Man's physical universe

xanabras

VITAMINS, ENZYMES, AND HORMONES 745

The medulla of the suprarenal glands secretes the powerful hormone

epinephrin, which activates the nervous system and muscles, strengthening

the heart beat and increasing the blood pressure.

When one is

angry, epinephrin is secreted. Epinephrin (one trade-name for which

is adrenaline) is a commercial extract of this hormone that produces

similar effects when injected into the body. It is used as a stimulant

in emergencies and to relieve asthma.

The thyroid gland secretes thyroxin, a deficiency of which results in

cretinism in children and myxedema in adults, while an excess produces

an abnormally high basal metabolic rate and a train of signs and symptoms

which if not halted by surgical removal of the larger part of the

gland results in death. In general thyroxin helps to control growth,

reproduction, and metabolism. {Metabolism is the process of utilization

of foods by the body, or sometimes the rate of this utilization.)

Thyroxin may be given children whose thyroid glands do not

function, thus enabling them to develop into normal adults rather than

imbeciles. Adults whose thyroxin deficiency causes them to be sluggish

and overweight may be made normal by taking the proper amounts of

thyroxin.

The parathyroid glands secrete parathormone, which regulates the

utilization of calcium and phosphorus by the body.

The cortex of the suprarenal glands secretes "cortin," which controls

the balance between sodium and potassium in the body and has

an important function in regulating carbohydrate metabolism. A

deficiency of "cortin" causes Addison's disease, while an excess

causes children to mature precociously and causes adult women to

acquire male voices and an abnormal growth of bodily and facial hair.

The pituitary gland produces a number of hormones, one of which

controls growth ;

giants and dwarfs result from an excess or deficiency

of this hormone. At least eight more hormones are said to be secreted

by the pituitary glands. These hormones control the various sexual

activities of men and women, including the ripening of germ cells,

the development of mammary glands, and the secretion of milk.

Several of these hormones control the functioning of the thyroid and

adrenal glands and the pancreas.

The islands of Langerhans in the pancreas secrete insulin, which is

poured directly into the blood stream; the absence of insulin causes

diabetes, which is characterized by inability to use carbohydrates

normally. The major part of the pancreas secretes an important

digestive juice, which is emptied into the intestine.

The gonads (sex glands) secrete hormones which regulate the growth

and development of sex organs and secondary sex characteristics.

More magazines by this user
Similar magazines