Mechanics of Breathing

  • Breathing is the process of moving air into and from the lungs for gas exchange.
  • All aerobic creatures need oxygen for cellular respiration.
  • Gas exchange takes place in the alveoli through diffusion.
  • The respiratory rate is the number of respiratory cycles per minute.
  • Homeostatic mechanisms control the partial pressures of carbon dioxide and oxygen in the arterial blood.
  • The diaphragm and intercostal muscles are involved in breathing.
  • The diaphragm primarily contributes to the expansion of the chest cavity.
  • Accessory muscles of inhalation aid in expanding the rib cage.
  • Exhalation involves relaxation of the muscles of inhalation and contraction of abdominal muscles.
  • The lungs expand when there is an increase in the volume of the thoracic cavity.

Passage of Air

  • The respiratory tract controls inhalation and exhalation.
  • Upper airways include the nasal cavities, pharynx, and larynx.
  • Inhaled air is warmed and moistened by the nasal mucosa.
  • The nasal cavities have narrow passages that expose a large area of nasal mucous membrane to the air.
  • Exhaled air from the lungs cools and dries in the cool and dry nose.

Gas Exchange

  • Gas exchange occurs in the alveoli of the lungs.
  • Oxygen is transported to the cells through the circulatory system.
  • Carbon dioxide is a waste product of cellular respiration.
  • The partial pressure of carbon dioxide in arterial blood affects pH.
  • Hyperventilation and hypoventilation can cause symptoms due to changes in arterial carbon dioxide levels.

Other Functions of Breathing

  • Breathing allows for speech, laughter, and emotional expressions.
  • Reflexes such as yawning, coughing, and sneezing involve breathing.
  • Some animals lose heat through panting.
  • Diaphragmatic breathing is also known as abdominal breathing.
  • Clavicular breathing may occur during labored breathing or in certain medical conditions.

Effects of Altitude on Breathing

  • Breathing at altitude results in decreased atmospheric pressure.
  • Alveoli are open to outside air, so lung pressure also decreases with altitude.
  • Pressure difference at altitude affects gas exchange in the lungs.
  • Effects of high altitude on humans can include altitude sickness and difficulty breathing.
  • Atmospheric pressure decreases with height above sea level.

Breathing Mentions

Breathing Data Sources

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