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63 Cards in this Set
- Front
- Back
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Control of TSH Secretion |
TSH is controlled by 2 methods: •by the level of Thyrotropin-releasing hormone (TRH) from the hypothalamus •by negative feedback by thyroid hormones |
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Hypopituitary Dwarfism: |
•Caused by deficiency of growth hormone (GH) during childhood •Short stature, but body proportions and mental development are normal •Treatment must start before bones completely ossify |
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Gigantism: |
•Caused by oversecretion of GH during childhood •Height may exceed 8 feet, may have other metabolic problems •Often caused by pituitary tumor |
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Acromegaly: |
•Caused by oversecretion of GH during adulthood •No increase in height, but bones thicken •Enlargement of tongue, nose, hands, feet, jaw, heart, thyroid gland |
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Posterior pituitary hormones (which ones): |
•Antidiuretic hormone (ADH, vasopressin) •Oxytocin |
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Posterior pituitary hormones (about): |
•Posterior lobe of pituitary gland consists of nerve fibers from hypothalamus and neuroglia •2 hormones are produced by neurons in the hypothalamus, and stored and released by the posterior pituitary gland •These hormones are transported to the posterior pituitary gland via the pituitary stalk (infundibulum) |
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Thyroid Gland |
•The thyroid gland has two lateral lobes, connected by isthmus •Lies just below the larynx, anterior and lateral to the trachea •Has special ability to remove iodine from blood |
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Thyroid gland produces 3 hormones: |
•T4 (thyroxine), •T3 (triiodothyronine) •Calcitonin Follicular cells produce T3 and T4 Extra-or parafollicular cells produce calcitonin |
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Structure of the Thyroid Gland |
•Thyroid is composed of follicles. •Each follicle surrounded by single layer of follicular cells. •Viscous colloid fills follicle cavities. •Extrafollicular (C) cells lie outside follicles. |
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Parathyroid Glands: |
•Located on posterior surface of the thyroid gland •There are usually 4 parathyroid glands •They secrete 1 hormone, PTH (Parathyroid hormone) |
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Actions of PTH: |
•Increases level of blood Ca+2 •Decreases level of blood PO4-2 •Exerts these effects by acting on bones, kidneys, intestines •Indirectly stimulates absorption of Ca+2 by stimulating a step in Vitamin D metabolism •PTH acts on kidney to cause final step in production of Active Vitamin D (also called Calcitriol, Dihydroxycholecalciferol) |
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Adrenal Glands |
•also called Suprarenal glands •closely associated with the kidneys •sit like a cap on each kidney •Hormones are secreted from the adrenal cortex and the adrenal medulla •Numerous hormones are secreted by the adrenal glands |
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Adrenal Gland contains 2 portions: |
•Adrenal cortex makes up outer portion of gland, and secretes steroid hormones •Adrenal medulla makes up central portion of gland, and secretes amine hormones |
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Adrenal Medulla secretes 2 hormones: |
•Epinephrine (Adrenalin, 80%) •Norepinephrine (Noradrenalin, 20%) |
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Adrenal Cortex produces several hormones: |
•Aldosterone, Cortisol, some sex hormones |
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Adrenal Cortex has 3 zones, each producing different types of hormones: |
Zona glomerulosa: •Outer zone •Produces aldosterone and other mineralocorticoids Zona fasciculata: •Middle zone •Produces cortisol and other glucocorticoids Zona reticularis: •Inner zone •Produces male sex hormones |
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Aldosterone and the Renin-Angiotensin System |
Renin-Angiotensin System: •helps maintain normal blood pressure •Product of this system, Angiotensin II,increases blood pressure, and promotes secretion of aldosterone •Aldosterone conserves Na+, and H20 is retained by osmosis. Aldosterone also promotes excretion of K+. |
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Regulation of Cortisol Secretion |
•regulated by a 3-step hormone pathway •Cortisol exerts negative feedback on its own production pathway |
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Addison Disease: |
•Due to insufficient hormone secretion from adrenal cortex •Results in electrolyte and glucose imbalances, dehydration, low blood pressure, fatigue, nausea, increased skin pigmentation •Can be fatal, due to severe electrolyte imbalance |
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Cushing Syndrome: |
•Due to hypersecretion of cortisol, because of adrenal tumor, or excess secretion of ACTH by anterior pituitary •Results in muscle wasting, loss of bone, elevated blood glucose, Na+ retention, H2O retention by osmosis, increased blood pressure, puffy skin, abnormal deposition of adipose tissue in face and back |
