Endocrine System
Function of endocrine system
Endocrine glands - Secrete chemicals, hormones, directly into bloodstream. - Ductless glands
Exocrine glands - Secrete substance through a ducti.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
Adrenal Medulla
also secretes nor
epinephrine –
increases BP and
heart rate and
constricts blood
vessels.
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 childhoodSmall size, but body proportions and intellect normalSexual immaturityRx – 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 glandToo much thyroxin leads to enlargement of gland
Symptoms – Consuming large quantities of food but lose weight – nervous irritabilityGoiter – Enlargement of glandExophthalmos – 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) – fixed with iodized salt
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, seizures
Rx – Vitamin D, calcium and parathormone.
Addison’s Disease
Adrenal glands don’t produce enough cortisol or aldosterone (steroid hormones)
Sxs – 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 insulinSymptoms – 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 metabolism2. Adrenalin – Stimulates the heart to beat faster3. Parathyroid – Regulates use of calcium4. Parathormone – Control use of calcium phosphorus5. Insulin – Secreted by pancreas6. Calcitonin – Affects neuromuscular functioing, blood
clotting, and holds cells together7. Estrogen – Governs reproduction and fertility8. Oxytocin – Causes the uterus to contract during
labor9. Gonad – Sex gland10. 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.
