Biology GCSE Unit 1- Nervous System & Hormones

Hormones are CHEMICALS released DIRECTLY INTO THE BLOOD

They are chemical messengers.

Carried in the blood plasma

All produced in various glands

They travel all over the body but only affect particular cells.

They have long lasting effects

HORMONES are chemcal messengers which travel in the blood to activate target cells

The pituitary gland produces many hormones: LH, FSH, ADH, it controls other glands       The pancreas produes insulin for the control of blood sugar

The ovaries (females only) produce oestrogen which promotes all female secondary sexual characteristics during puberty            

The adrenal gland produces adrenaline which controls increased blood sugar and heart & breathing rate

The testes produces testosterone and control all male secondary sexual characteristics during puberty

The thyroid produces thyroxine and triiodothyronie, this affects growth

THYROXINE- increases metabolic rate, controls levels of activity & essential for normal brain development ADRENALINE- fast acting, prepares the body for action           INSULIN- controls the body's blood sugar, glucose is stored as glycogen in the liver       OESTROGEN- controls development of female characteristics                   PROGESTERONE- made by ovary, prepares lining of uterus for implantation of an embryo                                                                                                   TESTOSTERONE- contols development of male characteristics                                  FSH (follice stimulating hormone) - causes ovaries to mature, causes ovaries to secrete oestrogen                                                                                                                  LH (luteinizing hormone) - stimulate ovulation (release of an egg)                                                                                                                      ADH - makes water to be reabsorbed into the kidney if blood is too concentrated  GROWTH HORMONE- causes growth of the body and skeleton