Hormones are chemicals released directly in to the blood stream, they are carried in the bloods plasma to other parts of the body. Hormones only affect target cells in particular areas of the body. Hormones control things in our organs that need constant adjustment.
Hormones are secreted by various glands, such as the pituitary gland and the ovaries.
Hormones have long lasting effects
The Mestrual Cycle
The menstrual cycle is the monthly release of an egg from a womens ovaries, and the build up and breakdown of the protective lining in the uterus.
Stage 1- The uterus lining starts to break down for about 4 days.
Stage 2-The lining of uterus starts to build up again, from day 4-14 it forms a thick layer of blood vessels, which are able to receieve a fertilised egg.
Stage 3-An egg is released from the ovaries at day 14.
Stage 4-The Lining of the uterus is maintained for about 14 days, until the 28th day. If the egg is not fertilised then the lining breaksdown again, and the cycle begins again.
Hormones involved in The Menstrual Cycle
FSH ( Folicile Stimulating Hormone)
1. Produced by the pituitary gland.2. Causes an egg to mature in thee ovaries.3. Stimulates the ovaries to produce oestrogen.
1. Produced in the ovaries.2. Causes the pituitary gland to produce LH.3. Inhibits further release of FSH.
LH ( Lutenising Hormone)-
1. Produced by the pituitary gland.2. Stimulates the release of an egg at the middle of the cycle.
Oestrogen can be used to prevent the release of an egg, also it inhibits the developing of the egg.
Progesterone also reduces fertility, as it builds up a thick mucus which prevents the sperm from fertilising the egg.
The pill is a combined oral contreceptive, which cntains amounts of progesterone and oestrogen. Smaller doses are now given due to the risk of blood clots.
IVF- in vitro fertilisation
IVF involves collecting eggs from the womens varies and fertilising them in lab with a mans sperm. These are grown into embryos.
When the embyos form 1 or 2 are transferedd into the womens uterus, to improve the chance of pregnancy.
FSH and LH are given beforre the eggs are collected as it will increase the yield of the collection.