EXSS1010 Lecture 4: EXSS1010 - ACUTE PULMONARY RESPONSES TO EXERCISE
30 May 2018
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EXSS1010 - ACUTE PULMONARY RESPONSES TO EXERCISE
LECTURE OBJECTIVES:
1. Understand the basic pulmonary anatomy and how pulmonary ventilation occurs
2. Describe the factors that influence pulmonary diffusion
3. List and describe the basic spirometry measures
4. Describe the factors that influence ventilation
5. Describe how ventilation changes at the onset of exercise
6. Discuss how they change under exercise related stress
a. Understand oxygen kinetics during exercise 1. Steady-state
b. Oxygen debt
c. Excess post-exercise oxygen consumption
RESPIRATORY AND CV SYSTEMS
• Work synergistically
• Delivery of O2 and removal of CO2 from working tissue.
o Pressure gradients
• Respiration can be separated into 4 processes
o External
• Pulmonary ventilation
• Pulmonary diffusion
o Internal
• Transport via blood
• Capillary diffusion
PULMONARY VENTILATION
• Exchanging ambient air with air in the lungs
• Air enters the nose mouth and trachea
o Increased temperature
o Filtered
o Humidified
• Two bronchi -> bronchioles -> alveoli
INSPIRATION
• Inspiration: active process involving the contraction of the diaphragm and external intercostal
muscles
o i.e. make lung volume larger to drop pressure which would draw air in to maintain an
equilibrium
o Also assists blood flow back to heart via respiratory pump
EXPIRATION
• Expiration: passive process involving relaxation of the inspiratory muscles
o Lung volume is reduced, pressure increases and air is forced out
PULMONARY DIFFUSION: PARTIAL PRESSURE OF GAS
• Diffusion of oxygen occurs at the alveoli
• Fick’s law of diffusion – gas diffuses through tissue:
o Directly proportional to:
• Tissue surface area
• A diffusion constant
• Pressure differential of the gas on each side of the membrane
o Inversely proportional to tissue thickness
• Partial pressure gradient most important factor for determining gas exchange
o Partial pressure gradient drives gas diffusion
o Without gradient, gases in equilibrium, no diffusion
PULMONARY DIFFUSION
• Gas exchange between alveoli and capillaries
o Inspired air path: bronchi -> arrives at alveoli
o Blood path: right ventricle -> pulmonary trunk -> pulmonary arteries -> pulmonary
capillaries
o Capillaries surround alveoli
• Serves two major functions
o Replenishes blood oxygen supply
o Removes carbon dioxide from blood
RESPIRATORY MEMBRANE
• Also called alveolar-capillary membrane
o Alveolar wall
o Capillary wall
o Respective basement membranes
• Surface across which gases are exchanged
o Large surface area: 300 million alveoli
o Very thin: 0.5 to 4 μm
o Maximizes gas exchange
Document Summary
Steady-state: oxygen debt, excess post-exercise oxygen consumption. Respiratory and cv systems: work synergistically, delivery of o2 and removal of co2 from working tissue, pressure gradients, respiration can be separated into 4 processes, external, pulmonary ventilation, pulmonary diffusion. Pulmonary ventilation: exchanging ambient air with air in the lungs, air enters the nose mouth and trachea. Increased temperature: filtered, humidified, two bronchi -> bronchioles -> alveoli. Expiration: expiration: passive process involving relaxation of the inspiratory muscles, lung volume is reduced, pressure increases and air is forced out. Pulmonary diffusion: partial pressure of gas: diffusion of oxygen occurs at the alveoli. Fick"s law of diffusion gas diffuses through tissue: directly proportional to, tissue surface area, a diffusion constant, pressure differential of the gas on each side of the membrane. Inversely proportional to tissue thickness: partial pressure gradient most important factor for determining gas exchange, partial pressure gradient drives gas diffusion, without gradient, gases in equilibrium, no diffusion.