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The pancreas is both an endocrine and exocrine gland: |
- Endocrine function: Secretes hormones into body fluids - Exocrine function: Secretes digestive juices through a duct |
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•3 hormones are secreted from the endocrine (islet) cells in the pancreas: |
•Alpha cells secrete glucagon •Beta cells secrete insulin •Delta cells secrete somatostatin |
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Structure of the Pancreas |
•Elongated, flattened organ •Posterior to stomach •Pancreatic duct transports digestive juice to duodenum •Endocrine portion consists of groups of cells called Pancreatic islets (Islets of Langerhans) |
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Hormones of the Pancreatic Islets |
Insulin Glucagon Somatostatin |
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Regulation of Blood Glucose |
•Insulin and glucagon regulate blood glucose concentration. •Effects of insulin and glucagon are antagonistic. •Negative feedback controls levels of both hormones. |
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Diabetes Mellitus |
•Metabolic disease resulting from lack of insulin or inability of cells to recognize insulin •Elevated blood glucose can damage eyes, heart, kidney, nerves •Results in disturbances in carbohydrate, protein and fat metabolism •Insulin promotes glucose uptake by adipose and muscle cells •Indiabetes mellitus, carbohydrates cannot enter cells in normal quantities •Results in hyperglycemia, or high blood glucose •Cells turn to other sources of energy, which promotes tissue wasting •Weight declines, hunger increases, fatigue increases, wounds do not heal well, growth stops in children •Glucose spills into urine (glycosuria), and H2O follows by osmosis, leading to dehydration and thirst |
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Type 1 Diabetes Mellitus: |
•Also called juvenile or insulin-dependent; usually begins before age of 20 •Autoimmune disease; immune system destroys beta cells of pancreas •Results in a lack of insulin production •5-10% of cases are Type 1 |
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Type 2 Diabetes Mellitus: |
•Also called maturity-onset or non-insulin-dependent •90-95% of cases are Type 2 •Insulin is produced, but body cells are unable to recognize it •Milder than Type 1 •Complications include coronary artery disease, nerve or retinal damage |
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Treating Diabetes Type 1 Diabetes Mellitus: |
•Requires administration of insulin •Insulin can be obtained from pigs and cows •Human insulin can be synthesized using recombinant DNA technology; insulin is produced by genetically altered bacteria •People receive insulin through injection, an insulin pump, or in aerosol form •Transdermal delivery system (skin patch) is being developed •Pancreatic islet transplantation is being used in some countries |
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Treating Diabetes Type 2 Diabetes Mellitus: |
•Low carbohydrate, high protein diet •Regular exercise •Gastric bypass surgery |
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•Pineal Gland: |
•Secretes melatonin •Regulates circadian rhythms |
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•Thymus Gland: |
•Secretes thymosins •Promotes development of T-lymphocytes •Important in role of immunity |
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•Reproductive Organs: |
•Ovaries produce estrogens and progesterone •Testes produce testosterone •Placenta produces estrogens, progesterone, and a gonadotropin |
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Other endocrine organs: |
•digestive glands, heart, and kidney |
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Stress and Its Effects |
•Survival depends on maintaining homeostasis •Factors that change the internal or external environment are potentially life-threatening •Certain potentially dangerous factors can trigger a loss of homeostasis •When sensory receptors detect changes, they send nerve impulses to the hypothalamus •Hypothalamus activates sympathetic nervous system and increases secretion of adrenal hormones •Factor capable of initiating this response is a stressor •Stress is the condition produced in response to stressors |
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Types of Stress: |
Psychological stress: Danger, personal loss, anger, fear, guilt Physical stress: Temperature extremes, infection, injury, O2 deficiency |
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Responses to Stress |
•Hypothalamus controls response to stress •Response is called General Adaptation or General Stress Syndrome |
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2 stages of General Stress Syndrome: |
Alarm Stage: •Immediate •Fight or flight response •Sympathetic impulses increase blood glucose, heart & breathing rate, and blood pressure, dilate air passages, shunt blood to skeletal muscles •Epinephrine intensifies and prolongs these responses Resistance Stage: •Long-term •Increased cortisol spares glucose for brain •Glucagon and GH mobilize energy sources for other tissues and organs •ADHand Renin cause water retention |
