2-19-10 Homeostasis and Allostasis - The Endocrine System-color

2-19-10 Homeostasis and Allostasis - The Endocrine System-color

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Unformatted text preview: Clicker Question Ernest Starling perfused the renal artery of a dog with cyanide and found that the amount of NaCl in the urine increased. This meant that ____________. Harry Lewis: Excellence Without a Soul: A conversation about undergraduate education A) NaCl is actively reabsorbed into the blood actively B) NaCl reabsorption requires cellular cellular C) NaCl reabsorption depends on a functioning D) NaCl reabsorption depends on ATP. ATP E) all of the above. above. Electron Electron Transport Chain. Cyanide and Happiness from the filtrate. respiration. Thursday, Thursday, February 25, 2010 9:30 – 11:00am 226 Weill Hall H.E.L.P. For Children For HELP. EDUCATE. LOVE. PROTECT. Educate and raise awareness for vulnerable children Fundraise and help plan events Gain hands on service learning experience Leadership positions available JOIN US AT OUR NEXT MEETING, SUNDAY, FEB. 21 AT AT 2:00 PM IN MANN 100 PM IN MANN 100 Contact dsj32 or jl655 with questions Cyanide and Happiness Comics Where are we? Last time I talked about… • How the kidney refreshes the blood through the processes filtration resecretion excretion of filtration, re-absorption, secretion and excretion. • How antidiuretic hormone (ADH) and aldosterone antidiuretic aldosterone help the body to retain water. • Kidney stones stone • How the kidney increases the number of red blood cells by erythropoietin producing erythropoietin. Today I will talk about… • Homeostasis: Maintaining a stable and sustainable internal milieu with the endocrine and the nervous systems • Allostasis: Maintaining a metastable (unsustainable) internal milieu in times of stress. Are we water creatures? living living in an environment surrounded by air; but that is only half of the truth. Each one of our cells surrounds one of our cells surrounds itself itself with a thin layer of thin We usually think of ourselves from where our ancestors may have originated. fluid that has a chemical composition that is not that far from the chemical composition of the sea 1 Internal Milieu This primordial sea water, which we carry inside our body, is called the interstitial interstitial fluid. Claude Bernard called this fluid Bernard called this fluid, along with the lymph and blood plasma, “The Internal Milieu.” The body goes to great lengths to keep the physical properties and chemical composition of the fluid that bathes our cells constant. constant Internal Milieu The interstitial fluid is interstitial partially separated from the blood in the rapidly moving circulatory circulatory system by the epithelial walls of the ith th capillaries. The similarity between the interstitial fluid in a given organ and the blood plasma results from the high permeability of high the epithelial cells in the capillary walls. The The Capillaries that Carry the Circulating Blood Are Immersed in the Interstitial Fluid The The Lymphatic Capillaries Recycle and Remove Proteins and Pathogens from the Interstitial Fluid The interstitial fluid is also in communication with the lymph lymph in the lymphatic capillaries of the lymphatic system. The lymphatic system The lymphatic lymphatic system uses peristalsis to peristalsis to return proteins from the interstitial fluid to the circulatory system. The lymphatic system also transports pathogens to the lymph nodes. The Lymphatic System PhysicoPhysico-Chemical Properties of the Internal Milieu • pH about 7.4 (buffered in part by a about bicarbonate buffer system and by a balance of bicarbonate re-absorption and reproton secretion in the kidney) proton secretion in the kidney). Osmotic pressure of about 285 mOsm/L. Internal temperature of about 37 °C temperature (98.6 °F) Calcium concentration is 10 mg/100 ml. Glucose concentration is 90 mg/100 ml. • • • • 2 Optimal and Sustainable: Not to Low, Not too High The Stability of the Internal Milieu is Regulated to a Large Degree by Hormones Produced by the Endocrine Glands Endocrine Glands The endocrine endocrine glands, including the Osmoregulation: Homeostatic Balance of Water and Salt • Dehydration causes the salt concentration of the blood to rise. The increased osmolarity of the blood plasma