As minute chemical messengers within the human body, hormones play a pivotal role in regulating various physiological functions. Their impact extends across growth, mood, metabolism, reproduction, and sleep, unveiling their intricate influence on daily life. Researchers have identified more than 50 hormones within the human body to date.
What are hormones?
First discovered by Ernest Starling in 1905, hormones are chemical substances that coordinate various functions in the body. Hormones are bio-important because they can orchestrate complex interactions between cells and organs and influence numerous physiological processes. Even slight alterations in hormone levels can significantly impact the body, contributing to various health conditions.
How are hormones produced?
Hormones are produced by ductless specialized glands called endocrine glands. These include the gonads (testes and ovaries), pancreas, hypothalamus, adrenal glands, thyroid gland, and parathyroid glands.
Hormones and the specialized glands that produce them make up the endocrine system. They are secreted directly into the blood and transmitted to target organs and tissues in response to specific stimuli where they exert specific functions. Hormonal signals instruct the body on what to do and when to do it. Different hormones affect different aspects of bodily functions and processes.
Importance of hormones
Homeostasis: By regulating factors like blood sugar, electrolyte levels, fluid levels, and body temperature, hormones ensure that different systems within the body work together harmoniously and respond appropriately to internal and external stimuli for optimal health and well-being.
Growth:
The human growth hormone (HGH) or somatotropin is crucial in stimulating protein production and coordinating fat synthesis to provide the energy necessary for tissue growth. For example, while HGH stimulates height, muscle growth, and bone length through childhood and adolescence, contributing to overall physical development, the sex hormones estrogen and testosterone facilitate the development of secondary sexual characteristics during puberty.
Reproductive Health:
Reproductive hormones regulate fertility, menstrual cycle, sperm production, and the development of secondary sexual characteristics. Testosterone promotes the development and maturation of male sexual characteristics in males. Likewise, progesterone stimulates breast milk production and uterine functions in people assigned females at birth.
Metabolism:
The thyroid, a tiny butterfly-shaped gland at the front of the neck, primarily regulates metabolism via the actions of thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (RT3), and calcitonin. These hormones control blood minerals and metabolic rate, which is how the body converts food into energy.
Blood Sugar and Blood Pressure Regulation:
Hormones such as insulin, glucagon, and aldosterone are crucial in maintaining blood sugar levels and blood pressure, respectively. Produced in the pancreas, glucagon raises blood sugar levels, while insulin lowers them, regulating the metabolism of glucose, fat, and protein.
Circadian Rhythm:
Secreted in the pineal gland, melatonin regulates the sleep-wake cycle by responding to environmental cues, including light and darkness. In the evening, when it gets dark, the pineal gland releases melatonin, promoting sleepiness, while exposure to light in the morning suppresses melatonin production, signaling wakefulness.
Stress Response:
Adrenaline (epinephrine) and noradrenaline (norepinephrine) regulate the fight-or-flight response. When the body perceives a threat, these hormones are released to prepare it to respond rapidly to the danger.
