Anatomy and Physiology The Endocrine System The endocrine system includes anything that secretes hormones directly into body fluids. Endocrine glands include: the thyroid, parathyroid, adrenal, kidney, hypothalamus, pituitary, pineal, pancreas, ovaries, testes, and thymus glands. The function of the endocrine systems is to regulate metabolic pathways (chemical rxns, electrolyte balance, membrane transport, reproduction, & digestion) by secreting hormones. http://www.worsleyschool.net/science/files/ho rmones/mainpic.gif Some terms: Hormone: a biochemical that affects a specific metabolic pathway in another cell. These are secreted into body fluids & blood. These are mostly steroids and made from cholesterol but some are amines, peptides, proteins, and glycoproteins. Target cells (or organs): cells or organs that receive the hormone (cell that is affected). These cells have binding sites (a.k.a. receptors) for specific hormones. Hormones are placed in 2 groups: Steroid hormones and Nonsteroid hormones. Steroid Hormones: lipid soluble, meaning they easily pass (diffuse) thru membranes. These are formed from cholesterol usually. Nonsteroid hormones must bind to receptors of target cells (do not diffuse thru membranes). These are amines, peptides, proteins, and glycoproteins. Hormonal Secretion Control: This is done by negative feedback control. Mechanism that regulates the production of hormones based on the accumulation of another substance along a metabolic pathway. For example: The adrenal gland produces chemical A which continues a pathway: A BC D E When E is accumulated, it prevents (or inhibits) the adrenal gland from producing A. This is a negative feedback mechanism. http://faculty.clintoncc.suny.edu/faculty/Michael.G regory/files/Bio%20102/Bio%20102%20lectures/e ndocrine%20system/cortisol.gif http://www.google.com/imgres The Endocrine Glands and Their Hormones The Pituitary Gland: found in the base of the brain has 2 parts: anterior and posterior (based on the lobe of the brain in which it is found). controlled by the hypothalamus (by releasing hormones) http://images.encarta.msn.com/xrefmedia/aencmed/targets/illus /ilt/T012393A.gif The Pituitary Hormones: Anterior Pituitary Hormones: Growth Hormone (GH): stimulates growth of cells (increase in size & cell division). Prolactin (PRL): stimulates and sustains the milk production in new mothers. Thyroid-Stimulating Hormone (TSH): controls thyroid gland secretions and is partially regulated by the hypothalamus. Anterior Pituitary Hormones (cont’d): Adrenocorticotropic hormone (ACTH): controls the hormone production of the adrenal cortex. Stress may increase ACTH. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH): are released in the gonads (testes and ovaries). These are called gonadotropins. The Posterior Hormones: Antidiuretic hormone (ADH): decreases urine production by regulating the amount of water the kidneys excrete; therefore, regulating [water] in body fluids. Oxytocin (OT): considered an antidiuretic; it stimulates the uterine muscles to contract (causing contractions & birth), lactation b/c it stimulates milk-producing glands, and milk ejection. The Thyroid Gland and its hormones: This is located on both sides of the larynx and in front of the trachea. Thyroxine (a.k.a. T4 or tetraiodothyronine) has 4 atoms of iodine and Triiodothyronine (a.k.a. T3) has 3 atoms of iodine (is 5 times stronger). Both regulate the metabolism of carbs (stimulate their use), proteins (stimulate their production), & lipids (stimulate their breakdown). Calcitonin: not technically a thyroid hormone (b/c of the location of production). This regulates the [Ca] and [phosphate ions] in the blood. Thyroid http://stb.msn.com/i/D8/DF6013611CDFDC22A8FB8E28C1DFF.jpg The Parathyroid Glands and their hormones: These 4 are found on the thyroid gland. These secrete parathyroid hormone (PTH): increases blood [Ca++] and decreases blood [phosphate ion], affecting the kidneys, bones & intestines. This works with calcitonin and is regulated by the [ ] of these ions in the blood. http://stb.msn.com/i/BD/F8BC26E3251ABD2F3FEA4 607A1D47.jpg The Adrenal Glands and their hormones: This is located on top of the kidneys and contains 2 portions: adrenal medulla (central portion) adrenal portion). cortex (outer http://www.massgeneral.org/cancer/crr/types/endocrine/images/ adrenal_gland.jpg The Adrenal Cortical Hormones: Aldosterone: regulates the [mineral] in the blood, stimulating water retention and sustaining b.p. and