bio paper 2

What are hormornes ?

They are chemical molecules released directly into the blood. They are carried by other parts of theh body but only affect particular cells in particular organs.

Where are hormornes produced and what do they make up ?

They are produced by endocrine glands and they make up the endocrine system

What is the Pituatry gland in the endocrine system ?

It produces many hormornes that regulate body conditions. It is sometimes called the master gland because these hormornes act on other glands directing them to release hormornes which bring about change

What are Ovaries in the endocrine system ?

They produce Oestrogen which is involved in the menstrual cycle

What are the testes in the endocrine sysem ?

They produce testorerone which controls puberty and sperm production in males

What is the thyroid in the endocrine system ?

Produces thyroxine which is involved in regulating heart rate, rate of metabolism and temperature.

What is the adrenal gland in the endocrine system?

Produces adrenaline which is used to prepare the body for fight or flight response.

What is the pancrease?

Produces insuline which is involved in the controlling the blood glucose level.

What are characteristics of nerves ?

Very fast action

act for a short time

act on a precise area

What are characteristics on hormornes?

slower action

act for a long gtime

act in a more general way

What are the four stages of the menstrual cycle?

Stage 1 - Day 1 - menstruation starts. The uterus lining breaks down for about four days.

stage 2 - the uterus lining builds up again from day 4 to 14 into a thick spongy layer of blood vessel ready to recieve a fertilised egg.

stage 3 - an egg is delevoped and released from the ovary at day 14 called ovulation.

stage 4 - the wall is then maintained for about 14days until day 28. If no fertilised egg has landed on the uterus wall by day 28, then the spongy layer starts to break down and the cycle repeats.

What is FSH?

One of the four hormornes that control the menstrual cycle. Its produced in the pituatry gland. Causes the egg to mature in one of the ovaries in a structure called the follicle. It stimulates the ovaries to produce Oestrogen.

What is Oestrogen /

One of the four hormornes that control the mentrual cycle. It causes the lining of the Uterus to grow. It also stimulates the release of LH and inhibits the the release of FSH.

What is LH?

Produced by the pituatry gland. Stimulates the release of a egg at day 14.

What is Progestorone?

Produced in the ovaries by the remains of the follicle after ovulation. Maintaisn the lining of the uterus during the second half of the cycle. When the level of progesterone falls the lining breaks down. It inhibits the release of LH and FSH.

What is adrenaline ?

A hormorne released by the adrenal glands which is just above the kidneys. Its released in response to stressful or scary situations causing your brain to detect fear and sends nervous impulses to the adrenal glands which respond by secreting adrenaline.

How does adrenaline get the body ready for fight or flight?

It triggers mechanisms that increase the supply of oxygen and glucose to cells in the brain and muscles.

How do negative feedbacks affect thyroxine?

It keeps the amount of thyroxine in the blood at the right level. When the level of thyroxine in the blood is higher than normal, the secretion of TSH from the pituraty gland is inhibited. This reduces the amount of thyroxine released from thyroid gland so the level in the blood falls back to normal.