Hormones

A hormone is a chemical substance secreted by an endocrine gland into the bloodstream, where it travels to target organs or tissues and regulates their physiological functions by binding to specific receptors, thereby altering their activity or behavior.

The endocrine system coordinates various physiological processes in the body through the release of chemical messengers called hormones. These hormones are secreted by specialized glands known as endocrine glands and are transported through the bloodstream to target organs or tissues. Once hormones reach their target organs, they bind to specific receptors and initiate cellular responses, thereby regulating the activity of these organs. Hormones can either speed up, slow down, or alter the activity of target organs, depending on the body’s needs.

Following their release into the bloodstream, hormones circulate throughout the body until they reach their target organs. However, hormones do not remain in the bloodstream indefinitely. Instead, they are metabolized by the liver into inactive compounds and eventually excreted from the body by the kidneys. This process helps maintain hormonal balance and prevents excessive levels of hormones from accumulating in the bloodstream.

For example, insulin, a hormone produced by the pancreas, regulates blood sugar levels by promoting the uptake of glucose into cells. After insulin is secreted into the bloodstream in response to elevated blood sugar levels, it circulates for a relatively short duration, typically around 4-8 hours, before being broken down by the liver and excreted by the kidneys. This ensures that insulin levels are tightly regulated and remain within the appropriate range to effectively regulate blood sugar levels without causing prolonged fluctuations.

Adrenal Gland 

The adrenal gland is a vital endocrine organ responsible for producing and releasing various hormones that regulate essential physiological functions in the body. One significant hormone produced by the adrenal gland is adrenaline, also known as epinephrine.

The adrenal glands are paired structures located above each kidney in the back of the abdominal cavity.

Structure of the Adrenal Gland:

The adrenal gland consists of two distinct regions: the adrenal cortex and the adrenal medulla.

• The adrenal cortex: 

The outer layer, primarily synthesizes steroid hormones such as cortisol and aldosterone.

• The adrenal medulla: 

The innermost part, is responsible for producing and releasing adrenaline and noradrenaline.