Endocrine System

Unit –P / AH-1

Endocrine System structure

Endocrine glands secrete hormones

A. Pituitary Gland

1. Tiny structure size of grape.

2. Located at base of brain – cranial cavity

3. Connected to hypothalamus.

4. Divided into anterior and posterior lobes.

Structure cont’d...

B. Thyroid Gland

1. Butterfly-shaped mass of tissue.

2. On either side of larynx, in front of the trachea.

3. H-shaped.

Structure cont’d…

C. Parathyroid Glands

1. Four glands, each the size of a grain of rice.

2. Attached to posterior thyroid – located in the neck

Structure cont’d...

D. Thymus1. Endocrine gland and lymphatic organ.2. Located behind sternum, above and in front of heart – thoracic cavity3. Begins to disappear at puberty.

E. Adrenal Glands1. Located on top of each kidney.

Structure cont’d…

F. Gonads1. Ovary in female.2. Testes in male.

Both in pelvic cavity

G. Pancreas1. Located behind the stomach.2. Endocrine and exocrine functions.

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 adrenalin

Function of endocrine system

Endocrine glands - Secrete chemicals,hormones, directly into bloodstream.

- Ductless glandsExocrine glands - Secrete substance through

a ducti.e.Sweat, salivary, lacrimal and pancreas.

Pituitary Gland

Tiny – size of a grape

Base of brain

Connected to hypothalamus

Anterior / Posterior lobes

“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 – 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 maleEstrogen – 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, 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 thyroxine 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)

Other cause – inflammation of thyroid which destryous 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 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.