Hormones – What are they? How do they work? Why have them?

Hormones – What are they? How do they work? Why have them?

What are they?

Hormones are the chemical messengers secreted by cells that travel through blood and regulate the function of other cells. Similar to messages sent down neural pathways with the major difference being that hormones take longer to take effect but last longer too.

Hormone = to excite

Most hormones can be classed as

AMINO ACID BASED – from simple amino acids, to peptides, to proteins

STEROID BASED – synthesised from cholesterol. Produced by the gonads and adrenal glands.

How do they work?

Hormones are very specific and will only influence cells that have receptors for a specific hormone. These cells are called target cells and their function is either increased or decreased from hormonal stimuli. The following changes usually occur

  • opening or closing ion channels (eg. changes in blood pressure, muscle contractility or fluid balance)
  • stimulates synthesis of enzymes or other proteins
  • activates or deactivates enzymes
  • induces secretion
  • stimulates mitosis (cell division)

Receptors are adaptive and can change their sensitivity. In cases where low levels of hormone are present, the target cells can form additional receptors for that specific hormone in a process called up-regulation. In the opposite case down-regulation can occur to prevent over-reactions.

Most hormones are affected by diurnal or ultradian rhythms meaning they follow day and night patterns or a course over several days (such as the menstrual cycle).

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Why have them?

Hormones target most cells of the body but are majorly involved in

  • reproduction (development of reproductive organs and sex cells)
  • growth and development
  • electrolyte, water and nutrient balance of the blood
  • cellular metabolism and energy balance
  • mobilisation of body defences

As you can see hormones are important through all stages of life! They help when giving birth, encourage milk ejection for breastfeeding, are important for bone and muscle development, regulate our metabolism, electrolyte and hunger, allow us to deal with stress, assist with immunity and also make us feel good (this is only a tiny list)!

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Keeping hormone levels normal isn’t easy, especially for women. What can you do to help achieve optimal hormone balance?

  • Maintain a diet full of nutritionally dense food (restrict packaged food)
  • Exercise regularly to keep hormones travelling through the blood and lymph effectively
  • See the sunlight! UV rays help synthesise vitamin-D and also help keep our circadian rhythm in check
  • De-stress every now and again. An imbalance in stress = an imbalance in hormones.
  • Ensure restful & regular sleep. Since hormonal release follows a pattern, so should your rest.



Hinson, J. (2010). The endocrine system: basic science and clinical conditions (2nd ed.). Edinburgh ; New York: Churchill Livingstone/Elsevier
Marieb, E. N. (2013). Human anatomy & physiology (9th ed.). Boston: Pearson
Wardlaw, G. M. (2013). Wardlaw’s perspectives in nutrition (9th ed.). New York: McGraw-Hill

I'm currently studying a Bachelor in Health Science - Nutritional Medicine with a background in dance and fitness. I believe sharing knowledge is the key. I hope my love for food, fitness and well-being along with my studies helps you in finding something useful. Enjoy!

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