THE EXPLAINER: HORMONES
The chemical regulators
that keep bodily processes in balance
What are hormones?
Hormones are chemical messengers that travel throughout the body, telling our cells and organs what to do. They regulate nearly all bodily processes and affect every aspect of our daily lives, influencing how we feel, what we look like and how we act, whether that’s hungry, hairy or happy.
Crucially, hormones are responsible for maintaining the body’s delicate internal balance, which is required for optimal health. But sometimes, hormones become imbalanced or lose their ability to function effectively. This can cause a number of serious negative impacts on our health.
In other words, hormones are of great importance to every one of us, so keeping them regulated and in balance is vital, because they affect us when they work, but they can have drastic impacts on us when they don’t.
What do hormones do?
Hormones provide an internal communication system between different parts of the body. The majority of hormones are produced and released by endocrine glands, which monitor and maintain the body’s internal environment – a process known as homeostasis. When imbalances in the body are detected, these glands release hormones that travel in the bloodstream carrying information to tell other glands or organs what to do to bring the body back into balance.
There are more than 200 hormones in the body, each with its own unique function. For example, after you eat a sweet treat, your blood sugar levels rise. This is detected by the pancreas, which responds by releasing the hormone insulin to stimulate muscle and fat cells to increase the absorption of glucose (sugar) from the bloodstream. Hormones also communicate with other glands, telling them to increase or decrease the release of certain hormones.
We often associate hormones with things like puberty or periods, but they actually play a major role in nearly all bodily processes. You might not realise it, but under the surface, hormones are continuously working to maintain nearly every aspect of your health.
This complex network of glands, hormones and organs is what’s known as the endocrine system.
HORMONES: NOT JUST FOR PUBERTY…
1. OXYTOCIN Oxytocin is produced by the hypothalamus in the brain and is secreted into the bloodstream via the pituitary gland. It’s responsible for facilitating childbirth, stimulating lactation for breastfeeding, and promoting human bonding.
2. SOMATOTROPIN Also known as the growth hormone, somatotropin is produced by the pituitary gland. It supports growth and development, and regulates normal body structure, metabolism and blood sugar.
3. MELATONIN Melatonin is produced by the pineal gland in the brain and is responsible for regulating the sleep-wake cycle, by stimulating feelings of sleepiness.
4. THYROXINE Thyroxine is produced in the thyroid gland and plays a role in regulating metabolism, digestion, muscle and heart function, brain development and bone health.
5. PARATHYROID HORMONE The parathyroid hormone is produced in the parathyroid gland in the neck (behind the thyroid gland) and helps regulate calcium levels in the body. This is particularly important for nervous system function and muscle and bone strength.
6. ADRENALINE Adrenaline is released from the adrenal glands, which are situated on top of the kidneys. It helps prepare the body for the effort of fleeing or defending itself, in response to stress or danger.
7. INSULIN Insulin is produced by the pancreas. It’s responsible for regulating blood sugar levels and the availability of glucose for cells to use as energy.
8. TESTOSTERONE In men, testosterone is produced by the testes. It plays a key role in sperm production, sex drive and the development of male physical characteristics. It also regulates bone mass, fat distribution and muscle strength.
9. OESTROGEN In women, oestrogen is produced by the ovaries. It’s responsible for the development of female physical characteristics and regulating the menstrual cycle, fertility and bone strength. Oestrogen also affects the function of other parts of the body, including the brain, heart and muscles.
How do hormones trigger changes in the body?
When a hormone is released from a gland, it travels in the bloodstream through the body in search of its target. Organs, tissues and other glands in the body have receptor sites that hormones must bind to in order to deliver their message and cause an effect. But because every hormone has its own unique shape, they are highly targeted and can only act on the parts of the body that have a receptor site with the corresponding shape. This mode of action can be likened to a lock and key mechanism – if the key doesn’t fit the lock, then nothing will happen.
When a hormone binds to its target, it sets off a cascade of other signalling pathways to create a change in the body. Once the desired effect has taken place, this signal is fed back to the glands to suppress any further hormone release. This is what’s known as a feedback loop and, when it’s functioning correctly, it allows the endocrine system to ensure the conditions in your body remain in balance.
What happens when hormones don’t function properly?
