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Transcript
Endocrine System What does the endocrine system consist of? All the organs of the body that are endocrine glands What do endocrine glands do? An endocrine gland secretes endocrine hormones. What are endocrine hormones? Endocrine hormones are hormones that are secreted into the blood. What are hormones? Hormones are substances that are secreted by one group of cells that affects the physiology of another group of cells (organs). What is the endocrine system controlled by? The endocrine system is controlled by the pituitary gland and the hypothalamus. Compared to most other organs in the body, is the endocrine well vascularized? Yes, endocrine organs are well vascularized. What does the endocrine system do? A system of ductless glands, they secrete messenger molecules called HORMONES. Interacts closely with the nervous system. What is ENDOCRINOLOGY? The study of hormones and endocrine glands. Major Endocrine Glands: Hypothalamus Pituitary Gland Thyroid Gland Parathyroid Glands Thymus Gland Adrenal Glands Pancreas Ovaries Testes Pineal Gland Where are the Endocrine Organs? They are scattered throughout the body Richly Vasculurized What are the pure endocrine organs? Pituitary Pineal Thyroid Parathyroid Adrenal Glands What organs contain endocrine cells? Pancreas Thymus Gonads Hypothalamus What is the endocrine system controlled by? The pituitary gland and the hypothalamus. Always controlled by feedback loops What happens if blood concentration declines below a minimum? More hormone is secreted. What happens if blood concentration exceeds maximum? Hormone production is halted Where is hypothalamus located and part of what system? The hypothalamus is located in the base of the brain. It is part of the limbic system. What does the limbic system control? The limbic system controls the autonomic nervous system and the endocrine systems. How does the hypothalamus control the endocrine system? By controlling the pituitary gland. Secretes releasing factors to release hormones. Secretes inhibiting hormones to turn off secretion of hormones. Where is the PITUITARY GLAND located? In the sella tursica (totally encased in bone), VERY important gland. What is the PITUITARY GLAND a major source of? The PITUITARY GLAND is a major source of steroid hormones in the body. What can trauma to the PITUITARY GLAND cause? Diabetes What can a tumor of the PITUITARY GLAND lead to? It can lead to blindness because it is so close to the optic chiasma. How many major hormones does the PITUITARY GLAND secrete? Secretes nine major hormones. How does the PITUITARY GLAND attach to the hypothalamus? Attached to the hypothalamus by the infundibulum. What are the two parts of the PITUITARY GLAND? 1. ADENOHYPOPHYSIS is the anterior pituitary. 2. NEUROHYPOPHYSIS is the posterior pituitary. The ADENOHYPOPHYSIS (Anterior Pituitary) secretes hormones which affect what glands? * Growth hormone (GH) : causes body to grow * Prolactin (PRL): Stimulates lactation in females Unknown effects in males * Thyroid Stimulating Hormone (TSH): Causes the thyroid gland to release thyroid hormone. *Adrenocorticotropic hormone (ACTH): Acts on adrenal cortex to stimulate the release of cortisol. Helps people cope with stress. * Melanocyte-stimulating hormone (MSH): Darkens skin pigmentation * Follicle-stimulating hormone (FSH): present in males & females, affects both. Stimulates maturation of sex cells. *Luteinizing hormone (LH): Induces ovulation What does the NEUROHYPOPHYSIS (posterior pituitary) do? It is a continuation of the brain; cell bodies of special neurons in the hypothalamus have axons which go to the neurohypophysis and synapse on the capillaries. What do Nerohypophysis release instead of neurotransmitters? They release hormones *Oxytocin -Childbirth contractions *Antidiuretic hormone (ADH) -Signals kidneys to increase water reabsorption. What controls the pituitary gland? The HYPOTHALAMUS (the master gland) What are some disorders of the pituitary gland? Gigantism and Acromegaly -Hypersecretion oh GH in children -Giantism is overall growth -Acromegaly is enlarged hand and feet. Pituitary dwarfism -Hyposecretion of GH Diabetes