ENDOCRINE
SYSTEM
Charles C. Cook, MD
ENDOCRINE SYSTEM

Endocrine system is complex and
illness associated with it are sometimes
very difficult to diagnose.
Regulating the functions of
the Human Body
Nervous System:
Biological communication system
Endocrine System:
Uses biochemicals called hormones
that travel in body fluids and act as
chemical messengers to their target
cells
Endocrine System
A system of glands that
function in the
coordination of body
activities through chemical
messengers
Endocrine Glands
Have
no ducts
Secrete hormones
–into extracellular fluids
–diffuse into the
bloodstream
Endocrine Glands
Pituitary
gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Exocrine Glands
 Secrete
products through ducts
that lead to the lumen of an organ,
body surface or body cavity
 Example:
– Sweat glands
– Salivary glands
– Liver and Gall bladder
Hormones
and
Negative
Feedback
Hormones
 Chemical
messenger
–Endocrine gland
–Blood or body fluids
 Target: specific site on a cell, tissue,
organ or organ system with hormone
binds
 Hypersecretion: greater than normal
 Hyposecretion: less than normal
Hormones
 Chemical
released from an
endocrine gland that
 Affects function of a target cell
 Diffuses into the blood
 Carried through the body
 Act on cells that have specific
receptor (hormone can attach)
Negative Feedback
Secretion
of most hormones by
endocrine gland
Mechanism for
–Maintaining stable amount
of hormone in the blood
stream
Negative Feedback
Example
 Thyroid
hormone falls below
normal
–Hypothalamus detects the
decrease
 Hypothalamus signal
–Anterior pituitary gland to
secrete TSH
 TSH
cause the thyroid to make &
secrete more TH (Thyroxine)
 Level of TH in the blood returns to
normal
 Higher concentration of TH shuts
off the signal both hypothalamus
& pituitary gland that led to
 Increase in secretion of TH
Functions of the Endocrine
System
 Help
to control internal environment
 Respond to marked changes
 Helps with growth and development
 Helps with reproduction process
 Regulate metabolism
–Maintain homeostatasis
–F/E and Acid Base Balance
The
Major
Endocrine
Organs
Major Endocrine
Organs
 Hypothalamus
 Pituitary
Glands
– Anterior lobe
– Posterior lobe
 Thyroid Glands
 Parathyroid Glands
 Adrenal
Glands
– Adrenal cortex
– Adrenal medulla
 Pancreas
Hypothalamus
 Middle
of the brain near floor of
the cranial cavity
 Connection between nervous
and endocrine system
 Sensory information & signals to
pituitary glands to secrete or not
secrete hormones
Pituitary Glands
 The
Master Gland
 Base of the brain (1cm in dia)
 In the sella turcisa
 Bony pocket of the cranial
cavity
 Has an Anterior and Posterior
Lobe
75% Total Wt.
Anterior Pituitary Gland
Releases 7 major hormones
 Growth
Hormone (GH)
 Prolactin (PRL)
 Thyroid Stimulating Hormone (TSH)
 Melanocyte Stimulating Hormone (MSH)
 Adrenocorticotrophic Hormone (ACTH)
 Follicle Stimulating Hormone (FSH)
 Lutenizing Hormone (LH)
Anterior Pituitary Hormones
 GH-
mainly promotes the
lengthwise growth of long bones
(Somatotropic)
 Prolactin- stmulates breast
development and lactation after
childbirth
 TSH- stimulating the thyroid gland
(Thyroxine & Triiodothyronine)
Anterior Pituitary Hormones
 ACTH-
stimulates the adrenal
cortex to secrete cortisol
 LH- regulates the functions of
estrogen, progesterone and
testosterone production
 FSH- regulates the functions of
the sperm and egg production
Posterior Pituitary Gland
 Nerve
fiber (impulses)
 Releases two hormones
–Antidiuretic hormone (ADH)
–Oxytocin (OT)
Thyroid-Stimulating
Hormone
a.k.a. TSH
Function
–Stimulates the thyroid
gland to secrete more of the
thyroid hormone
(Thyroxine)
Adrenocorticotropic
Hormone
 a.k.a
ACTH
 Stimulate the adrenal cortex to
manufacture & secrete its
hormones
 Mostly cortisol
–but also other hormones
Regulates
Cortisol
levels in the blood
are Lower than normal
Hypothalamus stimulates
the anterior pituitary gland
to secrete ACTH
Regulates
 Cortisol
levels in the blood is
Normal or higher than normal
 Cortisol inhibits the
hypothalamus from stimulating
the secretion of ACTH
 Inhibits the anterior pituitary
from secreting ACTH (-) feedback
The
Thyroid
Gland
Thyroid Gland
 Location
in the front of the neck
around the
–Larynx
–Trachea
 Main hormone of the thyroid
gland is
–Thyroxine and Calcitonin
Thyroxine
 Regulates
the metabolic rate of
the whole body
 Levels of thyroxine
–Increased: speed up metabolic
rate
–Decreased: slows metabolic
rate
Thyroid Disorders
Goiter
Hyperthyroidism
–Excessive secretion
Hypothyroidism
–Inadequate secretion
Goiter
Enlarged
thyroid gland
–tells you something is
wrongs
–Doesn’t tell you what
is wrong
Hyperthyroidism
 Excessive
secretion of thyroxine
 All sign & symptoms are rated
to increase in metabolic rate
-increase heart
-increase body temp
-fatigue
-weight loss
Hyperthyroidism
Produces
-elevated metabolic
rate
-restlessness
-overeating
-eyes protrude
-thyroid glands
enlarged (goiter)
Hypothyroidism
 Inadequate
secretion of
Thyroxine
 All signs & symptoms are
related to a decrease in the
metabolic rate
–decrease heart & respiratory
rate
Hypothyroidism
–constipation & weigh gain
– decrease body temperature
intolerance of cold
Hypothyroidism
Cretinism
Symptoms
-stunted growth
-abnormal
development
-low body temp
-sluggishness
Parathyroid Glands
Located
posterior surface of
the thyroid gland
There’s 4 structure
–2 superior glands
–2 inferior glands
Parathyroid hormone
 Regulate
calcium level in the
blood
 When PTH secreted
–Increase blood calcium levels
–Decrease blood phosphate levels
 Affects
the bones, kidneys, and
intestine
The
Adrenal
Gland
Adrenal Glands
Located
atop of each kidney
Adrenal medulla- is the
center (core) layer portion
Adrenal cortex- is the outer
layer portion
Adrenal Cortex
 Three
layers that synthesize
corticoids
 Outer (core) layer
 Three adrenal hormones
–Aldosterone
–Glucocorticoids
–Adrenal Androgens
Aldosterone
 Regulates
mineral electrolytes
 Kidneys to conserve sodium &
water excrete potassium
 If blood pressure falls- kidney
indirectly stimulate aldosterone
secretion
Glucocorticoids
 Plays
a role in maintenance of
blood pressure
 Influences Glucose Metabolism
 Adrenal Androgens
–Minimal levels of testosterone
are produced
Adrenal Medulla
Secretes
2 hormones
-epinephrine
-norepinephrine
80% is epinephrine
Prepares
the body for
–Action
–Stress
Sympathetic Nerve System
-flight or fight
-Adrenaline rush
 Resulting
In:
–increase
heart rate
blood pressure
respiration
blood sugar level

