Respiration During Exercise

Respiration During Exercise

• Respiration is the process of gas exchange between the external environment and the body, including replacing oxygen (O2) and removing carbon dioxide (CO2). It also regulates acid-base balance.

• Ventilation is the mechanical process of air movement into and out of the lungs.

• Diffusion is the random movement of molecules from a high concentration area to a low concentration area, crucial for gas exchange.

Objectives

• The presentation outlines understanding the respiratory system's physiological function and anatomical components.

• It covers major muscles involved in breathing at rest and exercise.

• It highlights the significance of matching blood flow to alveolar ventilation.

• Gases' transport across the blood-gas interface in the lung is addressed.

• It discusses how oxygen (O2) and carbon dioxide (CO2) are transported in the blood

• The impact of temperature change, pH, and 2-3 DPG levels on the oxygen-hemoglobin dissociation curve is examined.

• The ventilatory response to constant-load, steady-state exercise is described.

Function of the Lung

• The lung facilitates gas exchange.

• It facilitates the replacing of oxygen and removing carbon dioxide

• It regulates and maintains acid-base balance.

Structure of the Respiratory System

• The respiratory system includes the nose, nasal cavity, oral cavity, pharynx, larynx, trachea, bronchi, and lungs, among other components (Figure 10.1).

• The lungs comprise a bronchial tree, respiratory bronchioles, alveolar sacs, and alveoli (Figure 10.3).

• The lungs have different zones, separating conducting zones (for air movement) from respiratory zones (for gas exchange).

• The location of the diaphragm and pleura is also important (Figure 10.2).

Mechanics of Breathing

• Air movement occurs due to pressure differences.

• Inspiration involves diaphragm contraction, rib elevation, increasing lung volume, and decreasing intrapulmonary pressure.

• Expiration involves diaphragm relaxation, rib depression, decreasing lung volume, and increasing intrapulmonary pressure.

• Muscles of inspiration and expiration are visualized in diagrams.

Pulmonary Volumes and Capacities

• A diagram displays pulmonary volumes and capacities, including tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume, and total lung capacity.

Airway Resistance

• Airflow depends on the pressure difference across the airway and airway resistance.

• Airway resistance depends on airway diameter.

• Chronic obstructive pulmonary disease (COPD) and asthma are examples of conditions affecting airway resistance.

Partial Pressure of Gases

• Dalton's Law states that the total pressure is the sum of the partial pressures of each individual gas.

• Partial pressures of gases (O2, CO2, N2) in the air and alveoli are presented in a table for calculation.

Diffusion of Gases

• Fick's Law describes that the rate of gas diffusion is proportional to the tissue area, diffusion coefficient, pressure difference, and inversely to tissue thickness.

• The relationship between partial pressures and gas exchange is demonstrated.

Partial Pressures of O2 and CO2 and Gas Exchange

• Different partial pressures of oxygen (O2) and carbon dioxide (CO2) are shown at the alveoli, pulmonary and systemic circulations.

The Pulmonary and Systemic Circulation

• Diagrams illustrate the pulmonary and systemic circulations, showing the flow of oxygenated and deoxygenated blood.

Ventilation-Perfusion Relationships

• Effective gas exchange depends on matching blood flow to ventilation (ventilation perfusion ratio, or V/Q ratio).

• The ideal V/Q ratio is 1.0, or slightly greater, for optimal gas exchange.

O2 Transport in the Blood

• Most O2 is bound to hemoglobin (Hb) forming oxyhemoglobin.

Oxyhemoglobin Dissociation Curve

• The relationship between oxygen (O2) and hemoglobin (Hb) is graphically presented.

• Direction depends upon oxygen pressure (PO2)

• Factors such as PO2, temperature, pH, and 2,3-DPG affect the oxygen-hemoglobin dissociation curve, and influence O2 unloading.

Oxygen-Hemoglobin Dissociation Curve

• The graphic representation of different partial pressures of oxygen and the percentage of oxyhemoglobin saturation.

Effect of pH, Temperature, and 2-3 DPG on the O₂-Hb Dissociation Curve

• pH, temperature, and 2,3-DPG affect the hemoglobin's oxygen-binding capacity.

• Lower pH and higher temperature cause a rightward shift, reducing hemoglobin's affinity for oxygen (and enhancing its release). The byproduct 2-3 DPG has a similar effect.

O₂ Transport in Muscle

• Myoglobin (Mb) facilitates oxygen transport within muscle cells. Myoglobin has a high affinity for oxygen.

CO₂ Transport in Blood

• CO2 is transported in the bloodstream via dissolved plasma, bound to hemoglobin, or as bicarbonate.

• Carbonic anhydrase catalyzes CO2 hydration to bicarbonate and hydrogen ions.

• The chloride shift facilitates CO2 transport.

Ventilation and Acid-Base Balance

• Ventilation helps regulate blood pH by removing CO2 and hence H+ ions.

Ventilatory and Blood-Gas Responses to Exercise

• During exercise, breathing rate and oxygen/carbon dioxide partial pressures change (as demonstrated in diagrams).

Ventilatory Response to Incremental Exercise

• The diagram illustrates how ventilation and other measurements change with exercise intensity, demonstrating how different people respond differently to exercise.

Effect of Training on Ventilation

• Training generally doesn't alter the lungs at rest, but elite endurance athletes might have lower lung adaptation causing hypoxemia.

Does the Pulmonary System Limit Maximal Exercise Performance?

• Pulmonary limitations are less significant in low-to-moderate exercise.

• Respiratory muscles can become fatigued during high-intensity exercise, potentially limiting performance.

• Elite athletes may experience hypoxemia, limiting performance during endurance activities.

Example Exam Questions

• A variety of questions regarding different aspects of the respiratory system are provided to summarize the discussion on respiration during exercise.

Explore the physiological functions and anatomical components of the respiratory system during exercise. This quiz focuses on the mechanics of ventilation, diffusion processes for gas exchange, and the transport of gases in the blood. Understand the factors influencing oxygen delivery and carbon dioxide removal during physical activity.