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Advanced Study | Respiratory & Airway Part Two

Respiratory & Airway Part Two

Lower Airway: Runs from the glottic opening to pulmonary capillary membrane.

Trachea: Conducts air to the lungs. 10-15 cm long tube, between larynx and bronchi, anterior to esophagus

Right and left main bronchi: split at the carina

Secondary bronchi: one for each lobe of the lungs 3 right, 2 left Bronchioles: tertiary branches 10 right and 8 left

Alveoli: clusters of air sacs, 1-2 cells thick, primary site for O2 and CO2 exchange Beta 2 receptors of the sympathetic nervous system are situated throughout the tree. When stimulated, they lead to bronchodilation

Serous membrane: a two-layer epithelial membrane that lines body cavities and covers the surface of organs. Pleura is the one around the lungs. Two layers with a little liquid in between for lubrication:

  • Visceral – closely covers the lungs
  • Parietal – lines the inner surface of the chest wall, diaphragm, media stinum.

Lungs: rest on the base of the diaphragm – upper portion called the apex
Hilum: slit in the medial surface where primary bronchi, pulmonary blood vessels and nerves enter. Lungs move freely except at the hilum.

Pediatric Airways: Differences

  • Overall size is smaller
  • Larger tongue in proportion to mouth
  • Large, floppy epiglottis
  • Weak neck muscles
  • Tonsils and adenoids posterior pharynx _ Larynx is higher and funnel shaped
  • Cricoid cartilage is the narrowest portion of child’s upper airway (Glottis is the adults)
  • More dependent on diaphragm for breathing

Respiration: exchange of gases between the body cells and the atmosphere. Three parts:

  1. External respiration – the exchange of gases between circulating blood and air, carried on by expansion and contraction of the lungs
  2. Internal Respiration – exchange of dissolved gases between the circulating blood and interstitial fluids in the peripheral tissue
  3. Cellular respiration – actual use of O2 by the cells in the process of metabolism

Ventilation: the process of moving air in and out of the lungs. Includes inspiration and expiration. The insp. Starts as an impulse in the Medulla transmitted through the Phrenic nerve. Diaphragm goes down, decreasing air pressure in the lungs, pulling air in. Hering Brueuer relflex – stretch receptors keep the lungs from popping.

Respiratory volume: 500-800 mL of air

Tidal volume: amount in one breath cycle

Alveolar air: air that reaches the alveoli = approx 350mL Minute volume: air exchanged in one minute

Average adult male lung capacity = about 6 L

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