–decreased
digestive rate

The
Pancreas
Pancreas
Location-
behind the stomach
Exocrine- secretes digestive
juice (pancreatic duct) into
small intestine
Endocrine- Islets of
Langerhans
Hormones
Insulin:
Promotes the
transport of glucose from
the blood into the cells
Glucagon: Stimulates the
release of the stored
glucose from the liver into
the blood
Diabetes Mellitus
 Metabolic
levels are
disorder; blood glucose
–CHRONICALLY HIGH
 Type
I- can not produce enough
insulin
 Type II- insulin resistance
Signs and Symptoms
The
four (P’s)
(Polyuria) Frequent urination
(Polydipsa) Chronic thirst
(Polyphagia) Chronic hunger
(Poor wt maintenance)
Weight problems
Type
I
–destruction of the beta cells
Type II
–decrease or no response on
the target cells (mostly
liver, skeletal, muscle, and
adipose tissue)
–is almost always obese
Gonads/Sex Glands
 Ovaries
and Testes
– Male and female gamete producing glands
 Testes
– Located scrotal sac
– Produce Testosterone
 Ovaries
– Located in pelvic region
– Produces estrogen and progesterone
Thymus Gland
 Cortex
and Medulla region
–Largely composed of lymphocytes
 Hormone produced Thymosin
–Activate immune system
–Production of certain lymphocytes
–Important role in immunity
Endocrine Glands
 Digestive
glands
– Stomach and small intestine
 Erythropoietin
– Secreted by the kidneys
 Atria Natriuretic Factor (ANF)
– Secreted by the cell in the walls of the
atria
– ANF is an antagonist
– Decreases blood volume
That’s It!!!!!!