25) Breathing and gas exchange

• Why is breathing essential?

  - Provides oxygen to our tissues

  - Eliminates carbon dioxide from the system
• What are some non-respiratory functions of the respiratory system?

  - Blood pressure regulation

  - Acid/base balance

  - Blood and lymph flow

  - Vocalisation

  - Sense of smell

  - Protection and defence

  - Regulation of body temperature
• What is found in the upper respiratory tract?

  - Nose

  - Pharynx

  - Larynx
• What is found in the lower respiratory tract?

  - Pleural sac

  - Lungs

  - Thorax-rib cage

  - Diaphragm
• What is the nasopharynx?

  Upper part of throat behind nasal cavity
• What is the oropharynx?

  Middle part of throat located behind the mouth that extends from the soft palate to the epiglottis
• What is the laryngopharynx?

  Lowest part of Pharynx located behind the voicebox that extends downward to the oesophagus
• What is the larynx?

  - Cartilaginous chamber

  - Keeps food/drink out of airway

  - Sound production
• What is the trachea?

  - Anterior to the oesphagus

  - 16-20 rings of hyaline cartilage (support)

  - Cilia containing cells beat upward to remove debris in mucus
• What cells are involved in the respiratory system?

  - Simple squamous epithelium

  - Cuboidal, surfactant-secreting cells

  - Alveolar macrophages

  - Endothelial cells of the blood capillaries
• Boyle's Law:

  Initial pressure of gas (P1) x Initial volume of gas (V1) = Final Pressure of gas (P2) x Final volume of gas (V2)
• What does Boyle's law mean?

  - At a constant temperature, the pressure of gas is inversely proportional to its volume.

  -> So as volume of gas decreases, the pressure increases as gas molecules are confined to a smaller space
• What are the steps to inspiration?

  1. Diaphragm and external intercostal muscles contract
  2. Chest cavity expands, decreasing pressure in lungs
  3. Air from atmosphere rushes in following a pressure gradient
• What are the steps to expiration:

  1. Diaphragm and external intercostal muscles relax
  2. Thorax volume decreases, Increasing pressure in lungs
  3. Air flows out of lungs to atmosphere, following a pressure gradient
• What is inspiratory reserve volume?

  The maximum amount of air that can enter lungs in addition to the tidal volume
• What is tidal volume?

  The volume of air entering or leaving the lungs during one breath at rest
• What is expiratory reserve volume?

  The maximum amount of air that can be exhaled beyond the tidal volume
• What is residual volume?

  The remaining air in the lungs after a maximal expiration
• What is the role of chemoreceptors in regulating breathing?

  - Chemoreceptos respond to lower acidity in blood (more CO2 in blood)

  - Increases the rate of breathing