5.3 Hormonal coordination in humans Flashcards
1
Q
What is the endocrine system? (1)
A
- The body’s coordination system
- composed of glands
- which secrete hormones
- directly into the blood stream.
2
Q
What is a hormone? (1)
A
A chemical messenger.
3
Q
What does a hormone do? (1)
A
Travels in the blood to a target organ where it produces an effect.
4
Q
What is the main difference between the nervous system and the endocrine system? (1)
A
Effects are slower but last longer in endocrine system compared to nervous system.
5
Q
What is the pituitary gland? (1)
A
- The “master gland” that secretes several hormones into the blood
- in response to body conditions
- which in turn acts on other glands
- to stimulate the release of other hormones
- to bring about effects.
6
Q
What are the specific roles of the pituitary gland in the endocrine system? (4)
A
- Produce growth hormones - control human growth.
- Stimulate the thyroid gland.
- Stimulate production of sperm and testosterone in the testes.
- Stimulate ovulation and production of oestrogen in the ovaries.
7
Q
What is the role of the thyroid gland? (2)
A
Secrete thyroxine - controls basal metabolism rate, growth and development.
8
Q
What is the role of the pancreas? (1)
A
Secrete insulin - controls blood glucose levels/concentration.
9
Q
What is the role of the adrenal gland? (1)
A
Secrete adrenaline - controls body’s “fight or flight” response.
10
Q
What is the role of the ovaries? (2)
A
Secrete oestrogen - coordinates menstrual cycle and development of female secondary sexual characteristics.
11
Q
What is the role of the testes? (2)
A
Secretes testosterone - coordinates sperm production and development of male secondary sexual characteristics.
12
Q
What monitors and controls blood glucose concentration? (1)
A
Pancreas
13
Q
How does the pancreas respond when blood glucose levels are too high? (2)
A
- Secrete insulin allowing glucose in blood to move into cells.
- Excess glucose is converted into glycogen for storage in liver and muscle cells.
14
Q
How does the pancreas respond when blood glucose levels are too low? (2)
A
- Secretes glucagon which binds to liver cells
- Causes glycogen to be converted into glucose and released into the blood.
15
Q
How is blood glucose concentration controlled using a negative feedback loop? (2)
A
- If blood glucose concentration is above or below optimum levels, the pancreas secretes a hormone.
- The hormone’s action brings back the concentration to optimum levels.
16
Q
What is Type 1 diabetes? (1)
A
-An autoimmune disorder
- where the pancreas fails to produce sufficient insulin [to control blood glucose levels]
- leading to uncontrollably high blood glucose concentrations.
17
Q
What are treatments for Type 1 diabetes? (3)
A
- Insulin injection before meals - allows glucose to convert into glycogen.
- Reducing carbohydrate intake.
- Attempting pancreas and pancreatic cells transplants; or investigations into genetic engineering of pancreatic cells.
18
Q
What is Type 2 diabetes? (1)
A
- A disorder where body cells no longer respond to insulin
- leading to uncontrollable blood glucose concentrations,
- with risk factors linked to obesity and increasing age.
19
Q
What are the treatments for Type 2 diabetes? (4)
A
- Having controlled diet.
- Regular exercise.
- Losing weight.
- Using drugs which increase insulin production or effectiveness.
20
Q
What is the effect of osmotic changes to body cells? (1)
A
if too much water is lost or gained, they aren’t able to function efficiently.
21
Q
What ways does water leave the body? (3)
A
- Exhaling from lungs (no control of amount lost)
- Sweating (no control on amount lost)
- Urination (excess is removed - some reabsorbed by kidneys)
22
Q
What ways do ions and urea leave the body? (2)
A
- Sweating (no control on amount lost)
- Urination (excess is removed - some reabsorbed by kidneys)
23
Q
How are excess amino acids excreted? (3)
A
- Liver deaminates excess amino acids to form ammonia.
- Ammonia immediately converted into urea due to its toxicity.
- Urea is safely excreted from body via sweat and urine.
24
Q
How does the kidney maintain water balance in the body? (2)
A
Produces urine by:
- filtration of the blood to remove waste products (e.g urea)
- selective reabsorption for useful substances (e.g glucose, some ions and water).
25
What does ADH stand for? (1)
Anti-diuretic hormone
26
Where is ADH secreted?
The pituitary gland in the brain.
27
How does ADH control water levels in the body? (3)
1. ADH secreted by pituitary gland when blood is too concentrated.
2. ADH travels in bloodstream to kidneys causing kidney tubules to become more permeable to water.
3. This allows more water to be reabsorbed into blood [from kidney tubules], resulting in smaller volume of more concentrated urine.
28
Why is kidney failure dangerous? (3)
The blood may not be filtered properly leading to:
- the build up of toxic substances (such as urea)
- uncontrollable ion and water levels, leading cells to be damaged due to osmosis.
29
What are the main ways to treat kidney failure? (2)
- Dialysis
- Transplant
30
What is kidney dialysis? (1)
The use of specialist machines which act as kidneys.
31
How does kidney dialysis work? (1)
- Dialysis fluid consist of the same glucose and ion concentration as healthy blood
- so only excess and waste products are lost from the blood,
- whilst ions and glucose remain.
32
What is the function of reproductive hormones during puberty? (2)
Male: aid development of secondary sexual characteristics
Female: aid development of secondary sexual characteristics and maturation of eggs.
33
What is the main male reproductive hormone? Where is it produced? What does it do? (3)
Testosterone; testes; stimulates sperm production.
