Topic 7 Flashcards
What are hormones?
Chemical messengers sent in the blood
Name of 6 endocrine glands?
Pituitary gland, thyroid gland, adrenal glands, ovaries, testes and pancreas
What do the testes produce and what does the hormone do?
Produces testosterone which controls puberty and sperm production in males
What does the thyroid gland produce and what does the hormone do?
Produces thyroxine, which is involved in regulating things like rate of metabolism, heart rate and temperature
What does the pancreas produce and what does the hormone do?
Produces insulin, which is used to regulate blood glucose level
What does adrenal gland produce and what does the hormone do?
Produces adrenaline, which is used to prepare body for a ‘fight or flight’ response by activating processes that increase supply of O2 and glucose to cells
Differences between neurones and hormones?
Neurones: very fast action, act for a very short time, act on a very precise area
Hormones: slower action, act for a long time, act in a more general way
How does adrenaline cause increased respiration?
- During times of fear or stress the adrenal glands release adrenaline
- Adrenaline binds to specific receptors in heart, causing muscle to contract more frequently and with more force, so heart rate and blood pressure increase,
- This in turn, increases blood flow to muscles so cells receive more O2 and glucose
- Both O2 and glucose are needed for aerobic respiration and this prepares the body for fight or flight
How can your body control levels of hormones in blood using negative feedback systems?
When body detects that level of a substance has gone above or below normal level, it triggers a response to bring level back to normal again
What is metabolic rate?
Speed at which chemical reactions in body occur
What does TRH stimulate to release what?
TRH stimulates pituitary gland to release TSH
What does TSH stimulate to release what?
TSH stimulates thyroid gland to release thyroxine
How does blood thyroxine level rise back to normal when the blood thyroxine level is lower than normal?
- Hypothalamus stimulated to release TRH
- which stimulates pituitary gland to release TSH.
- TSH stimulates thyroid gland to release more thyroxine so blood thyroxine level normal
How does blood thyroxine level go fall to normal when blood thyroxine level becomes higher than normal?
Release of TRH from hypothalamus is inhibited, which reduces production of TSH so blood thyroxine level falls
How long is a menstrual cycle usually?
28 days
In 4 stages of menstrual cycle, what happens in stage 1? Which days? Which hormone released?
Menstruation starts, uterus lining breaks down and is released, days 1-4, FSH
In 4 stages of menstrual cycle, what happens in stage 2? Which days? Which hormone released?
Uterus lining repaired, from day 4-14, until it becomes a thick spongy layer full of blood vessels ready for a fertilised egg to implant there, oestrogen
In 4 stages of menstrual cycle, what happens in stage 3? Which days? Which hormone released?
Ovulation: an egg develops and is released from ovary at about day 14, LH
In 4 stages of menstrual cycle, what happens in stage 4? Which days? Which hormone released?
Lining maintained for about 14 days, until day 28. If no fertilised egg landed on uterus wall by day 28, spongy lining starts to break down again and whole cycle starts over, progesterone
What is FSH released by, causes, and stimulates?
FSH released by pituitary gland, causes follicle to mature in one of ovaries, and stimulates oestrogen production
What is oestrogen released by, causes, and stimulates?
Oestrogen released by ovaries, causes uterus lining to thicken and grown, and a high level stimulates an LH surge
What is LH released by, causes, and stimulates?
LH released by pituitary gland, stimulates ovulation at day 14 - egg released, and stimulates remains of follicle to develop into corpus luteum - which secretes progesterone
What is progesterone released by, causes and inhibits?
Progesterone released by corpus luteum after ovulation, maintains uterus lining, and inhibits release of FSH and LH
How does the menstrual cycle start again?
When level of progesterone falls and low oestrogen level, uterus lining breaks down. Low progesterone level allows FSH to increase and then whole cycle starts again
What happens to progesterone level if a fertilised egg implants the egg?
Level of progesterone will stay high to maintain uterus lining during pregnancy
Two examples of treating infertility?
Clomifene therapy and IVF (in vitro fertilisation)
What is clomifene therapy?
- Infertile women take drug called clomifene.
- It causes more FSH and LH to be released by body, which stimulates egg maturation and ovulation.
- By knowing when woman will be ovulating, couple can have intercourse during this time period to improve chance of pregnancy
What is IVF (in vitro fertilisation)?
- Involves collecting eggs from woman’s ovaries and fertilising them in lab using man’s sperm, which then grown into embryos.
- Once embryos are tiny balls of cells, one or two transferred to woman’s uterus to improve chance of pregnancy.
- FSH and lH given before egg collection to stimulate egg production
2 hormones used as contraceptives and how they work to prevent pregnancy?
Oestrogen - inhibits production of FSH to stop egg maturing
Progesterone - Stimulating production of thick cervical mucus, which prevents sperm getting through uterus entrance and reaching egg, inhibits FSH and LH so stops egg maturing and releasing
2 examples of barrier methods of contraception and how they prevent pregnancy?
Condoms and diaphragms which put barrier between sperm and egg so they don’t meet
2 pros of using hormonal methods of contraception?
- More effective at preventing pregnancy than barrier methods
- Using hormonal methods mean couple don’t have to stop and think about contraception each time for intercourse
2 cons of using hormonal methods of contraception?
Unpleasant side-effects such as headaches, acne and mood changes.
Don’t protect against STIs which condoms do.
What is homeostasis?
Maintaining a constant internal environment
3 examples of homeostasis?
