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WINTER SWIMMING - HEALTH OR HAZARD? Hanna Krauss Katedra Fizjologii Uniwersytetu Medycznego im. K. Marcinkowskiego w Poznaniu THE MOST IMPORTANT PARAMETERS OF THE INTERNAL ENVIRONMENT OF THE BODY: BODY TEMPERATURE pH of blood and body fluids osmotic pressure volume of the body fluids the concentration of chemicals in body fluids arterial blood pressure partial pressure of oxygen and carbon dioxide in the blood The control over these parameters is via receptors (mainly chemoreceptors) that transmit the information about the specified parameter values to the connection points where the comparison is made betweendetected value and the constant correct value (set point) or, more commonly, with its acceptable ranges. If the current parameter is too high or too low, the centre of the integrating forces effectors to give a response appropriate to the situation. THERMOREGULATION Thanks to the physiological mechanism the human body temperature is fixed at 37°C ± 0,5 - 0,7°C. BODY TEMPERATURE Is it possible to survive? Heatstroke Brain damage Thermal control seriously threatened Heat therapy Intensive exercising Normal Thermal control efficient during febrile diseases, working, health Thermal control threatened No thermal control MECHANISMS TO MAINTAIN THERMAL HOMEOSTASIS THERMOREGULATION ELEMENTS: THERMODETECTORS THERMORECEPTORS THERMOREGULATION CENTER CHEMICAL THERMOREGULATORY EFFECTORS PHYSICAL THERMOREGULATORY EFFECTORS THERMOREGULATORY CENTRE is located in the hypothalamus the front part is the centre that’s responsible for the elimination of the warmth and regulation of its loss in the rear there’s a heat preservation centre, which is responsible for the retention of the heat in the body and stimulating its production MECHANISMS ACTIVATED AT LOW TEMPERATURES: GENERATING THE HEAT CHILLS INCREASED METABOLISM INCREASED PHYSICAL ACTIVITY INCREASE IN THE ACTIVITY OF THE ENDOCRINE SYSTEM (T3, T4, CATECHOLAMINES, GLUCAGON) HEAT LOSS CUTANEOUS VASOCONSTRICTION RELOCATION OF THE BLOOD INTO INTERNAL ORGANS GOOSEBUMPS SLOWING OF THE BLOOD CIRCULATION WHERE DOES THE HEAT COME FROM? muscles work shivering intensification of metabolic processes in tissues (input of adrenaline, noradrenaline, thyroid hormones) WHERE DOES THE HEAT COME FROM? When body is subjected to low temperatures, skeletal muscles tremor, and increased tonicity becomes a source of heat. Muscle tremor is directly related to the breakdown of ATP (adenosine triphosphate) to ADP (adenosine diphosphate) and inorganic phosphate. ADP accelerates the oxidation of substrates in the mitochondria. This is accompanied by energy loss in the form of heat. The main source of energy for shrinking muscles are carbohydrates and lipids. Effects of hypothermia on the body TYPES OF HYPOTHERMIA: PRIMARY - there is a decrease in body temperature due to the impact of physical factors such as when the body is in cold water during the cold snowy blizzard, with no warm or waterproof clothing. SECONDARY -caused by cardiovascular and vasodilators agents lowering blood pressure, febrifuges, neuroleptic medications and drugs. Medications can alter body temperature in a specific way: -by acting on the thermoregulatory centres or non-specifically - acting on other nerve centres or neural pathways t 3 STAGES OF HYPOTHERMIA (according to clinical criteria) MILD 32-35°C MODERATE 28-35°C -amnesia, -apathy, -mental confusion,peripheral vasoconstriction, -increased heart rate,chills -EEG disturbances, -hallucinations, -loss of consciousnessdecrease in heart rate and cardiac output, -cardiac arrhythmias, -prolonged heart contraction,-partial reflexes, -stiffness, -no chills SEVERE <28°C -coma, -decreased brain electrical activity,-ABPdrop, -decrease in heart rate, -bradycardia, -no radial pulse,ventricular fibrillation or asystole,-apnoea, -lack of reflexes PHYSIOLOGICAL ZERO The limit of temperature for the tissue, below which physiological functions while retaining the ability of tissue to return to normal. 31C is the highest value of the physiological zero for the cerebral cortex, 27C-28C for the brain stem and 24C for the spinal cord. WHEN CAN IT OCCUR? Hypothermia is often accompanied by illnesses such as diabetic coma, hypoglycemia, hypothyroidism, massive bleeding or severe burns. Lowering of the body temperature can be observed in the following states such as anorexia nervosa and obesity. Slowly progressing lowering of the body temperature, even at room temperature, can be observed in the elderly, malnourished, with injuries to the central nervous system, autonomic or motor dysfunction of the nervous system. Hypothermia in the course of some infectious diseases (cholera, diphtheria, smallpox) is the result of toxic damage of organs involved in thermoregulation. BODY'S REACTION TO COLD When running cold, the body launches a number of adaptive responses. They occur when the internal temperature of the body drops below 36.5°C. Generally they can be divided into behavioral and autonomic. Organ and metabolic responses are the result of: exposure time and intensity with which cold works on the body, neural and humoral response to stress, speed of depletion of energy reserves, remaining conscious. THE RESPONSE TO LOW TEMPERATURES -To temporary setback of the temperature our body reacts with goosebumps - vestigal ruffled hair mechanism - so called pilomotor reflex. -At the same time the cutaneous blood flow through blood vessels is reduced - so that the body loses less heat. -Shivering - muscle contractions are known for releasing large amounts of heat. -Longer presence in low temperatures, causes body’s metabolic rate to rise, i.a. due to increasing the levels of thyroid hormones. HYPOTHERMIA <35°C ANIMATION PHASE 34°C-32°C CENTRES REDUCED ACTIVITY PHASE 32°C-27°C HEBETUDE PHASE <27°C-26 ADAPTIVE MECHANISMS - animation phase Stimulation of peripheral thermoreceptors starts stress response. The result is a stimulation of the adrenergic system, as well as secretion of the hormones of the adrenal medulla. Catecholamines stimulate the respiratory center and cardiovascular center in the medulla. Intensified work of heart and respiratory system is accompanied by increased heat production. At the same time, thermoregulatory center stimulates the α motor neurons, what leads to an increase in skeletal muscle tonicity, which, in turn, increases heat production by about 50%. If the amount of heat supplied in this way is insufficient - shivering thermogenesis is activated. ATP hydrolysis releases heat, and cell respiratory chain reactions running at the same time produce additional quantities. The result is an increase in metabolism and heat production by up to 500%. ADAPTIVE MECHANISMS As the cooling of the body advances, there’s secretion of both TSH and thyroid hormones, resulting in an increased metabolism (non-shivering thermogenesis) and heat production. Increase in heat production is accompanied by reduction of its loss, which occurs by constriction of the blood vessels of the skin and subcutaneous tissue (centralization of the blood flow) and the abolition of sweat gland activity. During this phase a characteristic blood flow, through the blood vessels of peripheral parts of the body occurs - the so-called Lewis reaction. If cooling is of significant degree, then periodic dilation appears and the blood flow increases. This mechanism is designed to protect the body against frostbite. If the temperature of these areas is further reduced, blood flow ceases completely vulnerable areas. REDUCED ACTIVITY OF THE CENTRES OF THE MEDULLA OBLONGATA When the body temperature drops below 34°C, there occurs progressive cardiac release - the impact of cold blood stimulus-conducting system of the heart. At temperatures below 28°C blocks appear in the heart; in the case of anesthesia and surgical ventricular fibrillation can occur. Coronary blood-flow during deep hypothermia is significantly reduced (to 40% of baseline), but proportionally greater than in other tissues and organs where it reaches values lower than 20% of the rate at the start. This is due to redistribution of the blood and selfregulation of coronary blood flow, the effect is proportional to the oxygen consumption by the heart. LESION Cold inhibits the activity of the respiratory center. Both the dead anatomical and physiological space increases as well as residual blood in the lungs. Typical of hypothermia is to increase the affinity of hemoglobin with oxygen (dissociation curve shifts to the left). In kidneys, proportionally to the decrease in temperature the feedback resorption in renal tubules reduces. It is particularly important to reduce the resorption of sodium ions. Increased loss of sodium ions, although filtration is reduced, causes the amount of urine to increase - at a temperature of 32°C twice or even three times at 30°C. Loss of the body water is the cause of increasing blood viscosity. There is reduction in K + ions concentration as a result of their displacement to the intracellular space. However, increase in the concentration of potassium in the extracellular fluid, reflects a deep acidosis, cell lysis, and the withering away of tissue. Acidosis is growing due to increased CO2 retention, caused by impaired microcirculation. Due to increased viscosity of the blood increases blood pressure. Only lowering the temperature of the organism below 32°C causes a decrease in blood pressure, mainly due to worsening heart failure. At a temperature of 25℃ left ventricular systolic pressure is reduced by more than 50%. LESION Lowering the body temperature is accompanied by decrease in cerebral blood flow by 6-7% for each 1°C. At the same time excitability of the cortical centres disappears. In humans, even at body temperature of 35°C, life-threatening psychiatric symptoms consisting mainly of a lack of willingness to fight for survival, confusion, inability to articulate speech can be observed. At 30°C, there is a loss of consciousness and inability to perform voluntary movements. The gastrointestinal tract reduces peristalsis. At lower temperatures up to 34°C, ileus can occur. Blood flow in the liver is reduced, although this decrease is smaller than in other organs; stagnation of blood increases and the fluids move into the extracellular space. Detoxifying abilities of the liver are reduced, the secretion of bile is decreasing. Pancreas’ exocrine function is inhibited. HEBETUDE letarg Symptoms similar to the symptoms of clinical death develop, i.e. cooling of the