is hypothalamus which sensed by the hypothalamus which in turn stimulates antidiuretic the secretion of antidiuretic hormone (ADH) from the neurosecretory cells of the posterior pituitary the neurosecretory cells of the posterior pituitary gland. The antidiuretic hormone (ADH) travels through the antidiuretic bloodstream to the kidney where it promotes the insertion of water channels in the collecting ducts so that more water is re-absorbed by the kidney and the reosmotic pressure of the blood returns to normal. When the osmotic pressure gets too low due to drinking too too much water, ADH secretion decreases and the water ADH secretion channels are removed so that more water gets diverted to the ureter to be expelled in the urine. secreting secreting hormones into the blood stream. hypothalamus, hypothalamus, pituitary, thyroid, parathyroid, parathyroid, adrenal and pancreas maintain homeostasis by • • Alcohol and Micturition Thermoregulation www.biorelief.com for him for him www www.biorelief.com for her for her Drinking alcohol inhibits the secretion of alcohol antidiuretic hormone (ADH) from the posterior pituitary gland. This results in a decrease in the number of water channels in the collecting duct and an increased production of urine. This is the reason that drinking alcohol micturite increases one’s need to micturite. • If our body temperature rises to 105 °F or drops to 93 • °F, our brains no longer function properly and we can brains become confused or delirious. delirious. For this reason, it is important for us to have an efficient temperature-regulation system. temperature- 3 Thermoregulation Hairless skin, as opposed to fur, and functional sweat sweat glands allows us to keep our brains at the allows proper proper operating temperature on hot days and during exercise without having to stop what we are doing and burrow in the cool mud. Pigs do not have functional sweat glands. Well, if we do, it is our own choice! The Body’s Thermostat is in the Hypothalamus Hypothalamus Thermoregulation: Warming Up the Core Due to Vasoconstriction of the Arterioles Near the Skin Near Thermoregulation: Cooling Down the Core Due to Near Vasodilation of the Arterioles Near the Skin • When it is cold, the temperature of our blood decreases and cold • the thermostat in the hypothalamus senses the decrease. The hypothalamus triggers the release of noradrenaline by the noradrenaline adrenaline sympathetic nervous system and adrenaline by the adrenal vasoconstriction gland which result in the vasoconstriction of the arterioles near the skin. Vasoconstriction reduces the flow of blood to the skin so that reduces we minimize the amount of heat lost by the surface of the minimize heat body. We get “cold feet”, but we keep our internal temperature relatively constant. • When it is hot, the temperature of our blood increases and the hot • thermostat in our hypothalamus senses the increase. The inhibits the hypothalamus then inhibits the release of adrenaline and noradrenaline. The lack of adrenaline and noradrenaline results vasodilation in the vasodilation of the arterioles near the skin. Vasodilation increases the flow of blood to the skin and increases increases the increases the amount of heat lost by the surface of the heat body, which keeps our internal temperature relatively constant. 4 Sweating Cools the Body Evaporation of sweat when our skin is hot cools efficiently cools the body since the transformation of a liquid to a gas consumes body heat. consumes Our skin has 150-340 sweat glands/cm2. 150We can sweat 1-3.5 liters/hour. 1It takes about 560 Calories of heat to vaporize each liter. This heat is lost from the body with the sweat. Other Processes Initiated by Hypothalamus that also Help Keep Us Warm • The hypothalamus triggers the release of an iodine iodine-containing hormone from the thyroid thyroid that increases the rate of cellular the rate of cellular respiration, respiration, which generates body heat. body triggers involuntary involuntary Thermal Insulation Hair keeps the insulating us. insulating us. Even warmth in by though we don’t have though we don’t have much much fur to raise, cold still induces the hairhair-raising response in humans, which is goose seen as goose bumps. • The hypothalamus muscle contraction or shivering shivering that generates body heat. body