Human Endocrine System (AQA GCSE Biology: Combined Science)

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Endocrine System Structure & Function

  • 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 regulates 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

The major endocrine glands in the body, IGCSE & GCSE Biology revision notesThe major endocrine glands in the body, IGCSE & GCSE Biology revision notes

The major endocrine glands in the body secrete hormones which circulate around the body in the bloodstream

Examiner Tip

Make sure you can recognise the structures listed in the diagram above in the exam.

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

How hormones work, IGCSE & GCSE Biology revision notes

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

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.