ENDOCRINE SYSTEM

ENDOCRINE SYSTEM

The chemical coordination of physiological processes to maintain the homeostasis is the work of the endocrine system. The endocrine system controls and coordinates the physical processes of growth, reproduction and sustenance of life.

The endocrine system consists of a number of endocrine glands and their hormones.
The endocrine glands are ductless glands (without ducts), secreting chemical substances called hormones. The hormones are carried by the blood from the site of production to the site of action.

The endocrine glands in man are distributed in the different regions of the body without interconnections. The various endocrine glands which are found in different regions of human’s body are as follows:

Blood Vessels

Blood Vessels
There are three distinct types of blood vessels namely, arteries, veins and capillaries.

Arteries
Arteries carry the blood from the heart to different parts of the body. They are the branches of aorta, supplying oxygenated blood to the various regions of the body (except pulmonary artery which carries deoxygenated blood). The aorta branches into arteries. Arteries branch into arterioles. Arterioles branch into fine tubes called meta arterioles. The meta arterioles end up in the tiny blood vessels called capillaries.

Capillaries
Capillaries are tiny blood vessels that form a network, called capillary network around the tissues. They enable the passage of substances from the blood into the tissues.

Veins
The veins carry the blood from different parts of the body to the heart. The capillaries reunite to form venules, which carry the deoxygenated blood from the tissues. The small venules rejoin the big veins and open into the superior venacava and inferior venacava. Except for the pulmonary veins, all other veins carry deoxygenated blood.