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Respiratory Pulmonary System Essentials of Exercise Physiology.

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Presentation on theme: "Respiratory Pulmonary System Essentials of Exercise Physiology."— Presentation transcript:

1 respiratory Pulmonary System Essentials of Exercise Physiology

2 respiratory Respiration External respiration: External respiration: ventilation and exchange of gasses in the lungs (pulmonary function). Internal respiration Internal respiration: ventilation and exchange of gasses in the tissues (pulmonary function).

3 respiratory Functions of Respiratory System Primary purpose of respiratory system is: Provide means of oxygen exchange between external environment and body Provide a means of carbon dioxide exchange between the body and the external environment Exchange occurs as result: Ventilation: mechanical Diffusion: random movement

4 respiratory Functions of Respiratory System Respiratory system also helps regulate acid-base balance in body, especially during exercise. Cl - + H + + NaHCO 3  NaCl + H 2 CO 3  CO 2 + H 2 O

5 respiratory Acid - Base Balance Acids - molecules which can liberate hydrogen ions Acids - molecules which can liberate hydrogen ions Bases - molecules which can accept hydrogen ions Bases - molecules which can accept hydrogen ions Buffer - resists changes in pH by either accepting hydrogen ions or liberating them depending upon local conditions Buffer - resists changes in pH by either accepting hydrogen ions or liberating them depending upon local conditions

6 respiratory Structure Pulmonary System Right and left lungs enclosed by membranes called pleura Right and left lungs enclosed by membranes called pleura Visceral pleura adheres to outer surface of lungs Visceral pleura adheres to outer surface of lungs Parietal pleura adheres to thoracic wall and diaphragm Parietal pleura adheres to thoracic wall and diaphragm

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8 Intrapleural Space Contains fluid which lubricates pleura Contains fluid which lubricates pleura Creates a low pressure area Creates a low pressure area –pressure is below atmospheric during inspiration, allowing the lungs to inflate

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10 respiratory Functional Zones of Air Passages Conducting zone Conducting zone –passageways leading to respiratory zone –area where no gas exchange occurs –nasal cavity, pharynx, larynx, trachea, bronchioles Respiratory zone Respiratory zone –where gas exchange actually occurs –alveoli

11 respiratory Roles of Conducting Zone Warms air Warms air Mucus traps small particles Mucus traps small particles Cilia sweep particles upwards Cilia sweep particles upwards Macrophages engulf foreign particles Macrophages engulf foreign particles

12 respiratory Roles of Respiratory Zone Provides large surface area for gas exchange Provides large surface area for gas exchange –600 million alveoli –Total surface area is 60 – 80 square meters or about size of half a tennis court Provides a very thin barrier for gas exchange Provides a very thin barrier for gas exchange –2 cell layers thick

13 respiratory Alveoli Type II alveolar cells secrete pulmonary surfactant Type II alveolar cells secrete pulmonary surfactant –form a monomolecular layer over alveolar surfaces –surfactant stabilizes alveolar volume by reducing surface tension created by moisture

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15 respiratory Mechanics of Ventilation Change in thoracic cavity volume produces corresponding change in lung volume Change in thoracic cavity volume produces corresponding change in lung volume Increase in lung volume results in decrease in lung pressure (Boyle’s law) Increase in lung volume results in decrease in lung pressure (Boyle’s law) Differences in pressure pulls air into the lungs Differences in pressure pulls air into the lungs –pressure within the lungs becomes less than the atmospheric pressure –bulk flow (from high pressure to low pressure)

16 respiratory Muscles of Inspiration Diaphragm Diaphragm –contracts, flattens, & moves downward up to 10 cm –enlarges & elongates chest cavity, expands volume –during quiet breathing diaphragm works alone External intercostals, pectoralis minor, sternocleidomastoid & scaleni External intercostals, pectoralis minor, sternocleidomastoid & scaleni –lift ribs up and outwards –during exercise, accessory muscles called into play

17 respiratory Muscles of Inspiration

18 respiratory Muscles of Expiration Expiration during quiet breathing is passive due to elastic recoil of chest cavity Expiration during quiet breathing is passive due to elastic recoil of chest cavity Decrease in lung volume forces air out of lungs Decrease in lung volume forces air out of lungs During exercise and voluntary hyperventilation, During exercise and voluntary hyperventilation, –rectus abdominus, transverse abdominus: push diaphragm up –internal intercostals: pull ribs downwards

