Koofers

chapter 9 - Flashcards

Flashcard Deck Information

Class:PHED 35345 - Exercise Physiology (with lab)
Subject:Physical Education
University:Rowan University
Term:Fall 2014
- of -
INCORRECT CORRECT
- INCORRECT     - CORRECT     - SKIPPED
Shuffle Remaining Cards Show Definitions First Take Quiz (NEW)
Hide Keyboard shortcuts
Next card
Previous card
Mark correct
Mark incorrect
Flip card
Start Over
Shuffle
      Mode:   CARDS LIST       ? pages   PRINT EXIT
The ventilatory system meets the bodys needs to maintain efficient gas exchange. It regulates the gaseous state of the external environment for aerating fluids of the internal environment during rest and physical activity
Three major functions
  1. supply O2 required in metabolism
  2. eliminate CO2 produced in metabolism
  3. regulate hydrogen ion concentration (H+) to maintain acid base balance
pulmonary ventilation In respiratory physiology, ventilation is the movement of air between the environment and the lungs via inhalation and exhalation. ambient atmospheric air
components of ventilatory system
  1. nose and mouth
  2. trachea
  3. bronchi
  4. bronchioles
  5. alveoli
Generated by Koofers.com
lungs provide a large surface area for gas exchange true
inspiration
  1. diaphragm contracts flattens out and moves downward
  2. external intercostals pill ribs up and rotate out
  3. air in lungs expands, reducing its pressure
  4. pressure differential between lungs and ambient air sucks air in through the nose and mouth to inflate lungs
  5. inspiration concludes when thoracic cavity expansion ceases and intrapulmonic pressure increases to equal atmospheric pressure
Expiration
  1. Predominantly passive process
  2. air moves out of lungs from recoil of stretched lung tissue and relaxation in inspiratory muscles. 
  3. sternum and ribs swing down, while diaphragm moves toward thoracic cavity
  • these movements decrease chest cavity volume and compress alveolar gas
  • forces air out through respiratory tract to atmosphere
boyle's law goes along with expiration

gases move by boyle's law where:  P= 1/V
Generated by Koofers.com
Tidal volume (TV) Static lung volume

air moved during inspiratory or expiratory phase of breathing cycle; between .4 to 1 L of air per breath
Inspiratory reserve volume (IRV) static lung  volume

2.5 to 3.5 L above TV; serves as inhalation reserve
Expiratory Reserve volume (ERV) static lung volume

after normal exhalation, additional volume exhaled; 1 to 1.5 L for for men, 10 to 20% lower for women
Forced vital capacity (FCV) static lung volume

total air volume moved in 1 breath from full inspiration to max expiration, varies with body size and body position when measuring
Generated by Koofers.com
residual lung volume (RLV) following max exhalation, air volume that cannot be exhaled; 1.2 to 1.6 L for men and 1 to 1.2 L for women
Dynamic lung volume 1. max air volume expired (FVC)
2. speed of moving a volume of air

these are what dynamic measures of pulmonary ventilation
FEV 1 percentage of FVC expelled in 1 sec.

Dynamic lung volume
FEV1/FVC reflects expiratory power and overall resistance to air movement in lungs; average 85%

dynamic lung volume
Generated by Koofers.com
Maximum voluntary ventilation dynamic lung volume

rapid, deep breething for 15 sec extrapolated to volume for 1 min ranges between 140 to 180 L.min -1 for men, 80 to 120 L. min -1 for women
two characteristic of pulmonary ventilation
  1. volume of air moved into or out of total respiratory tract per min
  2. air volume that ventilates only alveolar chambers per min

minute ventilation(Ve) = breething rate * tidal volume
alveolar ventilation portion of minute ventilation that mixes with air in alveolar chambers
determines gaseous concentrations at alveolar capillary membrane