- Blood glucose regulation
- osmoregulation
- thermoregulation
What and where is excess glucose stored as? And what and where if these stores are full?
Stored as glycogen in liver and in muscles
If liver and muscles full, then stored as lipid (fat) in tissues
What monitors and controls changes in blood glucose and using which hormones?
Pancreas, using hormones insulin and glucagon
What happens when blood glucose concentration is too high?
- Insulin is secreted by the Pancreas
- Liver turns Glucose into Glycogen due to Insulin
- Blood glucose concentration reduced and returns back to normal
What happens when blood glucose concentration is too low?
- Glucagon is secreted by the Pancreas
- Glucagon causes the Liver to release Glucose into the blood
- Blood glucose concentration is increased and returns back to normal
What is type 1 diabetes?
Condition where pancreas produces little or no insulin, which can result in person’s blood glucose rising to level that can kill them
What is insulin therapy?
- Involves injecting insulin into blood often at mealtimes to make sure that glucose is removed from blood quickly once food has been digested.
- This stops level of glucose in blood getting too high
3 treatment for type 1 diabetes?
- Insulin therapy
- Regular exercise to remove excess glucose from blood
- Limiting intake of foods rich in simple carbohydrates which cause blood glucose level to rise rapidly
What is type 2 diabetes?
Condition where pancreas doesn’t produce enough insulin or when person becomes resistant to insulin so blood glucose level rises
Which type of people have an increased chance of developing type 2 diabetes?
Obese people (over 30 BMI)
What waist-to-hip ratio is associated with an increased risk of type 2 diabetes for men and women and how?
1.0m for men and 0.85m for women as it indicates that a lot of fat is being stored around abdomen
5 ways of controlling type 2 diabetes?
- Healthy diet
- regular exercise
- losing weight if needed
- medication
- insulin injections
What effect does Glucagon have on the body?
Causes Liver to released stored Glucose
What effect does Insulin have on the body?
Insulin causes excess glucose to be stored
What causes Glucose to be removed from the blood? (2)
- Regular metabolism of cells
2. Increase of exercise, increases cell respiration
What is the regulation of temperature called?
Thermoregulation
Where is body temperature monitored and controlled? (2)
In the Thermoregulatory centre in the Hypothalamus
Why must temperature be controlled?
Enzymes must be kept in a specific, constant, thermal environment in order for them to function
How does the Thermoregulatory centre monitor internal temperature? (2)
Contains receptors that are sensitive to the blood temperature in the brain
How does the Thermoregulatory centre monitor external temperature? (2)
Receives impulses from the receptors in the epidermis and dermis of the skin
What happens when the body is too hot? (Describe) (3)
- Hair erector muscles relax so that the hair lies flat
- Sweat is produced and secreted from the pores
- Vasodilation occurs
Why does sweating cool down the body? (1)
The sweat evaporates from the skin, transferring thermal energy from the skin to the environment
Why does Vasodilation cool down the body? (3)
The blood is closer to the surface of the skin, increasing the transfer of thermal energy from the blood to the surroundings (by Radiation)
What happens when the body is too cold? (Describe) (4)
- Hair erector muscles contract, hair is erect
- Sweat production dramatically reduces
- Vasoconstriction occurs
- Muscles begin to contract and shiver
What does erect hair help the body warm up? (2)
Erect hair traps a layer of air and insulates it, warming up the surface of the skin
Why does vasoconstriction help the body warm up? (3)
Less blood flows near to the surface of the skin, reducing the transfer of thermal energy from the blood to the environment (by Radiation)
Why does shivering/ contracting muscles help the body warm up? (2)
Increases rate of respiration to transfer thermal energy to the body
Where does Osmoregulation occur?
In the kidneys
What happens if blood water concentration is too high? (2)
Too much water moves into the cells by Osmosis, and causes the cell to burst
What happens if blood water concentration is too low? (2)
Water will move out of the cells into the blood by Osmosis and cause the cell to shrink
What substances do the kidneys remove during Ultrafiltration? (4)
- Water
- Mineral ions
- Glucose
- Urea
what is osmoregulation
the control of the balance of water and mineral salts in the body
3 main roles of the kidney
- removal of urea from blood
- adjustment of ion levels in blood
- adjustment of water content in blood
Kidney part 1
- In each nephron (filtration unit), blood is forced out of the glomerelus and into the bowmans capsule at high pressure (ultrafiltration)
- Bigger molecules (proteins) and blood cells cannot pass through the membranes so they are not forced out
Kidney part 2
- As the liquid part of the blood flows through the nephron, useful substances are reabsorbed:
- All glucose is selectively reabsorbed by active transport
- Sufficient ions are reabsorbed
- Sufficient water is reabsorbed, according to the levels of ADH
Kidney part 3
- Whatever is not reabsorbed (urea, excess ions, excess water) continues out of the nephron via the collecting duct
- It then passes into the uretur and down to the bladder as urine
How is water controlled as a negative feedback system?
- The amount of water reabsorbed in the kidney nephrons are controlled by anti -diuretic hormones (ADH)
- The brain monitors the water content in the blood and instructs the pituitary gland to release ADH into the blood, according to how much id needed
- ADH makes thee collecting ducts of the nephron more permeable, so more water is reabsorbed into the blood. This stops the body from being dehydrated
If the brain detects water loss
The pituitary gland releases more ADH
-ADH makes the kidney reabsorb more water
If the brain detects water gain
- The pituitary gland releases less ADH
- Less ADH means kidneys reabsorb less water
