Chapter 17: Endocrine System
Give a physiological definition of stress.
Stress—situation that upsets homeostasis and threatens one's physical or emotional well-being -Injury, surgery, infection, intense exercise, pain, grief, depression, anger, etc.
Name several organs of the endocrine system.
hypothalamus. pituitary gland. thyroid. parathyroids. adrenal glands. pineal body. reproductive glands (which include the ovaries and testes) pancreas.
Contrast endocrine with exocrine glands.
Exocrine glands: -Have ducts; carry secretion to an epithelial surface or the mucosa of the digestive tract: "external secretions" -Extracellular effects (food digestion) Endocrine glands: -No ducts -Contain dense, fenestrated capillary networks which allow easy uptake of hormones into bloodstream -"Internal secretions" -Intracellular effects such as altering target cell metabolism **Liver cells defy rigid classification—releases hormones, releases bile into ducts, releases albumin and blood-clotting factors into blood (not hormones)
Explain what eicosanoids are and how they are produced.
•Eicosanoids—important family of paracrines -Derived from fatty acid called arachidonic acid •Lipoxygenase converts arachidonic acid into leukotrienes -Leukotrienes •Mediate allergic and inflammatory reactions
List the hormones produced by the hypothalamus and each lobe of the pituitary, and identify the functions of each hormone.
•Eight hormones produced in hypothalamus •Six hypothalamic releasing and inhibiting hormones stimulate or inhibit the anterior pituitary -TRH, CRH, GnRH, and GHRH are releasing hormones that promote anterior pituitary secretion of TSH, PRL, ACTH, FSH, LH, and GH -PIH inhibits secretion of prolactin, and somatostatin inhibits secretion growth hormone and thyroid-stimulating hormone by the anterior pituitary •Two other hypothalamic hormones are oxytocin (OT) and antidiuretic hormone (ADH) -Both stored and released by posterior pituitary -Paraventricular nuclei of hypothalamus produce OT -Supraoptic nuclei produce ADH -Posterior pituitary does not synthesize them
Discuss how hormones are removed from circulation after they have performed their roles.
•Hormone signals must be turned off when they have served their purpose •Most hormones are taken up and degraded by liver and kidney -Excreted in bile or urine •Metabolic clearance rate (MCR) -Rate of hormone removal from the blood -Half-life: time required to clear 50% of hormone from the blood -The faster the MCF, the shorter the half-life
Name the hormones these endocrine glands produce, what stimulates their secretion, and their functions.
•Pineal gland -May synchronize physiological function with 24-hour circadian rhythms of daylight and darkness -Synthesizes melatonin from serotonin during the night -May influence timing of puberty in humans •Thymus -Plays a role in three systems: endocrine, lymphatic and immune -Site of maturation of T cells, important in immune defense -Secretes hormones (thymopoietin, thymosin, and thymulin) that stimulate development of other lymphatic organs and activity of T lymphocytes •Thyroid -Increases metabolic rate, O2 consumption, heat production (calorigenic effect), appetite, growth hormone secretion, alertness, reflex speed -Follicular cells secrete thyroxine (T4 because of four iodine atoms) and triiodothyronine (T3) in response to TSH. -Stimulates osteoblast activity and bone formation in children. -Parafollicular cells secrete calcitonin in response to rising blood calcium levels. •Parathyroid Glands -Secrete parathyroid hormone (PTH) -Increases blood Ca2+ levels •Promotes synthesis of calcitriol •Increases absorption of Ca2+ •Decreases urinary excretion •Increases bone resorption •Adrenal Glands Cortex: •Has dual nature acting as an endocrine gland and a ganglion of the sympathetic nervous system -Innervated by sympathetic preganglionic fibers -Consists of modified sympathetic postganglionic neurons called chromaffin cells -When stimulated, release catecholamines (epinephrine and norepinephrine) directly into the bloodstream •As hormones, catecholamines have multiple effects -Increase alertness and prepare body for physical activity •Mobilize high-energy fuels, lactate, fatty acids, and glucose •Glycogenolysis and gluconeogenesis by liver boost glucose levels •Epinephrine inhibits insulin secretion and so has a glucose-sparing effect -Muscles use fatty acids, saving glucose for brain -Increase blood pressure, heart