THE ENDOCRINE SYSTEM: AN OVERVIEW Functions: 1. Reproduction 2. Growth & development 3. Maintenance of electrolytes, water and nutrient balance of the blood 4. Regulation of cell metabolism and energy balance 5. Mobilization of body defenses Negative Feedback Mechanism- primarily works with the Endocrine System CHEMISTRY OF HORMONES- made from organic compounds 1. Amino acid based hormones- amines, peptide, protein 2. (Lipid) Steroid based: made from cholesterol *anabolic steroids- synthetic steroids destroy the cell s nucleus will result in TUMORS 3. Prostaglandins- made by active lipids Structures: 1. Endocrine glands a. Pituitary b. Thyroid c. Parathyroid d. Adrenal e. Pineal 2. Neuroendocrine organ- hypothalamus 3. Other : organs containg endocrine tissues a. pancreas b. gonads c. placenta 4. chemical messengers- use blood and lymph to circulate a. autocrine b. paracrine Homeostatic Imbalances I. PITUITARY (pg.604) +GH: gigantism, acromegaly -GH: dwarfism -ADH: diabetes insipidus II. THYROID (pg. 611) - TSH: endemic goiter, cretinism III. PARATHYROID (pg. 613 +PTH: hyperparathyroidism -PTH: hypoparathyroidism IV. ADRENAL CORTEX(p.617) +ACTH: Cushing s Syndrome -Aldosterone/-Cortisol: Addison s Disease V. ADRENAL MEDULLA -Hyperglycemia VI. PANCREAS (pg.622) -Insulin: Diabetes Mellitus (Types 1 and 2)
Endocrine Gland Pituitary gland 1. Master Gland 2. dangles from brain The hypothalamus (a hormone-storage area and not a true endocrine gland) secretes hormones that stimulate the anterior pituitary gland to secrete hormones that stimulate other endocrine glands to secrete hormones Location Brain- pea on a stalk Anterior Pituitary Hormones Hormone 1. GH- stimulates growth in childhood and is important for maintaining a healthy body composition. In adults it is also important for maintaining muscle mass and bone mass. It can affect fat distribution in the body. (ie: constant growth/repair- think of mitosis = a cell s lifespan) 2. ACTH- stimulates production of cortisol by the adrenal glands. Cortisol, a so-called "stress hormone," is vital to survival. It helps maintain blood pressure and blood glucose levels. 3. LH- regulates testosterone in men and estrogen in women. (gonadotropin) During pregnancy, it helps maintain to end term and prepares the body to lactate 4. PRL-stimulates milk production from a woman's breasts after childbirth and can affect sex hormone levels from the ovaries in women and the testes in men. 5. FSH-FSH promotes sperm production in men and stimulates the ovaries to release eggs (ovulate) in women. LH and FSH work together to allow normal function of of the ovaries or testes. (gonadotropin) the presence of hcg (pregnancy test kits) helps create the corpus luteum and makes progesterone which maintains a pregnancy to full term. 6. TSH-stimulates the thyroid gland to make thyroid hormones, which, in turn, control (regulate) the body's metabolism, energy, growth and development, and nervous system activity. Posterior Pituitary Hormones 7. ADH- also called vasopressin, is stored in the back part of the pituitary gland and regulates water balance. If this hormone is not secreted properly, this can lead to problems of sodium (salt) and water balance, and could also affect the kidneys so that they do not work as well. 8. Oxytocin - causes milk letdown in nursing mothers and contractions during childbirth.
