The Endocrine System

• Controls many body • Derives its name from

functions the fact that various
– exerts control by glands release
releasing special hormones directly into
chemical substances into the blood, which in turn
the blood called
hormones
transports the
– Hormones affect other hormones to target
endocrine glands or body tissues via ducts.
systems
 The Endocrine System

• Exocrine glands - • Endocrine

transport their Emergencies:
hormones to target – from common:
tissues via ducts. • Diabetes
• to the unusual:
– Thyrotoxicosis
 The Endocrine System
• Pituitary gland: a small
gland located on a stalk
• Consists of several hanging from the base of the
brain - AKA
glands located in
various parts of the • “The Master Gland”
body.
– Primary function is to
control other glands.
– Produces many
hormones.
– Secretion is controlled by
the hypothalamus in the
base of the brain.
 The Endocrine System
• The two segments are:
• The Pituitary Gland is – Posterior Pituitary:
divided into 2 areas, • produces oxytocin and
antidiuretic hormone
which differ (ADH)
– structurally and – Anterior Pituitary:
functionally • produces thyroid-
stimulating hormone
– each area has (TSH)
separate types of • growth hormone (GH)
hormone production. • adrenocorticotropin
(ACTH)
• follicle-stimulating
hormone (FSH)
 The Endocrine System

• And even more… • Posterior Pituitary

– Oxytocin (the natural
– luteinizing hormone
form of pitocin)
(LH) • stimulates gravid
– prolactin uterus
• causes “let down” of
milk from the breast.
• Let’s go over these – ADH (vasopressin)
one at a time... causes the kidney to
retain water.
 The Endocrine System
• Anterior Pituitary • Anterior Pituitary…
– Primarily regulates – Growth hormone (GH)
other endocrine  glucose usage
glands  consumption of
– rarely a factor in fats as an energy
endocrinological source
emergencies – ACTH stimulates the
– TSH stimulates the adrenal cortex to
thyroid gland to release its hormones
release its hormones, – FSH & LH stimulates
thus  metabolic rate maturation & release of
eggs from ovary.
 The Endocrine System
• The Thyroid Gland • Within the colloid are the
thyroid hormones:
– lies in the anterior
– thyroxine (T4)
neck just below the
– triiodothyronine (T3)
larynyx.
• When stimulated (by
– Two lobes, located on
TSH or by cold),
either side of the
these are released
trachea, connected by into the circulatory
a narrow band of system and  the
tissue called the metabolic rate.
isthmus. – “C” cells within the
– Sacs inside the gland thyroid produce the
contain colloid hormone calcitonin.
 The Endocrine System

• Calcitonin, when • Myxedema symptoms:

released, lowers the – Facial bloating
amount of calcium in – weakness
the blood. – cold intolerance
– lethargy
• Inadequate levels of
– altered mental
thyroid hormones =
status
hypothyroidism, or – oily skin and hair
Myxedema. – TX: replacement of
thyroid hormone.
 The Endocrine System
• Increased thyroid – Long term
hormone release causes hyperthyroidism:
hyperthyroidism, • Exopthalmos
commonly called
– bulging of the
Graves’ disease.
eyeballs (picture
– Signs and symptoms:
Barbara Bush)
• insomnia, fatigue
• In severe cases - a
• tachycardia medical emergency
• hypertension called thyrotoxicosis
• heat intolerance can result.
• weight loss
 The Endocrine System

• Parathyroid Glands – produce parathyroid

– small, pea-shaped hormone -  level of
glands, located in the calcium in blood
neck near the thyroid
– usually 4 - number can – Hypocalcemia can
vary result if parathyroids
– regulate the level of are removed or
calcium in the body destroyed.
 The Endocrine System
• Pancreas • Islets of Langerhans
– a key gland located in – specialized tissues in
the folds of the which the endocrine
functions of the pancreas
duodenum
occurs
– has both endocrine and
– include 3 types of cells:
exocrine functions • alpha ( )
– secretes several key • beta ()
digestive enzymes • delta ()
– each secretes an
important hormone.
 The Endocrine System

