Bergdahl- Chapter 24 and 25 Flashcards Preview

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Flashcards in Bergdahl- Chapter 24 and 25 Deck (99):

what are the 4 stages of response to extreme exposition ?

1) acute reaction
2) exhaustion
3) adaptation
4) evolutionary adjustments


what is an acute emergency reaction like ?

maximal use of reserves, non-specific stress response
cannot be sustained permanently


what is exhaustion like ?

what happens when the exposure is too long or strong

eg Titanic sinking victims


what is adaptation like ?

selective strengthening of the most advantageous specific means of defense. however, it has limits

eg winter swimming, but even winter swimmers would not have survived the sinking of the Titanic


what are evolutionary adjustments ?

species/population change for many generations

eg Inuit are more resistant to cold


what elevations are considered high altitude ?

10 000 ft- 18 000 ft above sea level


what is altitude's physiologic challenge ?

decreased ambient PO2


how does air density change with altitude ?

it decreases progressively as one ascends above sea level


what is acclimatization ?

adaptations produced by changes in the natural environment


what is acclimation ?

adaptations produced in a controlled laboratory environment which simulates high altitude


how does sport performance change in altitude (anaerobic and aerobic)?

when sports are anaerobic, the altitude doesn't matter
however, for aerobic sports, makes a difference


how does the oxygen transport cascade differ at high altitudes ?

fig 24.2

begins lower and ends a bit lower


what are the two important immediate responses to altitude exposure ?

1) hyperventilation
2) increase in blood flow during rest and submax exercise


explain how the hyperventilation as an immediate response to altitude exposure comes about

reduced arterial PO2
peripheral chemoreceptors sensitive to reduced O2
therefore, inspiratory activity stimulates alveolar ventilation


what are the three immediate effects of high altitude ?

1) hyperventilation
2) increase in submax heart rate and cardiac output
3) catecholamine response


how does cardiovascular response immediately increase at high altitude ?

- increase in submaximal heart rate
- increase in submaximal cardiac output
- increase in submaximal blood flow
- SV and max CO don't change


what is the catecholamine response that is immediate in high altitude ? :)

it will progressively increase for NE and stay the same for E during rest and exercise
(plateau, then upward slope, then plateau at new concentration)


describe the fluid loss in high altitudes

body water evaporates since ambient air is cool and dry
leads to moderate dehydration


what is the purpose of long term adjustments in high altitude ?

improve tolerance to relative hypoxia


what are the 3 main long term adjustments in high altitude ?

1) regulation of acid-base balance of body fluids altered by hyperventilation
2) synthesis of hemoglobin and RBC
3) elevated SNS activity reflected by increased NE that peaks within 1 week


what is the main action of ventilation ?

breathing out too much CO2


in high altitude, explain the process of hyperventilation and how it'll change the blood pH

hypoxia, so induce hyperventilation. this will get rid of a lot of CO2.
therefore, there is not enough CO2 in the blood, which will shift the reaction to the left. bicarbonate (HCO3-) and H+ will become carbonic acid and become CO2. this causes a decrease in H+ concentration, meaning it causes alkalosis


what kind of pH condition will high altitude bring ?

alkalosis, pH increases


until an altitude of 3048m, does hemoglobin's percentage saturation really change ?



how does performance in anaerobic events change in high altitude ?

altitude does not impair short-term anaerobic energy system
rather, it may even improve because of the lower air density


as an immediate response to altitude exposure, what compensates for arterial desaturation ?

the increased submaximal flow


what is the most important long term adjustment to high altitude ?

increase in blood's oxygen-carrying capacity


what are the two factors that account for the blood's increased O2 carrying capacity as a long term adjustment ?

1) decrease in plasma volume (so increase in hematocrit)
2) increase in RBC and Hb synthesis

basically, larger O2 amount is going to tissues even though the O2 bound to Hb is lower than in normal conditions


what is polycythemia ?

increase in total amount of RBC (what happens in high altitude)


long-term, what happens to the HCO3- (bicarbonate) ?

it is excreted via the kidneys


what are the 6 different ways that the body adjusts long-term to better bring blood to the tissues ?