19 respiratory Total Lung Capacity Tidal volume (V T ) Tidal volume (V T ) –amount either inspired or expired during normal ventilation Inspiratory reserve volume Inspiratory reserve volume –maximal volume inspired after a normal inspiration Expiratory reserve volume Expiratory reserve volume –volume expired after a normal expiration During exercise V T increases largely from IRV. During exercise V T increases largely from IRV. Residual volume Residual volume –volume remaining in lungs after maximal expiration

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21 respiratory Lung Capacities Total lung capacity Total lung capacity –volume within lung after a maximal inspiration Inspiratory capacity Inspiratory capacity –maximal volume inspired from the end of tidal expiration Functional residual capacity Functional residual capacity –volume in lungs after normal expiration Vital capacity Vital capacity –maximal volume expired after maximal inspiration

22 respiratory Dynamic Lung Volumes Depend on volume and speed of air movement; more useful in diagnosing lung disease. Depend on volume and speed of air movement; more useful in diagnosing lung disease. FEV: Forced Expiratory Volume. Volume that can be forcefully expired after maximal inspiration within given time, usually 1 sec. FEV: Forced Expiratory Volume. Volume that can be forcefully expired after maximal inspiration within given time, usually 1 sec. MVV: Maximal Voluntary Ventilation. Volume of air that can be ventilated by maximal effort in one minute. Breathe maximally for 12 (or 15) seconds and total volume recorded, multiplied by five (or 4). MVV: Maximal Voluntary Ventilation. Volume of air that can be ventilated by maximal effort in one minute. Breathe maximally for 12 (or 15) seconds and total volume recorded, multiplied by five (or 4).

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24 Minute Ventilation Volume of gas ventilated in one minute Volume of gas ventilated in one minute –equal to tidal volume times frequency –Rest in 70 kg man, 6.0 L/min = 0.5 L x 12 –Maximal exercise, L/m = x –increases as oxygen consumption increases –closely associated with CO 2 production ERROR

25 respiratory Anatomical vs Physiological Dead Space Anatomical dead space Anatomical dead space –areas of conducting zone not designed for diffusion of gases –V T = V A + V D –At rest, V T = 500 ml = 350 ml ml Physiological dead space Physiological dead space –areas of lung and pulmonary capillary bed which are unable to perform gas exchange as designed

26 respiratory Anatomic Dead Space

27 respiratory Physiologic Dead Space Optimal diffusion requires matching of ventilation to perfusion: 1 ventilated alveoli/ 1 blood perfused alveoli Optimal diffusion requires matching of ventilation to perfusion: 1 ventilated alveoli/ 1 blood perfused alveoli Ventilation (V) / perfusion (Q) is not equal across the lung Ventilation (V) / perfusion (Q) is not equal across the lung Top of lung is poorly perfused Top of lung is poorly perfused –V / Q = 3.3 at top of lung Bottom of lung has more perfusion than ventilation Bottom of lung has more perfusion than ventilation –V / Q =.63 at bottom of lung V / Q values above.5 are generally adequate V / Q values above.5 are generally adequate

28 respiratory Minute Ventilation in Exercise Adjustments in breathing rate and depth maintain alveolar ventilation as exercise. Adjustments in breathing rate and depth maintain alveolar ventilation as exercise. Trained athletes maintain alveolar ventilation by increasing V T and minimal increase rate. Trained athletes maintain alveolar ventilation by increasing V T and minimal increase rate. Deeper breathing causes a greater percentage of incoming “fresh” V T to enter alveoli. Deeper breathing causes a greater percentage of incoming “fresh” V T to enter alveoli. Increasing V T in exercise results from encroaching primarily on IRV or ERV? Increasing V T in exercise results from encroaching primarily on IRV or ERV? V T plateaus at about 60% vital capacity. V T plateaus at about 60% vital capacity.

29 respiratory Disruptions in Normal Breathing Dyspnea shortness of breath or subjective distress in breathing. Dyspnea shortness of breath or subjective distress in breathing. Hyperventilation ≠ Hyperpnea Hyperventilation ≠ Hyperpnea Valsalva maneuver: forced exhalation against closed glottis. What happens to blood pressure? Valsalva maneuver: forced exhalation against closed glottis. What happens to blood pressure?

30 respiratory Gas Exchange Fick’s Law Diffusion occurs at a rate which is proportional to differences in partial pressure and the surface area available and is inversely proportional to the thickness of the membrane. Diffusion occurs at a rate which is proportional to differences in partial pressure and the surface area available and is inversely proportional to the thickness of the membrane. Diffusion rate = (P 1 - P 2 ) area Diffusion rate = (P 1 - P 2 ) area thickness thickness


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