Functional Redundancy: Various Thermoregulatory Responses Regulated by the Hypothalamus Calcium Homeostasis • Calcium, which is high in dairy products, is a structural structural component of teeth and bones and an important regulatory ion important regulatory ion for for nerves and muscles. Sufficient calcium is crucial for these processes, but too much calcium precipitates precipitates phosphatephosphate-containing molecules like ATP, making them unavailable. • 5 Calcium Homeostasis • When the calcium concentration in the too thyroid blood is too high, the thyroid gland releases calcitonin, which stimulates calcitonin bone calcium uptake into the bone and inhibits the re-absorption of calcium by rethe kidney the kidney. When the calcium concentration in the too parathyroid blood is too low, the parathyroid gland releases parathyroid hormone, which parathyroid promotes calcium absorption by the intestines intestines, stimulates calcium rerekidney absorption by the kidney and stimulates bone calcium release from the bone. • Thyroid Glucose Homeostasis • Eating candy results in too too much glucose in the blood. High High blood sugar stimulates pancreas to the pancreas to secrete insuli insulin which flows through the blood stream to the liver liver where the excess glucose is polymerized polymerized into glycogen glycogen (animal starch). Insulin also lowers the blood stimulating glucose level by stimulating body cells to take up more take glucose from the blood. Glucose Homeostasis • Skipping a meal results in not enough not glucose in the blood. stimulates the pancreas to pancreas to secrete glucagon glucagon which flows liver to the liver where it triggers the depolymerization of depolymerization of glycogen into glycogen into glucose. • Low blood suga sugar • Malfunction in Glucose Homeostasis • Diabetes mellitus is a disease in which the body is unable to reduce the level body of glucose in the blood. • Type 1 diabetes iis an autoimmune s autoimmune disease in which the body destroys the • insulin-producing cells of the pancreas. It n-pro th It is is treated by injecting insulin. Type 2 diabetes is a disease associated with obesity. In Type 2 diabetes, the obesity insulin receptors are relatively insensitive to the normal levels produced by the pancreas. It can be managed with a healthy diet and regular exercise, and, if necessary, injections of high doses of insulin. 6 GeneticallyGenetically-Engineered Human Insulin www.diabetes.org Humalog Humulin The Physiology of Change • Our body adapts to adapts means of both the Sympathetic Sympathetic Communication Among the Internal Organs • Galen (100) dissected pigs and apes and found that the nerves formed nerves extensive change involuntarily by autonomic autonomic nervous system and the endocrine system. • Later in the semester, I interconnections interconnections consciously consciously creating, sensing and responding to change. will discuss the role that the brain plays in brain • From these observations, between the organs. Galen concluded that there is sympathetic sympathetic communication among the internal organs of the body. Stimulations of Nerves Innervating the Visceral Organs have Opposing Effects • In 1845, Ernst and Eduard Weber found that electrical stimulation of the vagus nerve that goes to the heart slows down the heart beat. Gabriel Valentin, Alexander Valentin, von Humboldt and others found that electrical stimulation of other nerves that go to the heart speeds speeds up the heart beat. The Nerves also Affect the Vasomotor System • In 1840, Benedict Stilling realized that the blood vessels were surrounded by muscle and coined the term, “vasomotor system”. In 1851, Claude Bernard found In 1851, Claude Bernard found that that when he cut a sympathetic nerve that innervated an artery, the artery would relax and relax dilate (vasodilation). In 1852, Charles Brown-Sequard Brownfound that when he electrically stimulated the nerve, the artery would contract contract (vasoconstriction). • • • 7 Autonomic Nervous System is Composed of Two Sets of Nerves • Through making histological sections, Walter Gaskell (1886) traced the nerves that went to each of the visceral organs of the body body. He found that each visceral organ is innervated by two different systems of nerves. Gaskell postulated,“…the one The Sympathetic and