AQA GCSE Biology

Revision Notes

5.3.1 Human Endocrine System

Endocrine System Structure & Function

  • Students should be able to describe the principles of hormonal coordination and control by the 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 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 notes

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

Exam 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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Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.

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