1) increased cardiac output- more oxygenated blood moved
2) increased RBC, so there is a higher oxygen carrying capacity
3) 2,3-DPG levels are higher
4) more capillarization
5) increased myoglobin, meaning there is more O2 locally available
6) increased urine output is a temporary way to concentrate blood


what is acute mountain sickness ?

relatively benign
probably due to hypoxia


what is a high altitude pulmonary edema ?

fluid accumulates in brain and lungs
reversible if you go to a lower altitude


what is a high altitude cerebral edema ?

potentially fatal
neurologic syndrome that can develop in those with acute mountain sickness


how much time does it take to adapt to altitudes up to 2300 m ?

2 weeks


how much time does it take to acclimatize to a 610 m altitude increase when we're above 2300 m?

an additional week


to minimize detraining effects, when should athletes who compete at altitude begin training ?

immediately during acclimatization


after how much time do acclimatization adaptations dissipate after return to sea level ?

2-3 weeks


what is the relationship between decline of VO2 max and altitude ?

linear downward


what happens long term with VO2 max ? why ?

after several months, VO2max still remains below sea-level values, even with increases in Hb
this is because reduced circulatory capacity (due to lower maximum heart rate and stroke volume) offsets the benefits of Hb


long term what happens to maximum cardiac output ?



short term what happens to maximum cardiac output ?

doesn't really change, or decreases slightly


in submaximal exercise, what is the immediate altitude response ?

increase cardiac output
however, this diminishes as acclimatization progresses and does not improve with prolonged exposure


what happens to cardiac output in submax exercise ?

progressive decrease in heart's SV will decrease CO


how does submax VO2 change with high altitude ?

lower CO, but submax VO2 stays stable through an expanded a-v(mixed) O2 difference


what are 3 changes in the muscles that occur with hypoxic exposure ?

1) increased muscle effiency at mitochondrial level
2) greater muscle buffering
3) ability to tolerate lactic acid production


what happens to endurance during acclimatization ? what are the 3 factors that contribute to this ?

small improvement
1) more minute pulmonary ventilation
2) increased arterial oxygen saturation and cellular aerobic functions
3) blunted blood lactate response in exercise


what 2 changes offset adaptations that could improve exercise performance ?

1) muscle mass loss and reduced MHR and SV do not enhance performance
2) reduction in CO offsets benefits in the increase in the blood's oxygen carrying capacity


what is more important- the CO reduction or the increase in the blood's oxygen carrying capacity in terms of change ?

decrease in CO offsets the other


does endurance training at altitude improve subsequent sea level exercise performance ?

altitude acclimatization improves capacity for exercise at altitude


what adaptations could improve subsequent sea level performance ?

local circulation and metabolism
compensatory increases in blood's oxygen-carrying capacity

(live high, train low)


how must absolute workload be adjusted depending on the altitude ?

high altitude : absolute workload must be lowered to perform aerobic exercise at the same relative intensity


how high should an athlete live and train ? 3 rules

1) the elevation must be high enough to raise EPO (erythropoietin) levels to increase total RBC volume and VO2max
2) athlete must respond positively with increased EPO output
3) training must take place at an level low enough to maintain training intensity and exercise oxygen consumption at near sea level values


what is the Gamow Hypobaric Chamber ?

at-home acclimatization technique
a person rests and sleeps in it for 10 hrs/day, and the chamber's total air pressure decreases to simulate altitude exposure


how is it possible to simulate altitude at sea level by playing around with nitrogen ?

if you increase nitrogen percentage and live there for a little while


what is temperature ?

represents the mean kinetic energy of a substance's atoms as they move


what kind of declines and increases in body temperature can humans tolerate ?

decline of 10, increase of 5


when does heat conservation occur in blood flow ?

when blood shunts rapidly to the deep body cavities and muscle mass


what brain area controls temperature



how does hypothalamus turn heat on and off

it cannot turn off the heat
it can only initiate responses to protect the body from buildup of heat or cold


what provides the greatest contribution against cold ?



what are two ways to generate heat ?

shivering and physical activity


how does heat redirect to specific body parts ?

- stimulation of cutaneous cold receptors
- constrict peripheral blood vessels
- reducing flow of warm blood to surface, redirecting it to the core


what is the main duty of the body's thermoregulatory mechanisms ?

protecting against overheating


what are the 4 ways heat can leave the body. explain them

1) radiation : sun's effect on Earth
2) conduction : direct heat transfer from one molecule to another through a liquid, solid, or gas, eg immersing body in cool water
3) convection: air currents
4) vapor : sweat, vaporization in respiratory passages


what is the main heat loss mechanism we use ?



what are the three factors that influence the total amount of sweat vaporized from the skin and pulmonary surfaces ?

