What is the function of Hormones?
Everyone is familiar with the idea of hormones affecting our behavior. But what are they and how do they do this?
Hormones are chemical messenger molecules manufactured by special cells and released into the bloodstream to affect organs elsewhere in the body.
The molecules specific physical structure means they can only latch on to their intended target cells. Once attached, they either themselves pass – or produce chemical messengers that pass – into the cell nucleus with instructions to change the genetic activity in the cell.
The changes in cell activity then lead to effects that appear as a change in body function or behavior.
The Endocrine System
Hormones are produced by specialized cells. These cells are often grouped together as entire glands which produce specific hormones. These endocrine (meaning released within the blood) glands are located throughout the body.
Pituitary gland sits at the base of the brain connected to the hypothalamus- the part of the brain that controls it. The pituitary gland produces many stimulating different hormones that often affect the production of other hormones like thyroxine and cortisol.
Pineal gland: also in the brain but only produces melatonin in response to signals of darkness.
Thyroid gland: at the front of the neck produces thyroxine for metabolism
Parathyroid glands: four small pea sized glands embedded within the thyroid gland producing hormones that affect bone metabolism
Pancreas: hidden deep in the abdomen reads blood sugar and produces insulin or glucagon hormones as required in response
Adrenal glands: lie on top of the kidneys and produce cortisol
Ovaries: in the pelvis of females produce sex hormones of oestrogen and progesterone
Testicles: in the scrotum of males produce the sex hormone of testosterone
Hormones are also produced by specialized cells in many other areas of the body like the small intestine, where hormones to help digestion are released on contact with food.
Of the many hormones in the body, we will look at the ten most common ones that significantly affect human function:
1. Adrenaline – produced within minutes of stimulating or stressful situations
2. Cortisol – released more slowly in times of stress and according to natural waking cycles
3. Insulin – made in response to high blood sugar levels and absent or ineffective in diabetics
4. Vitamin D – is actually a hormone! Produced in response to sunlight and helps to strengthen bones
5. Thyroxine – the main hormone that controls metabolism in the body and is often at low levels in middle aged females
6. Oestrogen – the females sex hormone that controls puberty and the menstrual cycle
7. Testosterone – the male hormone controlling puberty, sperm production and muscle mass growth
8. Leptin – the hunger hormone that is the subject of much research since its recent discovery only 20 years ago
9. Melatonin – the sleep hormone that helps control sleep and waking cycles
10. Oxytocin – the love hormone that is released when a mother gives birth or when people bond socially
Typically, when a hormone is at an insufficient level or entirely missing, medical treatment is to replenish the hormone through medications containing them. For example, diabetes is treated with insulin injection, hypothyroidism is treated with thyroxine tablets and Vitamin D deficiency is treated with Vitamin D tablets.
Hormones are also commonly used to help women have more control over their life. Hormones form the basis of oral contraceptive pills that allow women to control their cycles, the emergency contraceptive pill in case of unexpected pregnancy risk and hormone replacement therapy to control menopause symptoms for older women.
Other hormone treatments- such as those of testosterone in older males and melatonin for sleep problems– are more controversial. For any further questions speak to your doctor or visit an endocrinologist- doctors who specialize in hormone conditions.