Endocrine System
Unit –P / AH-1
Function of endocrine system
Endocrine glands - Secrete chemicals,
hormones, directly into bloodstream.
- Ductless glands
Exocrine glands - Secrete substance through
a duct
i.e.Sweat, salivary, lacrimal and pancreas.
Hormones = chemical substances that
coordinate and direct target cells and
organs.
Negative Feedback
Drop in hormone level triggers chain reaction:
1. Blood level of hormone falls
2. Brain gets message and sends out
hormone to stimulate gland
3. Gland secretes more hormone
4. When blood levels of hormone increase, the
brain hormones stop
Nervous Control

In some cases, sympathetic nervous system
causes direct release of hormone from gland
i.e. stress may cause the adrenal medulla to
secrete adrenaline
Pituitary Gland
Tiny – size of a grape
Base of brain
Connected to
hypothalamus
Anterior / Posterior
lobes
Cranial cavity
“Master Gland”
Anterior Pituitary Lobe
GH – Growth hormone (somatotropin) responsible
for growth and development
Prolactin – develops breast tissue, stimulates
production of milk after childbirth
TSH – Thyroid stimulating hormone – stimulates
thyroid cells to produce thyroid hormone =
thyroxine (low TSH treated with synthroid)
ACTH – Adrenocortiocotropic hormone –
stimulates adrenal cortex
Anterior Pituitary cont’d
FSH – Follicle stimulating hormone –
stimulates growth of follicle and production of
estrogen in females and sperm in males
LH – Luteinizing hormone – stimulates
ovulation and formation of corpus luteum,
which produces progesterone in females
Posterior Pituitary Lobe
Vasopressin – converts to ADH (antidiuretic
hormone) in the bloodstream, acts on kidney
to concentrate urine and preserve water in
the body
Oxytocin – released during childbirth causing
contractions of the uterus
Thyroid Gland
Thyroid Gland
1. Butterfly-shaped mass of tissue.
2. On either side of larynx, in front of the
trachea.
3. H-shaped.
Thyroid – stimulating hormone (stimulates
cellular metabolism) – Main hormone
Thyroxine – controlled by secretion of TSH –
controls rate of metabolism
Calcitonin – controls calcium ion concentration
in the body – prevents hypercalcemia
Parathyroid Glands
4 glands size of a grain of
rice
Attached to posterior thyroid
Produce parathormone
which helps control blood
calcium, prevents
hypocalcemia.
Thymus Gland
Endocrine and lymphatic organ
Behind sternum, above and in front of heart
Begins to disappear at puberty
Produces Thymosin – reacts upon lymphoid
tissue to produce T-lymphocytes
Adrenal Glands
Adrenal Glands – above
kidneys
Adrenal cortex secretes
corticoids (anti-inflammatory
hormones) and sex
hormones
Androgens – Male sex
hormones
Adrenalin – hormone from
adrenal medulla, powerful
cardiac stimulant, “fight or
flight” hormone – response
to stress
Gonads
Gonads – ovaries in female and testes in
male
Estrogen – Development of female
reproductive organs, secondary sex
characteristics
Progesterone – Plays a part in the
menstrual cycle
Testosterone – Male reproductive organs
and secondary sex characteristics
Pancreas
Pancreas – abdominal cavity behind the
stomach
Endocrine and exocrine functions
Islets of Langerhans – Insulin production.
Insulin promotes utilization of glucose by the
cells – lowers blood sugar levels
Other hormones…
Prostaglandins – Tissue hormones - can
cause constriction of blood vessels and
muscle contractions - can be used to
induce labor.
