Respiratory System Review

Respiratory System Review

• Conducting Passageways: The respiratory system's air passages, from entrance to lungs.

  • Nose: Initial entrance to the system.
  • Pharynx: Throat; shared passage for food and air. The epiglottis closes during swallowing.
  • Larynx: Voice box; contains vocal cords. Epiglottis opens for air passage.
  • Trachea: Windpipe; cartilage rings support structure. Contains ciliated pseudostratified epithelium.
  • Bronchi (Right/Left): Branches off the trachea, carrying air to lungs.
  • Bronchioles: Smaller branches leading to alveoli.
  • Cilia: Microscopic hairs filtering inhaled air.
  • Mucus: Sticky substance trapping foreign particles.
  • Ciliated Mucosae: Inside trachea; cilia move mucus and trapped particles away from lungs.
  • Alveoli: Tiny air sacs in lungs; site of gas exchange.
  • Epiglottis: Flap of cartilage that covers trachea during swallowing.

Mechanics of Breathing

• Boyle's Law: Inverse relationship between pressure and volume; air moves from higher to lower pressure.
• Diaphragm: Muscle below lungs; contracts during inhalation pushing downwards.
• External Intercostals: Muscles between ribs; elevate ribs during inhalation.
• Inhalation (Inspiration): Rib cage expands, diaphragm contracts, increasing thoracic volume, decreasing intrapulmonary pressure, air inflates the lungs.
• Exhalation: Pressure increases, lung volume decreases; diaphragm and intercostals relax.

Respiratory Volumes & Capacities

• Residual Volume: Air remaining in lungs after maximum exhalation.
• Tidal Volume: Air exchanged with each normal breath.
• Inspiratory Reserve Volume: Extra air inhaled in forced breathing.
• Expiratory Reserve Volume: Extra air exhaled in forced breathing.
• Total Lung Capacity: Maximal air lung capacity.

Partial Pressure of Gases & Diffusion

• Diffusion: Movement of molecules from high to low concentration.
• Total Atmospheric Pressure: Weight of the atmosphere (760 mmHg).
• Partial Pressure: Pressure of each gas in a mixture (Px).
• Dalton's Law: Each gas in a mixture exerts its own pressure independently.
• Partial Pressure (Px) and Gas Diffusion: Larger pressure difference leads to faster gas movement (diffusion).
• Partial Pressure influences on Hemoglobin Affinity for O2: Partial pressure of oxygen (PO2) directly impacts hemoglobin's ability to bind oxygen. Factors like pH and temperature also affect hemoglobin's affinity for oxygen.

Factors influencing Hemoglobin Affinity

• pH: Lower pH (more acidic) reduces hemoglobin's affinity for oxygen.
• Temperature: Higher temperature reduces hemoglobin's affinity for oxygen.
• Altitude Sickness: Low oxygen levels at high altitudes causing symptoms (nausea, headache, shortness of breath).

Gas Transport in the Blood

• Oxyhemoglobin: Hemoglobin bound to oxygen.
• Hemoglobin: Iron-containing protein in red blood cells carrying oxygen.
• Iron: Essential for hemoglobin production and oxygen transport.
• Carbonic Acid: Weak acid formed from carbon dioxide dissolving in plasma.
• Bicarbonate Ion: Ion formed from carbonic acid dissociation in plasma.
• Carbon Dioxide Loading/Unloading: Oxygen binding to hemoglobin reduces carbon dioxide and hydrogen ion binding to hemoglobin.