Endocrine System PPT Part 2 PDF

Endocrine System Part 2  Thyroid Gland Lies inferior to thyroid cartilage of larynx Consists of two lobes connected by narrow isthmus – Thyroid follicles Hollow spheres lined by cuboidal epithelium Cells surround follicle cavity that contains v...

Endocrine System Part 2  Thyroid Gland Lies inferior to thyroid cartilage of larynx Consists of two lobes connected by narrow isthmus – Thyroid follicles Hollow spheres lined by cuboidal epithelium Cells surround follicle cavity that contains viscous colloid Surrounded by network of capillaries that – deliver nutrients and regulatory hormones – accept secretory products and metabolic wastes  The Thyroid Gland Thyriod-Releasing Hormone (TRH) – Released from the hypothalamus Thyroid-Stimulating Hormone (TSH) – Released from the anterior pituitary – Binds to membrane receptors on follicular cells – Activates enzymes in thyroid hormone production – Absence causes thyroid follicles to become inactive Neither synthesis nor secretion occurs T3 & T4- – Released from the thyroid gland – High levels inhibit TRH and TSH release (negative feedback inhibition)  Thyroid Gland Products Follicular Cells Produce: – Thyroglobulin (Globular Protein) Transport proteins Attach to most T4 and T3 molecules in the bloodstream – Thyroxine (T4) – contains 4 Iodine molecule- generally more T4 than T3 – Triiodothyronine (T3) – contains 3 Iodine molecules- more potent than T4 Parafollicular (C – Cells) Produce: – Calcitonin (more on this soon)  Thyroid Hormone Functions Thyroid Hormones (T3 and T4) – Enter target cells – Affect most cells in body – Bind to receptors in Cytoplasm Surfaces of mitochondria Nucleus – In children, essential to normal development of Skeletal, muscular, and nervous systems – Calorigenic Effect Cell consumes more energy resulting in increased heat generation Is responsible for strong, immediate, and short-lived increase in rate of cellular metabolism Thyroid Hormone Functions  Hyperthyroidism Hyperthyroidism- any elevation of T3/T4 above normal Graves Disease: – ONE CAUSE (not the only cause) of too much thyroxin produced and secreted – Autoimmune disease (Antibodies stimulate the thyroid gland to make T3/T4) – Signs/Symptoms: nervousness, and an increase in the following: body temp., heart rate, metabolic rate, blood pressure, weight loss  Graves Disease Signs Goiter= Enlarged Thyroid Gland Due to binding of the antibodies to the thyroid follicles Graves' ophthalmopathy (protrusion of eyes) Marty Feldman , Missy Elliott  Levels of Hormone Disorders Primary- Something is wrong at the level of the gland -I.E. Lack of iodine results in primary hypothyroidism Secondary- Something is wrong at the level of the pituitary gland -I.E. Pituitary gland tumor decreases TSH release resulting in decreased T3/T4 Tertiary- Something is wrong at the level of the hypothalamus -I.E. hypothalamic tumor decreases TRH release, which decreases TSH release, which decreases T3/T4 Hypothyroidis m Not enough iodine in the diet (iodine deficiency) – Causes swelling of the thyroid gland Leads to a decreased metabolic rate, weight gain, fatigue, depression, lower body temp. Iodine and T3/T4 Production  Hypothyroidism - Goiter The entire neck looks swollen because of the large thyroid. – Due to excess TSH stimulating follicular cell growth – Mass can compress the trachea & esophagus leading to coughing, waking up from sleep feeling like you can’t breath, and the sensation that food is getting stuck in the upper throat. – Once a goiter is large enough to cause these symptoms, surgical removal is the only means to relieve the discomfort  Thyroid Gland C (Clear) Cells of the Thyroid Gland – Produce calcitonin (CT) Helps regulate concentrations of Ca2+ in body fluids Inhibits osteoclasts, stimulates osteoblasts to retain Ca2+ , lowering blood calcium  Parathyroid Glands · 4 tiny masses on the posterior of the thyroid · Parathyroid hormone (PTH) · Produced by chief cells (in response to low concentrations of Ca2+)  Parathyroid Glands Four Effects of PTH 