insipidus -Not enough ADH (anti-diuretic hormone) What hormones does the Hypothalamus produce? *Thyroid Stimulating Hormone Release Hormone-(TSH-RH) This affects the adenohypophysis to secrete Thyroid Stimulating Hormone TSH affects the thyroid gland to secrete Thyroid hormone (TH) The hypothalamus can also secrete inhibiting hormones: TSH – Inhibiting Hormone prevents the adenohypophysis from secreting TSH. The hypothalamus affects the adenohypophysis & that’s about it. Where is the THYROID GLAND located? It is located in the anterior neck, inferior to thyroid cartilage. What does THYROID GLAND do? *Largest pure endocrine gland *Produces two hormones * Thyroid hormone (TH) -Acts on most cells of the body -Increases metabolic rate -Controlled by humeral (blood) elements -Iodine is needed to make TH *Calcitonin -Lowers blood calcium levels in children -Slows osteoclasts to allow for bone deposition (Vitamin D is synthesized and secreted by bone cells) What is the major stimulus for the release of thyroid hormone? It is humeral (Blood elements tell the body it needs more thyroid hormone) What is thyroid hormone partly made of? It is partly made of Iodine. Iodine is essential for the formation of thyroxin. If you do not eat enough iodine, they cannot make thyroid hormone. How does hypothalamus respond? The hypothalamus responds by putting out more TSH-RH How does pituitary respond? The pituitary will respond by releasing TSH. What is GOITER? If not enough iodine to make hormone (TH) the size of the follicle grows >gland grows>GOITER. What is Hyperthyroidism (Grave’s Disease)? *Caused by autoimmune disorder. *Leads to nervousness, weight loss, sweating and rapid heart rate. What is HYPOTHYROIDISM? Decreases metabolism, causes obesity. What is adult hypothyroidism? MYXEDEMA antibodies attack & destroy thyroid tissue Low metabolic rate & weight gain are common symptoms. What is hypothyroidism in children called? CRETINISM *Short, disproportionate body, thick tongue & mental retardation What are PARATHYROID GLANDS? These are 4 glands embedded in the thyroid gland. *Parathyroid hormone (PTH) *Increases blood concentration of Ca2+ *Tells osteoclasts to release calcium from bone *Tells kidneys to decrease secretion of calcium *Activates vitamin D which increases calcium uptake by intestines DOES NOT METABOLIZE CALCIUM What DOES NOT metabolize calcium? PARATHYROID GLANDS What does the THYMUS GLAND do? Hormones produced by this organ stimulate the production of T cells. Adrenal Glands – they are 2 glands in 1: What are they? Adrenal Cortex & Adrenal Medulla What does ADRENAL CORTEX do? Bulk of the adrenal gland Secretes Steroids: 1. CORTISONE: reduces inflammation 2. CORTISOL: helps body deal w/stressful situations like fasting, anxiety, trauma and infection. When the perceives a stressful situation, the hypothalamus tells the pituitary gland to secrete (ACTH), which travels to the adrenal gland & signals it to release cortisol to most of the cells in the body. 3. ALDOSTERONE: increases blood volume during hemorrhage or drop in blood pressure, causing kidneys to reabsorb more sodium, water follows with it, so blood volume increases. 4. SEX HORMONES: for opposite sex Males produce estrogen here, & females produce testosterone. What is the ADRENAL MEDULLA? What does the ADRENAL MEDULLA secrete? The adrenal medulla is a knot of nervous tissue within the gland. It secretes adrenalin neurotransmitter for the sympathetic nervous system. The adrenal medulla also has sympathetic neurons which synapse on it, so when you are spooked, the neurons fire and also stimulates the adrenal medulla to release more epinephrine to increase the effects of the sympathetic nervous system. What Adrenal Gland Disorders are there? CUSHING’S SYNDROME -Hypersecretion of cortisol -Round “moon” face and “buffalo bump” ADDISON”S DISEASE -Hyposecretion of cortisol -Low Blood pressure results What is the PINEAL GLAND? Shaped like a pinecone Pinealocytes secrete melatonin - A hormone that regulates circadian rhythms (sense of day & night; it regulates sleep cycle). “Pineal Sand” is radiopaque -mineral deposits within pineal gland -Used as a landmark to identify brain structures in XRays What is the