gland
gland A group of cells with a communal secretory function. Exocrine glands incorporate a duct, or a system of ducts like tributaries leading to a river, which open onto an external or internal body surface. Some are simple or spiral pits(such as sweat glands in the skin or those which secrete acid and enzymes into the stomach) with a few secreting cells in their depths; others vary in size and complexity from the small salivary glands to the mammary glands (breasts). Endocrine glands by contrast are ductless, and secrete hormones directly into the bloodstream. The activity of all glands is regulated by chemical or nervous signals, or both. Molecules in the local environment, or brought by the blood, or released from nerve endings of the autonomic nervous system bind to cell membrane receptors, starting a sequence of signals within the cells which results in an increase (or decrease) in extrusion of their own particular secretion.
The nodular enlargements which can be felt under the skin in association with an infection (such as those in the neck with a sore throat) are commonly called swollen ‘lymph glands’, but they are not secretory and are more correctly called lymph nodes.
See adrenal glands; alimentary system; breasts; hormones; pancreas; parathyroid glands; pituitary gland; sweating; thyroid.
The nodular enlargements which can be felt under the skin in association with an infection (such as those in the neck with a sore throat) are commonly called swollen ‘lymph glands’, but they are not secretory and are more correctly called lymph nodes.
Stuart Judge
See adrenal glands; alimentary system; breasts; hormones; pancreas; parathyroid glands; pituitary gland; sweating; thyroid.
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gland