1. It stimulates osteoclasts Accelerates mineral turnover and releases Ca2+ from bone 2. It inhibits osteoblasts Reduces rate of calcium deposition in bone 3. It enhances reabsorption of Ca 2+ at kidneys, reducing urinary loss 4. It stimulates formation and secretion of calcitriol at kidneys (calcitriol active version of vitamin D3, increases blood Ca levels) Parathyroi d Glands & Blood Calcium Homeosta sis  Suprarenal (Adrenal) Glands Lie along superior border of each kidney Divided into – Superficial adrenal cortex Stores lipids, especially cholesterol and fatty acids Manufactures steroid hormones: adrenocortical steroids (corticosteroids) – Inner renal medulla Secretory activities controlled by sympathetic division of ANS Metabolic changes persist for several minutes Supraren al (Adrenal) Glands  Adrenal Cortex Subdivided into 3 regions: 1. Zona glomerulosa Mineralocorticoids- primarily aldosterone 2. Zona fasciculata Glucocorticoids- cortisol, corticosterone, hydrocortisone 3. Zona reticularis Androgens- testosterone, DHEA  Adrenal Medulla – Makes Adrenaline (Epinephrine) Adrenal Medulla – Contains two types of secretory cells One produces epinephrine (adrenaline) – 75 to 80% of medullary secretions The other produces norepinephrine (noradrenaline) – 20 to 25% of  Zona Glomerulosa – Makes Mineralcorticoids Aldosterone (main mineralcorticoid) – Targets kidney tubules – Stimulates: CONSERVATION OF SODIUM IONS ELIMINATION OF POTASSIUM IONS – Increases sensitivity of salt receptors in taste buds – Secretion responds to: drop in blood Na+, blood volume, or blood pressure rise in blood K+ concentration Zona Fasciculate – Makes Glucocorticoids Produces glucocorticoids under stimulation by ACTH Glucocorticoids (ie: cortisol and hydrocortisone) – Targets most cells in the body – Accelerates glucose synthesis and glycogen formation (raises blood glucose) – Show anti-inflammatory effects: Inhibits activities of white blood cells and other components of immune system (when released in reasonable amounts) Zona Reticularis – Makes Androgens (Male Sex Hormones) Effects most cells in the body Network of endocrine cells Forms narrow band bordering each adrenal medulla Produces androgens under stimulation by ACTH  Adrenal Gland Negative Feedback Loop Short term Vs Long Term Stress  Pineal Gland Lies in posterior portion of roof of third ventricle Contains pinealocytes – Synthesize hormone melatonin Inhibiting reproductive functions Protecting against damage by free radicals Setting circadian rhythms (sleep – wake cycle)  Pancreas Lies between – Inferior border of stomach and proximal portion of small intestine Contains exocrine and endocrine cells – YOU SHOULD REMEMBER THE DIFFERENCE! Pancreas - Islets of Langerhans Insulin – lowers blood glucose Stimulates glucose uptake by cells (primarily liver and skeletal muscle) Produced by Beta Cells Glucagon – raises blood glucose Promotes of glycogen in the liver to glucose and  Insulin Pancreas – Is a peptide hormone released by beta cells – Affects target cells Accelerates glucose uptake Accelerates glucose utilization and enhances ATP production Stimulates glycogen formation Stimulates amino acid absorption and protein synthesis Stimulates triglyceride formation in adipose tissue  Glucagon – Released by alpha cells – Mobilizes energy reserves – Affects target cells Pancreas Stimulates breakdown of glycogen in skeletal muscle and liver cells Stimulates breakdown of triglycerides in adipose tissue Stimulates production of glucose in liver  Endocrine System Control Regulation of Blood Sugar insulin liver & skeletal body muscle reduces cells take stores appetite pancreas up sugar sugar from blood high blood sugar level (90mg/100ml) low Liver & skeletal muscle triggers releases hunger sugar pancreas glucagon  Type I Diabetes Mellitus Type 1 Diabetes is an autoimmune disorder – Both Type 1 & 2 are characterized by hyperglycemia Type 1 used to be called “juvenile onset”- In type 1 diabetes, the immune system destroys beta cells in the islets. No beta cells, no insulin