Control and Coordination Flashcards
What are hormones?
Chemical messengers that target organs in the body
How are hormones and nerves different?
Hormones have long-lived effects while nerves have short-term effects, nerve impulses work quickly while hormones take longer to work
What does the hypothalamus produce?
TRH and CRH which target the pituitary gland
What does the pituitary gland secrete?
TSH, LH, FSH and ADH, TSH targets the thyroid gland, ADH targets the kidneys, LH and FSH target the ovaries
What does the thyroid gland secrete?
Thyroxine which controls metabolic rate
What does the pancreas secrete?
Insulin and glucagon which target the liver, muscle and adipose tissue
What does the adrenal gland secrete?
Adrenaline which targets various organs eg. heart, liver, skin
What do the testis secrete?
Testosterone which targets the male reproductive organs
What do the ovaries secrete?
Oestrogen and progesterone, progesterone targets the uterus, oestrogen targets the ovaries, uterus and the pituitary gland
What is negative feedback?
When a factor rises below or above normal level a corrective mechanism happens to bring the factor back to normal level, production of thyroxine is an example of negative feedback
What does adrenaline do?
Bring about the ‘flight or fight’ response due to sudden stress
What are the effects of adrenaline?
- Increases heart rate
- Constricts some blood vessels to make blood pressure higher
- Dilates other blood vessels to increase blood flow to muscles
- Causes the liver to convert glycogen into glucose which is released into the blood
Which hormones are involved in the menstrual cycle?
Oestrogen, progesterone, FSH and LH
What is menstruation?
The breakdown of the uterus lining, it begins on day 1 and last for about 5 days
What happens in the second week of the menstrual cycle?
The uterus lining is gradually built up
What is ovulation?
The release of an egg, it takes place around day 14
When is fertilisation most likely to take place?
In days 14-16 of the menstrual cycle
What happens in weeks 3 and 4 of the menstrual cycle?
The uterus lining continues to build up
What happens if fertilisation does occur?
The uterus lining is maintained and menstruation doesn’t occur at the beginning of the next menstrual cycle
Give some examples of hormonal contraception
Pills, implants and injections
Give some examples of barrier methods
Male and female condoms, caps, sponges
What does FSH do?
Causes a follicle in the ovary to mature
What do high levels of oestrogen stimulate the release of?
LH
What does progesterone inhibit the release of?
LH and FSH
What does an LH surge cause?
Ovulation
What do maturing follicles stimulate?
Oestrogen production
What does increasing oestrogen cause?
Thickening of uterus lining
What do falling oestrogen and progesterone levels trigger?
Menstruation
What is clofimene?
A fertility drug that causes an increase in FSH and LH, they help women who produce too little FSH by stimulating eggs to mature and then be released
What is fertility?
The ability to have children
How does IVF work?
- Fertility drug given to woman to stimulate eggs to mature
- Eggs are taken from ovaries
- Eggs are mixed with sperm in a dish for fertilisation
- The fertilised eggs then develop into embryos
- When the embryos are tiny balls of cells, one or two of them are placed in the mother’s womb to develop
What does osmoregulation control?
The amount of water lost in urine, therefore controlling the amount of water in the body
How does osmoregulation work when you have too much water in the body?
- Your body gains water from food and drink, there is now too much water in the body
- The brain detects this change and makes the pituitary gland secrete less ADH
- Less ADH makes the collecting ducts less permeable so less water is reabsorbed from the kidney tubule and back into the blood
- This means you have a large amount of dilute urine so the water content in the body is brought back to normal
How does osmoregulation work when you don’t have enough water in the body?
- Your body loses water in sweat, when breathing out and in urine, there is now too little water in the body
- The brain detects this change and makes the pituitary gland secrete more ADH
- More ADH makes the collecting ducts more permeable so more water is reabsorbed from the kidney tubule and back into the blood
- This means you have a small amount of concentrated urine so the water content in the body is brought back to normal
What is thermoregulation?
The control of core body temperature at around 37 degress
How does thermoregulation work when the body is too hot?
- Body temperature rises due to hot environment or exercise
- Hypothalamus in brain detects this rise and causes body responses
- These responses include:
- Blood vessels dilating to increase blood flow through capillaries near the skin surface
- Sweat glands release more sweat onto skin surface to evaporate
- Sebaceous glands produce oil that helps sweat spread out over skin
- These responses mean that more heat is transferred to surroundings
How does thermoregulation work when the body is too cold?
- Body temperature falls due to cold environment
- Hypothalamus in brain detects this fall and causes body responses
- These responses include:
- Blood vessels constricting to decrease blood flow through capillaries near the skin surface this means that less heat is transferred to the surroundings
- Sweat glands stop producing sweat
- Body hairs raised by erector muscles in skin causing ‘goosebumps’
- These responses mean that less heat is transferred to surroundings
Why is it important that body temperature is controlled?