Parasympathetic Nervous Systems • John Langley defined the nervous system that is concerned with activation activation, the • • • He defined the nervous system that is involved in restoring and restoring conserving the body resources, the sympathetic nervous sympathetic nervous system. system. sets that tissue in activity and causes contraction, the other inhibits its action and causes relaxation….” parasympathetic parasympathetic nervous system. Sympathetic/ Sympathetic/Parasympathetic Nervous System • • • • • • • • • • Dilates/ Dilates/constricts pupils Dilates/ Dilates/constricts bronchi Accelerates/ Accelerates/slows heart Stimulates adrenaline and noradrenaline release adrenaline and noradrenaline Stimulates glucose release from liver Inhibits/ Inhibits/stimulates saliva production Inhibits/ Inhibits/stimulates stomach, intestines and pancreas Inhibits/ Inhibits/stimulates bladder contraction and sphincter relaxation that leads to urination Promotes an erection Promotes ejaculation and vaginal contractions The Sympathetic and Parasympathetic Nervous System • The sympathetic and sympathetic and parasympathetic parasympathetic nervous systems complement complement each other in Functional Functional Redundancy or Double Insurance • • regulating the degree to which the balanced body is balanced between the active mode or the tranquil mode. mode. The sympathetic nervous system sympathetic tends to put the body in the “flight or fight” mode. The parasympathetic nervous parasympathetic system tends to put the body in the “rest and digest” mode. Later experiments showed that the endocrine system mimics (as well as intensifies and prolongs) the sympathetic nervous system. 8 Unity in Diversity and seemingly unrelated responses that were I will describe many diverse diverse studied. Then, I will describe Then, how how in a moment of inspiration, Walter B. Cannon found the unity in the unity diversity and realized that and the “mind-body” continuum is “mindcomposed of two interrelated and complementary states. Adrenaline Mimics the Sympathetic Nervous System •George Oliver (1893) gave his son a small dose of an extract from the extract (adrenaline). •He noticed that the diameter of his son’s arteries decreased and his blood pressure rose. •Oliver was so excited about these results that he… adrenal glands Adrenaline Mimics the Sympathetic Nervous System Adrenaline Mimics the Sympathetic Nervous System •Immediately after the injection, the blood pressure rose past the limit of the blood pressure gauge. After seeing that, Oliver began a series of studies on the effect of adrenaline on the other organs of the adrenaline on the other organs of the body. body. •Noting that adrenaline caused an increase increase in the heart rate, certain blood vessels to contract and certain skeletal muscles to tone up, George Oliver concluded that the adrenaline adrenaline …injected adrenaline adrenaline into the vein of a dog. dog. mimicked the sympathetic nervous system. Adrenaline Causes Pupils to Dilate • William H. Bates (1896), a Cornell graduate (1881) also discovered that Adrenaline Mimics Sympathetic Nervous System John Langley (1901) showed that adrenaline mimicked adrenaline mimicked stimulation of the stimulation of the sympathetic sympathetic nervous system in more ways, including inhibition of • Max Lewandowsky (1898) noticed that adrenaline adrenaline also caused pupils to pupils dilate and eyeballs to bulge, two more effects usually caused by stimulation of the adrenaline adrenaline quickens prevents the pulse and prevents hemorrhaging due to the constriction of the constriction of small small arteries. sympathetic sympathetic nervous system. sphincter sphincter action in the stomach and bladder contraction. 