Endocrines : The glands of the body may be divided into those with an external
secretion (exocrine glands) and those with an internal secretion (endocrine
glands). Example of exocrine glands are the sweat, Lachrymal and mammary glands
which pass their secretion along the ducts to the external surface of the body
and the glands of the mouth, stomach, and intestine which pass their secretions
along ducts into the alimentary tract. The endocrine or ductless gland on the
other hand have no ducts or openings to the exterior.
The secretions are passed directly into the blood stream and transmitted
to the tissues.
A hormone is a chemical substance produced by the endocrine
glands and their overall function is to regulate the activities of various body
organs and their functions. The first hormone was discovered by Bayliss in
The main endocrine glands in the body are :
Islets of Langerhans
two tiny oval pairs (6mm x 2m) of glands situated at upper and lower poles of
lateral lobes of thyroid gland. It secretes the hormone, parathyroxine.
Functions of Parathyroxine
Increases the concentration of organic acid in the bone.
Increases the calcium and phosphorus solubility
Increases the reabsorption of calcium from the bones resulting in
increased serum calcium level.
Increases phosphate excretion in the urine.
Increases the reabsorption of calcium from the renal tubules.
Promotes the absorption of calcium and phosphorus from the intestine.
Stimulates the process of lactation in mammary gland.
Deficiency of Parathyroxine
Serum calcium level falls.
Blood reaction is more alkaline owing to excessive loss of CO
Decalcification of bones.
Increase in the heart and respiration rate.
Rise in body temperature.
General mental depression.
Tendency to cataract formation.
Under development of teeth.
Brittleness of nails.
Dryness of skin.
Lowered general resistance.
Twitching of muscles causing
Tetany is a condition, in which there is hyperexcitability of nervous system
with intermittent tonic spasms of muscles chiefly of the limbs, face, and back
of the neck. When the small muscles of hands are affected, the hand is held in
the same position. It is known as
Carpo - Pedal spasms. When the laryngeal muscle are affected laryngeal spasm
is seen. If tetany is not treated it may lead to paralysis of respiratory
muscle and cardiac arrest. Finally death may occur.