a portion of each inspired breath does not enter the alveoli and does not...... engage in gaseous exchange with blood
Generated by Koofers.com
Physiologic dead space portion of alveolar volume with poor tissue regional perfusion or inadequate ventilation
  • 150 to 200mL normal or 30% or resting total volume in healthy people
  • can increase to 50% of resting TV because: inadequate perfusion during hemorrhage. and blockage of pulmonary circulation from embolism or blood cut
breathing rate versus tidal volume Adjustments in breathing rate and depth during PA maintian alveolar ventilation
adjustments for alveolar ventilation
  • in moderation PA trained endurance athletes sustain adequate alveolar ventilation by increasing TV only mimimally increase breathing rate
  • with deeper training. alveolar ventilation increases from 70% of min ventilation at rest to more than 85% of total PA ventilation
  • increase occurs because greater percentage of incoming TV enters aveoli with deeper breathing
valsalva maneuver occurs often occurs in weightlifting and other activities that require a rapid, maximum, application of short-duration force. 

Generated by Koofers.com
valsalva maneuver impedes blood flow return to the heart. 
The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth, pinching one's nose shut while pressing out as if blowing up a balloon.
consequences of valsalva maneuver
  • performing prolonged valsalva maneuver during static or isometric straining-type movements dramatically reduces venous return and arterial blood pressure
  • these two effect diminsh brain's blood supply often producing dixxiness, 'spots before the eye' fainting
  • once glottis reopens and intrathoracic pressure stabilizes blood flow re-establishes with an 'overshoot' in arterial blood pressure
respired gases concentration and pressure
gas concentration: amount of gas in a given volume determined by product of gas partial pressure and solubility
Generated by Koofers.com
gas pressure force exerted by gas molecules against surfaces they encounter
partial pressure: percentage concentration *total pressure of gas mixture
ambient air PO2 = 159mm Hg; PCO2 = 0 mm hg;PN2 =600 mm Hg

Tracheal air PO2= 149mm Hg; PCO2 stays same
Generated by Koofers.com
alveolar air PO2 = 103 mm Hg; PO2 = 39 mm Hg
Gas movement in air Henry's law amount of gas dissolved in fluid depends on: pressure differential between gas above filled and dissolve in it 
and solubility of gas in fluid
Gas exchange in body in lungs first step in O2 transport involves transfer of O2 from alveoli into blood
three factors account for dilution of O2 in inspired air as it passes into alveolar chambers
  1.  water vapor saturates relatively dry inspired air 
  2. O2 continually leaves aveolar air
  3. CO2 continually enters alveolar air
gas exchange in body in tissues: O2 leaves capillary blood and flows toward metablizing cells, while CO2 flows from cell into blood
Generated by Koofers.com
gas exchange PO2 and PCO2 of ambient, tracheal, and alveolar air and gas pressures in venous and arterial blood and muscle tissure
Gas transfer pressure gradients at rest Time required for gas exchange. At rest, blood remains in pulmonary and tissue capillaries for about .75 sec. Pulmonary disease (orange dashed line) impairs rate of gas transfer across the alveolar-capillary membrane thus prolonging gas equilibration time
diffusion between pulmonary capillary and its adjacent alveolus happens in gas tranfer pressure gradients at rest
Oxygen transport in blood blood transports oxygen in two ways
  1. physical solution (1-2%)
  • dissolved in fluid portion of blood, establishes PO2 of blood and tissue fluids
2. Combined with Hb (98-99%)
  • in loose combination with iron-protein Hb molecule in RBC; increase blood's oxygen carrying capacity 65 to 70 times above normal
Generated by Koofers.com
two other combined with Hb facts
  1.  men: each 100 mL of blood contians approximately 15 to 16 g Hb
  2. women: 5 to 10% less; 14 g per 100 mL blood
Hemoglobin 1. consists of globin composed of four subunit polypeptide chains. Each polypeptide contains single heme groups with its single iron atom acting as oxygen 'magnet'