34
What is the main female reproductive hormone? Where is it produced? What does it do? (3)
Oestrogen; ovaries; responsible for menstrual cycle.
35
Describe the events of the menstrual cycle. (3)
1. Uterus lining thickens and eggs begin to mature in the ovaries.
2. Egg is released from one ovary (ovulation) whilst uterus lining remains thick.
3. If egg is fertilised, pregnancy may occur. If not, the lining and egg are shed during menstruation.
36
What is ovulation? (1)
The releasing of an mature egg from an ovary approximately every 28 days.
37
What is the menstruation cycle? (1)
The monthly cycle where physiological changes occur in females such as menstruation and ovulation.
38
What are the main hormones involved in the menstrual cycle? (4)
- Follicle stimulating hormone (FSH)
- Oestrogen
- Luteinising hormone (LH)
- Progesterone
39
What is the role of FSH in the menstrual cycle? (2)
[Released by pituitary gland]
- causes maturation of an egg in the ovaries
- triggers production of oestrogen by the ovaries.
40
What is the role of oestrogen in the menstrual cycle? (2)
[Produced by ovaries and released due to FSH action]
- causes uterus lining to thicken.
- stimulates release of LH and restricts more release of FSH.
41
What is the role of LH in the menstrual cycle? (1)
[Produced by pituitary gland and released due to oestrogen action]
- stimulates release of egg (ovulation)
42
What is the role of progesterone in the menstrual cycle? (2)
[Secreted from follicle of ovary]
- sustains/sheds uterus lining (menstruation)
- inhibits FSH and LH production.
43
What is contraception? (1)
Methods used to prevent pregnancy.
44
What are the two types of oral contraceptives? (2)
- Combination pill (contains oestrogen and progesterone)
- Mini pill (contains only progesterone)
45
How does the contraceptive pill prevent pregnancy? (3)
- Inhibits FSH production (eggs cannot mature).
- Prevents development of uterus lining (eggs cannot implant).
- Increase thickness of cervical mucus (immobilise sperm cells).
46
What is the contraceptive patch? (1)
Patch placed onto skin for 7 days at a time - slowly releases oestrogen and progesterone.
47
What is the contraceptive implant? (1)
Small rod inserted under skin that lasts for 3 years - slowly continually releases progesterone.
48
What is the contraceptive injection? (1)
An injection that lasts approximately 3 months - slowly releases progesterone.
49
What is the IUS and how does it prevent pregnancy? (3)
[Intrauterine system] plastic device inserted in uterus
- releases progesterone which thickens cervical mucus
- prevents thickening of uterine lining.
50
What is the IUD and how does it prevent pregnancy? (2)
[Intrauterine device] device containing copper inserted in the uterus
- prevents implantation of embryos
51
What is a spermicide and what are the disadvantages of using them? (2)
Chemical which immobilises or kills sperm cells.
- not very effective on its own - works better with barrier method.
52
What is a contraceptive barrier? (1)
Physical separation from sperm and egg.
53
What are examples of barrier methods of contraception? (2)
- Condom: thin sheath worn on penis or inside of vagina - protects against STIs but may tear.
- Diaphragm: thin cap placed over cervix - prevents entry of sperm.
54
What are surgical ways of preventing pregnancy? (2)
- Male sterilisation: sperm ducts tied (vasectomy).
- Female sterilisation: oviducts tied
55
What is abstinence when preventing pregnancy? (1)
Practice of not having sex when egg may be in oviduct (commonly around ovulation - rhythm method) to prevent pregnancy - not very reliable.
56
How do fertility drugs increase the chances of pregnancy? (2)
- Contain FSH - stimulates oestrogen productions and causes eggs to mature
- Contain LH - causes egg to be released from ovary (ovulation)
57
Describe the process of IVF treatment. (4)
1. Mother given FSH and LH to stimulate egg maturation and ovulation.
2. Eggs collected and fertilised using father’s sperm in laboratory.
3. Fertilised eggs develop into embryos
4. When they are tiny balls of cells, one or two embryos are inserted in the mother’s uterus/womb.
58
What are advantages of IVF treatment? (2)
- Enables infertile couples to have their own child.
- Mother’s eggs can be stored for later
59
What are the disadvantages of IVF treatment? (5)
- Can be very expensive process.
- Low rates of success (especially for older couples).
- Increased chances of multiple pregnancies - dangerous for mother and baby.
- Side effects of fertility drugs.
- Very emotionally and physically stressful.
60
What is negative feedback? (1)
A type of control where the body reacts to an increase or decrease in a factor by returning it to optimum levels.
61
What is thyroxine? (3)
- Hormone released by thyroid gland.
- Release triggered by TSH.
- Controls basal metabolic rate, growth and development.
62
How is the release of thyroxine controlled by negative feedback? (4)
1. Low levels of blood thyroxine detected by receptors in brain.
2. Pituitary gland releases more TSH.
3. TSH triggers increased production and release of thyroxine by thyroid gland.
4. Blood thyroxine levels return to normal.
63
What is adrenaline? (3)
- Hormone released by adrenal gland
- Released in times of fear or stress
- Responsible/controls “fight or flight” mode.
64
What are the effects of adrenaline to the body? (5)
- Increases heart and breathing rate - boosts delivery of oxygen and glucose to brain and muscles.
↳ stored glycogen converted to glucose.
↳ Pupils dilate
↳ Increased mental awareness
↳ Blood diverted away from digestive system to muscle.