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Life-Span Changes |
•Endocrine glands decrease in size •Muscular and skeletal strength decrease as GH levels decline •ADH levels increase due to slower elimination by liver and kidneys •Calcitonin levels decrease,increasing risk of osteoporosis •PTH level changes contribute to risk of osteoporosis, especially in females •Insulin resistance may develop •Changes in melatonin secretion affect the body clock •Thymosin production declines, increasing risk of infections |
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AnteriorPituitary Hormones |
Growth Hormone:Stimulates cells to enlarge anddivide rapidly, increases amino acid uptake and protein synthesis, decreasesrate of carbohydrate usage, increases rate of fat usage Prolactin:Promotes milk production infemales, uncertain function in males Thyroid-stimulating Hormone:Stimulates secretion of thyroidhormones (T3 and T4) from thyroid gland Adrenocorticotropic Hormone:Stimulates secretion of cortisoland other glucocorticoids from adrenal cortex Follicle-stimulating Hormone:Causes growth & development ofovarian follicles in females, sperm production in males Luteinizing Hormone: Causes ovulation in females, sexhormone production in both genders |
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AnteriorPituitary Hormones (ABOUT) |
•Anterior lobe of pituitary gland consistsof glandular epithelial tissue •Anterior pituitary hormones are producedin the anterior lobe, by 1 of 5 types of secretory cells •Each anterior lobe hormone is releasedin response to a releasing hormone from the hypothalamus; some are inhibited byinhibiting hormones from the hypothalamus |
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HypothalamicControl of Peripheral Endocrine Glands |
•The hypothalamus,which is an endocrine gland, controls hormone secretion from peripheral endocrine glands via 3-step pathways. •Each hypothalamic releasing hormone actson specific hormone-secreting cells in the anterior pituitary gland. •Anteriorpituitary hormone acts on cells in a peripheral endocrine gland, to stimulate its secretion. •Usually,there are multiple negative feedback controls involved in these pathways. |
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HypothalamicControl of Pituitary Gland |
•Anterior Lobe Regulaton: Hypothalamic releasinghormones aretransported through the Hypophyseal Portal System, and stimulate cellsof anterior lobe to release hormones •Posterior Lobe Regulation: Nerve impulses from thehypothalamus travel through the infundibulum, and stimulate nerve endings in posteriorlobe to release hormones |
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PituitaryGland |
•Lies atthe base of the brain, in sella turcica of sphenoid bone •Attachedto hypothalamus by pituitary stalk (infundibulum) •Consistsof 2 distinctportions: •Anterior lobe (adenohypophysis) •Posterior lobe (neurohypophysis) The pituitary gland isdirectlyconnected to the hypothalamus.Secretion from the 2lobes of the pituitary gland is controlledby different methodsby the hypothalamus. |
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ControlSources: Negative Feedback |
Hormone secretion is mainly underthe control of various negativefeedbackmechanisms. Negative feedback maintainsrelatively stable hormone concentrations, even though they fluctuate slightlyaround the average normal concentration. |
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ControlSources |
•Asmall number of cases of hormone control involve positivefeedback,mainly in reproductive system •Mainmethods of control of hormone secretion involve negative feedback •Negative feedback: A control mechanism in which rising level of a hormone leads to a decrease in hormone secretion •3methods in which negative feedback controls hormone secretion: 1. Tropichormones: Hormones that act on other glands, toregulate their hormone secretion 2. Nervoussystem control: Nervous system directly stimulates some glands to secrete their hormones (vianerve impulses) 3. Changesin composition of internal environment: Changing levels of a specific substance in the blood(an ion, glucose, etc.) stimulates or inhibits secretion of certainhormones |
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Control of Hormonal Secretions |
•Hormonesecretion is primarily controlled by negativefeedback mechanisms •Hormoneeffects canbe short-lived (a few minutes) or maylast for days •Hormonesecretionsare precisely regulated •Hormonesare excreted in the urine after exerting their effects •Hormonescan be broken down by enzymes, mainly from the liver, to stop their effects |
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Prostaglandins |
Prostaglandins: •Paracrinesubstances •Are verypotent in small amounts, like hormones •Are notstored in cells,butsynthesized just before release •Rapidlyinactivated after use •Regulatecellularresponses to hormones •Can activateor inhibit adenylate cyclase •ControlcAMPproduction •Altera cell’sresponseto hormones •Have awide variety of effects, such as contracting or relaxingsmooth muscle, stimulating or inhibiting secretion, regulating blood pressure,controlling movement of H2O andNa+ in kidneys, promoting inflammation |