Thyroid Neckbutterfly shaped 9. Thyroxin (T4= 4 iodine atoms) à Tri-iodothyronine (T3=3 iodine atoms) - both increase the rate at which cells release energy from carbohydrates; must have a diet with proper amount of iodine (iodine-rich foods: seaweed, seafood, dairy, grain, produce, breast milk, eggs) a. Initiates transcription for protein synthesis b. Increases metabolic rate and heat production (calorgenic effect) c. Maintains blood pressure d. Regulate tissue growth & development e. Skeletal & nervous system dev. f. Maturation for reproductive capabilities 10. Calcitonin regulates the blood concentration of calcium BY: a. CLEARS Ca in blood Lowers blood calcium levels by moving it into the bones b. antagonistic to the parathyroid gland Parathyroid Neck 11. PTH aka PARATHORMONE; takes calcium from the bones to make it available in the blood a. PUTS Ca in blood Calcium is essential for: nerve impulses, muscle contraction, and blood clotting b. Released if there is a decline of blood Ca by having the kidneys reabsorb the Calcium so it is not excreted. c. Active form: Stimulates CALCITROL- vita D source d. Inactive form: food and skin Adrenal Glands OUTER:Adrenal cortex- SECRETES STEROID HORMONES A beret above the kidneys Hormones of the Adrenal Cortex- balance water/electrolyte balance; includes (cortico- cortex ): corticosteroids, glucocorticoids and gonadocorticoid A. Corticosteroids 12. ALDOSTERONE a mineralcorticoid, keeps Na+ in the body by reabsorbing from kidneys; the balance of water influences the blood volume and pressure; low blood pressure will stimulate aldosterone. B. Glucocorticoid- stimulated by ACTH in Pituitary Gland 13. cortisol, cortisone, corticosterone; deals with long-term stress; depending on the amt of
cortisol= amt of stress; anti-inflammatory (can make synthetic HYDROCORTISONE as a medicine) C. Gonadocorticoid INNER:Adrenal medulla; made up of nervous tissue that are triggered by the sympathetic nervous system Pancreas tongue shaped organ behind your stomach that helps the body to maintain healthy insulin (glucose) levels. Sex Hormones regardless of your gender, it secretes 14. androgens (DHEA- less potent type of testosterone) and estroidal and estrogen (female hormones) throughout your life; hypersecretion of androgens in females are responsible for a stronger sex drive as well as the minimal production of estrogen during menopause. ` Hormones of the Adrenal Medulla- Catecholamines- deals with short term stress; it prolongs the flight or fight response; stimulated by the Nervous System 15. Epinephrine- increased heart rate, breathing rate, elevated blood pressure and blood glucose levels (fight or flight, response to stress) aka ADRENALINE to better prepare us in a stressful situation *stimulates metabolic activities, bronchial dilation, increased blood flow to muscles and heart. Epinephrine is used as a heart stimulant and dilate bronchioles during asthmatic attacks. 16. Norepinephrine similar to epinephrine AND a neurotransmitter; works synergistically with epinephrine. *blood pressure Contains cells called the Islets of Langerhans which secrete hormones: Alpha cells (glucagon synthesizing hormone) and Beta cells (insulin producing) work together in regulating blood glucose levels 17. Glucagon raises blood sugar concentration; NOT EATING will make your glucose levels drop and then liver breaks down glucose (glycogen); LOW sugar levels will trigger glucogen (glucose-is-gone) 18. Insulin lowers blood sugar concentrations, and allows glucose as energy to be used by cells; eating concentrated sugar will add it to your blood and TRIGGER insulin Glucogon is antagonistic to insulin
Thymus two lobes and is located directly in front of the heart and behind the sternum It is a critical part of the immune system because it trains and modifies T cells that are used by the body to fight foreign materials that can cause sickness.
Other GONADS Brain ********** Pregnancy The gonads are organs that make sex hormones and reproductive cells. Pineal Gland /pie-neal/ located between the cerebral hemispheres, secretes melatonin, important for maintaining Circadian rhythms (light and dark activity) the sun hits your eyes, then to hypothalamus, to the Sympathetic Nervous System and then to the pineal gland to turn off melatonin, waking you up. Disruption of melatonin: seasonal affective disorder: Short winter days, decreasing melatonin makes people feel tired. LIGHT THERAPY is prescribed. *************************************************************************** Placenta- a temporary organ providing oxygen, nutrients and waste between mother and child During pregnancy, the placenta becomes an extra endocrine organ and produces hormones that help maintain the pregnancy: hcg and progesterone The first hormone produced is called human chorionic gonadotropin (hcg). hcg helps maintain the corpus luteum during the early stages of pregnancy. Maintenance of the corpus luteum is important because it produces the hormone progesterone, which ensures that the lining of the uterus stays intact during the pregnancy. In later stages of pregnancy, the job of progesterone production is taken over by the placenta. The placenta also produces estrogen. During pregnancy estrogen helps prepare the breasts for milk production. Reproductive Glands testes and ovaries MALE: testosterone and FEMALE: progesterone, estrogen Function: these hormones influence the development of secondary sex characteristics. Female Gonad- FSH à the ovary- are functional at the time of puberty; LH à ovulation à corpus luteum Male Gonad- FSH à testes produce the most important male sex hormone and it helps control and guide male sexual development. Sufficient production of testosterone is necessary for normal sperm development and testosterone continues to be secreted by the testes throughout adulthood If any of the male or female sex hormones are under-produced, it will severely impede a couple's ability to conceive a child