What is an endocrine gland?
• Secretary structure
• Secretes hormone into interstitial fluid, then
blood
• Secretion rates are extremely low
• All are highly vascularized
What is a hormone?
• It is a chemical substance produced in the body that
encourages growth or influences how the cells and
tissues function.
• Small molecule, protein, glycoprotein or lipid
• Released into blood
• Binds to specific receptors
Hormone Secretion
Stimulus (another hormone, changes in blood chemistry or nerve stimuli)
Endocrine Gland
----------------Hormone
Hormone secretion
Blood
Binds to Receptor------------
Target
cell
Action
Pituitary Gland
• Also called hypophysis, weighs 0.5 grams with dimension of
10 x 13 x 6 mm
• Lies within the cavity of sella-turcica and hangs inferior to
hypothalamus.
-Releases 9 important peptide hormones
• Hormones bind to membrane receptors
• During embryogenesis hypophysis develops partly from oral
tissue and partly from nerve tissue
• The hypophysis actually consists of two glands:
- neurohypophysis (neural origin) and adenohypophysis
Figure 18–6
(oral origin)
Hypothalamus/pituitary gland
Hormones secreted by anterior pituitary gland
• Human growth hormone (somatotrophs)
which promotes growth
• Thyroid-stimulating hormone (thyrotrophs)
which regulates the endocrine function of the thyroid gland
• Follicle-stimulating hormone; luteinizing hormone
They act synergistically in reproduction
• Prolactin (lactotrophs). It stimulates the mammary glands to
produce milk (lactation)
• ACTH (adrenocorticotropic hormone). It effects are increased
production and release of corticosteroids and cortisol from the
adrenal cortex.
• MSH (melanocyte-stimulating hormone). They stimulate the
production and release of melanin
Neurohypophysis (= posterior pituary)
 This neurosecretory material consists of two hormones made up of cyclic peptides.
They are Antidiuretic hormone (ADH) and Oxytoxin.
• ADH is released in response to increased tonicity in blood due to lose of
water or increased salt absorption.
• Thus it regulate osmotic balance of the blood
Oxytocin


stimulate contraction of ducts and alveoli of mammary gland during nursing.
stimulates the contraction of smooth muscles of the uterus during copulation
and delivery..
Posterior pituitary
Pineal Gland
• It is a conical organ weighing about 120 mg that lies in posterior
portion of roof of third ventricle (diencephalons)
• Contains mostly pinealocytes and astrocytes:
– synthesize hormone melatonin composed of peptides
• The hormone involves in the inhibition of reproductive
functions.
• Protecting against damage by free radicals
• Setting circadian rhythms (biorhythms) associated with cyclic
environment and body.
Pancreas
 Alpha Cells = The alpha cells secrete glucagon
 Beta Cells = secrete insulin and amylin which functions
as synergistic partner to insulin
 Gamma Cells = secrete a polypeptide which reduces
appetite
 Delta Cells = secrete somatostatin / they work to
reduce the rate at which food is absorbed from the
contents of the intestine.
Adrenal Glands
• Each adrenal gland is separated into two distinct structures, the
adrenal cortex and medulla, both of which produce hormones.
• The cortex mainly produces cortisol, aldosterone, and androgens,
while the medulla chiefly produces epinephrine and norepinephrine.
• 1)Cortisol = It increases blood pressure and blood sugar, and reduces
immune responses.
• 2)Aldosterone = increases the reabsorption of sodium and water and
the release (secretion) of potassium in the kidneys.
• 3)Androgen = stimulates or controls the development and
maintenance of male characteristics in vertebrates by binding to
androgen receptors.
• 4)Epinephrine&Norepinephrine = When produced in the body it
increases heart rate, contracts blood vessels and dilates air passages
and participates in the "fight or flight" / norepinephrine has basically
same as epinephrine, but it acts more locally.
Common endocrine disorders
Diabetes
 Currently, there are approximately 23 million Americans with
diabetes and an additional 57 million Americans have prediabetes.
 Recent studies have found that controlling blood sugar helps
prevent serious problems that can be caused by diabetes. These
can include problems with the eyes, kidneys and nerves, which
can lead to blindness, dialysis, or amputation.
 Endocrinologists treat diabetes with diet and medications,
including insulin. They also work closely with patients to control
blood sugar and monitor them so they can prevent health
problems.
Thyroids
 estimated that up to 10% of Americans have some sort of thyroid
disease. Patients with thyroid disorders often have problems with their
energy levels.
 Hyper thyroid- over production of thyroids hormone.
 Hypo thyroid – underproduction of thyroids hormone.
 Almost half of the population will have tiny thyroid nodules at some point in
their lives but, typically, these are not noticeable until they become large
and affect normal thyroid size. Significant sized nodules, greater than a half
inch across (about 1 centimeter), occur in about 5 percent of people.
 More than 90 percent of all thyroid nodules are not harmful or
cancerous. In fact, thyroid cancer is found in only 8% of men and 4% of
women.
Bone
 Osteomalacia (rickets), which causes bones to
soften, and osteoporosis are bone diseases that
endocrinologists diagnose and treat. Osteoporosis is
a disease that weakens your skeleton.
 Endocrinologists treat other disorders that can
affect bones, such as too much parathyroid
hormone and long term use of steroids like
prednisone.
Obesity and Overweight
 According to the Centers for Disease Control and Prevention,
an estimated 65% of U.S. adults aged 20 years and older are
either overweight (defined as having a body mass index
(BMI) of 25 or higher) or obese (defined as BMI of 30 or
higher).
 Endocrinologists treat patients who are overweight or
obese, sometimes because of metabolic and hormonal
problems. When someone is obese they have too much
body fat. Thyroid, adrenal, ovarian, and pituitary disorders
can cause obesity.
 Endocrinologists also identify factors linked with obesity,
such as insulin resistance and genetic problems.
Pituitary Gland
 The pituitary is often called the master gland of the body because it
controls other glands. The pituitary makes several important hormones.
 Over or under production of pituitary hormones can lead to infertility,
menstrual disorders, growth disorders (acromegaly or short stature) and
too much cortisol production (Cushing's syndrome). Endocrinologists
control these conditions with medications and refer patients who need
surgery.
Growth
 Adults with growth hormone deficiency can experience emotional distress
and fatigue. Safe and effective growth hormone replacement therapy is
available for people whose growth hormone is abnormal.
Hypertension
 Hypertension is high blood pressure, and it is a risk factor
for heart disease.
 Up to 10% of people have hypertension because of too
much aldosterone, a hormone produced in the adrenal
glands. About half of these cases are caused by growths
that can be removed with surgery.
 Conditions such as the metabolic syndrome or a rare
adrenal growth called a pheochromocytoma also may cause
hypertension. These conditions also can be treated
successfully.