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ENDOCRINE SYSTEM
Endocrine Glands
 A gland is any organ that produces a
secretion.
 Endocrine glands are groups of tissues which
produce hormones from materials already
present in the blood or lymph.
 Hormones act as chemical messengers. They
coordinate and direct activities of target cells
and organs throughout the body.
HORMONAL CONTROL
Occurs through Negative Feedback
 a drop in the level of a hormone
 triggers a chain reaction that causes an increase
hormones in the blood
This feedback mechanism continues until the
correct level of hormone is found present in the
blood.
PITUITARY GLAND
 Divided into anterior and posterior lobes
 Known as the master gland because of its
major influence in body’s activities
Anterior Pituitary Lobe
Growth Hormone (GH)
 Is responsible for growth and development of
bones and muscles.
 Also helps fat to be used for energy (this
preserves glucose levels)
Anterior Pituitary Lobe
Prolactin hormone (PRL)
 Develops breast tissue and stimulates the
production of milk after childbirth.
 The function in males is unknown.
Anterior Pituitary Lobe
Tropic Hormones
Thyroid stimulating hormone (TSH)
 Stimulates the growth and secretion of the
thyroid gland.
Adrenocorticotropic hormone (ACTH)
 Stimulates growth and secretion of the adrenal
gland.
Posterior Pituitary Lobe
 Stores 2 hormones produced by the
hypothalamus:
1. Oxytocin
 Released during childbirth.
 Causes strong contractions of the uterus.
2. Vasopressin
 Changes into antidiuretic hormone (ADH)
when it enters the bloodstream.
 Maintains a water balance by increasing the
amount of water that is absorbed by the
kidneys.
 Results in decreased urine output and
increased blood volume.
THYROID GLAND
 Secretes 3 hormones:
 Triiodothyronine (T3)
 Thyroxin (T4)
 Calcitonin
These hormones are produced when thyroid
stimulating hormone triggers the thyroid to
become active.
Triiodothyronine and Thyroxine
 The first 2 hormones require iodine to work
properly.
 The iodine for these hormones comes from the
diet it combines with the AA tyrosine to form T3
and T4
 T 3 and T4 control the rate of cellular metabolism
throughout the body.
Calcitonin
 Controls the calcium ion concentration in the
bloodstream.
 High levels of calcium ions in the blood stimulate
the release of calcitonin.
 Ca+ is then stored in bones and calcium
concentrations in the blood stream decreases.
PARATHYROID GLANDS
Secrete a hormone called
parathormone (PTH)
Parathormone
 Extracts Ca+ from bones to correct low
blood calcium levels.
 The hormone causes an increase in
number and size of osteoclasts (bonedemineralizing cells) which remove
calcium from bones.
THYMUS GLAND
 The thymus secretes a hormone called thymosin.
Thymosin
 Stimulates the lymphoid cells which are
responsible for the production of Tcells an
important part of the immune system.
Epinephrine (adrenalin)
Released in response to stress.
Increases the heart rate and helps the liver
release glucose for energy needs.
Considered the “fight or flight” hormone
GONADS – sex organs
Ovaries – the female sex organs.
Found at the end of each Fallopian tube;
produces:
 estrogen for female characteristics and
progesterone which prepares the uterus for
implantation.
Testes - male sex organ; found in the scrotum
sac; produces:
 Testosterone for male characteristics.
PANCREAS
 Pancreas as an endocrine gland produces:
1. insulin - a hormone that promotes the uptake of
glucose by cells
2. glucagon - a hormone that causes the liver to
breakdown stored glycogen and release it as
glucose into the bloodstream
PINEAL GLAND
 Produces the hormone melatonin
Melatonin
 Amount of light entering the eye affects the
amount of melatonin secreted
 The darker it is, the more melatonin produced.
The lighter it is, the less melatonin produced.
 Causes low body temperature & sleepiness.
ENDOCRINE GLAND
DISORDERS
DISORDERS OF THE ENDOCRINE
SYSTEM
 Endocrine gland disturbances may be caused
by:
 Disease
 Infection
 Hyperactivity
 Hypoactivity
PITUITARY DISORDERS
 Hyposecretion of growth hormone during
childhood will result in:
Pituitary Dwarfism = body proportions are normal,
but the person has max height of 4’.
2’ 5”
< 2’
PITUITARY DISORDERS
 Hypersecretion of growth hormone during
childhood, prior to the ossification of the
epiphyseal growth plates, will result in:
Gigantism = body proportions are normal, but
the person reaches a height of 8 to 9 feet.
8’ 1.5”
8’ 11.5”
PITUITARY DISORDERS
 Hypersecretion of GH after the long bones have
finished growing will result in:
Acromegaly = the facial bones (lower jaw and
ridge of brow), hands and feet enlarged
tremendously.
7’2”
7’7”
THYROID DISORDERS
 Hyposecretion of the thyroxine due to a lack of
iodine in diet.
 The thyroid works overtime to try to make T3
and T4 hormones. Results in:
Hypothyroidism = is evidenced by the presence
of a goiter.
THYROID DISORDERS
 Hypersecretion of thyroxine (usually results
from a tumor on the thyroid gland); results in:
Hyperthyroidism also known as Grave’s
disease.
Evidenced by rapid heartbeat, nervous or
agitated behavior, and bulging eyes.
Exopthalmos = bulging eyes
THYROID DISORDERS
 Hyposecretion of thyroxine during childhood.
Would be due to a lack TSH; results in:
Cretinism = a type of dwarfism where the
body retains childlike proportions (the upper
body is larger than the lower body). Often
results in mental retardation.
PARATHYROID DISORDERS
Hyposecretion of parathormone:
Low levels of calcium affects the nerves and cause
uncontrollable muscle spasms known as tetany.
Hypersecretion of parathormone:
 Calcium is taken from the bones in excess, weakening
the bones.
 Calcium is deposited in the kidneys resulting in
kidney stones
Kidney stones
in the kidney
in the ureter
PANCREATIC DISORDERS
 The decreased secretion of insulin or the
ineffective use of insulin by cells.
Diabetes mellitus = results in high blood glucose
levels.