Unit 4

At high PO2 (X > ~60 mmHg) there is (high/low) hemoglobin saturation
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Terms in this set (108)
SaO2 (increases/decreases/does not change) as altitude increasesDecreasesat high altitude (i.e. 4000 m or higher), which is way lower than at sea level: -VO2 at an absolute sub-maximal workload -VO2 maxVO2 maxat high altitude, minute ventilation (VE) during exercise at an absolute submaximal workload is (higher/lower) than at sea levelhigherlower VO2 max is largely attributable to (higher/lower) SaO2 at high altitude than at sea levellowerCardiac output (increases/decreases/does not change) as altitude increasesDoes not change (so difference in VO2 max is dictated by amount of O2 carried in blood, not cardiac output)At sub maximal exercise intensities, heart rate (increases/decreases/does not change) as altitude increases but maximal heart rate does not changeincreasesaVO2 difference (increases/decreases/does not change) with altitudedecreases slightlyAt altitude oxygen transport cascade starts and ends with (higher/lower) PO2 as oxygen is extractedLower (starting at 80 mmHg compared to 110 mmHg)Absolute VO2 max does not change at altitude but VO2 max is much lower so a person works at a much (higher/lower) proportion of VO2 maxHigherAltitude hypoxiaOxygen not being available in sufficient amounts at the tissue levelImmediate response to altitude hypoxia-hyperventilation (minute ventilation is higher so more CO2 is blown off) -Increase in heart rate during sub maximal exercise -Decrease in plasma volume and increase in hematocritLong term response to altitude hypoxia-kidney clears more bicarbonate -increase in heart rate during sub maximal exercise sticks around -increase in hemoglobin concentration and red blood cell count -increase in capillaries in skeletal muscle -Increase in 2,3-DPG in red blood cells, which stimulates greater unloading of oxygen for any PO2 -Increase in mitochondria in muscle (increase in aerobic enzymes)How does red blood cell count increaseKidney senses low PO2 and produces erythropoietin, which stimulates procreation of red blood cellsCatecholamine secretion is (increased/decreased) in first week at altitudeIncreased. Stimulate sympathetic nerve activity (increases heart rate etc.)One studies best at altitude or sea levelSea levelAre higher or lower levels of blood lactate achieved at altitudeLower. Maximal blood levels are way lower at altitude so there is also impaired anaerobic functioningAcclimatizationincreased hematocrit (red blood cell count) and blood hemoglobin content (over course of 60 days of living at altitude)Supplemental ____ improves hematocrit response to altitudeIronAerobic events are impaired at altitude-No real effect on <2 min (mostly anaerobic) -Longer events at altitude are (more aerobic)Training at altitude (does/does not) improve sea level VO2 maxDoes not. Because you cannot train as hard at altitude so there is less training stimulusLive high, train lowA type of altitude training where the athletes live at a high altitude but travel down to sea level to train. -benefits of living at altitude: increased capillaries, hemoglobin, etc.) -benefit if training low: high intensity workoutsHypoxic tentMimic living at altitude by decreasing percentage of oxygenAs altitude increases, PaCO2 (increases/decreases/does not change)decreasesTwo main problems of exercising during heat-Production of metabolic heat -Limitations on coolingAt maximal exercise you can consume ____ L of oxygen per minute4. so 4l of oxygen at 5kcal per liters is 20 kcal of energy expenditure per minuteIf a person's max sweat rate is 30 mL per minute (and each 1 mL swat evaporation ~0.6kcal) max cooling is _____ kcal per minute18 (already less than energy expenditure)Body heat loss-Radiation -Conduction: body to object -Convection: body to air or water (air must be cooler than body) -Evaporation: most important (requires low humidity)body heat gain-basal metabolic rate -thermic effect of food -environmentEvaporative coolingenergy absorbed by water in its transition from fluid to vaporAn increase in core temperature --> (increase/decrease) in sweat rateIncreaseIncreasing body size, work rate, and temperature all (increase/decrease) sweat rateIncreaseHeat acclimatization-Lower threshold for start of sweating (sweat earlier to better control body temperature) -Lower electrolyte concentration in sweatSodium-decreases urinary output while exercising -better fluid retentionWhen it's