PO2 and Hb saturation
  • percentage saturation of Hb computes as

% saturation = (total O2 combined with Hb / Hb O2 -carrying capacity) *100
oxygen transport cascade Gas partial pressure as O2 moves from ambient air at sea level to mitochondria of maximally active muscle tissue
Generated by Koofers.com
bohr effect increases in acidity (H+) and CO2 and temp. cause oxyhemoglobin dissociation curve to shift downward and to the right to reflect enhanced unloading
other facts of the bohr effect
  • Occurs particularly in PO2 range of 20 to 50 mmHg
  • particularly important in vigorous PA because increased metabolic heat and acidity in active tissues augments O2 release
  • oxygen unloading to skeletal muscle from RBC about 25% at rest and can increase to about 40% during vigorous PA
Carbon dioxide transport in blood
  • blood transports CO2 to lungs in three ways
  1.  physical solution in plasma ( 7 to 10%)
  2. loose combination with Hb (20%)
  3. combination with water as bicarbonate ( 70%)
ventilatory control during rest: Neural factors
  • respiratory cycle comes from inherent, automatic activity of inspiratory neurons
  • exhalation begins by passive recoil of stretched lung tissue and raised ribs when inspiratory muscle relax
  • expiration facilitated by activation of expiratory neurons and associated muscles
  • as expiration proceeds, inspiratory center decouples from inhibition and progressively becomes more active
Generated by Koofers.com
ventilatory control  many factors affecting medullary control of pulmonary ventilation
during rest Humoral factors ventilatory control

  • chemical state of blood regulates pulmonary ventilation at rest 
variations in arterial
 Po2 and pco2 acidity and temp activate sensitve neural units in medulla plus arterial system
  • Chemoreceptors: structures that stimulate ventilation in response to increase CO2 temp acidity decrease in O2 and BP and probable decline in circulating K+ ions
other humoral factors CO2 pressure in arterial plasma provides most important respiratory stimulus at rest and during PA
Aortic and carotid cell bodies aortic arch and bifurcation of carotid arteries contain aortic and carotid cell bodies (chemoreceptors) sensitive to reduced plasma PO2 to defend against arterial hypoxia
Generated by Koofers.com
ventilatory control during PA: Chemical factors
  • PO2 - arterial PO2 does not decrease to stimulate ventilation by chemoreceptor activation. PO2. H+
  • chemical stimuli cannot fully explain hyperpnea during PA
values for PCO2 in mixed venous blood entering.... lungs, and alveolar PO2 and Pco2 related to VO2 during graded exercise

despite increased metabolism with PA alveolar Po2 and Pco2 remain near resting levels, Increases in mixed-venous Pco2 result from increased CO2 production in metabolism
ventilatory control during PA: Neurogenic factors
  • cortical influence- neural outflow from regions of motor cortex during PA and cortical activation in anticipation of PA stimulate respiratory neurons in medulla
  • peripheral influence- sensory input from joints, tendons, muscles adjust ventilation during PA (mechanoreceptors/proprioceptors)
Integrated regulation
  • Not single factor controls breathing in PA
  • Phase 1 ventilation- when PA begins.. Neurogenic stimuli from cerebral cortex and active limbs cause initial breathing increase
  • Phase 2 ventilation- central command input plus medullay control neurons and peripheral stimuli from chemorecptors adn mechanorecptors contribute to control minute ventilation, gradually increase to a steady level
Generated by Koofers.com
what is phase 3 ventilation fine tuning of ventilation through peripheral sensory feedback mechanism
Pulmonary ventilation during PA PA increases VO2 and CO2 prodution more than any other physiologic stress

relationship between pulmonary ventilation, blood lactate, and VO2 through steady rate and non-steady-rate PA levels to VO2 max
ventilation during steady-rate PA
  • ventilation during light and moderate PA increase linearly with VO2 by increase in TV
  • ventilatory equivalent for oxygen (Ve/VO2) 24:1 ratio
  • ratio of minute ventilation to VO2
  • remains relatively constant during steady- rate PA
ventilatory equivalent for carbon dioxide (Ve/VCO2) ratio of minute ventilation to O2 produced
remains constant during steady-rate PA because pulmonary ventilation eliminates CO2 produced during cellular respiration
Generated by Koofers.com
other steady rate PA facts
  • despite varitations in ventilatory equivalents among health people, complete aeration of blood takes palce because of 2 factors.
  1. alveolar Po2 and Pco2 remain at near-resting value
  2. transit time for blood flowing through pulmonary capillaries proceeds slowly enough to allow complete gas exchange
ventilation during non-steady rate PA ventilatory threshold (Tvent)

