Pituitary Gland: Major Organ Systems

¶ … Organ Systems: The Pituitary Gland

The pituitary gland, according to Davies (2007), "is a pea-sized endocrine gland at the base of the brain," linked to the hypothalamus by the infundibulum. It is divided into several parts; i.e. The anterior lobe (front part) and the posterior lobe (back part). The anterior lobe secretes seven hormones that are essentially responsible for the regulation of a number of activities that take place in the human body - from reproduction to growth. Of the seven, five are tropic hormones (induce other glands to secrete hormones). The pituitary gland secretes only two hormones. The targets and effects of the nine are presented in the table below.

The Anterior Pituitary

Tropic Hormones

Hormone

Target

Function

Adrenocorticotropic hormone (ACTH)

Adrenal glands

Involved in the stimulation of the cortex of the adrenal glands to secrete cortisol and aldosterone. Cortisol regulates blood pressure and blood sugar levels, as well as metabolism. It is an anti-inflammatory agent, helping the body in stress resistance, such as that resulting from fasting and bleeding. Aldosterone is the principal regulator of the water-salt balance in the body, although it also has some effect on the metabolism of proteins, carbohydrates and fats

Follicle-stimulating Hormone (FSH)

Ovaries in women; testes in men

Stimulation of the ovaries to develop, and produce the ovum; also stimulates the sex glands to secrete the hormones progesterone and estrogen, responsible for ovulation and the maintenance of pregnancy respectively.

In males, FSH stimulates cells in the testes to produce sperms

Growth Hormone (GH)

(Somatrophin)

Many different cells

Stimulates cell growth, and regulates the production, and release of the hormone somatomedin from the liver. In children, increase in height is the most significant effect of the growth hormone. The GH regulates the amount of fat and muscle, and helps in the healing of injuries through cell replacement

Luteinizing Hormone (LH)

Ovaries in women; testes in men

Causes the release of what later on becomes the ovum in females; in males, it is referred to as the interstitial cell-stimulating hormone and is responsible for the regulation of testosterone secretion

Thyroid-stimulating hormone (TSH)

Thyroid gland

Involved in the stimulation of the thyroid gland so as to produce the hormones triiodothyronine (T3) and thyroxin (T4), its very own hormones, responsible for controlling a number of bodily functions, including metabolism, temperature, and the heart rate

ii) Non-tropic hormones

Prolactin

breasts

Involved in the stimulation of breasts to develop, and produce milk; and is found in both pregnant and non-pregnant women

Melanocyte-stimulating hormone (MSH)

Brain and skin

Causes darkening of the skin if present in large amounts; also believed to have an influence on brain activity, though its actual role is still unclear

The Posterior Pituitary

Antidiuretic hormone (ADH) / vasopressin kidneys