hot, those who are (larger/smaller) with greater surface area to volume ratio have an advantageSmallerWater is extremely effective at (convective/conductive) coolingConvectiveHigh wind speeds (increases/decreases) evaporative and convective coolingIncreasesWhen temperature is really low, (convection/conduction) is a major cooling factorConvection (stops when air temperature is hotter than skin temperature)Evaporative heat loss (increases/decreases) in importance as temperature increases (assume humidity is low)IncreasesIf total heat loss is (greater/lower) than metabolic rate, core temperature goes uplowerAerobic training (increases/decreases) sweat NaCl concentrationdecreasesWhy does fluid replacement increase work time in the heatB/c heart rate increases if fluids are not replacedHow does heat acclimation (training under hot and humid conditions) increase performance-Lowers starting heart rate and lowers heart rate drift -suppresses increase in core temperature during exercise (through increased sweat volume)Which comes first? -Increased sweat volume -decreased core temperature -decreased heart rate during sub maximal exerciseIncreased sweat volume (--> decreased core temperature --> prevents rise in heart rate)How does a lower core temperature prevent rise in heart rateB/C not as much blood is being shunted to the skinEffects of aerobic training-initial jump in plasma volume subsidies after a few weeks -after four or five weeks there is a big increase in red blood cell mass and blood volumeTotal body water is (higher/lower) in trained athletesHigher (increase in plasma volume + increase in red blood cell volume --> increased blood volume) -Effects can be augmented by heat acclimationExercising in hot and humid environments-can lose 1-2 liter per hour in sweat -plasma volume is partially compensated by metabolic water and water complexed with glycogen -sweat loss: fluid and electrolytes (na+ determines amount of water)What sport gives the gives the least chance for an increase in core temperature and sweat ratewater sportsHyponatremia (low sodium)Small runners who don't sweat a lot are at riskEndurance work capacity declines if you lose 2% of body weight through fluid loss-Replacement of fluids is limited by rate of gastric emptying (fluid has to get out of stomach and into small intestine before it can be absorbed ) (~250mL per 15 minutes)T/F fluid loss of 3-5% of body weight (does/does not) affect strength or anaerobic performanceDoes not_________ degrades cognitive/mental performanceDehydrationEffects of Heat Acclimatization-increases sweating volume -decreases urinary water loss -decrease salt concentration in sweat -increases blood volume -increases efficiency of blood distributionDuring hot conditions, a large chunk of cardiac output goes to the skin to aid in cooling but takes away from blood flow to skeletal muscle, which (increases/decreases performance)decreases (working VO2max decreases)Diving-every 10 meters of depth adds 1 atm of pressure -gas volume is inversely related to pressure -lung volume decreases as depth increases (1/pressure in atm)At a depth of 10 m the pressure isabout twice sea level (2 atm)At a depth of 30 m the pressure is aboutfour times that of sea level (4 atm)if a person takes a breath and has an air volume of 6 L and dives 10 m the air volume will be3 litersIf a person is 10 m below sea level with 3 L of air in lungs and dead space, what will the volume be at sea level6 LAt 10 m below surface, pressure has doubled, lung volume has been halved, PO2 goes way upFact. PO2 is roughly doubled at 10 m below surfaceAt a depth of 90 the incredibly high PO2 will causeA relatively large amount of oxygen directly dissolved in plasma volumeResidual volume and total lung capacity-damage to lung occurs when lung volume is compressed below residual volume -greater total lung capacity protects against reaching the over compression limit -Greater ratio of TLC to residual lung volume means that deeper diving is less riskyReturn to surface-Must expire enough air so that lung expansion doesn't damage lung tissue -PO2 decreases when returning to surfaceT/F someone breathing high pressure PO2 is at a higher risk than a free diver for over expansion of air space on return to surfaceTrueBreath golding limit is determined byPaCO2. Hyperventilating before dive can extend dive time but too large a decrease in PaCO2 can cause vasoconstrictionMammalian diving response-Bradycardia (decrease in heart rate) -Decreased cardiac output -Peripheral