volume. Cortisol: a.ka. hydrocortisone, affects glucose, protein & fat metabolism. Adrenal Sex Hormones: in males, a.k.a. adrenal androgens; in females, a.k.a. estrogens. These supplement sex hormones & stimulate gonad development. The Adrenal Medulla Hormones: Epinephrine (a.k.a. adrenaline) and norepinephrine (a.k.a. noradrenaline) are released simultaneously. These increase the heart rate, increase heart contractions, increase breathing rate, increase b.p., increase blood glucose levels, & decrease digestion causing the typical “fight or flight reaction” The Pancreas and its Hormones: This is found by the stomach and has 2 functions: exocrine gland (secretes digestive juices) and endocrine (releasing hormones). The endocrine section contains groups of cells known as the Islets of Langerhans which contain alpha cells (secrete glucagon) and beta cells (secrete insulin). http://www.pancreatic.org/atf/cf/%7BA69EE36 7-5C5C-4B26-A09464E9EA47D990%7D/image001.jpg The Pancreatic Hormones: Glucagon: produced by alpha cells; stimulates the breakdown of glycogen and amino acids. It raises [blood sugar] and is regulated by a low blood sugar (hypoglycemia). Insulin: produced by beta cells; stimulates the liver to make glycogen, promotes the transport of glucose into cells, stimulates protein synthesis and stimulates fat storage; thus, it decreases [blood sugar] and is regulated by a high blood sugar (hyperglycemia). Blood Sugar Regulation: http://www.endocrineweb.com/images/su gar.gif Other Endocrine Glands Pineal Glands: This is found in the brain on the upper portion of the thalamus. This secretes melatonin which regulates circadian rhythms (response to light and dark conditions of the environment. These rhythms dictate sleep patterns & seasonal cycles of fertility in some mammals. http://training.seer.cancer.gov/module_anatomy/images/illu_pituitary_ pineal_glands.jpg Thymus Gland: This is found between the lungs (shrinks with age). This secretes thymosins which regulate the production & differentiation of white blood cells, specifically T cells (T lymphocytes) http://www.besthealth.com/besthealth/bodyguide/reftex t/images/Thymus_spleen.jpg Reproductive Glands: Ovaries: produce estrogens & progesterone Testes: produce testosterone Placenta: produces estrogens, progesterone & gonadotropin http://www.nlm.nih.gov/medlineplus/enc y/images/ency/fullsize/17122.jpg http://www.actionhealthinc.org/teenzone/ima ges/female.jpg http://www.malecontraceptives.org/methods/im ages/heat.jpg Heart: produces atrial natriuretic peptide (stimulates urinary Na secretion). Kidneys: produce erythropoietin (stimulates the production of rbc’s). http://www.nhlbi.nih.gov/health/dci/images/heart_interior.gif http://www.healthline.com/blogs/health_observances/upl oaded_images/kidney-713543.jpg Stress and Health: Stress is defined as a condition that causes change in the internal environment (a physiological response that alters homeostasis). A stressor is a factor that causes stress. http://www.google.com/imgres Stress and Health: There are types of stressors: physical which can be temperature changes internally or externally, [O2] changes, injury, illness (infections), exercise, noise, etc. psychological factors which include emotions, feelings (anger, joy, fear, grief, anxiety, depression, etc.), thoughts, losses, unpleasant and pleasant encounters, and sexual arousals/encounters. http://www.google.com/imgres Response to stress: These are physiological responses, called general stress syndrome, which is an adaptation to general stress. This is controlled by the hypothalamus which activates fight or flight rxns (increases epinephrine output). The physical responses include: Increased [blood glucose] levels increased heart rate increased rate of breathing increased b.p. air passage dilation http://www.google.com/imgres Other hormones are increased in output as well: glucagons, GH (both increase use of energy sources) and ADH (decrease urine output, conserving water, & maintaining blood volume). In addition, cortisol is increased which decreases the # of lymphocytes (increasing risk of infection/illness by lowering resistance and increasing the risk of high b.p., GI ulcers and atherosclerosis). Look up online or in text! Know the following: dwarfism, gigantism, acromegaly, diabetes insipidus, goiters, Grave’s disease, cretinism, exophthalmos, tetany, Addison’s disease, Cushing’s syndrome, diabetes mellitus, ketosis, polyuria, polydipsia, polyphagia, insulin resistance, and menopause.