  • Tvent; point at which PV increases disproportionately with VO2 during graded activity
  • relates directly to increased CO2 output from buffering of lactate that begins at accumulate from anerobic metabolism
  • anaerobic threshold originally defined the abrupt increase in Tvent caused by nonmetabolic CO2 production from lactate buffering
other non-steady rate PA fact Ve/VO2 can go to as much as 36:1 during vigorous PA
OBLA/ Anaerobic threshold/lactate threshold
  • sharp upswing in pulmonary ventilation related to VO2 during incremental activity.- implies imbalance between rate of blood lactate appearance and disappearance
  • occurs between 55 and 65% VO2 max in healthy untrained subjects and often equals less than 80% VO2 max in highly trained endurance athletes
  • OBLA point increase with aerobic training without accompanying increase in VO2 max
Generated by Koofers.com
Major variables contributing to oxygen transport and use
  • two factors influence endurance performance
  1. VO2 max
  2. Max level for steady rate activity (OBLA)
energy requirements of breathing
  • breathing normally requires a relatively small oxygen cost even during PA
  • in respiratory disease work of breathing become excessive and PA alveolar ventilation often becomes inadequate
  • two factors determine energy requirements of breathing 
  1. compliance of lungs and thorax 
  2. resistance of airways to smooth air flow
buffers consist of a weak acid and the salt of that acid
  • bicarbonate, phosphate, and protein chemical buffers provide rapid first line defense in acid-base regulation
  • lungs contribute to ph regulation through changes in alveolar ventilation that rapidly after free H+ concentration in extracellular fluids. 
  • renal tubules act as body's final defense by secreting H+ into urine and reabsorbing bicarbonate
  • anaerobic PA increases demand for buffering; makes pH regulation progressively more difficult
O2 cost of breathing PA up to max a. effects of increasing Ve on total O2 cost of breathing expressed as percentage of total VO2

b. effects of increasing Ve on O2 cost per liter air breathed per min
Generated by Koofers.com
intense PA effects a. inverse linear relation between blood lactate concentration and blood pH

b. Blood pH and blood lactate concentration related to PA intensity expressed as percentage of max. Decreased in blood pH accompany increases in blood lactate concentration
Generated by Koofers.com

List View: Terms & Definitions

  Hide All 69 Print
 
Front
Back
 The ventilatory systemmeets the bodys needs to maintain efficient gas exchange. It regulates the gaseous state of the external environment for aerating fluids of the internal environment during rest and physical activity
 Three major functions
  1. supply O2 required in metabolism
  2. eliminate CO2 produced in metabolism
  3. regulate hydrogen ion concentration (H+) to maintain acid base balance
 pulmonary ventilationIn respiratory physiology, ventilation is the movement of air between the environment and the lungs via inhalation and exhalation. ambient atmospheric air
 components of ventilatory system
  1. nose and mouth
  2. trachea
  3. bronchi
  4. bronchioles
  5. alveoli
 lungs provide a large surface area for gas exchangetrue
 inspiration
  1. diaphragm contracts flattens out and moves downward
  2. external intercostals pill ribs up and rotate out
  3. air in lungs expands, reducing its pressure
  4. pressure differential between lungs and ambient air sucks air in through the nose and mouth to inflate lungs
  5. inspiration concludes when thoracic cavity expansion ceases and intrapulmonic pressure increases to equal atmospheric pressure
 Expiration
  1. Predominantly passive process
  2. air moves out of lungs from recoil of stretched lung tissue and relaxation in inspiratory muscles. 
  3. sternum and ribs swing down, while diaphragm moves toward thoracic cavity
  • these movements decrease chest cavity volume and compress alveolar gas
  • forces air out through respiratory tract to atmosphere
 boyle's lawgoes along with expiration

gases move by boyle's law where:  P= 1/V
 Tidal volume (TV)Static lung volume

air moved during inspiratory or expiratory phase of breathing cycle; between .4 to 1 L of air per breath
 Inspiratory reserve volume (IRV)static lung  volume