9 Adrenaline as the Neurotransmitter? • Thomas Elliot continued work in “Adrenaline “Adrenaline might then be the chemical stimulant liberated on each occasion when the [sympathetic nerve] impulse arrives at the nerve] impulse arrives at the periphery.” periphery.” substance known as noradrenaline noradrenaline is the effective agent (i.e. neurotransmitter) that is released by the sympathetic nervous system at the target tissue. Langley’s lab and suggested that The The Power of Chemicals Walter Walter Dixon took a number of hallucinogens and realized the power the mescaline, he wrote: of certain chemicals on the the body. After taking After • Actually, an adrenaline-like adrenaline- “When “When sitting with closed eyes, balls of red fire pass slowly across the field of vision, Later these change to kaleidoscopic displays….” Walter Dixon Found and Agent that Slowed The Heart Beat Down In order to look for the effect of chemicals on important bodily functions, Dixon (1907) electrically stimulated a heart for 30 minutes Then he placed the heart in 30 minutes. Then he placed the heart in boiling boiling water for 10 seconds and extracted it with alcohol. He put the extract on a fresh beating heart and found that, in contrast to adrenaline, it slowed the heart beat down. The action of the parasympathetic extract mimicked the parasympathetic nervous system. Ergot of Rye • Henry Wellcome, head of the Burroughs Wellcome and Co. was interested in the history of medicine and knew that ergot of rye was used by ergot of rye was used by midwives midwives for centuries to produce produce contractions of the uterus. • Wellcome suggested to Henry Dale that he study the properties of ergot of rye in his spare time. Ergot of Rye Acetylcholine Mimics Parasympathetic Nervous System • Dale purified the compound from ergot of rye that caused the • The extract mimicked other parasympathetic effects, parasympathetic • contraction of the uterus. including stimulating salivation, stimulating contraction of the stomach, intestine and bladder and slowed down the heart beat. Dale isolated the chemical from ergot of rye that mimicked the parasympathetic parasympathetic nervous system and saw that it was acetylcholine acetylcholine. 10 Is Acetylcholine Naturally Produced by the Body? By 1914, Dale had concluded that acetylcholine acetylcholine was the most potent mimic of the Otto Loewi was a Good Guesser • Otto Loewi knew that the • • • • parasympathetic nervous system slows down the heart beat. He knew that Dixon had shown that the heart contains some chemical that that can slow down the heart beat. He knew that Dale had shown that acetylcholine mimicked the parasympathetic nervous system. He guessed that acetylcholine may acetylcholine be the chemical signal produced by the parasympathetic nervous parasympathetic system that slows down the heart. But how could he test his idea? than just an interesting product of a plant pathogen, but was naturally naturally produced by the body. parasympathetic th nervous system, but he had had not yet realized that acetylcholine was more more As He Slept, Otto Loewi Had a Dream In 1921, Loewi dream woke from a dream and jotted down an experiment that experiment that could could show that the stimulated nerve produced a chemical, that slowed down the heart beat. Isolation Isolation of Acetylcholine from the Body • After seeing Otto Loewi’s results, Henry Dale • produced in the body and he was determined to find it. Dale collected 71 pounds of spleens from horses 71 and oxen at a local slaughterhouse. He ground up the spleens and extracted them with alcohol. He purified 0.3 grams of acetylcholine and was THRILLED! believed that believed that acetylcholine was probably At At that moment, acetylcholine changed from a curious plant extract to a natural regulatory constituent of the body. Is Acetylcholine a Natural Regulator of the Heart Beat? • Stimulation of the parasympathetic parasympathetic heart beat. nervous system slows down the • Acetylcholine mimics the effect of th the the parasympathetic nervous system. • Acetylcholine is found in the spleen. • But, does the parasympathetic nervous system produce and release acetylcholine as a natural regulator natural of the heart beat? 11 The Leech Muscle Bioassay • Attach a Hungarian leech Hungarian • • • muscle to a strain gauge that can measure when a muscle contracts. Bathe the muscle in an aerated salt solution. Perfuse the solution with tiny amounts of acetylcholine (e.g. 1/500,000,000 dilution) and the muscle contracts. Add tiny amounts of an unknown. If the muscle contracts, the unknown unknown contains acetylcholine. Aside: Aside: Bioassays • Only a canary was sensitive enough to sense the presence of traces of odorless poison gas in a Victorian coal mine. Mi Miners used canaries to warn them of the presence of a poison gas. Similarly, in the 1930s, only a living system like the Hungarian leech was sensitive enough