rate, blood flow to muscles, pulmonary airflow, and metabolic rate -Decrease digestion and urine production Medulla: -Secretes several corticosteroids (hormones) from three layers of glandular tissue -Zona glomerulosa (thin, outer layer) •Cells are arranged in rounded clusters •Secretes mineralocorticoids—regulate the body's electrolyte balance -Zona fasciculata (thick, middle layer) •Cells arranged in fascicles separated by capillaries •Secretes glucocorticoids and androgens -Zona reticularis (narrow, inner layer) •Cells in branching network •Secretes glucocorticoids and sex steroids •Mineralocorticoids—from zona glomerulosa -Steroid hormones that regulate electrolyte balance -Aldosterone stimulates Na+retention and K+excretion •Water is retained with sodium by osmosis, so blood volume and blood pressure are maintained •Part of the renin-angiotensin-aldosterone (RAA) system •Glucocorticoids -Secreted by zona fasciculata and zona reticulata in response to ACTH -Regulate metabolism of glucose and other fuels -Cortisol and corticosterone stimulate fat and protein catabolism, gluconeogenesis (glucose from amino acids and fatty acids) and release of fatty acids and glucose into blood -Help body adapt to stress and repair tissues -Anti-inflammatory effect becomes immune suppression with long-term use •Medulla and cortex of adrenal gland are not functionally independent •Medulla atrophies without the stimulation of cortisol •Some chromaffin cells of medullary origin extend into the cortex -They stimulate the cortex to secrete corticosteroids when stress activates the sympathetic nervous system •Pancreatic Islets Glucagon—secreted by A or alpha (α) cells -Released between meals when blood glucose concentration is falling -In liver, stimulates gluconeogenesis, glycogenolysis, and the release of glucose into the circulation raising blood glucose level -In adipose tissue, stimulates fat catabolism and release of free fatty acids -Glucagon also released to rising amino acid levels in blood, promotes amino acid absorption, and provides cells with raw material for gluconeogenesis Insulin secreted by B or beta (β) cells -Secreted during and after meal when glucose and amino acid blood levels are rising -Stimulates cells to absorb these nutrients and store or metabolize them, lowering blood glucose levels •Promotes synthesis glycogen, fat, and protein •Suppresses use of already-stored fuels •Brain, liver, kidneys, and RBCs absorb glucose without insulin, but other tissues require insulin -Insufficiency or inaction is cause of diabetes mellitus •Somatostatin secreted by D or delta (δ) cells -Partially suppresses secretion of glucagon and insulin -Inhibits nutrient digestion and absorption which prolongs absorption of nutrients •Pancreas also has PP and Gcells of uncertain function •Hyperglycemic hormones raise blood glucose concentration (includes hormones from other glands) -Glucagon, growth hormone, epinephrine, norepinephrine, cortisol, and corticosterone •Hypoglycemic hormones lower blood glucose -Insulin •Gonads -Ovaries and testes are both endocrine and exocrine -Exocrine product: whole cells—eggs and sperm (cytogenic glands) -Endocrine product: gonadal hormones—mostly steroids •Ovarian hormones -Estradiol, progesterone, and inhibin •Testicular hormones -Testosterone, weaker androgens, estrogen, and inhibin •Ovary -Theca cells synthesize androstenedione -Converted to mainly estradiol by granulosa cells •After ovulation, the remains of the follicle becomes the corpus luteum -Secretes progesterone for 12 days following ovulation -Follicle and corpus luteum secrete inhibin •Functions of estradiol and progesterone -Development of female reproductive system and physique including adolescent bone growth -Regulate menstrual cycle, sustain pregnancy -Prepare mammary glands for lactation •Inhibin suppresses FSH secretion from anterior pituitary •Testes -Microscopic seminiferous tubules produce sperm -Tubule walls contain sustentacular (Sertoli) cells -Leydig cells (interstitial cells) lie in clusters between tubules •Testicular hormones -Testosterone and other steroids from interstitial cells nestled between the tubules •Stimulates development of male reproductive system in fetus and adolescent, and sex drive •Sustains sperm production -Inhibin from Nurse cells •Limits FSH secretion in order to regulate sperm production
Describe how hormones affect each other when two or more of them stimulate the same target cells.
