Hormones & The Menstrual Cycle

HORMONES....

are chemical messengers which travel in the blood to activate target cells.

• Hormones are chemicals released directly into the blood. they are carried in the blood plasma to other parts of the body, but they only affect the target cells in particular places; Hormones control thing in organs.
• Hormones are produced in various glands, such as the pituitary gland and the ovaries. they travel though the body at "the speed of blood"
• Hormones tend to have relatively long-lasting effect.

Nerves;

• Very fast action
• Act for a very short time
• Act on a very precise area

Hormones;

• Slower action
• Act for a long time
• Act in a more general way

The menstrual cycle in women is a recurring monthly process in which the lining of the uterus (the womb) is prepared for pregnancy. If pregnancy does not happen, the lining is shed at menstruation.

STAGE 1;

Day 1 is when the bleeding starts. The uterus lining break down for about four day.

STAGE 2;

The lining of the uterus build up again, from day 4 to day 14, into a think spongy layer ful of blood vessels, ready to recieve a fertilised egg.

STAGE 3;

An egg is released from the ovary at day 14.

STAGE 4;

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

FSH;

• Produced by the pituitary gland
• Causes an egg to mature in one of the ovaries
• Stimulates the ovaries to produce oestrogen

Oestrogen;

• Produced in the ovaries
• Causes pituitary to produce LH
• Inhibits the further release of FSH

LH

• Produced by the pituitary gland
• Stimulates the release of an egg at around the middle of the menstrual cycle