to detect the presence of acetylcholine. • Acetylcholine Acetylcholine is a Natural Regulator of the Heart Beat When Otto Krayer and Wilhelm Feldberg stimulated the parasympathetic nervous system of a dog and then added the venous blood dd bl to to the bioassay, the leech muscle contracted, indicating that the parasympathetic parasympathetic nervous system produces acetylcholine, acetylcholine, which which enters the blood stream. Walter Cannon found the underlying simplicity in this myriad myriad of results concerning adrenaline and acetylcholine. Walter Cannon: Intuition “As a matter of routine I have long trusted unconscious unconscious processes to serve me….[One] example I may cite was the interpretation of the significance of bodily changes changes which occur in great emotional excitement, such as fear and rage. These changes— changes—the more rapid pulse, the deeper breathing, the increase of sugar in the blood, the secretion from the adrenal glands— glands—were very diverse and seemed unrelated.” Walter Cannon Could Not Sleep “Then “Then one wakeful night, after a considerable collection of these changes had been disclosed, the idea flashed though my mind that they could be nicely integrated if conceived as bodily preparations for supreme effort in flight or in fighting.” 12 Adrenaline Moves through the Blood Stream in Response to Stress • So Cannon tested his hunch. • He measured the amount of • Then he measured the amount adrenaline in adrenaline in the blood of calm calm cats. The Effect of Stress on the Body Cannon Cannon wrote in his diary: January 20, “Got 1911. “Got idea that • Adrenaline is released into adrenaline of adrenaline in the blood of stressed cats that had been stressed out by a barking dog. the blood whenever a cat is stressed. adrenals in excitement adrenals in excitement serve serve to affect muscular power and mobilize sugar for muscular use—thus in use— a wild state readiness for flight or fight.” Homeostasis and Allostasis • The nervous system – In serene times, the parasympathetic nervous serene system acts by using acetylcholine as a neurotransmitter (which also travels through the blood) blood). stressful – In stressful times, the sympathetic nervous system acts by using adrenaline-like noradrenaline as a adrenalineneurotransmitter. – The sympathetic nervous system activates the adrenal glands to produce adrenaline. – The blood stream carries adrenaline throughout adrenaline Adrenaline Adrenaline Prepares one for Emergencies • During times of “fight or flight”, adrenaline dilates dilates • Adrenaline causes a release of sugar from the release the bronchi, so our cells get more oxygen. • Adrenaline also causes a dilation of the blood vessels Adrenaline also causes dilation of the blood vessels • liver into the blood and gives us a “second wind.” • The endocrine system the body to amplify and prolong the action of the sympathetic nervous system. that that bring blood to the heart, brain and skeletal heart brain skeletal muscles and diverts it from the skin and digestive system. This diversion of blood keeps us on our toes. The diversion of blood from the digestive system results in the stoppage of the mechanical movement of the digestive organs first observed by Cannon in 1897. To Each His/Her Own 13 Adrenaline, The Jefferson Memorial and Cherry Blossoms Mechanisms to Prevent Disaster • Walter Cannon, who coined the term homeostasis, realized that homeostasis maintaining the constancy of the internal environment, not only required the kinds of mechanisms we have been talking about that we have been talking about that respond respond to moderate changes in moderate the environment; but also required additional devices that functioned functioned to prevent disaster. These additional devices are called allostatic allostatic mechanisms. Allostasis Allostasis or other state comes from the other Greek for other (allo) and state (stasis). Jukichi Takamine (1901) isolated and purified adrenaline, the adrenaline first effective broncodilator for asthma, from animal glands. He was granted the right to use Adrenalin as a trademark. Adrenalin This provided him with financial success and in 1912, he donated the beautiful cherry trees in Washington D.C. and along acs Riverside Drive in NY. • Hans Selye: Stress in Moderation • Too much stress (hyperstress) is exceeds