Hormones and Negative Feedback Systems

Introduction to Hormones

Hormones are chemical messengers secreted by endocrine glands into the bloodstream.
They work over long distances and influence function of tissues and other organs.
They control physiological activities such as growth, metabolism, and reproduction.

Hormones can be broadly classified into two types: Protein hormones and Steroid hormones.
Protein hormones, such as insulin and glucagon, are soluble in water but not in lipids.
Steroid hormones, like cortisol and oestrogen, are soluble in lipids but not in water.

The effects of hormones in the body are widespread and often long lasting.
Hormones can stimulate or inhibit the growth of cells, control the rate of metabolic processes, and orchestrate physiological events like the menstrual cycle and reproductive processes.

Negative feedback systems are the primary mechanism by which the levels of hormones are regulated in the body.
Negative feedback systems work to keep the level of a certain substance in the body relatively constant.
In this system, a change in the level of a substance triggers a response that works to counteract the initial change.

The level of a hormone in the bloodstream often regulates its own production and secretion via negative feedback.
For example, if the system detects that the level of a particular hormone in the bloodstream is too high, it will send a signal to reduce the production and release of that hormone.
If the level of that hormone is too low, it will signal the body to increase the production and release of the hormone.

An excellent example of a negative feedback system in hormone regulation is the control of blood glucose levels by insulin and glucagon.
When blood glucose levels rise, the pancreas secretes insulin which promotes the absorption of glucose from the bloodstream, lowering blood sugar.
When blood glucose levels fall, the pancreas secretes glucagon which promotes the breakdown of glycogen to glucose, increasing blood sugar levels.
This system of checks and balances ensures that the body maintains a healthy, steady state of blood glucose levels.

Hormones and negative feedback systems play important roles in maintaining the overall health and balance of the body. Understanding these systems can provide insights into how the body responds to changes, and how medical conditions can occur if these systems don’t function properly.