Transcript The Endocrine System

Chapter 10
Pathology
 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.
 Exocrine glands -
transport their hormones
to target tissues via
ducts.
 Endocrine Emergencies:
 from common:
 Diabetes
 to the unusual:
 Thyrotoxicosis
 Pituitary gland: a small
 Consists of several
glands located in
various parts of the
body.
gland located on a stalk
hanging from the base of the
brain - AKA
 “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.
 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 thyroidstimulating hormone
(TSH)
 growth hormone (GH)
 adrenocorticotropin
(ACTH)
 follicle-stimulating
hormone (FSH)
 And even more…
 Posterior Pituitary
 luteinizing hormone
 Oxytocin (the natural
(LH)
 prolactin
form of pitocin)
 stimulates gravid
uterus
 causes “let down” of
milk from the breast.
 ADH (vasopressin)
causes the kidney to
retain water.
 Let’s go over these one
at a time...
 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.
 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.
 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.
 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.
 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.
 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.
 Alpha () cells release
 The surge of glucagon
glucagon, essential for
stimulates the liver to
controlling blood glucose
release glucose stores
levels.
(from glycogen and
additional storage sites).
 When blood glucose
 Also, glucagon stimulates
levels fall,  cells  the
amount of glucagon in
the liver to manufacture
the blood .
glucose  gluconeogenesis.
 Beta Cells () release
 Insulin is rapidly broken
insulin (antagonistic to
glucagon).
 Insulin  the rate at
which various body cells
take up glucose. Thus,
insulin lowers the blood
glucose level.
down by the liver and
must be secreted
constantly.
 Delta Cells () produce
somatostatin, which
inhibits both glucagon
and insulin.
 Adrenal Glands
 2 small glands that sit
atop 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).
 The Adrenal Cortex
secretes 3 classes of
hormones, all steroid
hormones:
 gluticocorticoids
mineralocorticoids
 androgenic hormones
 One at a time…
 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.
 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
 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.
 Gonads and Ovaries:
 Ovaries:
 the endocrine glands
 located in the
associated with human
reproduction.
 Female ovaries produce
eggs
 Male gonads produce
sperm
abdominal cavity
adjacent to the uterus.
 Under the control of LH
and FSH from the
anterior pituitary they
manufacture
 both have endocrine
functions.
 estrogen
 protesterone
 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.
 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
 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.
 Breakdown of sugars is
carried out by enzymes
in the gastro intestinal
system.
 As simple sugars, these
are absorbed from the
GE 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.
 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.
 Diseases of Thyroid
 Myxedema – Hypothyroid Syndrome
 Symptoms include sluggishness, weight gain, edema
 If from lack of Iodine in nutrition, a Colloidal Goiter can
emerge.
 Diseases of Thyroid
 Myxedema – Hypothyroid Syndrome
 Symptoms include sluggishness, weight gain, edema
 If from lack of Iodine in nutrition, a Colloidal Goiter can
emerge.
 Grave’s Disease –
Hyperthyroid Activity
 Symptoms are elevated
metabolic rate, sweating,
weight loss.
 Calcitonin
 Lowers Blood Calcium Levels by depositing calcium into
the Bone.
 Produced by the Parafollicular Cells
 Direct Antagonist to Parathyroid Hormone