ENDOCRINE SYSTEM

�   Endocrine system helps to regulation and coordination of body activities .

�   The endocrine system and nervous system work together.

GLANDS

�    Glands are organs specialized for secretion of substances needed by the organisms.

�    Some glands secrete ther secretions into some organs by ducts that caled EXOCRINE GLANDS.

�    Other glands release their secretion directly into the bloodstream that called ENDOCRINE GLANDS.

HORMONES

�    The secretion of endocrine glands is called hormone.

�    Hormone is a type of chemical substance which carry information from a part of body to another.

�    Hormones are somtemies called �Chemical messengers�.

�    Each type of hormone effects only some specific tissues which are called �target tissue�.

The processes in the body that are regulated by hormones include:

�           Overall metabolism

�           Maintenance of homeostasis

�           Growth

�           Reproduction

Types of hormones

�Protein-Type Hormones consist of chain of amino acids or related compounds.

�Steroid Hormones are lipid like, carbon ring compounds that are chemically similar to cholesterol and bile.

Regulation of hormone secretion

�    The rate of hormone secretion varies with the needs of the body.

�    The signals or messages that cause a gland to speed up, slow down or stop.

�    The mechanism the alters the activity of a gland is usually an example of NEGATIVE FEEDBACK.

�     Negative feedback has the effect of returning a condition toward its normal value.

�     If the condition decreases below its normal level, negative feedback acts to increase it.

�     If the condition rises above normal, negative feedback acts to decrease it.

�     The secretion of a hormone is controlled by the concentration of another substance in the blood, often another hormone.