Endocrine Glands

The endocrine system consists of glands that secrete hormones directly into the blood stream rather than through a duct (exocrine glands).

Pineal Gland – located in the vertebrate brain and has the shape of a tiny pine cone (hence its name).  Produces the hormone melatonin, a serotonin derivative, that affects the modulation of waking and sleeping patterns.  Serotonin is biochemically derived from tryptophan; contributes to feelings of well-being and happiness.

Pituitary Gland – located in at the bottom of the hypothalamus at the base of the brain.  Produces nine hormones that regulate homeostasis (internal environment of the body, like temperature or pH).

Thyroid Gland – located in the neck below the thyroid cartilage (‘Adam’s Apple’ area).  One of the largest endocrine glands.  Produces proteins and controls how the body uses energy and how sensitive the body should be to other hormones.  The thyroid gets its name from the Greek word for “shield” – from the shape of the cartilage.

Thymus Gland – located underneath the top of the breast bone.  It animals it is known as the sweetbreads.  The thymus process a type of white blood cell know as T-lymphocyte which govern cellular immunity (destroying bacteria, virus), abnormal cell growth like cancer.

Pancreas Gland (organ) – located in the digestive system near the bottom of the stomach.  It both a gland which produces hormones (insulin, glucagon, somatostatin) and an digestive organ which secretes pancreatic juice to assist in the absorption of nutrients in the small intestine.

Adrenal Gland – located at the top of the kidneys.  In humans, the right gland is triangular shape and the left gland is semilunar shaped.  Produce hormones in response to stress through the synthesis of corticosteroids such as cortisol and catecholamines such as epinephrine.  The adrenal glands affect kidney function through the secretion of aldosterone, a hormone that regulates the ‘strength’ of blood plasma.

Gonads – Gonads in males are the testes and for females they are the ovaries.  Produces gametes, spermatozoon (sperm) or egg cells.