Endocrine System

Endocrine System The endocrine system’s primary aim is to maintain a stable and balanced internal environment, known as homeostasis. It does this by regulating bodily functions such as metabolism, growth and sexual development. It works through a series of glands that release hormones into the bloodstream.

Function of endocrine system Endocrine glands - Secrete chemicals(message), 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)For example: The adrenal medulla releases epinephrine and targets the heart, bronchioles, and blood vessels.

Negative Feedback Drop in hormone level triggers chain reaction: Blood level of hormone falls Brain gets message and sends out hormone to stimulate gland Gland secretes more hormone 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

Pineal Gland Small endocrine gland found in brain responsible for mood and sleep/wake cycles. Secretes melatonin only when it’s nighttime Allows our brain to tell what time of the day it is and what season it is Sets up our circadian rhythm ***internal clock

Pineal Gland

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; spurs growth in children and adolescents. It also helps to regulate body composition, body fluids, muscle and bone growth, sugar and fat metabolism, and possibly heart function Prolactin – develops breast tissue, stimulates production of milk after childbirth

Anterior Pituitary Lobe TSH – Thyroid stimulating hormone –Stimulates the thyroid gland to secrete its own hormone, which is called thyroxine(low TSH treated with synthroid) ***metabolism ACTH – Adrenocortiocotropic hormone – stimulates adrenal cortex to produce cortisol***AKA stress hormone

Anterior Pituitary cont’d FSH – Follicle stimulating hormone – stimulates growth of follicle (in ovaries) and production of estrogen in females. Also acts on the cells of the testes to stimulate ___________ production. LH – Luteinizing hormone – stimulates ovulation and formation of corpus luteum(glandular structure), which produces progesterone in females; in males, cell production of testosterone

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 ***what is pitocin???*****

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 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. Calcitonin lowers blood Ca levels. Also promotes formation of _______.

 Thyroid-stimulating hormone, also known as thyrotropin, is secretedfrom cells in the anterior pituitary called thyrotrophs, finds its receptors on epithelial cells in the thyroid gland, and stimulates that gland to synthesize and release thyroidhormones.

Parathyroid Glands 4 glands size of a grain of rice Attached to posterior thyroid Produce parathormone which helps control blood calcium, prevents hypocalcemia by raising blood calcium levels when needed

Thymus Gland Endocrine and lymphatic organ (more lymphatic than endocrine) 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 glucocorticoids (anti-inflammatory hormones) and sex hormones Androgens – Male sex hormones Adrenaline (epinephrine) – 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.

Adrenal Medulla Helps us cope with physical and emotional 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 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 Steroid abuse = liver damage, heart disease, testicular changes, breast growth in males

Cushing’s Syndrome Hypersecretion of glucocorticoids (cortisol) from adrenal cortex. Could be caused by tumor or excessive use of steroids Symptoms: hyperglycemia, hirsutism (excessive hair growth in women), poor wound healing, bruise easily, “moon face” buffalo hump Treatment: surgical removal of tumor, radiation, cortisol inhibiting drugs

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 80-100 mg. – screening=urinalysis

Type 1 diabetes is a chronic illness characterized by the body’s inability to produce insulin due to the autoimmune destruction of the beta cells in the pancreas. Onset most often occurs in childhood, but the disease can also develop in adults in their late 30s and early 40s.

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 functioning, 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.