being produced No insulin means that glucose circulates in the blood stream instead of being taken up and stored Signs/Symptoms-3 P’s – Polyuria- excessive urination – Polydipsia-excessive drinking – Polyphagia-excessive eating – Fatigue  Type II Diabetes Mellitus Type 2 Diabetes Causes Obesity/hyperglycemia due to lifestyle – Sedentary – Poor diet Genetic inheritance – No single “diabetes” gene for most people Signs/Symptoms-3 P’s – Polyuria- excessive urination – Polydipsia-excessive drinking – Polyphagia-excessive eating – Fatigue  Type II Diabetes Mellitus Type 2 Diabetes – Beta cells still produce insulin. – Stages of Type 2 Diabetes 1st- the body starts oversecreting insulin due to chronic hyperglycemia 2nd- downregulation of insulin receptors on target cells due to excess insulin 3rd- Cells think they are starving due to lack of glucose b/c insulin receptors are not allowing the cells to take up glucose. So the cells send signals to liver for more glucose 4th- Liver secretes more glucose, so pancreas secretes more insulin 5th- Pancreas no longer able to secrete insulin “Islet Cell Burnout”  Gestational Diabetes Cause Hormones from the placenta can block the action of the mother's insulin in her body- called insulin resistance. – Results in hyperglycemia. – Growing fetus needs additional nutrition, this ensures that the baby receives enough nutrients About 4% of all pregnant women - about 135,000 cases in the United States each year. Most of the time giving birth solves the problem, some women develop persistent DM type 2 following birth.  Results from problems in pituitary gland or hypothalamus Diabetes – Does NOT result in hyperglycemia – Insipidus – Caused by ADH deficiency (aka vasopressin). Decreased ADH secretion decreases kidney’s ability to conserve water, so more urine is created. – Trauma or tumors may also cause the condition  Growth Hormone (GH) · Also called Somatotropin · Major effects are directed to growth of skeletal muscles and long bones · Causes amino acids to be built into proteins · Causes fats to be broken down for a source of energy In children Supports muscular and skeletal development In adults Maintains normal blood glucose concentrations Mobilizes lipid reserves  Gigantism Stimulates development of the long bones of the body Gigantism: oversecretion of GH; usually the result of a 12 year old boy tumor on the pituitary Measure 6-5 gland Oversecretion of growth hormone Occurs during childhood Tallest man 8 feet 11 inches! Tallest Man Video Clip  Acromegaly Growth Hormone over-secretion after epiphyseal plates have closed – Occurs in adults – Bones of hands face and feet are enlarged  Andre The Giant Both acromegaly & gigantism 7'4" and 500 pounds Princess Bride  Dwarfism Dwarfism is not always caused by GH deficiencies Pituitary or proportionate dwarfism – Under secretion of growth hormone during childhood. – Patients have short stature but proportional bodies.  Growth In General Hormones Important to Growth – GH – Thyroid hormones – Insulin – PTH – Calcitriol – Reproductive hormones  Growth Hormones Thyroid Hormones – If absent during fetal development or for first year Nervous system fails to develop normally Cognitive deficits result – If T4 concentrations decline before puberty Normal skeletal development will not continue Insulin – Allows passage of glucose and amino acids across plasma membranes Parathyroid Hormone (PTH) and Calcitriol – Promote absorption of calcium salts for deposition in bone – Inadequate levels causes weak and flexible  Growth Hormones Reproductive Hormones – Androgens in males, estrogens in females – Stimulate cell growth and differentiation in target tissues – Produce gender-related differences in Skeletal proportions Secondary sex characteristics  General Adaptation Syndrome (GAS) Our body’s reaction to stress 3 stages – Stage 1: Alarm reaction (AR) – Stage 2: Stage of resistance (SR) – Stage 3: Stage of exhaustion (SE) TREATMENT Typically involves one or more stress reduction strategies which generally fall into one of three categories: Avoiding stressors; Changing one's reaction to the stressor(s); Relieving stress after the reaction to the stressor(s).  