Endocrine System

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Endocrine System The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things. The endocrine system is made up of the pituitary gland, pineal gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females) and testicles (in males),

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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 glands.) Hormones = chemical substances that coordinate and direct target organ cells (only specific cells respond to specific organs)

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Glands Work by 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

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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 - Known as “Master Gland” -Tiny – size of a grape -Found in Cranial cavity at Base of brain -Connected to hypothalamus -Divided into Anterior / Posterior lobes

Anterior Pituitary Lobe secretes hormones: 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)

Anterior Pituitary cont’d ACTH – Adrenocortiocotropic hormone – stimulates adrenal cortex (assists body’s ability to cope with stress) 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 & causes interstitial cells in the testes to secrete testosterone in makes

Posterior Pituitary Lobe Secretes: -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

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Thyroid Gland 1. Butterfly-shaped mass of tissue. 2. On either side of larynx, in front of the trachea. 3. H-shaped.

Thyroid Gland produces Hormones: -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 (causes removal of excess calcium in the blood to be stored in the bones)

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Parathyroid Glands 4 glands size of a grain of rice Attached to posterior thyroid Produce parathormone which helps control blood calcium, prevents hypocalcemia (causes breakdown of bone to release calcium into the blood)

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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 (plays a role in development & function of immune system)

Adrenal Glands Adrenal Glands – above kidneys Adrenal cortex secretes corticosteroids (anti- inflammatory hormones) and small amt sex hormones which are called Androgens – (“Male sex hormones” in both sexes) Adrenalin (epinephrine) – hormone from adrenal medulla, powerful cardiac stimulant, “fight or flight” hormone – response to stress Adrenal Medulla also secretes norepinephrine – increases BP and heart rate and constricts blood vessels.

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Gonads - ovaries in female and testes in male OVARIES: Produces Estrogen – Development of female reproductive organs, secondary sex characteristics (breasts, pubic hair, menstrual cycle) & Produces Progesterone – Plays a part in the menstrual cycle TESTES: Male Reproductive Organs- Produces Testosterone – Develops secondary sex characteristics (chest & pubic hair, deep voice, increased muscle mass)

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Pancreas Located in abdominal cavity below the stomach Works as an Endocrine and Exocrine Gland (as Exocrine gland it is part of digestive system) Contains Islets of Langerhans – Which produces Insulin (Insulin promotes utilization of glucose by the cells- which lowers blood sugar levels)

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Endocrine Disorders – Dwarfism- All dwarfs are short (adult height of 4 feet 10 inches or less), but different types of dwarfism have different causes and different physical traits. - Hypofunction of pituitary in childhood -Small size, but body proportions and intellect normal …….. People with achondroplasia have an average-size torso (the upper body) but noticeably shorter arms and legs. Their heads are usually larger than average, with a prominent forehead. Their fingers are typically short. -Sexual immaturity Rx – Early diagnosis, injection of growth hormone

Gigantism Gigantism : Hyperfunction of pituitary – Too much growth hormone In preadolescence causing Overgrowth of long bones leads to excessive tallness

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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 Acromegaly

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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 Trt – Partial or total removal of gland, drugs to reduce that include thyroxine radiation

Hypothyroidism Not enough thyroxine May be due to lack of iodine (causing a simple goiter which is when gland enlarges to compensate for lack of iodine in diet) – 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.

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Tetany- tonic muscle spasms In hypoparathyroidism, decreased calcium levels affect functions of nerves causing spasms or twitching of the nerves Symptoms – Convulsive twitching or seizures develop, person can die of spasms in the respiratory muscles Rx – Vitamin D, calcium and parathormone.

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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

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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 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 mg. – screening=urinalysis (to check for sugar in urine)

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 food, 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.

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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 11. Acromegaly – Enlargement of bones of the extremities. 12. Adenectomy – Removal of any gland.

Endocrine Terminology Cont. 13. Adrenogenic – Originating in the adrenals. 14. Dwarfism – Condition of being abnormally small. 15. Endocrine – Ductless; to secrete within. 16. Exocrine – To secrete through a duct. 17.Goiter – Enlarged thyroid gland. 18. Goitrogens – Any substance that causes a goiter. 19. Parathyrotoxicosis – Poisonous condition of the parathyroid. 20. Pinealoma – Tumor of the pineal gland. 21. Pituitarigenic – Originating in the pituitary. 22. Thyroadenitis – Inflammation of the thyroid gland.

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