• Alpha () cells • The surge of glucagon

release glucagon, stimulates the liver to
essential for release glucose stores
controlling blood (from glycogen and
glucose levels. additional storage sites).
• When blood glucose • Also, glucagon
levels fall,  cells  stimulates the liver to
manufacture glucose -
the amount of
glucagon in the blood . • gluconeogenesis.
 The Endocrine System
• Beta Cells () release • Insulin is rapidly
insulin (antagonistic to broken down by the
glucagon). liver and must be
• Insulin  the rate at secreted constantly.
which various body • Delta Cells ()
cells take up glucose. produce somatostatin,
Thus, insulin lowers which inhibits both
the blood glucose glucagon and insulin.
level.
 The Endocrine System

• Adrenal Glands • the Adrenal Medulla

– 2 small glands that sit secretes the
atop both kidneys. catecholamine
hormones
– Each has 2 divisions, norepinephrine and
each with different epinephrine (closely
functions. related to the
sympathetic component
of the autonomic
nervous system).
 The Endocrine System
• One at a time…
• The Adrenal Cortex – gluticocorticoids:
secretes 3 classes of – accounts for 95% of
hormones, all steroid adrenal cortex hormone
production
hormones:
  the level of glucose in
– gluticocorticoids the blood
mineralocorticoids – Released in response to
– androgenic hormones stress, injury, or serious
infection - like the
hormones from the
adrenal medulla.
 The Endocrine System

• Mineralocorticoids: • Signs & Symptoms of

– work to regulate the Cushing’s Disease:
concentration of   in blood sugar levels
potassium and sodium – unusual body fat
in the body. distribution
• Prolonged  in – rapid mood swings
adrenal cortex
hormone results in
Cushing’s Disease.
 The Endocrine System

• Sodium can also be

• And - if there is an 
retained by the kidney,
in mineralocorticoids
resulting in
as well hyponatremia.
– A serious electolyte – Causes:
imbalance will occur • dysrhythmias
due to the  potassium • coma
excretion by the • death
kidney, which results – usually results from a
in hypokalemia. tumor - TX? Removal of
tumor.
 The Endocrine System

• Gonads and Ovaries: • Ovaries:

– the endocrine glands – located in the
associated with human abdominal cavity
reproduction. adjacent to the uterus.
– Female ovaries produce – Under the control of
eggs LH and FSH from the
– Male gonads produce anterior pituitary they
sperm manufacture
• both have endocrine • estrogen
functions. • protesterone
 The Endocrine System

• Estrogen and • Testes:

Progesterone have – located in the scrotum
several functions, – produce sperm for
reproduction
including sexual
– manufacture testosterone
development and -
preparation of the • promotes male growth
uterus for implantation and masculinization

of the egg. – Controlled by anterior

pituitary hormones FSH
and LH.
 The Endocrine System

• Endocrine Emergencies: • Complications of

• Diabetes Mellitus Diabetes:
– one of the most common – contributes to heart
diseases in North disease
America. – stroke
  insulin secretion by – kidney disease
the Beta () cells of the
– blindness
islets of Langerhans in
the pancreas.
 The Endocrine System

• Pathophysiology of • The other 2 major food

Diabetes: sources are
• Glucose Metabolism – proteins
– Glucose (dextrose) is a – fats
simple sugar required by • Most sugars in the
the body to produce human diet are complex
energy.
and must be broken
– Sugars, or carbohydrates, down into simple sugars:
are 1 of 3 major food
glucose, galactose and
sources used by the body.
fructose - before use.
 The Endocrine System

• Breakdown of sugars • To be converted into

is carried out by energy, glucose must
enzymes in the gastro first be transmitted
intestinal system. through the cell
– As simple sugars, these membrane. BUT - the
are absorbed from the glucose molecule is
GE system into the large and doesn’t
body.
readily diffuse through
– More than 95% enter
the cell membrane.
the body as glucose.
 The Endocrine System

• Glucose must pass into • The rate at which

the cell by binding to a glucose can enter the cell
special carrier protein is dependent upon insulin
on the cell’s surface. levels.
– Facilitated diffusion - – Insulin serves as the
doesn’t use energy. The messenger - travels via
carrier protein binds blood to target tissues.
with the glucose and – Combines with specific
carries it into the cell. insulin receptors on the
surface of the cell
membrane.