. Limiting the intake of foods rich in simple carbohydrates
49
What causes diabetes type 2
the pancreas doesnt produce enough insulin or when a person becomes resistant to insulin (body cells dont respond properly to the hormone) This causes blood glucose levels to rise
50
Is there a correlation between obesity and type 2 diabetes?
Yes
51
What is the formula for working out BMI?
WEIGHT/ HEIGHT SQUARED
52
What is the waist to hip formula?
waist to hip ratio = waist circumference / hip circumference
53
What waist to hip ratio is associated with tye 2 diabetes with men and women
Women: above 0.85 Men: above 1.0
54
How can type 2 diabetes be controlled?
1. by eating a healthy diet 2. Getting regular exercise 3. losing weight if necessary 4. Some people also have medication and insulin injections
55
What can happen if water content in the body is too high?
Water may move into body cells by osmosis and cause the cells to burst
56
What can happen if water content in the body is too low?
Cells may shrink
57
Briefly outline what the kidneys do to control water content
They control how much water is reabsorbed and how much is lost in urine
58
Name 6 features of the urinary system
1. Renal vein 2. Renal artery 3. Ureter 4. Kidneys 5. Bladder 6. Urethra
59
What are the three main roles of the kidneys
1. Removal of urea from the blood. Urea is produced in the liver from the breakdown of excess amino acids 2. Adjustement of ion levels in the blood 3. Adjustment of water content in the blood
60
What are nephrons?
Filtration units in the kidneys
61
Describe step 1 of the process in each nephron?
1) liquid part of the blood (containing water, urea, ions and glucose) is forced out of the gomerulus and into the Bowman's capsule at high pressure (ultrafiltration). Bigger molecules and blood cells cant pass through the membranes and arent forced out
62
Describe step 2 of the process in each nephron
2) As the liquid flows along the nephron, useful substances are reabsorbed - all of the glucose is selectively reabsorbed - its moved back into blood against the conc gradient - Sufficient ions are reabsorbed - Sufficient water is reabsorbed according to the level of the hormone ADH
63
Describe step 3 of the process in each nephron
3) Whatever isnt reabsorbed (urea, excess water/ions) continues out of the nephron via the collecting duct. It passes through the ureter and down to the bladder as urine. It is released through the urethra
64
What is the hormone that controls the water absorbed in the kidney nephrons called?
Anti diuretic hormone (ADH)
65
What stops the body from being dehydrated?
The brain monitors water content of the blood and instructs the pituitary gland to release ADH into the blood according to how much is needed. ADH makes collecting ducts more permeable so that water is reabsorbed back into the blood
66
What is the whole process of water content regulation called?
Negative feedback system
67
What does a dialysis machine do?
It filters blood mechanically for those who have kidney failure and cant filter their blood properly
68
Why does dialysis have to be done regularly
To keep dissolved substances at the right concentrations, and to remove waste
69
What would it mean if dialysis fluid has the same concentration of salts and glucose as blood plasma
This means those arent removed from the blood
70
What is the barrier in dialysis machines permeable/not permeable to?
It is permeable to things like ions and waste substances but not big molecules like proteins (like membranes in the kidney). So the waste substances (urea), plus excess ions and water from the blood move across the membrane into the dialysis fluid. Cells and proteins stay in the blood
71
What is the only cure for kidney disease at the moment?
a kidney transplant from healthy kidneys
72
What is a risk of donor kidneys?
The donor kidney can be rejected by the patients immune system - treated like a foreign body and attacked by antibodies
73
What precautions are taking to prevent the risk of kidney rejection from happening?
1) A donor with a tissue type that closely matches the patient is chosen 2) The patient is treated with drugs that suppress the immune system, so that their immune system wont attack the transplanted kidney
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