What are hormones?
Chemical molecules released directly into the blood to regulate bodily processes / chemical messengers that travel in the blood to activate cells in target organs
Name six endocrine glands of the body
- pituitary gland
- thyroid gland
- adrenal glands
Explain why the pituitary gland is known as the ‘master‘ gland
It produces many hormones that regulate the body and many of the hormones act on other glands to stimulate production of other hormones
What does thyroxine (the hormone produced by the thyroid gland) regulate?
Rate of metabolism, heart rate and temperature
What is the role of insulin in the body?
To regulate the blood glucose level
Name the response that adrenaline is involved in
The ‘fight or flight‘ response
State what oestrogen (the hormone released by the ovaries) controls
State what testosterone (the hormone released by the testes) controls
Puberty and sperm production in males
Compare the differences between nerves and hormones
HORMONES - slower acting - act on the body for a long time - act in a more general way NERVES - fast acting - act for only a short time - act on a very precise area
Name the hormone whose release is stimulated by the sex hormones
Where does the growth hormone stimulate cells to divide?
Muscles and bones
What does the growth hormone stimulate the digestive system to do?
Absorb calcium ions used to make strong bones
Name the four hormones produced by the pituitary gland
- growth hormone
Use a flowchart to describe how a change in the amount of sex hormone produced during puberty in females leads to an increase in growth
Ovaries secrete more oestrogen into the circulating blood —> oestrogen stimulates pituitary gland to release greater amounts of growth hormone —> growth hormone stimulates muscle and bones to increase the rate of cell division (rate of growth)
What happens when your brain detects danger or stress?
Brain sends nerve impulses to the adrenal glands
What does adrenaline increase the supply of to cells?
Oxygen and glucose
What is caused by adrenaline binding to specific receptors in the heart?
Heart muscle contracts with more force and frequency
What does adrenaline binding to specific receptors in the heart (casing the heart muscles to contract with more force and frequency) increase?
Heart rate and blood pressure
What do muscle cells receive more of due to the increased blood flow to them?
More oxygen and glucose
Why do muscle cells need more oxygen and glucose?
Increased respiration for muscle contraction
What is caused by adrenaline binding to receptors in the liver?
Liver breaks down glycogen stores into glucose which is released into the blood
What does adrenaline binding to receptors in the liver do to the blood glucose level?
Explain why it is important for adrenaline to bind to receptors in the liver to happen during the ‘fight or flight‘ response
To fuel respiration in the muscle cells for contraction
Describe what happens to blood vessels leading to muscles when the amount of adrenaline in the blood is increased
The diameter of the blood vessels widens
Explain why the diameter of blood vessels leading to muscles widens when the amount of adrenaline in the blood increases
To increase blood flow to muscles
Describe what happens to blood vessels leading to other organs (eg. the stomach) when the amount of adrenaline in the blood increases
The diameter of the blood vessels narrows
Explain why the diameter of blood vessels leading to other organs narrows when the amount of adrenaline in the blood increases
To decrease the blood flow to the other organs and increase overall blood pressure
Name three target organs of adrenaline
- blood vessels
(Also the brain, eyes - pupil dilation)
Name some processes that require the transfer of energy when the body is fully at rest
Any life process that is continuous and essential for life, such as:
- conducting impulses by neurones (eg. in the brain)
- heart beating
- glands making hormones
- organs responding to hormones