Endocrine System
Health Science One
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 organ cells (only
specific cells respond)
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 (posterior) 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 (breasts,
pubic hair, menstrual cycle)
Progesterone – Plays a part in the menstrual cycle
Testosterone – Male reproductive organs and
secondary sex characteristics (chest hair, deep
voice, increased muscle mass)
Pancreas
Pancreas – abdominal cavity behind the stomach
Endocrine and exocrine functions – also part of
digestive system
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 thyroxin leads to
enlargement of gland
Symptoms – Consuming large
quantities of food but lose
weight – nervous irritability
Goiter – Enlargement of
gland
Exophthalmos – Bulging of
eyeballs
TX – 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) – fixed with
iodized salt
Other cause – inflammation of
thyroid which destroys the
ability of the gland to make
thyroxine
Sx – Dry, itchy skin; dry and
brittle hair, constipation,
muscle cramps at night.
Tetany
In hypoparathyroidism, decreased calcium
levels affect functions of nerves
Sx– Convulsive twitching develops, person dies
of spasms in the respiratory muscles,
seizures
Rx – Vitamin D, calcium and parathormone.
Addison’s Disease


Adrenal glands don’t produce enough cortisol
or aldosterone (steroid hormones)
Sx – muscle weakness, darkening of skin
(hyperpigmentation), salt craving, irritability,
hair loss, depression, weight loss, n/v/d,
hypoglycemia, low BP
Steroid abuse = liver damage, heart disease,
testicular changes, breast growth in males
Diabetes Mellitus
Cause – Decreased secretion of insulin
Sx-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 insulin-dependent – 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. ACTH – 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.