•Synergistic effects -Multiple hormones act together for greater effect •Synergism between FSH and testosterone on sperm production •Permissive effects -One hormone enhances the target organ's response to a second later hormone •Estrogen prepares uterus for action of progesterone •Antagonistic effects -One hormone opposes the action of another •Insulin lowers blood glucose and glycogen raises it
Explain how target cells regulate their sensitivity to circulating hormones.
•Target-cell sensitivity adjusted by changing the number of receptors •Up-regulation means number of receptors is increased -Sensitivity is increased •Down-regulation reduces number of receptors -Cell less sensitive to hormone -Happens with long-term exposure to high hormone concentrations
Describe similarities and differences between the nervous and endocrine systems.
Both systems serve for internal communication: •Speed and persistence of response -Nervous: reacts quickly (ms timescale), stops quickly -Endocrine: reacts slowly (seconds or days), effect may continue for days or longer •Adaptation to long-term stimuli -Nervous: response declines (adapts quickly) -Endocrine: response persists (adapts slowly) •Area of effect -Nervous: targeted and specific (one organ) -Endocrine: general, widespread effects (many organs) •Several chemicals function as both hormones and neurotransmitters: -Norepinephrine, dopamine, and antidiuretic hormone •Both systems can have similar effects on target cells -Norepinephrine and glucagon both cause glycogen hydrolysis in liver •The two systems can regulate each other -Neurotransmitters can affect glands, and hormones can affect neurons •Neuroendocrine cells share characteristics with both systems -Neuron-like cells that secrete oxytocin into blood •Target organs or cells—those organs or cells that have receptors for a hormone and can respond to it -Some target cells possess enzymes that convert a circulating hormone to its more active form
Define hormone and endocrine system.
Hormones—chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another tissue or organ, often a considerable distance away. Endocrine system—glands, tissues, and cells that secrete hormones.
Briefly describe some common disorders of pituitary, thyroid, parathyroid, and adrenal function.
Pituitary Disorders: •Hypersecretion of growth hormone (GH) -Acromegaly: thickening of bones and soft tissues in adults •Especially hands, feet, and face -Problems in childhood or adolescence (before growth plates are depleted) •Gigantism if hypersecretion •Pituitary dwarfism if hyposecretion—rare since growth hormone is now made by genetically engineered bacteria Thyroid and Parathyroid Disorders: •Congenital hypothyroidism (decreasedTH) -Hyposecretion present a birth -Treat with oral thyroid hormone •Myxedema (decreased TH) -Adult hypothyroidism -Treat with oral thyroid hormone •Goiter—any pathological enlargement of the thyroid gland -Endemic goiter (disease occurs in a geographic locality) •Dietary iodine deficiency, no TH, no feedback, increasedTSH stimulates hypertrophy •Hypoparathyroidism -Surgical excision during thyroid surgery -Fatal tetany (spasms in larynx) in just a few days due to rapid decline in blood calcium level •Hyperparathyroidism: excess PTH secretion -Parathyroid tumor -Bones become soft, fragile, and deformed -Ca2+and phosphate blood levels increase -Promotes renal calculi formation Adrenal Disorders •Cushing syndrome—excess cortisol secretion -Hyperglycemia, hypertension, weakness, edema -Rapid muscle and bone loss due to protein catabolism -Abnormal fat deposition •Moon face and buffalo hump •Adrenogenital syndrome (AGS) -Adrenal androgen hypersecretion (accompanies Cushing) -Enlargement of external sexual organs in children and early onset of puberty •Newborn girls exhibit masculinized genitalia -Masculinizing effects on women •Increased body hair, deeper voice, beard growth
Identify some classes and functions of eicosanoids.