1) surface exposed
2) temperature and relative humidity of the ambient air
3) convective air currents around body


what is the main factor in determining the effectiveness of evaporative heat loss ?

relative humidity (ratio of water in ambient air at a particular temperature compared to total quality of moisture)


how does the circulatory system work to maintain thermal balance ?

at rest in the heat, the HR and CO increase while superficial arterial and venous blood vessels dilate to divert warm blood to the body periphery


how does sweating (evaporation) work to maintain thermal balance ?

begins within several seconds of exercise
effective when it is combined with large cutaneous blood flow


what hormones are released in response to cold stress ?

E, NE, thyroxine


how do hormonal adjustments work to maintain thermal balance while sweating?

sweating makes people lose water and electrolytes
stimulates release of aldosterone to increase sodium reabsorption and to decrease sweat sodium concentration to further conserve electrolytes

also, vasopressin is released to facilitate fluid retention


describe the competitive cardiovascular demands on the body during heat

arterial blood diverting to periphery to cool body down cannot deliver the O2 to the active muscle


how do HR and SV look in heat for submax

lower SV, causing higher HR


in maximal exercise in heat, what happens to cardiac output ?

HR increase cannot offset SV decrease so CO decreases


how does dependence on anaerobic metabolism change in heat in submax exercise ?

submax exercise will rely more on anaerobic system which means there will be earlier lactate buildup, glycogen reserves use, early fatigue in prolonged exercise


what are 2 factors that increase blood lactate accumulation in heat in submax ?

1) decreased lactate uptake by the liver due to reduced hepatic blood flow (since the blood is going to the periphery)
2) less muscle catabolism of circulating lactate


how does fatigue coincide with temperature ?

fatigue generally coincides with a higher core temperature, which directly impairs muscle activation from a higher brain temperature


moderate exercise for more than 1 h produces what volume of sweat ?

0.5-1 L


what 5 factors do fluid loss in heat coincide with ?

1) decreased plasma volume
2) reduced skin blood flow for a given core temperature
3) reduced stroke volume
4) increased near-compensatory HR
5) general deterioration of efficiency in exercise


what must fluid replacement focus on ?

maintaining plasma volume


how does ingesting fluid change blood flow ?

it increased blood flow to skin for more effective cooling


at what rate should one replace one's water losses from sweating ?

at a rate close to or equal to sweating rate


how can sodium benefit rehydration ?

moderate to high amounts of sodium in rehydration drink can help


how can potassium affect rehydration ?

enhances water retention in intracellular space and reestablishes potassium excretion that accompanies sodium retention


what is the recommended amount of g Na / L fluid

0.5-0.7 g/ L fluid


by how much should ingested fluid exceed sweat loss ?

25-50% since kidneys also continually form urine regardless of hydration status


what are 5 factors that modify heat tolerance ?

1) acclimatization
2) training status
3) age
4) gender
5) body fat level


what are heat cramps ?

severe involuntary, sustained, and spreading muscle spasms occur during or after intense physical activity, usually in active muscles


what is heat exhaustion ?

caused by ineffective circulatory adjustments- depletion of extracellular fluid, principally plasma volume, from excessive sweat


what is heat stroke ?

most serious
failure of the heat-regulating mechanisms from an excessively high core temperature


how do body fat difference influence physiologic function in the cold ?

additional body fat = more insulation
eg good for swimmers


a child has a distinctly large ratio of body surface area to mass. what are the implications of that ?

it's good and facilitates heat loss in warm environment
however, also means that in cold body dissipates rapidly


how do children rely (2 ways) on adjustments in body to tolerate cold during exercise ?

1) augmented energy metabolism
2) more effective peripheral vasoconstriction


do we have more capacity for cold or heat exposure ?



how will cold adaptation occur ?

with regular, prolonged exposure


in severe cold, what happens to the brain ?

temperature decreases, reducing O2 needs
CNS benefits from blood redistribution from tissues that will compromise their supply to save the brain


does cold ambient air pose a danger to respiratory passages ? why ?

because incoming air will warm


what will happen to airways in exercise in the cold ?

loss of airway moisture
dry mouth
irritation and dehydration