1. Growth Hormone (gh):

It controls metabolism especially protein synthesis, accordingly it controls the physical growth of the body.

Hypo secretion of this hormone during childhood causes Dwarfism, and its hyper secretion during the same period cause Gigantism. Hyper secretion of GH in adults causes Acromegaly which is characterized by increase bone growth at the extremities and characterized by enlarged hands, feet, fingers, and bones of the face.

2. Pituitary Trophins:

A group of hormones that affect the activity and secretion of other glands, and include:

a) Thyrotrophin (thyroid stimulating hormone) (T.S.H).

b) Adrenocorticotrophic hormone (A.C.T.H):

Which affects the function of the adrenal (suprarenal) cortex.

c) Gonadotrophic hormones:

Which affect the function of gonads (ovaries in females and testes in

males). This group includes:

1) Follicle stimulating hormone (F.S.H): Which affects the growth of

the ovarian follicles and formation of Graafian follicles in females

and formation of seminiferous tubules, spermatozoa, and prostate

gland in males.

2) Lutinizing Hormone (L.H.): Which stimulates the formation of

corpus luteum in females and the formation and secretion of the

interstitial cells in the testes of males.

These two hormones are important for sexual maturity as they are

responsible for secretion of male and female sex hormones.

3) Prolactin: Stimulates milk formation and secretion from

mammary glands (Breasts) and the secretion of the hormone

Progesteron from the Corpus luteum.

Hormones of the Neurohypophysis (the posterior lobe):

Two hormones are secreted from the nerve cells in the hypothalamus and reach the neurohypophysis (posterior lobe of pituitary gland) through the infundibulum after which they are secreted to the blood stream. These two hormones are:

1) Antidiuretic hormone (a.D.H) (Vasopression):

This hormone increases the re-absorption of water from the kidney tubules and decreasing the volume of urine excreted. In addition, it increases blood pressure.

2) Oxytocin:

This hormone affects the uterine contraction and increases it during delivery (labour). Gynacologests use this hormone to accelerate the birth of a baby by stimulating strong contractions of uterine muscles. In addition, Oxytocin stimulates the release of milk from mammary glands with the beginning of lactation (milk letting hormone).

Second: The Thyroid Gland

The gland lies in the neck in front of and in close contact with the trachea. The colour is slightly red. The gland consists of two lobes connected together by an isthmus.

Its function:

The gland secretes the hormone Thyroxin. Iodine is essential for the formation of this hormone. Thyroxin has many effects on different parts of the body. As for example:

1) It affects and stimulates physical and mental growth and development.

2) It affects the basal metabolic rate.

3) It increases the absorption of carbohydrates (Glucose) from the intestine.

4) It maintains healthy skin and hair.

The gland secretes another hormone called Calcitonin which decreases the Calcium level in the blood by decreasing its release form bones and prevents its absorption from the bones.

Goiter:

The enlargement of the thyroid gland associated with abnormal activities of the gland. There are two types of Goiter:

1) Simple goiter:

It occurs due to Iodine deficiency in food, water, and air. The treatment involves administration of Iodine supplement in food.

2) Exophthalmic goiter:

It’s the enlargement of the gland with protrusion of the eye balls. It results from hyper secretion of the gland (hyperthyroidism). Hyper secretion of Thyroxin leads to an increase in food oxidation and metabolic rate, loss of weight, increase in heart beats and nervous irritability. The treatment of this case is by either surgical removal of a part of the gland or by the use of other medications to suppress the gland.

Hypothyroidism:

Hypothyroidism is the decrease in the secretion of the thyroxin hormone from the gland. The symptoms resulted depends on the age:

a) Hypothyroidism in children:

It leads to a condition called Cretinism. Cretinism is characterized by retardation in physical and mental growth associated with large head, short stature, short neck, permanent mental retardation and a delay in sexual maturity.

b) Hypothyroidism in adults:

It causes a condition called Myxodema which is characterized by dry skin, loss of hair, decreased mental and physical activity, weight gain, and obesity, decreased basic metabolic rate and cold intolerance, decreased heart beats, and rapid fatigability. The treatment is by regular consultation of a specialist and by administration of Thyroxin or gland extracts.