•Cyclooxygenase converts arachidonic acid to three other types of eicosanoids: -Prostacyclin •Inhibits blood clotting and vasoconstriction -Thromboxanes •Produced by blood platelets after injury •Overrides prostacyclin •Stimulates vasoconstriction and clotting -Prostaglandins •PGE—relaxes smooth muscle in bladder, intestines, bronchioles, uterus; stimulates contraction of blood vessels •PGF—causes opposite effects Anti-Inflammatory Drugs •Cortisol and corticosterone -Steroidal anti-inflammatory drugs (SAIDs) -Inhibit inflammation by blocking release of arachidonic acid from plasma membrane and inhibit synthesis of eicosanoids •Disadvantage—produce symptoms of Cushing syndrome •Aspirin, ibuprofen, and celecoxib (Celebrex) -Nonsteroidal anti-inflammatory drugs (NSAIDs) •COX inhibitors since block cyclooxygenase (COX) •Do not affect lipoxygenase function or leukotriene production •Useful in treatment of fever and thrombosis -Inhibit prostaglandin and thromboxane synthesis
Describe several physiological roles of prostaglandins.
Prostaglandins •PGE—relaxes smooth muscle in bladder, intestines, bronchioles, uterus; stimulates contraction of blood vessels
Recognize the standard abbreviations for many hormones.
Thyroid-releasing hormone (TRH) Corticotropin-releasing hormone (CRH) Gonadotropin-releasing hormone (GnRH) Growth hormone releasing hormone (GHRH) Prolactin-inhibiting hormone (PIH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Thyroid-stimulating hormone (TSH) Thyroid hormone (TH) Oxytocin (OT) Antidiuretic hormone (ADH) Adrenocorticotropic hormone (ACTH) Prolactin (PRL) Growth hormone (GH)
Distinguish between the anterior and posterior lobes of the pituitary.
•Adenohypophysis (anterior lobe) constitutes anterior three-quarters of pituitary -Linked to hypothalamus by hypophysealportal system •Primary capillaries in hypothalamus connected to secondary capillaries in adenohypophysis by portal venules •Hypothalamic hormones regulate adenohypophysis cells -Hypothalamic-releasing and -inhibiting hormones travel in hypophysealportal system from hypothalamus to anterior pituitary -Different hormones are secreted by anterior pituitary •Neurohypophysis (posterior lobe) constitutes the posterior one-quarter of the pituitary -Nerve tissue, not a true gland •Nerve cell bodies in hypothalamus pass down the stalk as hypothalamo-hypophyseal tract and end in posterior lobe •Hypothalamic neurons secrete hormones that are stored in neurohypophysis until released into blood
Describe the effects of growth hormone.
•GH has widespread effects on the body tissues -Especially cartilage, bone, muscle, and fat •Induces liver to produce growth stimulants -Insulin-like growth factors (IGF-I) or somatomedins (IGF-II) •Stimulate target cells in diverse tissues •IGF-I prolongs the action of GH •Hormone half-life—the time required for 50% of the hormone to be cleared from the blood -GH half-life: 6 to 20 minutes -IGF-I half-life: about 20 hours •Induces liver to produce growth stimulants (continued) -Protein synthesis increases: boosts transcription and translation; increases amino acid uptake into cells; suppresses protein catabolism -Lipid metabolism increases: stimulates adipocytes to catabolize fats (protein-sparing effect) -Carbohydrate metabolism: glucose-sparing effect, mobilizing fatty acids reduces dependence of most cells on glucose, freeing more for the brain; stimulates glucose secretion by liver -Electrolyte balance: promotes Na+, K+, and Cl−retention by kidneys, enhances Ca2+absorption in intestine; makes electrolytes available to growing tissues •Bone growth, thickening, and remodeling influenced, especially during childhood and adolescence •Secretion high during first 2 hours of sleep •Can peak in response to vigorous exercise •Also activated by ghrelin, which is released by the empty stomach •GH levels decline gradually with age •Average 6 ng/mL during adolescence, 1.5 ng/mg in old age -Lack of protein synthesis contributes to aging of tissues and wrinkling of the skin -Age 30, average adult body is 10% bone, 30% muscle, 20% fat -Age 75, average adult body is 8% bone, 15% muscle, 40% fat
Discuss how the body adapts to stress through its endocrine and sympathetic nervous systems.
