KIN2230 Introduction to Exercise Physiology PDF

Breathe it in KIN2230: Introduction to Exercise Physiology School of Kinesiology Learning Outcomes Learners will have the opportunity to Learn about the Fick Equation, and the importance of arterial oxygen Review the pressure-driven process of breathing Learn about...

Breathe it in KIN2230: Introduction to Exercise Physiology School of Kinesiology Learning Outcomes Learners will have the opportunity to Learn about the Fick Equation, and the importance of arterial oxygen Review the pressure-driven process of breathing Learn about gas exchange Learn about how ventilation is adjusted in response to exercise Pulmonary Ventilation 1 Metabolic “Decisions” Picking Energy Utilization of a given energy system is dependent on: Rate of energy demand Magnitude Timeline Substrate availability Local (in the mitochondria) oxygen supply Pulmonary Ventilation 2 Metabolic “Decisions” Picking Energy Energy can be provided by any of the energy systems BUT: Stored ATP is limited Stored PCr is limited Lactate (H+) production accelerates fatigue Preference is to use aerobic metabolism BUT: Requires O2 in the right amounts in the right location at the right time to utilize it. How do we improve oxygen delivery?? Pulmonary Ventilation 3 Oxygen Supply Its all Around us! How do we improve oxygen delivery?? Oxygen: Moving from the air into the Mitochondria Hungry Hungry The Heart of Ex Breathe it in Muscles Phys Going with the Flow Pulmonary Ventilation 4 Oxygen Supply Fick Equation VO2= CO * a-vO2diff VO2= HR * SV * a-vO2diff Cardiac: will come back to this Arterial-venous O2 Difference Pulmonary Ventilation 5 Breathing Arterial-venous O2 Difference a-vO2diff: difference in oxygen content between the arterial side and the venous side of circulation Depends on: How much oxygen gets into the arterial blood How much oxygen gets extracted before blood reaches venous side Pulmonary Ventilation 6 Breathing Why do we Breathe? Supply oxygen for aerobic metabolism Clear carbon dioxide: Produced aerobically Produced by bicarbonate buffering of H+ Pulmonary Ventilation 7 What’s with Breathing? Pulmonary System Comprised of: Airways Trachea to bronchi Lungs Bronchiole to Alveoli to capillary beds Pulmonary Ventilation 8 What’s with Breathing? Pulmonary System Comprised of: Airways Trachea to bronchi Lungs Bronchiole to Alveoli to capillary beds Pulmonary Ventilation 9 Gas “Flow” Pressure Rules Gas (air) will flow from an area of higher pressure to areas of lower pressure If we want air to go somewhere, then we need to create a pressure differential If we want air to flow into the lungs, then the pressure in the lungs must be lower than ambient pressure If we want air to flow out of the lungs, then the pressure in the lungs must be higher than ambient pressure Pulmonary Ventilation 10  Pressure Cooking Inspiration: Diaphragm contracts, flattens out, moves downward Air in lungs expands, reducing its pressure Pressure differential between lungs and ambient air sucks air in to inflate lungs Expiration: Diaphragm relaxes, sternum and ribs swing down Air in lungs compresses, increasing its pressure Pressure differential between lungs and ambient air pushes air out of lungs Pulmonary Ventilation 11  Pressure Cooking Inspiration: Diaphragm contracts, flattens out, moves downward Air in lungs expands, reducing its pressure Pressure differential between lungs and ambient air sucks air in to inflate lungs Expiration: Diaphragm relaxes, sternum and ribs swing down Air in lungs compresses, increasing its pressure Pressure differential between lungs and ambient air pushes air out of lungs Pulmonary Ventilation 12 What’s with Breathing? Respiration: 1. Diaphragm and inspiratory muscles contract 2. Visceral pressure decreases 3. Lungs inflate 4. Gas exchange: alveoli to capillary 5. Diaphragm relaxes and expiratory muscles activate 6. Lung walls recoil and air is expired 7. Repeat Pulmonary Ventilation 13 What’s with Breathing? Ventilation Minute Ventilation (VE): the volume of air expired every minute Dependent on both: How much the lung expires each breath (Tidal volume; VT) How often the air is expired (breathing frequency; BF or RR) VE= VT * BF Pulmonary Ventilation 14 What’s with Breathing? Ventilation Minute Ventilation (VE): the volume of air expired every minute Dependent on both: How much the lung expires each breath (Tidal volume; VT) VTexpired How often the air is = 500ml(breathing frequency; BF or RR) VE= VT * BF 6 breaths over 30s: BF=12 breath/min VE= 0.5 L/breath * 12 breath/min VE=6 L/min Pulmonary Ventilation 15 What’s with Breathing? Both VT and BF increase during VE= VT * BF exercise to increase VE Pulmonary Ventilation 16 Gas Exchange Dead Space Volume of air that does not contribute to gas exchange: Oxygenated air does not reach capillaries Pulmonary Ventilation 17 Gas Exchange Dead Space Volume of air that does not contribute to gas exchange: Oxygenated air does not reach capillaries Pulmonary Ventilation 18 Gas Exchange Dead Space Volume of air that does not contribute to gas exchange: Oxygenated air does not reach capillaries Pulmonary Ventilation 19 Gas Exchange Dead Space Alveolar ventilation (VA): Volume of gas (per min) that participates in gas exchange (only includes air that reaches alveoli) Dead Space Ventilation (VD): Volume of gas (per min) that does not contribute to gas exchange: Stays in respiratory passages Enters non-perfused alveoli VA= VE - VD VA= BF * (VT – VD) Pulmonary Ventilation 20 What’s with Breathing? Ventilation Minute Ventilation (VE): the volume of air expired every minute Dependent on both: How much the lung expires each breath (Tidal volume; VT) How often the air is expired (breathing frequency; BF or RR) VE= VT * BF VA= BF * (VT – VD) Breathing VT BF VE VD*BF (ml/min) VA (ml/min) (ml) (br/min) (ml/min) Shallow 150 40 6000 (150*40)=6000 0 Normal 500 12 6000 (150*12)=1800 4200 Deep 1000 6 6000 (150*6)=900 5100 Pulmonary Ventilation 21 Into the Alveoli Gas Exchange Gas Exchange: depends on diffusion across membranes. Fick’s Law of Diffusion: rate of diffusion is: Directly proportional to: surface area differential in partial pressure of gas on both sides of membrane (ΔP = P1 – P2) diffusion constant – determined by gas solubility and molecular weight Inversely proportional to: thickness of tissue thru which gas must diffuse (0.5 μm) Diffusion = Area Rate * Diffusion constant * ΔP Thickness Pulmonary Ventilation 22  Into the Alveoli Alveolar-capillary Interface Is the site of pulmonary diffusion Optimized for gas exchange 300 million alveoli provide huge surface area (~85m2 per lung) Very thin 0.5-4 μm Oxygen diffuses from alveoli to capillary Carbon dioxide diffuses from capillary to alveoli Pulmonary Ventilation 23 Into the Alveoli Ventilation (VA) – Perfusion (Q) Relationship In most healthy individuals: air flow to alveoli matches blood flow to that alveoli For example: 1 mL/min air for 1 mL/min blood flow; VA/Q= 1.0 Some alveoli may be well ventilated but poorly perfused (VA/Q>1.0): “wasted ventilation” Some alveoli may be poorly ventilated but well perfused (VA/Q1.0): “wasted ventilation” Some alveoli may be poorly ventilated but well perfused (VA/Q