Endocrine system
Some notes adapted from The University of Maryland Medical
Centre: http://www.umm.edu
Pineal gland
• Effects on reproduction
• Shows some effect on sleep-wake cycles
Pituitary gland/master – controls
others
•
•
•
•
•
•
•
anterior lobe:
growth hormone
prolactin - to stimulate milk production after giving birth
ACTH (adrenocorticotropic hormone) - to stimulate the adrenal glands
TSH (thyroid-stimulating hormone) - to stimulate the thyroid gland
FSH (follicle-stimulating hormone) - to stimulate the ovaries and testes
LH (luteinizing hormone) - to stimulate the ovaries or testes
•
•
•
•
intermediate lobe:
melanocyte-stimulating hormone - to control skin pigmentation
posterior lobe:
ADH (antidiuretic hormone) - to increase absorption of water into the blood
by the kidneys
oxytocin - to contract the uterus during childbirth and stimulate milk production
•
Thyroid gland
• The thyroid plays an important role in regulating the
body's metabolism and calcium balance. The T4 and T3
hormones stimulate every tissue in the body to
produce proteins and increase the amount of oxygen
used by cells. The harder the cells work, the harder the
organs work. The calcitonin hormone works together
with the parathyroid hormone to regulate calcium
levels in the body.
• Levels of hormones secreted by the thyroid are
controlled by the pituitary gland's thyroid-stimulating
hormone, which in turn is controlled by the
hypothalamus.
Thymus
• Produces T-Lymphocyte cells that helps the
body to fight diseases
Adrenal gland
• Anatomy of the adrenal glands:
Adrenal glands, which are also called suprarenal glands, are small,
triangular glands located on top of both kidneys. An adrenal gland is
made of two parts: the outer region is called the adrenal cortex and
the inner region is called the adrenal medulla.
• Function of the adrenal glands:
The adrenal glands work interactively with the hypothalamus and
pituitary gland in the following process:
• the hypothalamus produces corticotropin-releasing hormones,
which stimulate the pituitary gland.
• the pituitary gland, in turn, produces corticotropin hormones,
which stimulate the adrenal glands to produce corticosteroid
hormones.
• Both parts of the adrenal glands -- the adrenal cortex and the
adrenal medulla -- perform very separate functions.
• The adrenal cortex, the outer portion of the adrenal gland, secretes
hormones that have an effect on the body's metabolism, on
chemicals in the blood, and on certain body characteristics. The
adrenal cortex secretes corticosteroids and other hormones directly
into the bloodstream. The hormones produced by the adrenal
cortex include:
• corticosteroid hormones
– hydrocortisone hormone - this hormone, also known as cortisol,
controls the body's use of fats, proteins, and carbohydrates.
– corticosterone - this hormone, together with hydrocortisone
hormones, suppresses inflammatory reactions in the body and also
affects the immune system.
• aldosterone hormone - this hormone inhibits the level of sodium
excreted into the urine, maintaining blood volume and blood
pressure.
• androgenic steroids (androgen hormones) - these hormones have
minimal effect on the development of male characteristics.
• The adrenal medulla, the inner part of the adrenal gland, is
not essential to life, but helps a person in coping with
physical and emotional stress. The adrenal medulla
secretes the following hormones:
• epinephrine (also called adrenaline) - this hormone
increases the heart rate and force of heart contractions,
facilitates blood flow to the muscles and brain, causes
relaxation of smooth muscles, helps with conversion of
glycogen to glucose in the liver, and other activities.
• norepinephrine (also called noradrenaline) - this hormone
has little effect on smooth muscle, metabolic processes,
and cardiac output, but has strong vasoconstrictive effects,
thus increasing blood pressure.
Pancreas
• The pancreas has digestive and hormonal functions:
• The enzymes secreted by the exocrine tissue in the
pancreas help break down carbohydrates, fats, proteins,
and acids in the duodenum. These enzymes travel down
the pancreatic duct into the bile duct in an inactive form.
When they enter the duodenum, they are activated. The
exocrine tissue also secretes a bicarbonate to neutralize
stomach acid in the duodenum (the first section of the
small intestine).
• The hormones secreted by the endocrine tissue in the
pancreas are insulin and glucagon (which regulate the level
of glucose in the blood) and somatostatin (which prevents
the release of the other two hormones).
Ovary and testis
• In addition to producing egg cells, the ovaries
produce estrogen and progesterone, which affect
many of the female characteristics and
reproductive functions. The levels of these
hormones secreted is controlled by gonadotropic
hormones produced by the pituitary gland. The
ovaries also contain the egg cells necessary for
reproduction.
• The testes in a man produce testosterone, which
affect many of the male characteristics and sperm
production.