Hormonal Control in Humans Flashcards
What are hormones?
Chemical molecules released directly into the blood
Where are hormones produced?
Endocrine glands
What hormones are produced in the pituitary gland? (Master gland)
Many hormones that regulate body conditions, these hormones act on other glands, directing them to release hormones.
What hormones is produced in the ovaries?
Oestrogen, which is involved in the menstrual cycle
What hormone is produced in the testes?
Testosterone, which controls puberty and sperm production in males
What hormone is produced in the thyroid?
Thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature
What hormone is produced in the adrenal gland?
Adrenaline, which is used to prepare your body for a fight or flight response
What hormone is produced by the pancreas?
Insulin, which is used to regulate the blood glucose level
What are the differences between hormones and nerves?
Nerves have a very fast action, act for a very short time on a precise area.
Hormones have a slower action, act for a long time in a more general way.
What else is blood glucose controlled as a part of?
Homeostasis- insulin and glucagon are the two hormones involved
What does eating foods containing carbohydrates do?
It puts glucose into the blood from the gut
What does the normal metabolism of cells do?
Removes glucose from the blood
What does vigorous exercise do?
Removes much more glucose from the blood
What can excess glucose be stored as?
Glycogen in the liver and muscles
What monitors and controls the level of glucose in the blood?
The pancreas- using the hormones insulin and glucagon in a negative feedback cycle
If blood glucose levels are too high what happens?
Insulin is added
If blood glucose levels are too low what happens?
Glucagon is added
What is diabetes?
A condition that affects your ability to control your blood sugar level
What are the two types of diabetes?
Type 1 and type 2
What is type 1 diabetes?
Where the pancreas produces little to no insulin
What do people with type 1 diabetes need?
Insulin therapy- this usually involves several injections of insulin throughout the day, most likely at mealtimes
What else do people with type 1 diabetes need to think about?
Limiting their intake of food rich in simple carbohydrates e.g sugars, which can cause the blood glucose to rise rapidly
And taking regular exercise- which helps to remove excess glucose from the blood
What is type 2 diabetes?
Where a person becomes resistant to their own insulin
What can increase your chance of developing type 2 diabetes?
Being overweight
How can type 2 diabetes be controlled?
By eating a carbohydrate-controlled diet and getting regular exercise.
What happens at puberty?
Your body starts releasing sex hormones that trigger off secondary sexual characteristics
What are the 4 stages of the menstrual cycle?
- Day 1: menstruation starts. The uterus lining breaks down for about 4 days
- The uterus lining builds up again, from day 4 to day 14, into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
- An egg develops and is released from the ovary at day 14 - this is called ovulation.
- The wall is then maintained for about 14 days until day 28. If no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again.
What are the 4 hormones that control the menstrual cycle?
FSH, LH, oestrogen, progesterone
Where is FSH produced and what does it do?
It is produced in the pituitary gland and causes an egg to mature in one of the ovaries in a structure called a follicle. It also stimulates the ovaries to produce oestrogen
Where is LH produced and what does it do?
Produced by the pituitary gland and stimulates the release of an egg
Where is oestrogen produced and what does it do?
Produced in the ovaries
Causes the lining of the uterus to grow
Stimulates the release of LH and inhibits the release of FSH
Where is progesterone produced and what does it do?
- Progesterone is produced in the ovaries by the remains of the follicle after ovulation.
- It maintains the lining of the uterus during the second half of the menstrual cycle and inhibits the release of LH and FSH.
What hormones can be used to reduce fertility and how?
Oestrogen- if it is taken every day and the level is kept permanently high it inhibits the production of FSH
Progesterone- it stimulates the production of thick mucus which prevents any sperm getting through and meeting the egg
What is the pill?
An oral contraceptive containing oestrogen and progesterone
How effective is the pill?
Over 99% effective at preventing pregnancy
What side effects can the pill have?
headaches and nausea
What is the downside of the pill?
Doesn’t protect against STDs
What is the other type of pill and why is it good?
Progesterone only pill- it has fewer side effects than the pill and is just as effective
What are the other methods of contraception that use hormones and how long do they last? (3)
The contraceptive patch - 1 week
The contraceptive implant - 3 years
The contraceptive injection - 2-3 months
What is an intrauterine device?
Is a T shaped device that is inserted into the uterus to kill sperm and prevent implantation of the fertilised egg.
What are the two main types of intrauterine device?
Plastic- release progesterone and copper
Copper- prevent the sperm swimming to the uterus
What is the diaphragm?
A plastic cup that fits over the cervix (opening to the womb) to form a barrier.
What is sterilisation?
Involves cutting or tying the fallopian tubes or the sperm duct, it is permanent but there is a very small chance that the tubes will re-joined
What are the cons of giving a women FSH and LH to stimulate ovulation?
It doesn’t always work so some women have to do it many times which can be expensive.
Too many eggs can be stimulated resulting in unexpected multiple pregnancies (triplets)
What does IVF involve?
Why are FSH and LH given before egg collection in IVF?
What are the cons of IVF?
) Multiple births can happen if more than one embryo grows into a baby:
- More dangerous for mother and baby
- Higher risk of miscarriage and stillbirth
2) Success rate is low (around 26% success rate in the UK)
3) Emotional and physical stress for the woman - Can have a strong reaction to the hormones e.g abdominal pain, vomiting, dehydration
Why are some people against IVF?
- results in unused embryos (potential human life) which are the then
destroyed - genetic testing of embryos before implantation
makes some people think it could lead to the
selection of preferred characteristics
When is adrenaline released?
In response to stressful or scary situations- your brain detects fear or stress and sends nervous impulses to the adrenal gland which then secrete adrenaline
How does adrenaline get the body ready for ‘fight or flight’?
By triggering mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles e.g adrenaline increases heart hate
How can your body control the levels of hormones in the blood?
by using negative feedback systems- when the body detects that the level of a substance has gone above or below the normal level, it triggers a response to bring the level back to normal again.
What is the role of thyroxine?
It plays an important role in regulating the basal metabolic rate.
It helps stimulate protein synthesis for growth and development
What happens if the level of thyroxine in the blood gets too high?
The secretion of TSH from the pituitary gland is stopped which reduces the amount of thyroxine released from the thyroid gland so the level in the blood falls back towards normal