limits when your body exceeds the limits of its ability to adapt and begins to breakdown breakdown. Too little stress (hypostress) leads to a life of boredom, sensory life of boredom sensory deprivation, deprivation, physical immobility, and lack of mental stimulation, motivation and goals. We must find a balance between the balance equally destructive forces of hyperstress hyperstress and hypostress. hypostress In so doing, maximize good stress good (eustress) and minimize distress. distress Optimal Stress Levels Help You Focus and Do Better on Exams! • • • Coffee Shops: Optimal Stress for Studying? Coffee Shops: Optimal Stress for Studying? http://manndiblecafe.com/ 14 Too Much Stress How How long and how often can this emergency system be used? • In emotionally stressful emotionally situations, whether real or same imagined, we use the same adrenalineadrenaline-based allostatic mechanisms. increase in blood sugar, prolonged stress is likely to lead diabetes to a “psycho-somatic” diabetes. “psychoSince adrenaline causes vasoconstriction, prolonged high stress can also lead to high blood pressure and an and heart increased risk of heart attack and stroke. stroke • Since adrenaline causes an • Stress also Can Cause Ulcers Stress and Corticosteroids • The cortex of the adrenal glands produce steroids cortex adrenal steroids • • • in response to stress and these steroids are known as corticosteroids corticosteroids. They are synthesized from cholesterol cholesterol. Aldosterone is a corticosteroid that stimulates the corticosteroid kidney to reabsorb NaCl and consequently more water kidney to reabsorb NaCl and consequently more water to to increase the blood volume/pressure. The higher the blood pressure, the faster the blood flows and it is more likely that the brain, heart and brain heart necessary skeletal muscles will get sufficient skeletal oxygen. Prolonged hypertension will result in artery, heart and kidney damage as well as greater risks of heart attack and stroke. Stress and Corticosteroids • Other corticosteroids, including cortisol, induce cortisol the breakdown of skeletal breakdown muscle proteins into into glucose and ammonia so that glucose and ammonia so that the the glucose can be used for energy. While this provides readilyreadilyusable energy in times of emergency, prolonged prolonged • exposure to stress leads to the breakdown of the body itself. 15 Products that Claim to Block the Harmful Effects of Cortisol Products that Claim to Prevent Weight Gain Due to Cortisol Federal Trade Commission Again, it is the golden age of biology! If you understand biology, you can get rich! stresseraser Walter Cannon (1939): Homeostasis and Society “It seems…that the means employed by the more highly evolved animals for preserving uniform and stable their internal economy…may present some general principles for the establishment regulation and control of steady establishment, regulation and control of steady states, states, that would be suggestive for other kinds of organization—even social and industrial— organization— industrial— which suffer from distressing perturbations. Perhaps a comparative study would show that every complex organization must have…effective selfself-righting adjustments in order to prevent a check on its functions or a rapid disintegration of its parts when it is subjected to stress.” Indeed, the principle of homeostasis the in the body is indeed the principle of principle checks and balances that the founder wrote into the Constitution of the United States. As the Declaration of Independence suggests, our government is founded on the Laws of Nature is founded on the Laws of Nature. 16 Crisis: Danger and Opportunity Find Balance in your Life • 17 The Biological Effects of Stress • Stress: Friend or foe? 5 Ways to Stay in the Green Zone • Sleep – at least 8 hours per night • Exercise – 30 minutes; 10,000 steps • Healthy diet – give your body & mind the fuel it needs to be productive throughout the day it th th • Identify and practice a repertoire of short-term stress management techniques • Plan time to be with people who are supportive Stress can improve your performance up to a point. After that you will experience a decline in performance and functioning. W h Visit: www.gannett.cornell.edu 18 ...
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