Human Endocrine System

The human endocrine system is composed of glands which secrete chemicals called hormones directly into the bloodstream

The blood carries the hormone around the body, and when it reaches a target cell/organ it produces an effect

Compared to the nervous system the effects of hormones are slower but they act for longer

Important structures in the endocrine system are:

• Pituitary gland: a ‘master gland’ making hormones such as FSH and LH 

• Pancreas: produces insulin which regulate the blood glucose level

• Thyroid: produces thyroxine which controls metabolic rate and affects growth

• Adrenal glands: produces adrenaline

• Ovaries (females): produce oestrogen 

• Testes (males): produce testosterone

Pituitary Gland

The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions

These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects

• For example, in certain conditions, the pituitary gland makes and secretes thyroid - stimulating hormone (TSH) which stimulates the thyroid to release thyroxine 

Hormones are synthesized and released into the bloodstream from a gland (such as the pituitary gland) and  circulate in the bloodstream, having an effect on target cells