Respiration Quiz

Respiration

• The process of extracting energy from food.
• Divided into three types:
  • External Respiration: Gas exchange between the alveoli and pulmonary blood.
  • Internal Respiration: Gas exchange between blood and tissues.
  • Cellular Respiration: Extraction of energy from food within mitochondria, the core purpose of respiration.

Normal Respiration (Eupnoea)

• Silent and involuntary.
• Shoulders should not move during breathing.
• Rate:
  • Adults: 16 breaths per minute.
  • Newborns: 24 breaths per minute.
• Consists of three phases:
  • Inspiration (inhalation).
  • Expiration (exhalation), slightly longer than inspiration.
  • Expiratory pause.
• During rapid or hyperventilation, only two phases occur:
  • Inspiration.
  • Expiration, followed immediately by the next inspiration without an expiratory pause.

Respiratory Passages

• Pathway: nose, nasopharynx, larynx, bronchus, bronchial tree (23 generations).
• Divided into two main parts:
  • Conducting Part: Non-respiratory, also known as "dead space," includes the upper respiratory passage and the first 16 generations of the bronchial tree.
    • Functions:
      • Air conduction.
      • Air filtering.
      • Air conditioning.
      • Protection through sneezing and coughing.
      • Vocalization.
      • H2O regulation through evaporation.
      • Heat regulation (in animals lacking sweat glands).
  • Non-Conducting Part (Respiratory Part): Lower respiratory passage with thin walls allowing gas exchange. Includes:
    • Last 7 generations of the respiratory passage (terminal bronchioles).
    • Alveoli.
    • Functions:
      • Gas exchange.
      • Blood pH regulation.
      • Buffering mechanisms.
      • Respiration stimulation and regulation.

Important Definitions

• Eupnoea: Normal respiration.
• Hyperpnoea: Hyperventilation.
• Apnoea: Cessation of respiration.
  • Temporary: During deglutition, vomiting, coughing, labor, straining, and sneezing.
  • Permanent: In death.
• Dyspnoea: Difficulty in breathing. Types:
  • Orthopnoea: Difficulty breathing in a recumbent position (lying down).
  • Paroxysmal Nocturnal Dyspnoea: Difficulty breathing in a recumbent position only at night.
  • Dyspnoea on Exertion: Difficulty breathing during physical activity.
  • Dyspnoea at Rest: Difficulty breathing even when at rest.
  • Note: Orthopnoea, dyspnoea on exertion, and dyspnoea at rest are commonly associated with heart failure.

Degrees of Dyspnoea

• Severity:
  • Dyspnoea on exertion: Severe, moderate, and mild.
  • Paroxysmal nocturnal dyspnoea.
  • Orthopnoea.
  • Dyspnoea at rest.

Respiratory Muscles

• Inspiration:
  • Normal Respiration:
    • Diaphragm: Increases the volume of the thoracic cage vertically, contributing to 2/3 of the increased volume.
    • External intercostal muscles: Increase the volume of the thoracic cage transversely, contributing to 1/3 of the increased volume.
  • Deep Respiration:
    • Muscles of normal inspiration (diaphragm and external intercostal muscles).
    • Accessory muscles:
      • Sternocleidomastoid muscle.
      • Serratus anterior muscle.
      • Scalene muscle.
• Expiration:
  • Normal Respiration: Passive, no muscle activity.
  • Deep Respiration: Active, including:
    • Internal intercostal muscles.
    • Abdominal muscles.

Respiratory Pressures

• Intrapleural Pressure (intrathoracic pressure): The most important pressure within the pleural cavity.
  • Values:
    • Beginning of inspiration: -4 mmHg.
    • End of inspiration: -6 mmHg (may reach -80 mmHg during deep inspiration).
    • Beginning of expiration: -6 mmHg (may reach -80 mmHg after deep inspiration).
    • End of expiration: -4 mmHg.
  • Note: Intrapleural pressure is always NEGATIVE.
• Intra-alveolar Pressure (intra-pulmonary pressure): Pressure within the alveoli.
• Intra-abdominal Pressure: Pressure within the abdominal cavity.
• Transmural Pressure: Difference between intrapleural and intra-alveolar pressures.