Endocrine System

Endocrine System
Endocrine System is a set of glands (secreting hormones directly into blood) working together to coordinate body functions.

Hypothalamus
The hypothalamus is at the base of the brain, just above the pituitary gland. It releases hormones that actually control the release of other hormones from the pituitary gland. These can include growth hormones and follicle-stimulating hormones (for hair growth at puberty).

Pituitary Gland
The pituitary gland is located at the base of the brain. It is sometimes called the 'master gland' because its hormones affect the many body's organs.

The pituitary is divided into two part, front (anterior) and back (posterior).

Anterior Pituitary Hormones

 * Prolactin: stimulates milk production after childbirth.
 * Growth hormone: promotes growth in children; in adults used to maintain muscle and bone mass.
 * Adrenocorticotropin: controls productions of cortisol by the adrenal glands. Cortisol helps maintain blood pressure and blood glucose levels.
 * Thyroid-stimulating hormone: controls the production of thyroid hormones by the thyroid.
 * Luteinizing hormone or LH: this hormone controls testosterone levels in men and estrogens levels in women.
 * Follicle-stimulating hormone or FSH: this causes sperm production in men and makes the ovaries release eggs in women

Posterior Pituitary Hormones

 * Oxytocin: causes milk production in nursing mothers and contractions during childbirth.
 * Antidiuretic: regulates the body's water balance. If this hormone malfunctions, it can lead to problems with sodium build-up and adversely affect the kidneys.

Thyroid
Regulates the body's metabolism, growth and development, and nervous system.

Parathyroid
The gland behind the thyroid gland which is responsible for calcium regulation as well as secreting a hormone that involves in increasing blood calcium levels and decreasing blood phosphate levels.

Pancreas
The pancreas makes insulin so that the body can use glucose. It also makes enzymes that help the body digest food. The pancreas has cells that make glucagon, which raises the level of glucose in the blood; and other cells that make insulin, which allows glucose to enter the cells.

Insulin converts starch into glucose while glucagon converts glucose back into starch.

Adrenal Gland

 * The small gland that produces steroid hormones, adrenaline and noradrenaline.
 * Adrenaline is useful for readiness of body for flight - flight response.
 * Noradrenaline helps blood vessel constrict.
 * Constriction of blood vessel causes blood to travel faster causing an 'adrenalin rush'
 * Adrenal Cortex - Cortisone functions to form and store glycogen
 * Adrenal Cortex - Cortiocosterone functions to maintain blood sugar and stimulate the conversion of protein to carbohydrates.
 * Adrenal Cortex - Aldosterone functions to regulate sodium and potassium metabolism

Ovaries

 * Produces the female hormones oestrogen and progesterone that affect the menstrual cycle.
 * Oestrogen is important for the maintenance of normal brain function and development of nerve cells.
 * Progesterone induces changes in the lining of the uterus essential for successful implantation of a fertilized egg.
 * The ovaries produce the female reproductive cells (eggs).

Testicles

 * Testicles produce the male hormone testosterone and to a lesser extent oestrogen (for the maintenance of normal brain function and development of nerve cells).
 * The testicles produce the male reproductive cells (sperm).

Hormones
Hormones are chemical substances produced by living organism which controls the rate of biochemical processes. Hormones are transported from point to point within the organism and thus effect action at a distance from the region in which they are made.

Insulin and glucagon are the chief hormones that control carbohydrates metabolism. Insulin is a powerful hypoglycaemic agent, whereas glucagon, its counterpart, is a hyperglycaemic agent.

In the liver, glycogen is easily broken down to glucose (glycogenolysis).

Glycogen is broken down into pyruvic acid or lactic acid in anaerobic condition in the muscle tissue, which are then converted to glucose in the liver.