2.5 to 3.5 L above TV; serves as inhalation reserve
 Expiratory Reserve volume (ERV)static lung volume

after normal exhalation, additional volume exhaled; 1 to 1.5 L for for men, 10 to 20% lower for women
 Forced vital capacity (FCV)static lung volume

total air volume moved in 1 breath from full inspiration to max expiration, varies with body size and body position when measuring
 residual lung volume (RLV)following max exhalation, air volume that cannot be exhaled; 1.2 to 1.6 L for men and 1 to 1.2 L for women
 Dynamic lung volume1. max air volume expired (FVC)
2. speed of moving a volume of air

these are what dynamic measures of pulmonary ventilation
 FEV 1percentage of FVC expelled in 1 sec.

Dynamic lung volume
 FEV1/FVCreflects expiratory power and overall resistance to air movement in lungs; average 85%

dynamic lung volume
 Maximum voluntary ventilationdynamic lung volume

rapid, deep breething for 15 sec extrapolated to volume for 1 min ranges between 140 to 180 L.min -1 for men, 80 to 120 L. min -1 for women
 two characteristic of pulmonary ventilation
  1. volume of air moved into or out of total respiratory tract per min
  2. air volume that ventilates only alveolar chambers per min

minute ventilation(Ve) = breething rate * tidal volume
 alveolar ventilationportion of minute ventilation that mixes with air in alveolar chambers
determines gaseous concentrations at alveolar capillary membrane


 a portion of each inspired breath does not enter the alveoli and does not......engage in gaseous exchange with blood
 Physiologic dead spaceportion of alveolar volume with poor tissue regional perfusion or inadequate ventilation
  • 150 to 200mL normal or 30% or resting total volume in healthy people
  • can increase to 50% of resting TV because: inadequate perfusion during hemorrhage. and blockage of pulmonary circulation from embolism or blood cut
 breathing rate versus tidal volumeAdjustments in breathing rate and depth during PA maintian alveolar ventilation
 adjustments for alveolar ventilation
  • in moderation PA trained endurance athletes sustain adequate alveolar ventilation by increasing TV only mimimally increase breathing rate
  • with deeper training. alveolar ventilation increases from 70% of min ventilation at rest to more than 85% of total PA ventilation
  • increase occurs because greater percentage of incoming TV enters aveoli with deeper breathing
 valsalva maneuver occursoften occurs in weightlifting and other activities that require a rapid, maximum, application of short-duration force. 

 valsalva maneuverimpedes blood flow return to the heart. 
The Valsalva maneuver or Valsalva manoeuvre is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth, pinching one's nose shut while pressing out as if blowing up a balloon.
 consequences of valsalva maneuver
  • performing prolonged valsalva maneuver during static or isometric straining-type movements dramatically reduces venous return and arterial blood pressure
  • these two effect diminsh brain's blood supply often producing dixxiness, 'spots before the eye' fainting
  • once glottis reopens and intrathoracic pressure stabilizes blood flow re-establishes with an 'overshoot' in arterial blood pressure
 respired gasesconcentration and pressure
 gas concentration:amount of gas in a given volume determined by product of gas partial pressure and solubility
 gas pressureforce exerted by gas molecules against surfaces they encounter
 partial pressure:percentage concentration *total pressure of gas mixture
 ambient airPO2 = 159mm Hg; PCO2 = 0 mm hg;PN2 =600 mm Hg

