BSC 2086 1st Edition Lecture 6 Outline of Last Lecture I. HormonesII. Pituitary Gland Outline of Current Lecture I. Thyroid GlandII. Parathyroid GlandIII. Adrenal Gland IV. Pineal GlandV. Pancreas VI. Endocrine Tissues of Other SystemsVII. Hormone InteractionsCurrent LectureI. Thyroid Glanda. Location: i. Anterior to thyroid cartilage of the larynx (throat)ii. Made up of 2 lobes connected by isthmus 1. Thyroid follicles: surrounded by capillary network that delivers nutrients and hormones as well as accepts wastes and other products that need to be secreted.b. Hormones:i. Thyroxine (T4)1. AKA. tetraiodothyronine2. Made of 4 iodide ionsii. Triiodothryronine (T3)1. Made of 3 iodide ionsc. Binding molecules i. Thyroid-binding Globulins (TBGs)1. Bind majority of T4 and T3ii. Transthyretin and albumin (protein abundant in blood)1. Binds almost all remaining thyroid hormones iii. Some remain unboundd. Thyroid Stimulating Hormone (TSH)i. Secreted by anterior pituitary glandii. Stimulates the production of thyroid hormone iii. Absence of TSH leads to inactivation of thyroid follicles iv. Absence of iodine reduces production since the thyroid hormones are made up of iodide ions. The thyroid gland begins to enlarge because its cells are overworking themselves to make the hormones with only a limited supply of iodine. e. Calorigenic Effecti. Heat is generated due to increase energy consumption by the cellii. This causes increased rate in cell metabolism immediately for a short period of timeiii. Essential to child’s normal development f. Functions:i. Rise of body temperature due to elevation in oxygen and energy consumptionii. Raises blood pressure by increasing heart rate iii. Increases sensitivity to sympathetic stimulationiv. Keeps normal sensitivity to respiratory centersv. Stimulates red blood cell formation and activity in endocrine tissuesvi. Speeds up turnover of minerals in boneg. Abnormal thyroid hormone productioni. Congenital hypothyroidism: stunted bone growth and mental retardation 1. Cretinism ii. Adult hypothyroidism: slow heart rate, low body temperature, sensitive to cold, muscle weakness 1. Myxedema iii. Hyperthyroidism: excessive release of TH1. Graves disease: antibodies mimic TSH, causing an autoimmune disease h. C cells Calcitonini. Calcitonin (CT) is used to lower calcium concentrations by inhibiting osteoclasts and stimulating calcium excretion by kidneys II. Parathyroid Glanda. Location:i. Posterior surface of thyroid gland b. Hormones:i. Parathyroid Hormone (PTH)1. Respond to low concentrations of calcium2. Antagonist of calcitonin3. Increases calcium levels 4. Stimulates osteoclasts and stops osteoblasts5. Reabsorption of calcium in the kidneys 6. Starts formation and secretion of calcitriol by the kidneysa. Compliments and enhances PTH III. Adrenal Gland a. Location: i. Upper border of the kidneyb. Divided into:i. Superficial adrenal cortex1. Controlled by ACTH which is secreted by the anterior pituitary2. Manufactures corticosteroids3. Stores lipids and glucoseii. Inner adrenal medulla1. Controlled by sympathetic division of ANS2. Makes epinephrine and norepinephrine a. Increases heart rate and reduces blood flow to stomach and intestines so more blood can reach the brain and the heartc. Adrenal Cortex Hormones:i. Mineralocorticoids (Ex. Aldosterone)1. Regulate ion levels conserves sodium and eliminates potassium2. Responds to drop in potassium 3. Aldosteronism: excess aldosteronea. Increases body weight due to sodium retentionii. Glucocorticoids (Ex. cortisol (hydrocortisone) with corticosterone)1. Regulate glucose metabolism2. Some cortisol will be converted to cortisone by liver, and some willgo back to hypothalamus and receive hormones 3. Regulated by nugatory feedback4. Inhibits production of:a. Corticotropin-releasing hormone (CRH) in hypothalamusb. ACTH in anterior pituitary c. Inhibits its own release5. Has anti-inflammatory effects by stopping activities of white bloodcells a. Cant be used to treat open wounds iii. Androgens 1. Virilization: excessive hair growth caused by hypersecretion2. Amenorrhea: loss of menstruation in women caused by hypersecretion iv. Abnormal Production1. Addison’s Disease: hyposecretion of glucocorticoids and aldosteronea. Energy reserves are low, causing tiredness and loss of appetiteb. High potassium, low sodium2. Cushing’s Syndrome: hypersecretion of cortisola. Released in times of stressb. Moon face and buffalo humpc. Breakdown of proteins in muscles d. Adrenal Medulla Hormones:i. Epinephrine (adrenaline)ii. Norepinephrine (noradrenaline)e. Functions:i. Both work to increase metabolic rate for a fight or flight responseii. Skeletal muscles:1. Trigger mobilization of glycogen reserves2. Speeds up break down of glucose to create ATP which increases muscles strength and endurance iii. Adipose tissue:1. Break down stored fats into fatty acids 2. Release into blood for other tissues to use to make ATPiv. Liver1. Break down glycogen into glucose which is released into blood 2. Used by neural tissue v. Heart1. Beta 1 receptors stimulated and cause increase in rate and force of cardiac muscle IV. Pineal Gland a. Location: i. In the brain, on posterior part of 3rd ventricleb. Synthesized melatonin which:i. Inhibits reproductive functionsii. Is an effective antioxidant by protecting against free radicalsiii. Influences day and nigh cycles, as well as other circadian rhythmsV. Pancreasa. Location: i. Inferior to the stomach and proximal to small intestineb. Exocrine Pancreasi. Roughly 99% of pancreatic volumeii. Pancreatic acini: clusters of gland cellsiii. Secrete alkaline (enzyme rich fluid)1. Helps with digestionc. Endocrine Pancreasi. Pancreatic islets: cluster of cellsii. Alpha cells: produce glucagon to break down glycogen when glucose is lowiii. Beta cells : produce insulin after a meal to capture glucose moleculesd. Insulini. Peptide hormoneii. Accelerates glucose uptake and utilization to increase ATPiii. Stimulates formation of glycogen and triglycerides in adipose tissueiv. Stimulates protein synthesisv. Diabetes Mellitus:1. Type 1: insulin dependent a. Inadequate insulin production by beta cellsb. Hyperglycemia: high glucose levels in the blood i. Glycosuria: glucose in urineii. Polyuria: excessive urine2. Type 2: non-insulin dependent a. Most commonb. Insulin resistancec. Associated with obesity 3. Complications: a. Diabetic nephropathyi. Kidney degenerationb. Diabetic retinopathyi. Retinal damage
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