Introduction to the Human Endocrine System

This page is a basic introduction to the Human Endocrine System.

General Introductory Notes:

Basic summary notes about the endocrine system include:

• Hormones are 'chemical messengers'.
• Hormones have 'target organs'.
• Endocrine glands are ductless glands that secret hormones directly into the blood.

Functions of Hormones:

1. Hormones help to regulate:
   • Volume and Chemical Composition of Extra-Cellular Fluid.
   • Metabolism - see also metabolic rate
   • Biological Clock (Circadian Rhythms)
   • Glandular Secretions
   • Contraction of smooth and cardiac muscle fibres
   • Some immune system activities.
     
     
2. Hormones control growth and development.
   
   
3. Hormones govern the opertation of reproductive systems.

Comparison between the Endocrine System and the Nervous System:

1. Hormones are transported around (to their target organs) the body by the blood.
   Therefore hormonal responses are relatively slow compared with nervous responses.
   
   
2. Many hormonal responses (e.g. growth) occur over relatively long periods of time.
   
   
3. The main purpose of the Endocrine System is to maintain Homeostasis within the body (that is, to keep the internal environment constant/within balance), whereas
   the key function of the Nervous System is to receive and respond to stimuli.
   
   
4. Generally, the endocrine system is controlled by the Nervous System (through the Hypothalamus, mediated by the Pituitary Gland).

This is the end of this page but information about the Locations of and Hormones secreted by the main Endocrine Glands and other aspects of the Endocrine System, such as Diabetes and other Conditions that Affect the Endocrine System are included on other pages of this website.