BMS100 - Chapter 16 Outline

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Nose, Nasal Cavity & Paranasal Sinuses
1. Bone and cartilage support the nose.
2. The mucous membrane in the nose filters, warms, and moistens incoming air.
3. The nasal septum and nasal conchae divide the nasal cavity into passageways and increase the surface area of the mucous membrane.
4. Cilia push mucus to the pharynx, where it is swallowed.
5. Paranasal sinuses
   • spaces in certain skull bones
   • connected to nasal cavity by small passages
   • lined by mucous membrane
   • functions: make skull lighter, produce mucus, act as resonating chambers for voice production

Pharynx & Larynx
1. pharynx
   • posterior to ("behind") the nasal cavity, oral cavity, and larynx
   • is a passageway for air and food
   • What are the seven (7) passages into / out of the pharynx?
2. larynx
   • conducts air only
   • composed of nine pieces of cartilage and lined with mucous membrane
   • vocal folds ("true vocal cords") = ligaments, covered by mucous membrane
   • glottis = vocal folds and the space between them
   • vocal cords vibrate and produce sound when air passes between them
   • voluntary muscles control the glottis by controlling the position and tension in vocal cords
   • glottis & epiglottis help prevent food and liquid from entering the trachea

Trachea & Bronchial Tree
1. trachea (anterior to esophagus) - divides into right primary bronchus & left primary bronchus
2. bronchial tree = branched air passages that lead from the trachea to the alveoli ("air sacs" at end of each branch)

Alveoli & Gas Exchange (p. 443)
1. respiratory membrane
   • consists of alveolar walls and capillary walls
   • alveoli allow gas exchange between air and blood (gases diffuse across respiratory membrane)
2. total atmospheric pressure at sea level = approx. 760 mm. Hg.
3. partial pressure of oxygen in different locations
   • in atmosphere = 160 mm. Hg. (O₂ contributes 160/760 of total atmospheric pressure)
   • in alveoli = 100 mm. Hg.
   • in "deoxygenated" blood = 40 mm. Hg.
   • in "oxygenated" blood = 100 mm. Hg.
4. Gases diffuse from regions of higher partial pressure to regions of lower partial pressure.
5. Oxygen diffuses from alveolar air into blood. Carbon dioxide diffuses from blood into alveolar air.

Breathing Mechanism (p. 436)
1. Boyle's Law
   • If volume increases, pressure decreases.
   • If volume decreases, pressure increases.
2. Changes in the size of the thoracic cavity drive inspiration and expiration.
3. Inspiration (Inhalation)
   1. is always "active" (requires muscle contraction)
   2. occurs when the pressure inside alveoli decreases below atmospheric pressure and atmospheric pressure forces air into the lungs
   3. pressure within alveoli decreases when
      • the diaphragm contracts & moves downward
      • the external intercostal muscles contract & pull the ribs "up & out"
4. Expiration (Exhalation)
   1. may be active or passive (not dependent on muscle contraction)
   2. passive expiration - caused by elastic recoil of lung tissue and other factors
   3. “forced” (active) expiration - air is forced out by abdominal wall muscles, internal intercostal muscles, and others

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Chapter 16 Questions at OLC - 3, 4, 5, 6, 8, 10, 11, 14, 17, 19, 20, 23, 24, 25, 26, 29, 31, 32, 35

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Fall 2010