The endocrine system is responsible for regulating many body functions through the release of hormones into the bloodstream, originating from various glands including the pituitary, thyroid, parathyroid, pancreas, adrenal glands, and gonads. Key hormones control metabolism, growth, and reproductive functions, while endocrine emergencies such as diabetes and thyrotoxicosis highlight critical health concerns. The document outlines the structure and function of these glands, their associated hormones, and common endocrine disorders.

1. Endocrine system
summary
Ronald Kiiza

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

4. The Endocrine System
• Exocrine glands -
transport their
hormones to target
tissues via ducts.
• Endocrine
Emergencies:
– from common:
• Diabetes
• to the unusual:
– Thyrotoxicosis

5. The Endocrine System
• Consists of several
glands located in
various parts of the
body.
• Pituitary gland: a small
gland located on a stalk
hanging from the base of the
brain
• “The Master Gland”
– Primary function is to
control other glands.
– Produces many
hormones.
– Secretion is controlled by
the hypothalamus in the
base of the brain.

6. The Endocrine System
• The Pituitary Gland is
divided into 2 areas,
which differ
– structurally and
functionally
– each area has
separate types of
hormone production.
• The two segments are:
– Posterior Pituitary:
• produces oxytocin and
antidiuretic hormone
(ADH)
– Anterior Pituitary:
• produces thyroid-
stimulating hormone
(TSH)
• growth hormone (GH)
• adrenocorticotropin
(ACTH)
• follicle-stimulating
hormone (FSH)

7. The Endocrine System
– luteinizing hormone
(LH)
– prolactin
• Posterior Pituitary
– Oxytocin (the natural
form of pitocin)
• stimulates gravid
uterus
• causes “let down” of
milk from the
breast.
– ADH (vasopressin)
causes the kidney to
retain water.

8. The Endocrine System
• Anterior Pituitary
– Primarily regulates
other endocrine
glands
– rarely a factor in
endocrinological
emergencies
– TSH stimulates the
thyroid gland to
release its hormones,
thus  metabolic rate
• Anterior Pituitary…
– Growth hormone (GH)
 glucose usage
 consumption of
fats as an energy
source
– ACTH stimulates the
adrenal cortex to
release its hormones
– FSH & LH stimulates
maturation & release of
eggs from ovary.

9. The Endocrine System
• The Thyroid Gland
– lies in the anterior
neck just below the
larynyx.
– Two lobes, located on
either side of the
trachea, connected by
a narrow band of
tissue called the
isthmus.
– Sacs inside the gland
contain colloid
• Within the colloid are the
thyroid hormones:
– thyroxine (T4)
– triiodothyronine (T3)
• When stimulated (by
TSH or by cold),
these are released
into the circulatory
system and  the
metabolic rate.
– “C” cells within the
thyroid produce the
hormone calcitonin.

10. The Endocrine System
• Calcitonin, when
released, lowers the
amount of calcium in
the blood.
• Inadequate levels of
thyroid hormones =
hypothyroidism, or
Myxedema.
• Myxedema symptoms:
– Facial bloating
– weakness
– cold intolerance
– lethargy
– altered mental
status
– oily skin and hair
– TX: replacement of
thyroid hormone.

11. The Endocrine System
• Increased thyroid
hormone release causes
hyperthyroidism,
commonly called
Graves’ disease.
– Signs and symptoms:
• insomnia, fatigue
• tachycardia
• hypertension
• heat intolerance
• weight loss
– Long term
hyperthyroidism:
• Exopthalmos
– bulging of the
eyeballs (picture
Barbara Bush)
• In severe cases - a
medical emergency
called thyrotoxicosis
can result.

12. The Endocrine System
• Parathyroid Glands
– small, pea-shaped
glands, located in the
neck near the thyroid
– usually 4 - number can
vary
– regulate the level of
calcium in the body
– produce parathyroid
hormone -  level of
calcium in blood
– Hypocalcemia can
result if parathyroids
are removed or
destroyed.

13. The Endocrine System
• Pancreas
– a key gland located in
the folds of the
duodenum
– has both endocrine and
exocrine functions
– secretes several key
digestive enzymes
• Islets of Langerhans
– specialized tissues in
which the endocrine
functions of the pancreas
occurs
– include 3 types of cells:
• alpha ( )
• beta ()
• delta ()
– each secretes an
important hormone.

14. The Endocrine System
• Alpha () cells
release glucagon,
essential for
controlling blood
glucose levels.
• When blood glucose
levels fall,  cells 
the amount of
glucagon in the blood .
• The surge of glucagon
stimulates the liver to
release glucose stores
(from glycogen and
additional storage sites).
• Also, glucagon
stimulates the liver to
manufacture glucose -
• gluconeogenesis.

15. The Endocrine System
• Beta Cells () release
insulin (antagonistic
to glucagon).
• Insulin  the rate at
which various body
cells take up glucose.
Thus, insulin lowers
the blood glucose
level.
• Insulin is rapidly
broken down by the
liver and must be
secreted constantly.
• Delta Cells ()
produce somatostatin,
which inhibits both
glucagon and insulin.

16. The Endocrine System
• Adrenal Glands
– 2 small glands that sit
atop of both kidneys.
– Each has 2 divisions,
each with different
functions.
• the Adrenal Medulla
secretes the
catecholamine
hormones
norepinephrine and
epinephrine (closely
related to the
sympathetic component
of the autonomic
nervous system).

17. The Endocrine System
• The Adrenal Cortex
secretes 3 classes of
hormones, all steroid
hormones:
– gluticocorticoids
mineralocorticoids
– androgenic hormones
– gluticocorticoids:
– accounts for 95% of
adrenal cortex hormone
production
  the level of glucose in
the blood
– Released in response to
stress, injury, or serious
infection - like the
hormones from the
adrenal medulla.

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

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

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

21. The Endocrine System
• Estrogen and
Progesterone have
several functions,
including sexual
development and
preparation of the
uterus for implantation
of the egg.
• Testes:
– located in the scrotum
– produce sperm for
reproduction
– manufacture testosterone
-
• promotes male growth
and masculinization
– Controlled by anterior
pituitary hormones FSH
and LH.

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

23. The Endocrine System
• Pathophysiology of
Diabetes:
• Glucose Metabolism
– Glucose (dextrose) is a
simple sugar required by
the body to produce
energy.
– Sugars, or carbohydrates,
are 1 of 3 major food
sources used by the body.
• The other 2 major food
sources are
– proteins
– fats
• Most sugars in the
human diet are complex
and must be broken
down into simple sugars:
glucose, galactose and
fructose - before use.

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

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

26. END
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