Endocrine Disorders - Dwarfism
Hypofunction of
pituitary in
childhood
Small size, but
body proportions
and intellect normal
Sexual immaturity
Rx – Early
diagnosis, injection
of growth hormone
Gigantism
Gigantism
Hyperfunction of
pituitary – Too much
growth hormone
In preadolescence –
Overgrowth of long
bones leads to
excessive tallness
Acromegaly
Hyperfunction of pituitary – too much growth
hormone in adulthood
Overdevelopment of bones in face, hands and
feet
Attacks cartilage – so the chin protrudes - lips,
nose and extremities enlarge
Rx – drugs to inhibit growth hormone –
radiation
Before
After
Hyperthyroidism
Overactive thyroid gland
Too much thyroxine leads
to enlargement of gland
Symptoms – Consuming large
quantities of food but lose
weight – nervous irritability
Goiter – Enlargement of
gland
Exophthalmos – Bulging of
eyeballs
Trt – Partial or total removal of
gland, drugs to reduce
include thyroxine radiation
Hypothyroidism
Not enough thyroxine
May be due to lack of
iodine (simple goiter)
Other cause – inflammation
of thyroid which destroys
the ability of the gland to
make thyroxine
Symptoms – Dry, itchy
skin; dry and brittle hair,
constipation, muscle
cramps at night.
Tetany
In hypoparathyroidism, decreased calcium
levels affect functions of nerves
Symptoms – Convulsive twitching develops,
person dies of spasms in the respiratory
muscles
Rx – Vitamin D, calcium and parathormone.
Diabetes Mellitus
Cause – Decreased secretion of insulin
Symptoms – Polyuria, polyphagia,
polydipsia, weight loss, blurred
vision, and possible diabetic
muscles.
If not treated, excess glucose in blood
(hyperglycemia) and secreted in
urine (glycosuria)
If too much insulin given, blood sugar
can get too low (hypoglycemia) and
person can develop insulin shock.
Type II diabetes is not insulindependent – Most common, usually
familial, occurs later in life, usually
treated with diet.
Test for diabetes – Blood sample at
home, normal blood sugar is 80-100
mg. – screening=urinalysis
Hyperglycemia
(High Blood Glucose)
Causes: Too much food, too
little insulin or diabetes
medicine, illness or stress.
Onset: Gradual, may progress
to diabetic coma.
Symptoms: Extreme thirst,
frequent urination, dry skin,
hunger, blurred vision,
drowsiness, and nausea.
What can you do? Take blood
glucose tests, and if over 250
mg/dL for several tests, call
your doctor.
Hypoglycemia
(Low Blood Glucose)
Causes: Too little good, too much insulin or diabetes medicine, or extra exercise.
Onset: Suddon, may progress to insulin shock.
Symptoms: Shaking, fast heartbeat, sweating, anxious, dizziness, hunger,
impaired vision, weakness fatigue, headache, and irritablility.
What can you do? Drink ½ glass of orange juice or skim milk, or eat several hard
candies, test your blood glucose; if symptoms don’t stop call your doctor, within 30
minutes after symptoms go away, eat a light snack (a ½ peanut butter or meat
sandwich and a ½ glass of mik.
Endocrine Terminology
1. Thyroxine – Regulates body metabolism
2. Adrenalin – Stimulates the heart to beat faster
3. Parathyroid – Regulates use of calcium
4. Parathormone – Control use of calcium phosphorus
5. Insulin – Secreted by pancreas
6. Calcitonin – Affects neuromuscular functioing, blood
clotting, and holds cells together
7. Estrogen – Governs reproduction and fertility
8. Oxytocin – Causes the uterus to contract during
labor
9. Gonad – Sex gland
10. ATCH – Hormone secreted by the pituitary gland
Endocrine Terminology Cont.
11. Acromegaly – Enlargement of bones of the
extremities.
12. Adenectomy – Removal of any gland.
13. Adenoidectomy – Removal of the adenoids.
14. Adrenogenic – Originating in the adrenals.
15. Dwarfism – Condition of being abnormally small.
16. Endocrine – Ductless; to secrete within.
17. Endocrinotherapy – Treatment with endocrine
preparation.
18. Exocrine – To secrete through a duct.
19.Goiter – Enlarged thyroid gland.
Endocrine Terminology Cont.
20. Goitrogens – Any substance that causes a goiter.
21. Lymphycytopenia – Deficiency of lymph cells.
22. Pancreatolysis – Breakdown of the pancreas.
23. Parathyrotoxicosis – Poisonous condition of the
parathyroid.
24. Pinealoma – Tumor of the pineal gland.
25. Pituitarigenic – Originating in the pituitary.
26. Thyroadenitis – Inflammation of the thyroid gland.