General Adaptation Syndrome Stage 1: Alarm reaction (AR) (GAS) Immediate reaction to a stressor. "fight or flight" response- prepares the body for physical activity. However, this initial response can also decrease the effectiveness of the immune system, making persons more susceptible to illness during this phase.  General Adaptation Stage 2: Stage of resistance (SR) Syndrome (GAS) Also might be named the stage of adaptation The body adapts to the stressors it is exposed to. Changes at many levels take place in order to reduce the effect of the stressor. For example, if the stressor is starvation (possibly due to anorexia), the person might experienced a reduced desire for physical activity to conserve energy, and the absorption of nutrients from food might be maximized.  General Adaptation Syndrome Stage 3: Stage of exhaustion (SE) (GAS) Stress has continued for some time (weeks to months) Resistance to the stress may gradually be reduced, or may collapse quickly. The immune system, and the body's ability to resist disease, may be almost totally eliminated. May result in heart attacks or severe infection due to reduced immunity. For example, a person with a stressful job may experience long-term stress that might lead to high blood pressure and an eventual heart attack.  Endocrine Tissues of Other Systems Many organs of other body systems have secondary endocrine functions – Intestines (digestive system) – Kidneys (urinary system) – Heart (cardiovascular system) – Thymus (lymphoid system and immunity) – Gonads (reproductive system) – Breast Tissue (reproductive system)  Endocrine Tissues of Other Systems Intestines (more on this in the digestion unit!) – Produce hormones important to coordination of digestive activities Gastrin- causes secretion of HCl Cholestocystikinin- causes emptying of gallbladder & pancreas Kidneys (more on this in the renal unit!) – Calcitriol- hormonally active metabolite of Vitamin D, causes calcium uptake from digestive system – Erythropoietin- stimulates formation of red blood cells – Produce the enzyme renin which is critical for angiotensin formation  Endocrine Tissues of Other Systems Heart – Produces natriuretic peptides (ANP and BNP) When blood volume becomes excessive Action opposes angiotensin II Resulting in reduction in blood volume and blood pressure Thymus – Produces thymosins (blend of thymic hormones) Critical for development of immune system and T cells during childhood Help maintain adult immune system  Endocrine Tissues of Other Systems Testes (Gonads) – Produce androgens in interstitial cells Testosterone is the most important male hormone – Secrete inhibin in nurse cells Support differentiation and physical maturation of sperm  Endocrine Tissues of Other Systems Ovaries (Gonads) – Produce estrogens Principle estrogen is estradiol – After ovulation, follicle cells Reorganize into corpus luteum Release estrogens and progestins, especially progesterone Mammary Tissue responds to Prolactin (PRL) Stimulates and maintains milk production following childbirth Function in males is unknown  Endocrine Tissues of Other Systems Adipose Tissue Secretions – Leptin Feedback control for appetite – Resistin Reduces insulin sensitivity  Hormone Interactions Antagonistic (opposing) effects – – glucagon & insulin Synergistic (additive) effects – – norepinephrine & epinephrine Permissive effects: one hormone is necessary for another to produce effect – Thyroid hormone needed for epinephrine to increase metabolism Integrative effects: hormones produce different and complementary results – Parathyroid hormone and calcitriol increase blood calcium in different manners  Hormone Imbalance & Aging s Hormone Imbalance Effect – Can alter intellectual capabilities, memory, learning, and emotional states – Affect behavior when endocrine glands are over- secreting or under-secreting Aging – Decline in concentration of Growth hormone Reproductive hormones