 Tracheal airPO2= 149mm Hg; PCO2 stays same
 alveolar airPO2 = 103 mm Hg; PO2 = 39 mm Hg
 Gas movement in air Henry's lawamount of gas dissolved in fluid depends on: pressure differential between gas above filled and dissolve in it 
and solubility of gas in fluid
 Gas exchange in body in lungsfirst step in O2 transport involves transfer of O2 from alveoli into blood
three factors account for dilution of O2 in inspired air as it passes into alveolar chambers
  1.  water vapor saturates relatively dry inspired air 
  2. O2 continually leaves aveolar air
  3. CO2 continually enters alveolar air
 gas exchange in body in tissues:O2 leaves capillary blood and flows toward metablizing cells, while CO2 flows from cell into blood
 gas exchangePO2 and PCO2 of ambient, tracheal, and alveolar air and gas pressures in venous and arterial blood and muscle tissure
 Gas transfer pressure gradients at restTime required for gas exchange. At rest, blood remains in pulmonary and tissue capillaries for about .75 sec. Pulmonary disease (orange dashed line) impairs rate of gas transfer across the alveolar-capillary membrane thus prolonging gas equilibration time
 diffusion between pulmonary capillary and its adjacent alveolushappens in gas tranfer pressure gradients at rest
 Oxygen transport in bloodblood transports oxygen in two ways
  1. physical solution (1-2%)
  • dissolved in fluid portion of blood, establishes PO2 of blood and tissue fluids
2. Combined with Hb (98-99%)
  • in loose combination with iron-protein Hb molecule in RBC; increase blood's oxygen carrying capacity 65 to 70 times above normal
 two other combined with Hb facts
  1.  men: each 100 mL of blood contians approximately 15 to 16 g Hb
  2. women: 5 to 10% less; 14 g per 100 mL blood
 Hemoglobin1. consists of globin composed of four subunit polypeptide chains. Each polypeptide contains single heme groups with its single iron atom acting as oxygen 'magnet'

 PO2 and Hb saturation
  • percentage saturation of Hb computes as

% saturation = (total O2 combined with Hb / Hb O2 -carrying capacity) *100
 oxygen transport cascadeGas partial pressure as O2 moves from ambient air at sea level to mitochondria of maximally active muscle tissue
 bohr effectincreases in acidity (H+) and CO2 and temp. cause oxyhemoglobin dissociation curve to shift downward and to the right to reflect enhanced unloading
 other facts of the bohr effect
  • Occurs particularly in PO2 range of 20 to 50 mmHg
  • particularly important in vigorous PA because increased metabolic heat and acidity in active tissues augments O2 release
  • oxygen unloading to skeletal muscle from RBC about 25% at rest and can increase to about 40% during vigorous PA
 Carbon dioxide transport in blood
  • blood transports CO2 to lungs in three ways
  1.  physical solution in plasma ( 7 to 10%)
  2. loose combination with Hb (20%)
  3. combination with water as bicarbonate ( 70%)
 ventilatory control during rest: Neural factors
  • respiratory cycle comes from inherent, automatic activity of inspiratory neurons
  • exhalation begins by passive recoil of stretched lung tissue and raised ribs when inspiratory muscle relax
  • expiration facilitated by activation of expiratory neurons and associated muscles
  • as expiration proceeds, inspiratory center decouples from inhibition and progressively becomes more active
 ventilatory control many factors affecting medullary control of pulmonary ventilation
 during rest Humoral factorsventilatory control

  • chemical state of blood regulates pulmonary ventilation at rest 
variations in arterial
 Po2 and pco2 acidity and temp activate sensitve neural units in medulla plus arterial system
  • Chemoreceptors: structures that stimulate ventilation in response to increase CO2 temp acidity decrease in O2 and BP and probable decline in circulating K+ ions
 other humoral factorsCO2 pressure in arterial plasma provides most important respiratory stimulus at rest and during PA
 Aortic and carotid cell bodiesaortic arch and bifurcation of carotid arteries contain aortic and carotid cell bodies (chemoreceptors) sensitive to reduced plasma PO2 to defend against arterial hypoxia
 ventilatory control during PA: Chemical factors
  • PO2 - arterial PO2 does not decrease to stimulate ventilation by chemoreceptor activation. PO2. H+
  • chemical stimuli cannot fully explain hyperpnea during PA
 values for PCO2 in mixed venous blood entering....lungs, and alveolar PO2 and Pco2 related to VO2 during graded exercise

