Environmental Physiology Flashcards
how long does it take people to acclimatize to any enviroment
8-14 days
how long does it take people to lose adaptations?
14-28 days
how does hereidatry influence adaptations to environments?
- people may work better at different environments (sherpas in alps)
- people vary in how they respond to the same stressor = different outcomes/ different developed tolerances
- affect a person’s ability to meet physical or psychosocial demands
how does psychological factors effect environmental stressors?
if the stressors arent harmful or alarming, they may produce small or opposite responses
- complaining
- cold, think about hot –> sweat
- these can occur before stressor has been applied
physiological responses can be excessive in what ways?
- inappropriate, inadequate, diesordered
- exaggerated by other diseases and disorders (heart problems and renal function)
what core temp does the hypothalamus (central monitoring system) maintain?
37 degrees celcius
what efferent feedback systems does the hypothalimus stimulate if one becomes hypothermic or hyperthermic?
SNS or PSNS to dissipate or conserve heat?
what are the four heat transfer mechanisms?
Radiation- direct transfer of heat (sun to body or radiate heat out of body)
Convection- fluid air or water movement over skin (water is more effective)
Conduction- contact with skin or a solid object (grabbing something hot or cold)
Evaporation- sweat vaportization
which heat transfer mechanisms take heat away from us by air
evaporation and radiation
which mechanisms heat or cool us down
convection and conduction
what ways do you keep cool in hot environments?
- increase blood flow by vasodialation
- vasodilation causes heat to go from core to environments
- sweating releases fluid for evaporation
- blood plasma volume decreases
- kidneys retain H2O and NaCl to offset fluid loss
- core temp increases
- no hormones
what happes when humidity rises about 50-70% in hot conditions
the effectiveness of evaporation decreases because sweat is insulated and skin stays hot and flushed
how is exercise perfomance influenced with heat?
when core temp increases, performance decreases
- max strength unaffected
- dehydration
- heat exhaustion
- cramps
- syncope (blacking out)
how does the body acclimatize to heat
- sweating improves (faster, more, lower temps, more dilute to save electrolytes)
- blood volume increases (from sweat loss) to lower HR
- decreased core temp
- improved exercise tolerance
How do you keep warm in cold conditions? (acute responses)
- SNS causes shivering (skeletal muscle tremors)
- Thyroid releases thyroxin to increase BMR and core temp
- vasoconstriction causes increased blood flow to core to keep heat around vital organs
- Decreased max HR and Q from Hb from vasoconstriction
- decreased dissociation of O2 on Hb b/c hb wants to hold onto O2 so you rely less on aerobic
- skin and hair trap air and warm it
- decreased blood plasma volume from some evaporative cooling
- Kidneys retain H2O and Na+ to offset dehydration
How is exercise performance changed with cold conditions?
- more clothes may conserve heat or increase exertion
- shivering increases Vo2 max at submax conditions but also decreases motor coordination.
- more reliance on anaerobic energy from decreased Q and O2 delivery shortens fatigue time
- increased risk of hypothermia and frostbite
why is the risk of dehydration increased with cold?
because vasoconsriction causes blood to be at the core, so there is no decrease of blood volume detected to trigger thirst responses
how does the body acclimatize to cold?
- more effecient thermoregulatory capabilities
- greater reliance of FFA because of Epi and Norepi relsase from sns
- reduced skin blood flow increases venous return which increases SV
- lower lactate production from glycogen sparing effect of FFA use
- cold may ease exercise effort
what volunatry responses may you do to adapt to cold
- heating
- warm clothing
- eating to increase metabolism
- exercise
which involunatry responses happen with detection of decreased core temp by hypothalamus?
- reduced sweating (psns)
- goose bumps (piloerection
- norepi reslease–> vasoconstriction
- increased BMR (thyroxin or SNS)
- shivering (warms blood that passes through muscles)
what involunatry responses to heat happen by cerebral cortex?
- cooling mechanisms (fan)
- minimal clothing
- cold drinks
- resting
what involuntary responses are regulated by the hypothalimus with heath
Psns (up regulates) -sweating (ach release) -lethargy Sns (down regulates) -decreased bmr -vasodilation (heat to external environement through radiant heat or sweating)
how does CV drift relate to environmental phys?
losing electrolytes through sweating decreases SV and increases HR. this causes us to retain more Na+ and H2O in kidney to midigate losses and prevent cramping
what acute responses happen exercising in thin air?
- air densities decrease
- resting and submax Ve increase to maintain Hb O2 saturation –> increases PAO2 a