•General adaptation syndrome (GAS) -Consistent way the body reacts to stress; typically involves elevated levels of epinephrine and glucocorticoids (especially cortisol) The Alarm Reaction •Initial response -Mediated by norepinephrine from the sympathetic nervous system and epinephrine from the adrenal medulla -Prepares body for fight or flight -Stored glycogen is consumed -Increases aldosterone and angiotensin levels •Angiotensin helps raise blood pressure •Aldosterone promotes sodium and water conservation The Stage of Resistance 1 •After a few hours, glycogen reserves gone, but brain still needs glucose •Provide alternate fuels for metabolism •Stage dominated by cortisol •Hypothalamus secretes corticotropin-releasing hormone (CRH) •Pituitary secretes ACTH -Stimulates the adrenal cortex to secrete cortisol and other glucocorticoids -Promotes breakdown of fat and protein into glycerol, fatty acids, and amino acids, for gluconeogenesis The Stage of Resistance 2 •Cortisol has glucose-sparing effect—inhibits protein synthesis leaving free amino acids for gluconeogenesis -Adverse effects of excessive cortisol: •Depresses immune function •Increases susceptibility to infection and ulcers •Lymphoid tissues atrophy, antibody levels drop, and wounds heal poorly The Stage of Exhaustion •When stress continues for several months, and fat reserves are gone, homeostasis is overwhelmed -Often marked by rapid decline and death •Protein breakdown and muscle wasting •Loss of glucose homeostasis because adrenal cortex stops producing glucocorticoids •Aldosterone promotes water retention and hypertension -Conserves sodium and hastens elimination of K+and H+ -Hypokalemia and alkalosis leads to death •Death results from heart and kidney infection or overwhelming infection
Explain some general causes and examples of hormone hyposecretion and hypersecretion.
•Hyposecretion—inadequate hormone release -Tumor or lesion destroys gland or interferes with its ability to receive signals from another gland •Head trauma affects pituitary gland's ability to secrete ADH -Diabetes insipidus: chronic polyuria •Autoantibodies fail to distinguish person's own gland from foreign matter -One cause of diabetes mellitus •Hypersecretion—excessive hormone release -Tumors or autoimmune disorder •Pheochromocytoma—tumor of adrenal medulla secretes excessive epinephrine and norepinephrine •Toxic goiter (Graves disease)—autoantibodies mimic effect of TSH on the thyroid (bind and activate TSH recetor), causing thyroid hypersecretion
Describe how hormones stimulate their target cells.