Because enzymes in the main organs are most active at body temperature
How is skin structured to have a key role in thermoregulation?
- Has sweat glands that release sweat when the body is warm to lose heat by evaporation
- Has a hair muscle that contracts when cold to pull hairs upright, this traps an insulating layer of air, hairs lie flat when warm
- Vasoconstriction/dilation occurs to change blood flow through surface capillaries depending on temperature
What is vasoconstriction?
Where more blood flows through deep skin blood vessels so less blood flows through surface capillaries, this decreases the amount of heat transferred to surroundings
What is vasodilation?
Where less blood flows through deep skin blood vessels so more blood flows through surface capillaries this increases the amount of heat transferred to surroundings
Which hormones are involved in blood glucose regulation?
Insulin and glucagon
How does blood glucose regulation work when there is too much glucose in the blood?
- Blood glucose concentration rises (probably after a meal)
- Pancreas detects this rise
- Pancreas secretes more insulin and less glucagon
- Insulin causes muscle and liver cells to remove glucose from blood and store it as glycogen
- This causes blood glucose concentration to fall back to a normal level
How does blood glucose regulation work when there isn’t enough glucose in the blood?
- Blood glucose concentration falls (probably after exercise)
- Pancreas detects this fall
- Pancreas secretes more glucagon and less insulin
- Glucagon causes liver cells to convert glycogen to glucose and release it into the blood
- This causes blood glucose concentration to rise back up to a normal level
What is diabetes?
A condition when someone can’t control their blood glucose concentration properly
What causes type 1 diabetes?
Type 1 diabetes is caused when a person’s immune system damages the person’s insulin-secreting pancreatic cells meaning the person does not produce insulin
How can type 1 diabetes be controlled?
The person has to inject insulin into the fat just below the skin, they have to work out the right amount of insulin to inject so their blood glucose concentration is kept within safe limits
What causes type 2 diabetes?
Type 2 diabetes is caused when a person doesn’t produce insulin because their liver and muscle cells have become resistant to it
How can type 2 diabetes be controlled?
The person must eat foods that contain less sugar, exercise more and use medication if needed
How do you calculate BMI?
Weight (kg) / height^2 (m)
How do you calculate waist:hip ratio?
Waist measurement / hip measurement
What does the urinary system do?
Maintain water balance, removes excess substances absorbed from food and removes waste products from metabolism such as urea
What do the renal veins do?
Put cleaned blood back into circulation
What do the renal arteries do?
Carry blood to the kidneys
What do the kidneys do?
Remove substances like urea from the blood and make urine
What does the bladder do?
Store urine
What do the ureters do?
Carry urine from the kidneys to the bladder
What does the urethra do?
Allow urine to flow through it so it can exit the body
What keeps urine in the bladder?
Circular muscles called sphincters
How is urea produced?
Urea is produced from the breakdown of excess amino acids in the liver, urea is toxic in excess
What are nephrons?
Tiny tubules inside the kidneys that make urine
What is the glomerulus?
A small knot of capillaries
How do the kidneys work?
- Small molecules including water, salts, glucose and urea from the blood are filtrated into the tubules
- Glucose is selectively reabsorbed from the tubules back into the blood by active transport
- Water that the body needs is reabsorbed back into the blood (this is called osmoregulation)
What does ADH do?
Increases permeability of the collecting ducts
What is kidney failure?
When the kidney stops working properly causing excess water, mineral ions and urea to build up in the body
What are the different types of kidney treatment?
Dialysis and kidney transplant
How does dialysis work?
It restores the normal concentrations of dissolved substances in the blood, it’s able to do this because of the dialysis fluid. Dialysis tubing is partially permeable so excess substances in the blood can diffuse into the dialysis fluid.
How does dialysis fluid prevent glucose and useful mineral ions from being lost?
It has the same concentration of glucose and useful mineral ions as the blood
How often does dialysis need to be carried out?
Every 2 to 3 days usually in a hospital
How do kidney transplants work?
A healthy kidney is connected to the blood circulation, to do the work of diseased kidneys
What are the problems with kidney transplants?
The antigens from the transplanted kidney cells are different from antigens in cells in the patient’s body, this causes the antibodies in the patient’s immune system to attack the transplanted kidney and reject it
How can rejection of a transplanted kidney be prevented?
- Antigens on the transplanted kidney must be as similar in type to antigens in the patient’s cells as possible
- The patient must be treated for life with drugs that reduce the effects of the immune system, this means the patient may get infections more often than normal
