ENDOCRINE
SYSTEM
The endocrine system produces hormones
that function to control and regulate many
different body processes. The endocrine
system coordinates with the nervous
system to control the functions of the other
organ systems. Cells of the endocrine
system produce molecular signals called
hormones.
Hormones are released
into body fluids, usually
blood, which carries them
to their target cells where
they elicit a response.
The cells that secrete hormones
are often located in specific organs,
called endocrine glands, and the
cells, tissues, and organs that
secrete hormones make up the
endocrine system.
Examples of endocrine organs include the
pancreas, which produces the hormones insulin and
glucagon to regulate blood-glucose levels, the
adrenal glands, which produce hormones such as
epinephrine and norepinephrine that regulate
responses to stress, and the thyroid gland, which
produces thyroid hormones that regulate metabolic
rates.
The endocrine glands secrete hormones
into the surrounding interstitial fluid; those
hormones then diffuse into blood and are
carried to various organs and tissues
within the body. The endocrine glands
include the pituitary, thyroid, parathyroid,
adrenal glands, gonads, pineal, and
pancreas.
The pituitary gland, sometimes
called the hypophysis, is located at
the base of the brain.
It is attached to the hypothalamus.
(a) The pituitary gland sits at the base of the brain, just
above the brain stem. (b) The parathyroid glands are
located on the posterior of the thy- roid gland. (c) The
adrenal glands are on top of the kidneys. d) The pancreas
is found between the stomach and the small intestine.
(credit: modification of work by NCI, NIH)
The thyroid gland is located in the
neck, just be- low the larynx and in
front of the trachea. It is a butterfly
shaped gland with two lobes that are
connected. The thyroid follicle cells
synthesize the hormone thyroxine.
Aims for regulation of your
weight, energy levels, internal
temperature, skin, hair, nail growth,
metabolism and is an important
part of the endocrine system.
The parathyroid glands located on the
posterior surface of the thyroid gland and it
produces parathyroid hormone. Parathyroid
hormone increases blood calcium
concentrations when calcium ion levels fall
below normal.
The adrenal glands are located
on top of each kidney. It produces
aldosterone, which regulates the
concentration of ions in urine, sweat,
and saliva.
The pancreas is an elongate organ
located between the stomach and the
proximal portion of the small intestine. It
contains both exocrine cells that excrete
digestive enzymes and endocrine cells
that release hormones.
The thymus is found behind the
sternum. The thymus produces hormones
referred to as thymosins, which contribute
to the development of the immune
response in infants. Adipose tissue, or fat
tissue, produces the hormone leptin in
response to food intake.
Endocrine Associated
Functions
glands hormones
Growth hormone promotes growth of body tissues
Prolactin promotes milk production
Thyroid-stimulating
stimulates thyroid hormone release
hormone
Pituitary Adrenocorticotropic
(anterior) hormone stimulates hormone release by adrenał cortex
Follicle-stimulating
Hormone stimulates gamete production
Luteinizing stimulates androgen production by gonads in males;
Hormone stimulates ovulaüon and production of estrogen arid
progesterone in females
Triiodothyronine
stimulate metabolism
Thyroid
Calcitonin reduces blood Ca2 levels
Parathyroid
Parathyroid Hormone increases blood Ca2 levels
Aldosterone increases blood hla” levels
Adrenal Cortisol.
(cortex)
Corticosterone, increase blood-gluœse levels
cortisone
Adrenal Epinephrine,
(medulla) norepinephdne stimulate fight-or-light response
Insulin reduœs blood-glucose levels
Pancreas Glucagon