•Neural stimuli -Nerve fibers supply some endocrine glands and elicit the release of their hormones •The sympathetic nervous system stimulates the adrenal medulla to secrete epinephrine and norepinephrine in situations of stress •In childbirth, nerve signals originate from stretch receptors in the uterus, travel up the spinal cord and brainstem to the hypothalamus, and stimulate the release of oxytocin •Hormonal stimuli -Hormones from the hypothalamus regulate secretion by the anterior pituitary gland -Pituitary hormones stimulate other endocrine glands to release thyroid hormone, sex hormones, and cortisol •Humoral stimuli -Refers to blood-borne stimuli. •Rising blood glucose concentration stimulates the release of insulin •Low blood osmolaritystimulates the secretion of aldosterone •Low blood calcium level stimulates the secretion of parathyroid hormone •Peptide hormones -Cannot penetrate target cell -Bind to surface receptors and activate intracellular processes through second messengers •Steroid hormones -Penetrate plasma membrane and bind to internal receptors (usually in nucleus) -Influence expression of genes of target cell -Take several hours to days to show effect due to lag for protein synthesis •Estrogen binds to nuclear receptors in cells of uterus -It activates the gene for the progesterone receptor -Progesterone comes later in the menstrual cycle and binds to these receptors stimulating transcription of a gene for a nutrient synthesizing enzyme •Thyroid hormone enters target cell by means of an ATP-dependent transport protein -Within target cell, T4is converted to more potent T3 -T3binds to nuclear receptors and activates gene for the sodium-potassium pump
Describe the structure and location of the remaining endocrine glands.
•Pineal gland—attached to roof of third ventricle beneath the posterior end of corpus callosum. •Thymus- bilobedgland in the mediastinum superior to the heart. •Thyroid- is the largest gland that is purely endocrine. It is composed of two lobes and an isthmus below the larynx. •Parathyroid Glands- usually four glands partially embedded in the posterior surface of the thyroid gland. Can be found from as high as hyoid bone to as low as aortic arch. •Adrenal Glands- a gland located on the top of both kidneys. Adrenal medulla is the inner core (about 10% to 20% of gland) and adrenal cortex surrounds the medulla. •Pancreatic Islets- located inside the pancreas, an elongated , spongy gland located below and being the stomach. •Gonads- In women these are the ovaries and in men they are the testicles.
Describe the anatomical relationships between the hypothalamus and pituitary gland.
•Pituitary gland is suspended from hypothalamus by a stalk—infundibulum •Housed in sella turcica of sphenoid bone •Size and shape of kidney bean •Composed of two structures with independent origins and separate functions -Adenohypophysis (anterior pituitary) -Neurohypophysis (posterior pituitary)
Explain how the pituitary is controlled by the hypothalamus and its target organs.
•Rates of secretion are not constant: -Regulated by hypothalamus, other brain areas, and feedback from target organs •Hypothalamic and cerebral control: -Brain monitors conditions and influences anterior pituitary accordingly •In times of stress, hypothalamus triggers release of ACTH •During pregnancy, hypothalamus triggers prolactin secretion -Posterior pituitary is controlled by neuroendocrine reflexs •Hypothalamic osmoreceptors trigger release of ADH when they detect a rise in blood osmolarity •Infant suckling triggers hypothalamic response to release oxytocin •Negative feedback—increased target organ hormone levels inhibit release of hypothalamic and/or pituitary hormones -Example: thyroid hormone+ inhibits release of TRH by hypothalamus and of TSH by anterior pituitary •Positive feedback can also occur -Stretching of uterus increases OT release, causes contractions, causing more stretching of uterus, etc. until delivery
Discuss the hormones produced by organs and tissues other than the classical endocrine glands.
