There are 2 acute responses of the respiratory system:
1. Increased breathing rate.
2. Increased tidal volume.
Increased breathing rate
During exercise, there is a minor rise in breathing rate which is known as 'anticipatory rise' . When exercise begins there is an immediate and significant increase in breathing rate so the athlete can get enough oxygen to work with. This is the result of the 3 types of receptors.
3 receptors:
Chemoreceptors - this receptor is located in the cartoid artery and arctic arch. It detects increased acidity in the blood which is caused by the carbon dioxide. They result in sending signal to the respiratory control centre that run in turn to speed up the concentration of the inspiratory muscles. This increases the breathing rate.
Mechanoreceptors - they are located in the limbs, they inform the respiratory control centre when there is an increase in movement. this results in sending signals to the respiratory muscles, increasing their contraction rate.
Increased Tidal Volume:
Tidal volume is the amount of air you breathe in one breath. During exercise, there is increase in tidal volume because the demand for oxygen increase. The lungs have meet the demands of the body for oxygen; this is required for the cells in the body to produce enough energy to function. The lungs do this by bringing fresh air into the body every time we breath in; this is measured by the tidal volume and measuring how much of fresh air is being breathed into the body in a single breath.
Increased minute ventilation:
Minute ventilation is the amount of air inspired or expired in one minute. this is dependent on breathing rate and total volume. It is expressed as VE = volume of air expired in a minute and VI = volume of air inspired in a minute. Minute ventilation increase during exercise because the tidal volume and the breathing rate increase. The tidal volume and the breathing rate will increase proportionally at low intensity exercise.
Increased strength of respiratory muscles:
Increased strength of respiratory muscles is when the diaphragm and intercostal muscles increase in strength. This allows for greater expansion of the thoracic (chest) cavity. More expansion provides more efficient inhalation and expiration.
Increased oxygen diffusion rate:
This is when there is increase in number and size of capillaries leads to more efficient diffusion:
- More oxygen from capillaries to tissues.
- More carbon dioxide from cells the blood.
- Regular training leads to better transportation of oxygen/carbon dioxide, therefore there is an increase in oxygen diffusion rate.
http://www.newhealthguide.org/Vital-Capacity.html
http://www.livestrong.com/article/402142-how-does-exercise-affect-breathing/