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AbusingHormones to Improve Athletic Performance |
Steroids: •Usedto increase muscular strength •Canhave many harmful effects, such as decreasing natural testosterone production,stunting growth, breast development in males, male sexual characteristics infemales, damage to kidneys, liver or heart, increase in LDL cholesterol,psychiatric problems Growth Hormone: •Usedto enlarge muscles •Usedinstead of, or along with, steroids Erythropoietin: •Usedto increase the number of red blood cells and oxygen delivery to muscles •Easierthan “blood doping” •Canlead to heart attack and death |
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NonsteroidHormones |
•Nonsteroidhormones cannot penetrate the lipid bilayer of cell membranes •Theybind to receptors on the target cell membrane •Hormoneis considered a first messenger •Chemicalthat induces changes leading to hormone’s effect is considered a second messenger •Manyhormones use cyclic adenosine monophosphate (cAMP) as a second messenger |
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Steroidand Thyroid Hormones |
•Steroidand thyroid hormones have poor water-solubility •Steroidhormones can diffuse through lipid bilayer of cell membranes •Thyroidhormones are thought enter cell by specific transport methods •Bindto receptors inside cell, usually in nucleus |
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Actionsof Hormones |
•Hormonesexert effects by altering metabolic processes - Mayalter enzyme activity - Mayalter rate of membrane transport of a substance •Hormonesdeliver messages by binding to their receptors on/in target cell• •Numberof receptors determines strength of response, and can be changed to alter theresponse: - Upregulation: Increase in number of receptors on targetcell, in response to a decrease in hormone level - Downregulation: Decreasein number of receptors on target cell, due to an increase in hormone level |
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Chemistryof Hormones |
Hormones are organic compounds; 2types of hormones: • Steroid or steroid-like hormones: •Steroids:lipids containing complex rings of carbon and hydrogen atoms •All steroidhormones are produced from cholesterol •Examples:Sex hormones (testosterone, estrogens), and adrenal cortexhormones(cortisol, aldosterone) • Non-steroid hormones: • Amines:Derived from tyrosine (epinephrine, norepinephrine) • Proteins:Composed of long chains of amino acids (growth hormone) • Peptides:Short chains of amino acids (oxytocin) • Glycoproteins:Carbohydrates joined to proteins (TSH) |
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Hormone Action |
•Hormones are released into extracellular spaces around endocrine cells •Hormones diffuse into bloodstream for distribution around body |
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Locationsof Major Endocrine Glands |
•Themajor endocrine glands are not physically connected •Many hormones are produced by larger endocrine glands: •Hypothalamus •Pituitary gland •Thyroid gland •Adrenal glands •Pancreas •Somehormones are produced by small groups of special cells |
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ChemicalCommunication |
•Endocrinesystem is precise, in that only target cells can respond to a specific hormone. •Targetcells contain particular receptors for the hormone; these receptors are notpresent on other cells. |
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ComparisonBetween Nervous & Endocrine Systems |
•Boththe nervous and endocrine systems function in communication •Bothsystems communicate via chemicals that bind to receptor molecules •Nervous system releases neurotransmitters intosynapses •Endocrine systemsecretes hormones intobloodstream |
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General Characteristics of theEndocrine System |
•Endocrine glands: •Thecells, tissues, and organs that make up the endocrine system •They areductless •They secretehormones into the bloodstream •“Endocrine”means “internal secretion” •Hormonesact onlyon target cells •Exocrine glands: •Glandsthat secrete into ducts or tubes that lead to a body surface •Theysecrete externally •They delivertheir products directly to a specific site• •Therearealso glandsthatsecrete messenger molecules, including paracrinesecretions(which affect nearby cells) and autocrinesecretions, (which affect cellsthatsecrete the substances) |
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•Antidiuretic hormone (ADH, vasopressin) |
Decreases urine production by reducing volume of H2O the kidneys excrete; also causes vasoconstriction to increase blood pressure |
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•Oxytocin |
Causes muscle contraction inuterine wall during childbirth, milk ejection during lactation; has no known function in males |
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Insulin |
Decreases blood glucose, when it is too high |
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Glucagon |
Increases blood glucose, when it is too low |
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Somatostatin |
Helps regulate glucose metabolism by inhibiting secretion of insulin and glucagon |