•Skin -Keratinocytes convert a cholesterol-like steroid into cholecalciferol using UV from sun •Liver—involved in the production of at least five hormones -Converts cholecalciferol into calcidiol -Secretes angiotensinogen (a prohormone) •Precursor of angiotensin II (a regulator of blood pressure) -Secretes 15% of erythropoietin (stimulates bone marrow) -Source of IGF-I that controls action of growth hormone -Hepcidin: promotes intestinal absorption of iron •Kidneys—play role in production of three hormones -Convert calcidiol to calcitriol, the active form of vitamin D •Increases Ca2+absorption by intestine and inhibits loss in the urine -Secrete renin that converts angiotensinogen to angiotensin I •Angiotensin II created by converting enzyme in lungs -Constricts blood vessels and raises blood pressure -Produces 85% of erythropoietin •Stimulates bone marrow to produce RBCs •Heart -Atrial muscle secretes two natriuretic peptides in response to an increase in blood pressure -These decrease blood volume and blood pressure by increasing Na+and H2Ooutput by kidneys and oppose action of angiotensin II -Lowers blood pressure •Stomach and small intestine secrete at least 10 enteric hormones secreted by enteroendocrine cells -Coordinate digestive motility and glandular secretion -Cholecystokinin, gastrin, ghrelin, and peptide YY (PYY) •Adipose tissue secretes leptin -Slows appetite •Osseous tissue—osteocalcin secreted by osteoblasts -Increases number of pancreatic beta cells, pancreatic output of insulin, and insulin sensitivity of body tissues -Inhibits weight gain and onset of type 2 diabetes mellitus •Placenta -Secretes estrogen, progesterone, and others •Regulate pregnancy, stimulate development of fetus and mammary glands
Describe how hormones are synthesized and transported to their target organs.
•Synthesized in same way as any protein -Gene is transcribed to mRNA -Peptide is assembled from amino acids at ribosome -Rough ER and Golgi may modify peptide to form mature hormone •Example: Proinsulin has connecting peptide removed to form insulin (two peptide chains connected by disulfide bridges) •Melatonin is synthesized from the amino acid tryptophan •Other monoamines come from the amino acid tyrosine •Thyroid hormone is composed of two tyrosines -Follicular cells absorb iodide (I−)ions from blood and oxidize them to a reactive form -The cells also synthesize the large protein thyroglobulin (Tg) and store it in follicle lumen -Iodine (one or two atoms) is added to tyrosineswithin Tg -When two tyrosines within Tg meet, they link to each other forming forerunners of T3(three iodines) and T4(four iodines) -When follicle cell receives TSH, it absorbs Tg and employs lysosomal enzymes to split Tg and free thyroid hormone (TH) -TH (mostly as T4) is released from basal side of follicle cell into blood capillary
Identify the chemical classes to which various hormones belong.
•Three chemical classes: steroids, monoamines, and peptides -Steroids •Derived from cholesterol •Sex steroids (such as estrogen) from gonads and corticosteroids (such as cortisol) from adrenals -Monoamines (biogenic amines) •Made from amino acids •Catecholamines(dopamine, epinephrine, norepinephrine), melatonin, thyroid hormone -Peptides and glycoproteins •Created from chains of amino acids •Examples include hormones from both lobes of the pituitary, and releasing and inhibiting hormones from hypothalamus •Insulin is a large peptide hormone
In more detail, describe the causes and pathology of diabetes mellitus.
•Type 1 diabetes mellitus (IDDM)—5% to 10% of cases in United States -Insulin is always used to treat type 1 •Insulin injections, insulin pump, or dry insulin inhaler •Monitoring blood glucose levels and controlled diet -Hereditary susceptibility -If susceptible individual is infected with certain viruses (rubella, cytomegalovirus), autoantibodies attack and destroy pancreatic beta cells •Type 2 (NIDDM)—90% to 95% of diabetics -Problem is insulin resistance •Failure of target cells to respond to insulin -Risk factors are heredity (36 genes so far known to increase risk), age (40+), obesity, and ethnicity (Native American, Hispanic, and Asian) -Treated with weight-loss program and exercise since: •Loss of muscle mass causes difficulty with regulation of glycemia •Adipose signals interfere with glucose uptake into most cells -If necessary, also use glycemia-lowering oral medications and, if still not enough, use insulin •Pathogenesis—cells cannot absorb glucose, must rely on fat and proteins for energy needs, thus weight loss and weakness -Fat catabolism increases free fatty acids and ketones in blood •Ketonuria promotes osmotic diuresis, loss of Na+and K+, irregular heartbeat, and neurological issues •Ketoacidosis occurs as ketones decreaseblood pH -Deep, gasping breathing and diabetic coma are terminal result