PANCREAS? This is an endocrine & an exocrine gland Exocrine glands secrete into a duct The pancreas has channels that end in exocrine glands. What are interspersed among the pancreas channels that end in exocrine glands? PANCREATIC ISLETS, which are endocrine Exocrine Cells-acinar cells-secrete digestive enzymes Endocrine cells-pancreatic islets (islets of Langerhans) *About one million islets-scattered in thru pancreas *Secrete Insulin *Secretes Glucagon What does GLUCAGON do? *Signals liver to release glucose from glycogen *Raises blood sugar What does INSULIN do? *Signals most body cells to take up glucose from the blood *Promotes storage of glucose as glycogen in liver *Lowers blood sugar - What are 2 different kinds of DIABETES? 1. DIABETES INSIPIDUS 2. DIABETES MELLITUS What is DIABETES INSPIDUS? When the pituitary gland does not secrete antidiuretic hormone or the kidney does not respond to the hormone. What causes DIABETES INSIPIDUS? It can be caused by damage to the pituitary or kidney damage. What is DIABETES MELLITUS? Tends to be hereditary, caused by lack of insulin secretion in the pancreas, or resistance to insulin in the body’s cell. Two different types: Type I & Type II What is TYPE I DIABETES? Insulin dependent, develops in children It is caused by the destruction of pancreatic islets by autoimmune disorders. They must have insulin injections daily throughout life. What is TYPE II DIABETES? Much more common Usually appears after 40 It is a consequence of obesity They produce insulin, but their cells are less sensitive to the effects of insulin. Steps of treatment: 1. Diet & exercise 2. Oral medicine or injected insulin What do the OVARIES do? Secrete progesterone: prepares uterus for pregnancy Secrete estrogen: * Female characteristics * Stores enough for several months What is the primary sex organ in males? *Testes are primary sex organ, NOT the penis! *Promotes formation of sperm *Maintains secondary sex characteristics. Endocrine gland: What does the Heart do? Pumps blood & produces hormones The heart is an organ that is an endocrine gland What does the GI Tract do? Digest food & produces hormones The GI TRACT is an organ that is an endocrine gland What does the Liver do? Makes enzymes & produces hormones (Calcium metabolism) The liver is an organ that is an endocrine gland What do the kidneys do? Calcium metabolism RBC Production The kidneys are organs that is an endocrine gland Function of DERMIS? Calcium Metabolism Vitamin D *Epithelial glands that have ducts are NOT endocrine glands! The dermis is an organ that is an endocrine gland What is the function of the LUNGS? Oxygenates & produces hormones The lungs are organs that is an endocrine gland The function of BONES? Synthesize & secrete Vitamin D Bones are organs that is an endocrine gland The function of the PLACENTA? Oxygenates & produces hormones The placenta is an organ that is an endocrine gland What does NOT make hormones? Epithelial Glands The only thing that does NOT make hormones is epithelial glands that have ducts. (Hormone glands are by definition without ducts) Hormone: ADH Where Made: Posterior Pituitary Target Organ: Kidney Effect: Increases water absorption Hormone: Parathyroid Where Made: Parathyroid Gland Target Organ: Bone, Kidney & Intestines Effect: Increases blood volume Hormone: Thyroid Where Made: Thyroid Gland Target Organ: Most Cells Effect: Increases Metabolic Rate Hormone: ACTH Where Made: Anterior Pituitary Target Organ: Adrenal Cortex Effect: Stimulates release of cortisol Hormone: Cortisol Where Made: Adrenal Cortex Target Organ: Most Cells Effect: Affects glucose & protein blood levels & metabolic rates Are steroids dangerous? Yes, because: - Synthetic testosterone is taken in doses 100X larger than a prescription. Increase rage & aggression Cause kidney & liver disease Cause impotency & sterility Baldness Decrease the size of testicles Cause low sperm count Give women hair on face & chest Enlarge breast on males Decrease female breasts Cancer Severe Acne High blood pressure & high cholesterol Can stunt bone growth in those that have not yet finished growing Shorten life span by several decades Which gland sits on top of each kidney? adrenal