despite increased metabolism with PA alveolar Po2 and Pco2 remain near resting levels, Increases in mixed-venous Pco2 result from increased CO2 production in metabolism
 ventilatory control during PA: Neurogenic factors
  • cortical influence- neural outflow from regions of motor cortex during PA and cortical activation in anticipation of PA stimulate respiratory neurons in medulla
  • peripheral influence- sensory input from joints, tendons, muscles adjust ventilation during PA (mechanoreceptors/proprioceptors)
 Integrated regulation
  • Not single factor controls breathing in PA
  • Phase 1 ventilation- when PA begins.. Neurogenic stimuli from cerebral cortex and active limbs cause initial breathing increase
  • Phase 2 ventilation- central command input plus medullay control neurons and peripheral stimuli from chemorecptors adn mechanorecptors contribute to control minute ventilation, gradually increase to a steady level
 what is phase 3 ventilationfine tuning of ventilation through peripheral sensory feedback mechanism
 Pulmonary ventilation during PAPA increases VO2 and CO2 prodution more than any other physiologic stress

relationship between pulmonary ventilation, blood lactate, and VO2 through steady rate and non-steady-rate PA levels to VO2 max
 ventilation during steady-rate PA
  • ventilation during light and moderate PA increase linearly with VO2 by increase in TV
  • ventilatory equivalent for oxygen (Ve/VO2) 24:1 ratio
  • ratio of minute ventilation to VO2
  • remains relatively constant during steady- rate PA
 ventilatory equivalent for carbon dioxide (Ve/VCO2)ratio of minute ventilation to O2 produced
remains constant during steady-rate PA because pulmonary ventilation eliminates CO2 produced during cellular respiration
 other steady rate PA facts
  • despite varitations in ventilatory equivalents among health people, complete aeration of blood takes palce because of 2 factors.
  1. alveolar Po2 and Pco2 remain at near-resting value
  2. transit time for blood flowing through pulmonary capillaries proceeds slowly enough to allow complete gas exchange
 ventilation during non-steady rate PAventilatory threshold (Tvent)

  • Tvent; point at which PV increases disproportionately with VO2 during graded activity
  • relates directly to increased CO2 output from buffering of lactate that begins at accumulate from anerobic metabolism
  • anaerobic threshold originally defined the abrupt increase in Tvent caused by nonmetabolic CO2 production from lactate buffering
 other non-steady rate PA factVe/VO2 can go to as much as 36:1 during vigorous PA
 OBLA/ Anaerobic threshold/lactate threshold
  • sharp upswing in pulmonary ventilation related to VO2 during incremental activity.- implies imbalance between rate of blood lactate appearance and disappearance
  • occurs between 55 and 65% VO2 max in healthy untrained subjects and often equals less than 80% VO2 max in highly trained endurance athletes
  • OBLA point increase with aerobic training without accompanying increase in VO2 max
 Major variables contributing to oxygen transport and use
  • two factors influence endurance performance
  1. VO2 max
  2. Max level for steady rate activity (OBLA)
 energy requirements of breathing
  • breathing normally requires a relatively small oxygen cost even during PA
  • in respiratory disease work of breathing become excessive and PA alveolar ventilation often becomes inadequate
  • two factors determine energy requirements of breathing 
  1. compliance of lungs and thorax 
  2. resistance of airways to smooth air flow
 buffers consist of a weak acid and the salt of that acid
  • bicarbonate, phosphate, and protein chemical buffers provide rapid first line defense in acid-base regulation
  • lungs contribute to ph regulation through changes in alveolar ventilation that rapidly after free H+ concentration in extracellular fluids. 
  • renal tubules act as body's final defense by secreting H+ into urine and reabsorbing bicarbonate
  • anaerobic PA increases demand for buffering; makes pH regulation progressively more difficult
 O2 cost of breathing PA up to maxa. effects of increasing Ve on total O2 cost of breathing expressed as percentage of total VO2

b. effects of increasing Ve on O2 cost per liter air breathed per min
 intense PA effectsa. inverse linear relation between blood lactate concentration and blood pH

b. Blood pH and blood lactate concentration related to PA intensity expressed as percentage of max. Decreased in blood pH accompany increases in blood lactate concentration
36, "/var/app/current/tmp/"