vasoconstriction (makes skeletal muscle more reliant on glycolysis) (lactate accumulates)Human response to diving-Decreased heart rate at depth decreases cardiac output -Response is greater in colder temperatureBradycardiadecreased heart rateSnorkel length and diameter-At low depths, the diaphragm can't overcome increase in pressure and snorkel breathing cannot occur -large increase in dead space limits PaO2Open circuit breathing systemScuba tank: breath in O2 breath out CO2Closed circuit breathing system-Used for long dives -CO2 scrubber -does not blow bubblesHazards of diving-Air embolism: occurs when diver does not breath on way up - can block blood flow --Could lead to Pneumothorax: rupture of lung tissue -vacuum can pull eyes out -Nitrogen narcosis: high dissolved N2 levels can cause intoxicating effects at high pressures________ chambers can prevent decompression injuryHyperbaric (prevent nitrogen bubbles from forming in tissues and bloodstream)height (increases/decreases) in microgravityIncreases (due to less compression)Center of gravity (CG/M) goes (higher/lower) in gravityHigher b/c body fluids move towards upper bodyT/F body posture improves in spaceTrueModels of microgravity-Parabolic flight -head down bedrest -immobilization -wheelchair confinement -water immersion -hind-limb suspension for animalsEffects of microgravity-change in fluid distribution (less venous return --> less control of blood pressure) -Loss of extracellular fluid cleared by kidney (reduced body water and blood volume) -less stimulus on bone so loss of bone and calcium -less stimulus on muscles leading to muscle atrophy and loss of mitochondria -Decrease in stroke volume -decreased plasma volume and red blood cell mass -decreased hemoglobinMicrogravity and exercise-Microgravity decreases aerobic fitness (VO2 max) unless you work out ~3 times per week for >20 minDecreased skeletal muscle function after space flight-mostly from atrophy -reduction in torque production -shift in muscle fibers from Type I to Type II (better at greater angular velocities)T/F explosive power decreases during and after time in spaceTrueBone-loading stimulates maintenance and increase of mineral density -if there's no load, osteoblasts outstrip osteoclasts --> loss of BMD --Also loss of total body calciumparasympathetic nervous system and central venous pressure-decrease in physical stress --> decrease muscle loading --> muscle atrophy --> decrease in force production and strength --> decrease in mitochondria --> decrease in VO2 max --> increased reliance on anaerobic pathways -->greater fatigue -Decrease in PNS activity so resting heart rate goes up -Blood volume goes down -less cardiac filling -decrease in stroke volume -decrease in # of capillaries -decrease in oxygen delivery -So AVO2 difference is greaterReturn to earth-Fluid shifts back down -person is impaired in controlling blood pressures (orthostatic intolerance) so they feel a little faint until they regain ability of vasoconstriction to force blood back up towards heart over time) -decrease in sympathetic nervous system activity -loss of mineral (potassium)Moment armdistance between a joint axis and line of force acting on that join (less torque required to pick up box when squatting versus bending over)Moment of inertia-Resistance to acceleration -lower moment of interim = going faster -you can swing arms a lot harder with bend -choke up on bat -skaters keep arms closeHumans increase _____ _____ to increase enduranceStride length (unless you're a sprinter)4 legged animals increase _____ _____ to increase enduranceStride frequency (more costly)Large loading surfaces (i.e. those at the knee) allow (higher/lower) stress for humans than monkeyslowerLarger gluteus Maximus leads to (greater/lesser) stability at hipGreaterhaving no hair, being tall and narrow (increases/decreases) surface area to volume ratioincreases (all allow for greater cooling as does expanded cranial circulation)(longer/shorter) toes corresponds to less torque required at forefoot strikeLongerImpact of foot strike in running is higher under (forefoot/rear-foot) strikeRear-foot strikeIs running strike learned?Yes, partially. -Habitual shoe-wearers increase rear foot strike -habitual bare-foot runners increase forward and mid foot strikeSlower runners are likely to be _____ foot strikerRearInjury rate is higher for ____ foot strikersRearRunning economy is greater for (shoe/barefoot) runnersBarefoot. they are less likely to fatigueBody composition lecture