L16 - Respiratory physiology

• What is the primary function of the respiratory system?

  Intake and elimination of respiratory gases
• What is pulmonary ventilation?

  Movement of air into and out of the lungs
• What is external respiration?

  Exchange of O2 and CO2 between lungs and blood
• What is internal respiration?

  Exchange of O2 and CO2 between blood and tissues
• What does Boyle's law state?

  Pressure of a gas varies inversely with its volume
• How does pulmonary ventilation occur?

  Through changes in the volume of the thoracic cavity
• What happens to air flow during inspiration?

  Air flows into lungs when pressure decreases
• What occurs during quiet inspiration?

  Diaphragm and intercostal muscles contract
• What is forced inspiration?

  Accessory muscles contract to increase thoracic volume
• What is quiet expiration?

  Passive process relying on elastic recoil of lungs
• What is forced expiration?

  Active process involving contraction of abdominal muscles
• How are the respiratory and circulatory systems linked?

  They work together to transport gases
• What factors affect gas solubility in liquids?

  Partial pressure, solubility, and temperature
• What is the significance of partial pressure in gas exchange?

  It drives the movement of gases between mediums
• What is the primary way oxygen is transported in blood?

  Carried by hemoglobin (Hb)
• How does hemoglobin bind oxygen?

  Up to four O2 molecules can bind to Hb
• How does the affinity of hemoglobin for oxygen change?

  It changes with each O2 molecule bound or released
• What happens to hemoglobin's affinity for oxygen at high PO2?

  Affinity is high, saturation curve is flat
• What occurs at low PO2 in relation to hemoglobin?

  Hemoglobin easily releases O2 in tissues
• How is carbon dioxide transported in blood?

  In three ways: dissolved, bound to Hb, bicarbonate
• What is the carbonic acid-bicarbonate buffer system?

  It regulates blood pH by CO2 and H2O reactions
• What role does carbonic anhydrase play?

  Facilitates reactions between CO2 and H2O
• How does blood CO2 level affect pH?

  Increased CO2 lowers pH, increases H+
• What happens during slow, shallow breathing?

  CO2 increases, pH decreases
• What happens during rapid, deep breathing?

  CO2 decreases, pH increases
• What is the average PO2 in deoxygenated blood at rest?

  Less than 40 mmHg
• What is the average PCO2 in deoxygenated blood at rest?

  Greater than 45 mmHg
• What is the significance of the steep partial pressure gradient for O2?

  Facilitates rapid diffusion from alveoli to blood
• What is the significance of the less steep partial pressure gradient for CO2?

  Allows for slower diffusion from blood to alveoli
• How does oxygen offloading from hemoglobin occur in metabolic tissues?

  More easily due to higher metabolic activity
• How is carbon dioxide primarily transported in blood?

  Bound to globin molecules of hemoglobin
• What are the steps involved in pulmonary ventilation?

  • Diaphragm and intercostal muscles contract for inspiration
  • Thoracic volume increases, causing air to flow in
  • Elastic recoil of lungs aids in expiration
  • Abdominal muscles contract for forced expiration
• What are the factors affecting gas solubility in liquids?

  1. Partial pressure of the gas
  2. Solubility of the gas in the liquid
  3. Temperature of the liquid
• What are the mechanisms of oxygen transport in blood?

  • 1.5% dissolved in plasma
  • 20% bound to hemoglobin
  • 70% as bicarbonate ions
• What are the mechanisms of carbon dioxide transport in blood?

  • 7–10% dissolved in plasma
  • 20% carried on hemoglobin
  • 70% as bicarbonate ions
• What is the role of the carbonic acid-bicarbonate buffer system?

  • Regulates blood pH
  • Forms carbonic acid and bicarbonate ions
  • Releases or absorbs H+ ions
• What are the true or false statements regarding respiratory physiology?

  • True: Inhalation increases lung volume, decreasing alveolar pressure
  • False: Quiet expiration is an active process
  • True: Gas solubility is affected by partial pressure, solubility, and temperature
  • True: CO2 diffuses more quickly from blood to alveoli
  • True: Oxygen offloading occurs more easily in metabolic tissues
  • False: CO2 is primarily transported bound to hemoglobin