Hormones

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Hormones are biochemical substances produced by various glands in the body that travel through the bloodstream to signal specific cells or tissues to behave in a certain way. They are essential components of the endocrine system, coordinating complex processes like growth, metabolism, and fertility. Hormones can influence the function of the immune system, alter behavior, and induce healing processes.

Types of Hormones

Hormones can be broadly classified into three main types based on their chemical structure:

• Protein and peptide hormones - These are made up of chains of amino acids and include hormones like insulin, which regulates glucose levels, and growth hormone, which controls physical growth.
• Steroid hormones - These are derived from cholesterol and include hormones like estrogen and testosterone, which play key roles in sexual and reproductive development and health.
• Amine hormones - These are derived from single amino acids, such as thyroxine produced by the thyroid gland, and adrenaline (epinephrine) from the adrenal gland.

Function

Hormones serve a wide array of functions in the body, including:

• Regulation of metabolism - Hormones like thyroxine increase the metabolic rate of cells.
• Growth and development - Hormones such as growth hormone and follicle-stimulating hormone (FSH) guide growth and reproductive development.
• Homeostasis - Many hormones help maintain internal balance; for example, insulin and glucagon regulate blood glucose levels.
• Reproductive functions - Hormones like estrogen and testosterone manage reproductive functions and sexual characteristics.
• Response to environment - Hormones like adrenaline help the body respond to stress or danger.

Regulation

The production and release of hormones are primarily regulated by a feedback mechanism involving the hypothalamus and the pituitary gland. The hypothalamus sends signals to the pituitary gland, which in turn sends signals to other glands to produce hormones. Feedback loops help maintain an appropriate level of hormones in the body.

Disorders

Hormonal imbalances can lead to various medical conditions, such as:

• Diabetes mellitus, due to insufficient production or function of insulin.
• Hyperthyroidism and hypothyroidism, which involve overactive and underactive thyroid gland, respectively.
• Polycystic ovary syndrome (PCOS), which affects hormone levels in women, leading to various symptoms and fertility issues.

See Also

• Endocrinology
• Hormone replacement therapy
• Neuroendocrinology
• Pheromones