Respiratory System

• What are the two main functions of the respiratory system?

  Pulmonary ventilation and gaseous exchange
• What is pulmonary ventilation?

  The inspiration and expiration of air
• What does gaseous exchange involve?

  Extraction of oxygen into the bloodstream
• How do respiratory muscles function?

  They cause volume changes in the thoracic cavity
• What percentage of blood is plasma?

  55%
• What percentage of blood consists of blood cells?

  45%
• How is oxygen transported in the blood?

  97% combines with haemoglobin, 3% dissolved
• What is oxyhaemoglobin represented as?

  HbO2
• How is carbon dioxide transported in the blood?

  70% as carbonic acid, 23% with haemoglobin
• What percentage of carbon dioxide is dissolved in blood plasma?

  7%
• What are the three main measures of respiration?

  • Breathing frequency: number of breaths per minute
  • Tidal volume: air volume per breath
  • Minute ventilation: air volume per minute
• What does breathing frequency represent?

  Number of breaths taken per minute
• What is tidal volume?

  Volume of air inspired or expired per breath
• How is minute ventilation measured?

  Volume of air inspired or expired per minute
• What happens to the diaphragm during inspiration at rest?

  It contracts and flattens.
• In what units is tidal volume measured?

  Millilitres or litres
• What muscles contract during inspiration at rest?

  External intercostal muscles.
• In what units is minute ventilation measured?

  Millilitres or litres
• How does the rib cage move during inspiration at rest?

  It moves up and out.
• What happens to the volume of the thoracic cavity during inspiration at rest?

  It increases.
• What happens to the pressure of the thoracic cavity during inspiration at rest?

  It decreases.
• What is the direction of air movement during inspiration at rest?

  From higher pressure outside to lower pressure in the lungs.
• What happens to the diaphragm during expiration at rest?

  It relaxes and returns to a dome shape.
• How does the rib cage move during expiration at rest?

  It moves down and in.
• What muscles relax during expiration at rest?

  External intercostal muscles.
• What happens to the volume of the thoracic cavity during expiration at rest?

  It decreases.
• What happens to the pressure of the thoracic cavity during expiration at rest?

  It increases.
• What is the direction of air movement during expiration at rest?

  From higher pressure inside to lower pressure outside.
• What type of process is expiration at rest?

  It is passive.
• What happens to the diaphragm during inspiration during exercise?

  It contracts and flattens more than at rest.
• What happens to the external intercostal muscles during inspiration during exercise?

  They contract more than at rest.
• What additional muscles are recruited during inspiration at exercise?

  Sternocleidomastoid, scalenes, and pectoralis minor.
• How does the rib cage move during inspiration at exercise?

  It moves up and out further than at rest.
• What happens to the diaphragm during inspiration at rest?

  It contracts and flattens.
• What happens to the volume of the thoracic cavity during inspiration at exercise?

  It increases more than at rest.
• What muscles contract during inspiration at rest?

  External intercostal muscles.
• What happens to the pressure of the thoracic cavity during inspiration at exercise?

  It decreases more than at rest.
• How does the rib cage move during inspiration at rest?

  It moves up and out.
• How does the amount of air moved during inspiration at exercise compare to rest?

  More air moves than at rest.
• What happens to the volume of the thoracic cavity during inspiration at rest?

  It increases.