To get from an endocrine gland to its target cell, a hormone must travel through what?

Additional tools

What is the endocrine system?

The endocrine system is a complex network of glands, hormones and receptors. It provides the key communication and control link between the nervous system and bodily functions such as reproduction, immunity, metabolism and behaviour.

In nearly all complex multicellular animals, there are two main systems controlling and coordinating the processes within the body:

• The nervous system, which exerts rapid point-to-point control by means of electrical signals passing down the nerves to particular organs or tissues.
• The endocrine system, which is a slower system based on chemical messengers, the hormones, which are secreted into the blood (or other extracellular fluids) and can reach all parts of the body.

The nervous system works in tandem with the endocrine system to control all bodily functions and processes. The endocrine system has three main components:

Endocrine glands, situated at various sites around the body, and in specialised areas of the brain. The cells in these glands secrete specific chemicals called hormones.

Hormones circulate around the body via the blood stream and modulate cellular or organ functions by binding with receptors in the target cells. Hormones that stimulate and control the activity of other endocrine glands are called trophic hormones.

Receptors in the target cells, once activated by binding of the hormone, regulate the functions and processes in the tissue through interactions with the cell's DNA or other complex intracellular signalling processes.

The main human hormones and their functions are shown below :

The production and circulating levels of hormones are controlled by means of negative feedback processes. For example, synthesis of thyroid hormone is stimulated by thyroid stimulating hormone (TSH) produced by the pituitary gland. If blood levels of thyroid hormone fall, a part of the brain, the hypothalamus, responds to the change and releases thyroid hormone releasing hormone (TRH), which stimulates a particular cell type in the pituitary to increase TSH synthesis. As thyroid hormone levels in blood again rise in response to TSH, TRH production is reduced and, in turn, TSH secretion is suppressed. Such feedback systems maintain the balance of various body systems (operating in a fashion analogous to the system that controls a domestic central heating system) - a process known as homeostasis.

Summary

• Endocrine glands secrete hormones straight into the bloodstream.
• Hormones help to control many body functions, such as growth, repair and reproduction.
• The endocrine system involves many organ systems and hormones, many of which are still being investigated and understood.

This page has been produced in consultation with and approved by:

This page has been produced in consultation with and approved by:

From other websites

Content disclaimer

Content on this website is provided for information purposes only. Information about a therapy, service, product or treatment does not in any way endorse or support such therapy, service, product or treatment and is not intended to replace advice from your doctor or other registered health professional. The information and materials contained on this website are not intended to constitute a comprehensive guide concerning all aspects of the therapy, product or treatment described on the website. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions and to ascertain whether the particular therapy, service, product or treatment described on the website is suitable in their circumstances. The State of Victoria and the Department of Health shall not bear any liability for reliance by any user on the materials contained on this website.

How does the hormone travel from the gland to the target cell?

How are endocrine hormones transported?

How are hormones typically transported to target cells?

What does the endocrine system use to deliver hormones to their targets?