Pulmonary System & Exercise Flashcards
Functions of the pulmonary system
- supply oxygen required in metabolism
- eliminate carbon dioxide produced in metabolism
- regulate hydrogen (H+) to maintain acid-base balance (pH)
How does inspiration work
- diaphragm contracts, flatness out, and moves downward
- the lungs expand along with the thoracic cage causing the pressure to lower
- the lower pressure in the lungs then suck air in through the nose and mouth to inflate the lungs
How does expiration work
- the recoil from the lungs being stretched and the diaphragm relaxing pushes air out of the lungs
- the sternum and ribs swing down decreasing chest cavity volume
Define tidal volume (TV)
- volume inspired or expired per breath
- 0.4-1.0 L
Define inspiratory reserve volume (IRV)
- maximum inspiration at end of tidal inspiration (forced inhale)
- 2.5-3.5 L above TV
Define expiratory reserve volume (ERV)
- the additional volume that can be exhaled after a normal exhalation
- 1.0-1.5 L for men and 10-20% lower for women
Define forced vital capacity (FCV)
- maximum volume expired after maximum inspiration
Define residual lung volume (RLV)
- volume of air that remains after maximal exhalation that cannot be exhaled
- 1.2-1.6 L for men and 1.0-1.2 L for women
Equation for minute ventilation
Minute Ventilation Ve = breathing rate x tidal volume
Define anatomic dead space
the air that fills the nose, mouth, trachea, and other nondiffusible conducting portions of the respiratory tract
Define physiologic dead space
the portion of the alveolar volume with poor tissue regional perfusion or inadequate ventilation
Define dyspnea
shortness of breath or subjective distress in breathing
Define hyperventilation
an increase in pulmonary ventilation that exceeds the oxygen needs of metabolism
Define gas concentration
the amount of gas in a given volume determined by the product of the gas’ partial pressure and solubility
Define gas pressure
the force exerted by the gas molecules against the surfaces they encounter
Define partial pressure
percentage concentration x total pressure of gas mixture
Define Henry’s law
The amount of a gas dissolved in fluid depends on:
- pressure differential between the gas above the build and dissolved in it
- solubility of the gas in the fluid
Neural factors for ventilatory control during rest
- temperature
- receptors in lung tissue
- proprioceptors in joints & muscles
- chemical state of blood in medulla
- peripheral chemoreceptors
- motor cortex
- subcortical regions
Define chemoreceptors
- structures that stimulate ventilation in response to increased carbon dioxide, temperature, and acidity, a decrease in oxygen & blood pressure, and perhaps a decline in circulating potassium
Chemical factors of ventilatory control during exercise
- Po2
- Pco2
- H+
Peripheral influence on ventilatory control during exercise
- sensory input from joints, tendons, and muscles adjust ventilation during exercise
Cortical influence on ventilatory control during exercise
- neural outflow from regions of the motor cortex during exercise and cortical activation in anticipation of exercise stimulate respiratory neurons in the medulla
Phase I Ventilation
- neurogenic stimuli from the cerebral cortex & active limbs cause the initial, abrupt increase in breathing when exercise begins
Phase II Ventilation
- central command input plus medullary control system neurons & peripheral stimuli from chemoreceptors & mechanoreceptors contribute to the control of minute ventilation gradually increasing to a steady level
Phase III Ventilation
- “fine tuning” of ventilation through peripheral sensory feedback mechanism
What is ventilatory equivalent for oxygen (Ve/VO2)
- ratio of minute ventilation to oxygen uptake
- it remains relatively constant during steady-rate exercise
What is ventilatory equivalent for carbon dioxide (Ve/VCO2)
- ratio of minute ventilation to oxygen produced
- it remains constant during steady-rate exercise bc pulmonary ventilation eliminates the CO2 produced during cellular respiration
What is ventilatory threshold
- the point at which pulmonary ventilation increases disproportionately with oxygen uptake during graded exercise
- relates directly to CO2 increased output from the buffering of lactate that begins to accumulate from anaerobic metabolism
Describe OBLA (onset of blood lactate accumulation)
- is 4 mMol/L in everyone
- occurs between 55-65% of VO2 max in healthy untrained individuals and closer to 80% VO2 max in highly trained endurance athletes
Define lactate threshold
- it’s the point of intensity when lactate production exceeds lactate removal
What factors determine the energy requirements of breathing
- compliance of lungs & thorax
- resistance of airways to the smooth flow of air
- breathing normally requires a relatively small oxygen cost even during exercise
