a physical feeling of intense excitement and
stimulation caused by the release of adrenaline
from the adrenal glands.
The endocrine system is made up of glands and the
hormones they secrete.
The function of the endocrine system is the production
and regulation of chemical substances called hormones.
A gland is an organ whose cells
secrete materials to be brought
to the different regions of the
body.
The primary endocrine glands
are the:
q pituitary (the master gland)
q pineal, thyroid
q parathyroid
q islets of Langerhans
q adrenals
q ovaries in the female
q testes in the male.
A hormone is a chemical transmitter.
It is released in small amounts from
glands and is transported in the
bloodstream to target organs or
other cells.
Hormones are chemical messengers,
transferring information and
instructions from one set of cells to
another.
Hormones regulate growth, development, mood,
tissue function, metabolism, and sexual function.
Hyposecretion (too little) or hypersecretion (too much)
of any hormone can be harmful to the body. Controlling
the production of hormones can treat many hormonal
disorders in the body.
The endocrine system and nervous system work
together to help maintain homeostasis… balance.
Hypothalamus produces chemicals that either stimulate
or suppress hormone secretions of the pituitary gland.
Pea-sized gland
Produces hormones that
stimulate growth, and
controls the functions of
other glands
Also secretes
endorphins, the
hormones responsible
for reducing feelings of
pain
Pituitary Gland has two
lobes:
• Anterior (front) lobe
• Posterior (rear) lobe
1. Growth Hormone (GH):
Stimulates the growth of bones
and tissues
also enhances protein synthesis,
decreases the use of glucose,
and promotes fat destruction.
2. Adrenocorticotropin (TRŌ pun)
(ACTH):
essential for the growth of the
adrenal cortex; stimulates the
adrenal glands to produce
related steroid hormones
3. Thyroid-Stimulating Hormone
(TSH):
Stimulates the thyroid gland
to produce thyroid hormone
Gonadotrophic Hormones:
stimulate the gonads (ovaries and testes). They
are not necessary for life but are essential for
reproduction.
4. Follicle-Stimulating Hormone
(SH) & Luteinizing Hormone (LH)
Controls sexual function and
production of the sex hormones:
estrogen and progesterone in females,
or testosterone in males
6. Prolactin (PRL):
stimulates the development
and growth of the mammary
glands and milk production
during pregnancy.
The sucking motion of the
baby stimulates prolactin
secretion.
7. Melanocyte-stimulating
hormone (MSH):
regulates skin pigmentation
and promotes the deposit of
melanin in the skin after
exposure to sunlight
Antidiuretic Hormone (ADH):
stimulates the reabsorption
of water by the renal tubules.
Controls water loss in the
kidneys.
Oxytocin:
stimulates the uterus to
contract during childbirth.
A synthetic version of this
hormone, used to induce labor,
is called Pitocin. It also
stimulates the mammary
glands to release milk.
Located just under the larynx or
voice box.
Secretes three hormones:
q Triiodothyronine (T3)
q Thyroxine (T4)
q Calcitonin
Thyroid hormones help maintain heart rate, blood pressure,
muscle tone, and reproductive functions.
Thyroxine (T4) and triiodothyronine
(T3):
ü both contains iodine
ü essential to metabolism (how
quickly food is burned up in the
body);
ü influences development and
maturation
Hypersecretion of T3 and T4 = hyperthyroidism (which
can develop high blood pressure, feel irritable, sweat
profusely, and lose weight)
Hyposecretion T3 and T4 = hypothyroidism (which
causes weight gain, lethargy, and intolerance to cold)
Severe iodine deficiency = goiter in adults
Calcitonin: lowers the blood
calcium level in the body
The two pairs of parathyroid glands
are located on the dorsal or back side
of the thyroid gland.
They secrete parathyroid (PTH) which,
which along with Calcitonin, regulates
blood calcium levels in the body in an
antagonistic manner.
Calcitonin and PTH are referred to
as antagonistic hormones, as their
actions are diametrically opposite.
While calcitonin is secreted when
blood calcium level is extremely
high, PTH is secreted when the
blood calcium level is too low.
Both these hormones are known
to regulate the Ca++ levels in
blood.
The thymus is found behind the
breastbone.
The thymus gland has two lobes,
and is part of the lymphatic
system. It is a ductless gland,
and secretes thymosin. This is
necessary for the Thymus’ normal
production of T cells for the
immune system.
The triangular-shaped adrenal
glands are located on the top of
each kidney. The inside is called
the medulla and the outside
layer is called the cortex.
Cortisol: regulates carbohydrate,
protein, and fat metabolism; has an
anti-inflammatory effect; helps the
body cope during times of stress
Hyposecretion results in Addison’s
disease; hypersecretion results in
Cushing’s disease
Adrenaline/Epinephrine: plays an
important role in the body’s coping
mechanism against short-term
physical and emotional stress
The pancreas is part of the
digestive system, and also
an endocrine organ.
Produces two types of
hormones:
q Insulin
q Glucagon
The pancreas is part of the
digestive system, and also
an endocrine organ.
Produces two types of
hormones:
q Insulin
q Glucagon
The human reproductive organs
are collectively called gonads.
Females: ovaries
Males: Testes
The testes produce androgens, of
which the most important is the
male sex hormone called
testosterone. The male hormones
induce the development of facial
hair, body mass, deep voice, and
the production of sperm.
The ovaries produce several estrogen
hormones and progesterone. These
hormones prepare the uterus for
pregnancy, promote the development
of mammary glands, play a role in sex
drive, and develop secondary sex
characteristics in the female.
Estrogen is essential for the growth,
development, and maintenance of
female sex organs.
During pregnancy, the placenta
serves as an endocrine gland.
It produces chorionic
gonadotropin hormone,
estrogen, and progesterone.
The pineal gland is pine-cone-shaped and only about 1 cm in
diameter.
Melatonin:
ü regulates body rhythms and
sleep patterns
ü helps the body adapt to
seasonal changes
Jet lag – the condition resulting
to travelling across
multiple time zones
The mucosa of the pyloric
area of the stomach secretes
the hormone gastrin, which
stimulates the production of
gastric acid for digestion.
