Hormones

Question 1

What is a hormone?

Answer 1

A chemical messenger that are carried in the blood.
They are relased from a range of endocrine glands.

Question 2

Thyroid gland

Answer 2

This produces thyroxine, which is involved in regulating things like the rate of metabolism, heart rate and temperature
This gland is in our neck
It is regulated by a negative feedback loop

Question 3

The pituitary gland

Answer 3

Produces many hormones that regulate body conditions. It is also called the master gland because these hormones act on other glands, dirceting them to release hormones to bring out change.

It is found in the brain and is linked to the hypothalamus

The pituitary gland relases hormones in response to changes detected by

Question 4

The pancreas

Answer 4

Produces insulin which is used to regulate the blood glucose level

Question 5

Adrenal gland

Answer 5

Produce adrenaline which is used to prepare the body for a ‘fight or flight’ responce when an organism is presented with a dangerous situation Used in times of fear and stress
The two adrenal glands are situated above each kidney
Adrenaline enlarges the air passages of the lungs and alters metabloism to boost faster delivery of oxygen and glucose to the brain and muscles

Question 6

Testes

Answer 6

Male only
They produce testosterone which controls puberty and sperm production in males

Question 7

Ovaries

Answer 7

Female only
Produce oestrogen which is involved in the menstural cycle and controls pubery

Question 8

Difference between hormones and neurones

Answer 8

Neurones have a very fast action whereas hormones have a slower action
Neurones act for a very short time whereas hormones act for a long time
Neurones act on a very precise area whereas hormones act in a more general way

Question 9

What does adrenaline do?

Answer 9

Prepares the body for ‘fight or flight’ by activating processes that increase the supply of oxygen and glucose to cells

Question 10

How does heart rate and blood pressure increase?

Answer 10

Adrenaline binds to specific receptors in the heart causing the heart muscle to contract more frequently and with more force do the heart rate and blood pressure increase
This increases blood flow to the muscles so the cells recive more oxygen and glucose for increased respiration

Question 11

How increase to blood glucose level?

Answer 11

Adrenaline also binds to receptors in the liver causing the liver to brack downits gluogen stores to release glucose
This increases blood glucose level, so there’s more glucose in the blood to be transported to the cells

Question 12

Negative feedback

Answer 12

A control mechanism reacting to change in a condition by trying to bring levels back to normal

Question 13

What happens when blood thyroxine level is lower than usual?

Answer 13

The hypothalamus is stimulated to release thyrotropin releasing hormone (TRH).
TRH stimulates the pituitary gland to release thyroid stimulating hormone.
TSH stimulates the thyroid gland to relase thyroxine so the blood thyroxine level rises back towards normal.

Question 14

What happens when blood thyroxine level is higher than usual?

Answer 14

The release of TRH from the hypothalamus is inhibited, which reduces the production of TSH, so the blood thyroxine level falls.

Question 15

What is the menstural cycle?

Answer 15

The monthly sequence of events in which the female body releases an egg and preapers the uterus in case the egg is fertilised

Question 16

Stage 1 of the menstural cycle

Answer 16

Day 1 is when the menstuation starts
The lining of the uterus breaks down and is relased

Question 17

Stage 2 of the menstural cycle

Answer 17

The uterus lining is repaired from day 4 to day 14 untill it becomes a thick and spongy layer full of blood vessels ready for a fertilised egg to implant there

Question 18

Stage 3 of the menstural cycle

Answer 18

An egg develops and is released from the ovary (ovulation) at about day 14

Question 19

Stage 4 of the menstural cycle

Answer 19

The lining is then maintained for about 14 days. untill day 28. If no fertilised egg ahs landed on the uterus wall by day 28, the spongy lining starts to brek down again and the whole cycle starts over.

Question 20

Role of FSH

Follicle-stimulating hormone

Answer 20

It is released by the pituitary gland
Causes a follicle (an egg and its surrounding cells) to mature in one of the ovaries
Stimulates oestrogen production

Question 21

Oestrogen

Answer 21

Released by the ovaries
Causes the lining of the uterus to thicken and grow
A high level stimulates an LH surge

Question 22

Role of LH

Luteinising hormone

Answer 22

Released by the pituitary gland
The LH surge stimulates ovulation at day 14 -the folliocle ruptures and the egg is released
Stimulates the remains of the follicle to develop into a structure called a corpus luteum - which secretes progesterone

Question 23

Role of progesterone

Answer 23

Released by the corpus lutrum after ovulation
Maintains the lining of the uterus
Inhibits the release of FSH and LH
When the level of progesterone falls, and there’s a low oestrogen level, the uterus lining breaks down
A low progesterone level allows FSH to increase and then the whole cycle starts again.