The pituitary gland is also called hypophysis cerebri. It is a pea-shaped compact mass of cells located at the base of the midbrain just below the hypothalamus.
Location of pituitary gland
The pituitary is attached to the hypothalamus via the pituitary stalk. It is the smallest endocrine gland that weighs about \(0.5 \ grams\).
Pituitary stalk attached with hypothalamus
The pituitary gland is composed of two main lobes, which perform different functions. The two lobes are:
1. Anterior lobe (Adenohypophysis )
2. Posterior lobe (Neurohypophysis )
A third lobe, called the intermediate lobe, is a part of the adenohypophysis. It is non-existent in humans.
Adenohypophysis consists of three regions: the pars distalis (most anterior), the pars intermedia, and the pars tuberalis. The anterior lobe makes up to about \(75\%\) of the pituitary gland.
Anterior and posterior pituitary
The pituitary gland is the most important endocrine gland in most vertebrates. It controls and regulates other endocrine glands and thus called the "Master gland".
Hormones secreted by Adenohypophysis:
The anterior pituitary is made up of different types of cells which secrete hormones. These hormones, in turn, stimulates the production of hormones by other endocrine glands. The secretion of hormones from the anterior pituitary is regulated by hormones secreted by the hypothalamus called releasing hormones.
Structure of adenohypophysis - To stimulate this part, hypothalamus secretes separately and reaches
to the anterior part by hypophyseal portal system.
The hormones secreted by the anterior pituitary include:
1. Growth hormone (GH) or Somatotrophin
2. Thyroid-stimulating Hormone (TSH)
3. Adrenocorticotropic Hormone (ACTH)
4. Gonadotropic Hormone which constitutes Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)
5. Prolactin (PRL)
Most of the hormones secreted by adenohypophysis are trophic hormones - TSH, ACTH, FSH and LH.Dwarfism:
Chandra Bahadur Dangi - His height was 1ft 9.5inchGigantism:Acromegaly:
1. Growth hormone (GH):
GH promotes the development and enlargement of tissues present in the body. It stimulates the growth of muscles, long bones and cartilage. GH controls the cell metabolism and promotes the protein anabolism and conversion of glycogen to glucose. The improper secretion of the hormone leads to gigantism, dwarfism, and acromegaly.
It is caused due to growth hormone deficiency or decreased secretion of GH in children. The characteristic features of dwarfism include:
- Stunted growth
- Delayed skeletal formation
- Mental disability
Chandra Bahadur Dangi - His height was 1ft 9.5inch
Excessive secretion of growth hormones results in excessive growth and causes gigantism in children. The characteristic features of gigantism include:
- Overgrowth of all body tissues and organs.
- Individuals attain an abnormal increase in height.
Robert Wadlow - He stood 8ft tall
Acromegaly is derived from "Acro", which means "extremity", and "megaly" means large. Excessive secretion of growth hormone causes acromegaly in adults. This leads to abnormal enlargement of the head, face, hands and feet.
Sultan Kosen - He had been diagnosed with acromegaly
Other symptoms of acromegaly are follows:
Persons affected with acromegaly