B3.2 - Hormones, Edocrine System, Menstrual Cycle Flashcards
What is the menstrual cycle
The menstrual cycle is the monthly sequence of events in which the female body releases an egg and prepares the uterus (womb) in case it receives a fertilised egg
What happens on day 1 in the menstrual cycle
The uterus lining breaks down and is released
What happens from day 4 to 14 in the menstrual cycle
The lining of the uterus builds up again into a thick spongy layer full of blood vessels ready to receive a fertilised egg
What happens at day 14 in the menstrual cycle
An egg develops and is released from an ovary (ovulation)
What happens from day 14 to 28 in the menstrual cycle
The lining of the uterus is maintained. If no fertilised egg has planted into the uterus wall by day 28, the spongy lining starts to break down again and the whole cycle starts over
Where is FSH and LH released, and what do they do
FSH and LH are released from the pituitary gland in the brain. They help to control the menstrual cycle
Where is progesterone produced and what does it do
It is produced in the ovaries. It helps to support pregnancy and is involved in the menstrual cycle
Where is oestrogen prod fed and what does it do
It is produced in the ovaries. It’s involved in the menstrual cycle and promotes female sexual characteristics. Oestrogen is the main female sex hormone
Where is testosterone produced and what does it do
It is produced in the testes. It stimulates sperm production and is important for the development of the male reproductive system. Testosterone is the main male sex hormone
The menstrual cycle is controlled by 4 hormones. What does FSH do?
Causes an egg to mature in one of the ovaries.
Stimulates the ovaries to produce oestrogen.
The menstrual cycle is controlled by 4 hormones. What does oestrogen do?
Causes the lining of the uterus to thicken and grow.
Stimulates the production of LH
Inhibits the production of FSH so that only one egg is released in each cycle.
The menstrual cycle is controlled by 4 hormones. What does progesterone do?
Maintains the lining of the uterus. When the level of progesterone falls and there’s a low oestrogen level, the lining breaks down.
Inhibits the production of FSH and LH.
A low progesterone level allows FSH to increase and then the whole cycle starts again.
The menstrual cycle is controlled by 4 hormones. What does LH do?
Stimulates the release of an egg at day 14 (ovulation).
Indirectly stimulates progesterone production.
What are hormones
Hormones are chemicals produced in various glands called endocrine glands. These glands make up your endocrine system
How do hormones travel and where are they released
Hormones are released directly into the blood. The blood then carries them to other parts of the body. They travel all over the body but they only affect particular cells in particular places
What do target cells have
They have the right receptors to respond to that hormone
What is adrenaline
A hormone released by the adrenal glands
What does adrenaline prepare the body for
Adrenaline prepares the body for ‘fight or flight’
Fill in the gaps
Hormones are ______ compared to nervous impulses but they have _______ lasting effects
Slower
Longer
Adrenaline binds to specific receptors in the heart which causes…..
The heart muscle to contract more frequently and with more force so heart rate and blood pressure increase. The increases blood flow to the muscles, so the cells receive more oxygen and glucose for increased respiration
Adrenaline also binds to receptors in the liver which causes…..
The liver to break down it’s glycogen stores to release glucose. This increases the blood glucose level so there’s more glucose in the blood to be transported to the cells
What happens when you brain detects a stressful situation
The brain sends nervous impulses to the adrenal glands which respond by secreting adrenaline. This gets the body ready for action
How can your body control the levels of hormones in the blood
By using negative feedback systems
What is 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 being the level back to normal again
What is thyroxine and what is it made from
Thyroxine is a hormone released by the thyroid gland (found in the neck). Thyroxine is made in the thyroid gland from iodine and amino acids
What is the role of thyroxine
It regulates metabolic rate (or metabolism) - the speed at which chemical reactions in the body occur. It’s important for loads of processes in the cosy such as growth and protein synthesis
Thyroxine is realised in response to…
Thyroid stimulating hormone which is released from the pituitary gland
What does a negative feedback system do in terms of thyroxine
It keeps the amount of thyroxine in the blood at the right level
What happens if a fertilised egg implants in the uterus (I.e. the women become pregnant)
The progesterone level will stay high to maintain the uterus lining during pregnancy
What does it mean if a person is infertile
They can’t reproduce naturally