body and pale skin, no pulse at the periphery, no neurological reflexes and muscle stiffness. Cardiovascular activity and respiration is almost inconceivable. In deep stage of hypothermia reduction of neurosecretion within the hypothalamic-pituitary axis can be observed, and reduced secretion of thyroid hormones. The secretion of catecholamines is reduced, which at temperatures below 20°C stops completely, peripheral effects of adrenaline are also abolished. In this phase, thermoregulation activities are still preserved which is reflected in shivering and increased oxygen consumption during the heating of the system. If effects of cold on the system are long-termed-changes are similar then, but after a few hours death occurs, as a result of exhaustion of energy reserves of the system. BRAIN FUNCTIONS IN HYPOTHERMIA 32oC – first changes in EEG 31oC –inhibiting activity of the cerebral cortex loss of consciousness < 25oC – loss of brain and spinal reflexes 20o-18oC – electric silence in EEG ACCLIMATIZATION TO COLD The increase in thermal insulation properties of the coatings development of subcutaneous adipose tissue ntensity of metabolic processes The role of the brown adipose tissue WINTER SWIMMING Clubs of walruses around the world Ideas of winter swimming:> health >energy >extreme sport THE EFFECTS OF SWIMMING IN COLD WATER psychological metabolic endocrinal cardiovascular HAZARD or HEALTH >Usually the walruses immerse themselves in water for a very short time - about 10-20 seconds, though there are some who do it up to a few minutes, even though it’s not too safe.>Some plunge their heads, but most people enter only deep enough for the water to reach their neck. The icy water stimulates the whole body, starting with the skin receptors. >Danger signals activate the nervous, endocrinal and immune system etc. The production of heat dramatically rises, followed by dermic vasoconstriction which prevents heat loss.The body warms up, the internal temperature rises, the skin cools. HAZARD? Source/Quelle: Massachusettsmike H A Z A R D ? In the United Kingdom, each year, from 400 to 1,000 people die from hypothermia during swimming in cold water (including fatal accidents, ships and boats). The causes of death are usually myocardial infarction and heart failure, abnormal blood flow in the brain and heart rhythm disturbances, caused by the autonomic nervous system. Tipton M., Eglin C., Gennser M., Golden F. Lancet 1999, 354, 626-629 HAZARD? >Concentration of stress hormones in the blood increases rapidly, in order to stimulate the production of heat by generating the chills. Chills begin very quickly to generate more heat through muscle work. This leads to increased muscle tension, chills and muscle fatigue in less experienced swimmers, resulting in a dramatic deterioration of swimming skills. >If panic adds up, we can expect higher risk of drowning. If the person does not drown, then the low temperature will lead to hypothermia, which may also lead to death. Tipton M., Eglin C., Gennser M., Golden F. Lancet 1999, 354, 626-629 HAZARD? RESPONSE TO COLD WATER: -Uncontrolled, very quick and rapid breathing, followed by hyperventilation. -Heart attack, which can occur when the temperature of the blood returning to the heart is suddenly reduced. This can cause atrial fibrillation.-Drowning and cardiac arrest are the most common causes of demise, although it is the low temperature and hypothermia that are commonly believed to be responsible for the death. Kolettis TM et al. Medical Hypotheses, 2003, 61, 654-656 HEALTH? Bathing in an air-hole causes change in walruses psyche. The increase in the secretion of endorphins -mild euphoria, -tide of vitality -peace of mind HEALTH? Human body has a very high potential to adapt to operating in difficult environments. Taking a cold shower (10 degrees Centigrade) for about 3 minutes reduces the stress caused by the cold by about 20-30%. REGULAR EXPOSURE TO COLD Stimulation of tolerance to low temperatures: thermogenesis: -non-shivering -shivering circulatory system WALRUSES THERMOGENESIS The mechanism of non-shivering thermogenesis: -β-adrenergic receptors more sensitive to catecholamines -adrenergic stimulation of muscle tissue and / or fat Simeckova M. et al. J. Therm Biol 2000, 25, 437-442 Simonsen L. et al. Int.J.Obes.Relat.Metabol.Disord.1993, 17 (suppl.3), S47-S51 POSITIVE EFFECTS OF REGULAR WINTER SWIMMING -Improved insulin tolerance in patients with type II diabetes -Reduction of endothelial dysfunction vascular -Inhibition of atherosclerosis Hermanussen M et al. Archic Med. Res 1995, 54, 45-51 Dugue B et al. Clin Physiol 2000, 20, 114-121 POSITIVE EFFECTS OF REGULAR WINTER SWIMMING -The increase in white blood cells, IL-6 -Strengthen the immune response -Reduction (by 40%) in the number of cases of respiratory diseases Arcaro G et al. Circulation, 2002, 105, 576-582 Brenke R Therapeutikon 1990, 4,466-472 POSITIVE EFFECTS OF REGULAR WINTER SWIMMING Improved antioxidant protection: -increase in the activity of antioxidant enzymes-increase in plasmas antioxidant capacityshielding tissues from damage caused by free radicals Siems W G et al. QJMed 1999, 92, 193-198 Siems W G et al. Free Rad Biol Med. 1994, 16, 299-305 Kloner R A et al. Circulation 2001, 104, 2981-2989