Many hormones are short peptide sequences or small proteins.
Pituitary hormones control many other endocrine organs.
Hormones of the adrenal medulla stimulate a "fight or flight"
response.
Thyroid and parathyroid hormones regulate
metabolic rate and calcium.
The pancreas produces hormones that regulate glucose metabolism.
Other digestive organs produce hormones that regulate
digestive functions.
Anterior pituitary gland: Derived from tissue that detaches from the
roof of the mouth and lodges at the base of the brain. Many of the hormones
produced here are called trophic hormones because they stimulate other
glands to release their hormones.
- Follicle-Stimulating Hormone (FSH): Stimulates growth and maturation
of the gonads in both sexes, including secretion of their hormones.
- Luteinizing hormone (LH): Stimulates ovulation in females.
- Luteotrophic hormone (LTH): Stimulates secretion of progesterone.
- Adrenal CorticoTrophic Hormone (ACTH): Stimulates adrenal cortex
to produce its hormones.
- ThyroTrophic Hormone (TTH): Stimulates the thyroid gland to produce thyroxin.
- Growth Hormone (GH, somatostatin): Stimulates growth.
- Melanocyte-Stimulating Hormone (MSH): Stimulates pigment cells.
Posterior pituitary hormones:
- Vasopressin (Anti-Diuretic Hormone, ADH): Stimulates urinary
retention of water and concentration of urine; lack of hormone causes
excessive levels of urination, thirst, and drinking.
- Oxytocin: Stimulates uterine contractions in childbirth, also
milk production.
Pineal gland: Secretes melatonin during darkness, which
regulates circadian rhythms and clues the body to day length and
seasonal changes.
Adrenal medullary hormones: The medulla of the adrenal gland secretes
epinephrine ("adrenalin") and norepinephrine. These hormones
are also neurotransmitters. They stimulate a more rapid heartbeat and
breathing, more blood flow to muscles (and less to the digestive tract),
lowering of nerve thresholds (so nerves fire more easily), and shortening
of blood clotting time. Overall, they prepare the body to "fight or flee."
Thyroid and parathyroid hormones:
- Thyroxin (produced by thyroid gland):
An iodine-containing hormone that increases metabolic rate.
- Calcitonin (produced by thyroid gland):
Stimulates bone deposition by depletion of calcium from the blood.
- Parathyroid hormone: Stimulates release of calcium from
bones, raising blood calcium levels.
Gastrointestinal hormones:
- Gastrin: Stimulates gastric secretion.
- Enterogastrone: Delays emptying of stomach contents.
- Secretin: Stimulates pancreas and liver secretions.
- Pancreozymin: Stimulates more concentrated pancreatic secretions.
- Cholecystikinin: Stimulates gall bladder to release bile into intestines.
Pancreatic hormones (produced by islets of Langerhans):
- Insulin: Aids in glucose metabolism and glycogen breakdown;
deficiency produces diabetes mellitus.
- Glucagon: Opposite in effect to insulin, stimulates
glycogen storage and depletion of glucose from blood.
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