Hormones are essential for our survival and support the everyday function of many important bodily processes. But sometimes, parts of the endocrine system don’t behave as they should, resulting in a type of medical condition called an endocrine disorder.
Typically, endocrine disorders cause abnormally high or low levels of hormones. They can also affect the body’s ability to respond effectively to certain hormones. When this happens, our delicate internal balance becomes disrupted, and our health suffers. Think of it like a recipe for a cake – if you add too much or too little of any one ingredient, the final product is affected.
For example, hypothyroidism is an endocrine disorder in which the thyroid gland doesn’t produce enough thyroxine. This causes a range of symptoms including fatigue, constipation, weight gain, depression and muscle weakness. Gigantism is another endocrine disorder, but in this instance the pituitary gland produces too much growth hormone (somatotropin) in children or adolescents, causing them to grow abnormally tall.
Endocrine disorders can arise for several reasons, such as a genetic disorder, problems with the endocrine feedback system, injury to an endocrine gland, infections, or a tumour on an endocrine gland. Most hormonal conditions can’t be cured, but, thankfully, they can be managed effectively with medication.
How can you tell if you have a hormone imbalance?
Some hormones fluctuate naturally as you age, or because they’re part of a cycle, such as the menstrual cycle. But for others, even the slightest increase or decrease can cause major changes and impact your health. Some of the most common signs of hormone imbalances are related to your metabolism (the chemical reactions that convert food into energy), including changes to your heartbeat, weight, energy levels, bowel movements, skin and mood.
Other imbalances are related to sex hormones, which can cause a loss of libido, loss or excessive growth of body hair, infertility, menstrual cycle and vaginal changes, and erectile dysfunction. But all of these symptoms can also be signs of other medical conditions, making it difficult to tell if you have a hormone imbalance without the help of a professional. If you experience any unusual changes in your body, always seek medical advice.
How do you keep your hormones balanced?
While hormone imbalances are sometimes caused by endocrine disorders, there are other factors that influence hormone health. Eating a healthy, nutritious diet supports good gut health, and optimises the production and function of hormones and their signalling pathways. Hormones love healthy fats, fibre and protein, but they aren’t so fond of sugar, processed foods, or alcohol.
Alongside a healthy diet, regular exercise also helps keep hormones in check. This is because physical activity increases blood flow and hormone receptor sensitivity, allowing hormones to deliver their messages more effectively.
Sleep is also important for regulating hormone levels. Not getting enough shut-eye at night can upset the balance of multiple hormones. For example, sleep deprivation increases levels of the stress hormone cortisol and decreases levels of the appetite-suppressing hormone leptin. As a result, you might wake up the next day feeling unusually stressed and hungry.
Stress is another factor that may harm your hormones. Generally, when you experience a stressful situation, your body releases stress hormones like cortisol and adrenaline, which initiate a cascade of other effects in the body. Once the stressor has passed, the endocrine system’s feedback mechanism suppresses the production of further hormones. However, long-term stress prevents this from happening, meaning your hormone levels aren’t able to return to normal.
FIVE WAYS HORMONES CAN INFLUENCE THE WAY WE FEEL
Mood
Serotonin and dopamine are two key players involved in regulating our emotions. These are often referred to as ‘happy hormones’ as they promote feelings of pleasure, positivity and, as the nickname suggests, happiness!
Sleep
Melatonin helps control your body’s natural sleep-wake cycle. As night draws in and low light levels are detected by the eyes, melatonin production increases, telling the body it’s time to go to sleep.
Hunger
Ghrelin is an appetite stimulating hormone, mainly produced by the stomach. When you haven’t eaten in a while and your stomach is empty, ghrelin secretion increases. This sends a signal to your brain to tell you that you’re hungry.
Stress
Cortisol is released by the adrenal glands in response to stress. It helps the body prepare for ‘fight-or-flight’ by making glucose and other nutrients more available, while suppressing non-essential bodily processes like digestion.
Love
Oxytocin is often referred to as the ‘love hormone’ because it plays a role in romantic attachment. Levels increase during physical intimacy, such as hugging and sex. It also promotes parent-child bonding and feelings of trust and empathy.
by HOLLY MCHUGH
Holly is a freelance health writer with a BSc in biological sciences. She specialises in writing about hormones, nutrition, women’s health, human anatomy and physiology.