PATH OF AIR

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PATH OF AIR

• Nose- three events that occur
• a. air is filtered- nose hairs
• b. air is warmed- capillaries
• c. air is moistened- mucus membranes
• 2. pharynx- back of throat

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• 3. Larynx- voicebox- vocal cords
• ligaments attached to cartilage
• vibrate when air passes over
• 4. Epiglottis- flap of tissue
• swallow- points downward
• shuts off opening to trachea

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• 5. Trachea windpipe- passage of air to
• lungs
• ciliated- sweep debris upward
• rings of cartilage- keep it open
• 6. Bronchi ( bronchus) branch off trachea
• go to lungs
• smaller tubes called bronchioles

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• 7. Lungs- paired elastic cone-shaped
• pleural membrane- sac-like structure that
  lines outer surface
• alveoli- grape-like clusters of air sacs
• gas exchange occurs here
• surrounded by capillaries

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• 8. Diaphragm- sheet-like muscle
• aids in breathing
• partition between thoracic and abdominal
  cavities

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NASAL CAVITY
ORAL CAVITY (MOUTH)
PHARYNX (THROAT)
EPIGLOTTIS
LARYNX (VOICE BOX)
TRACHEA (WINDPIPE)
PLEURAL MEMBRANE
LUNG (ONE OF A PAIR)
INTERCOSTAL MUSCLE
BRONCHIAL TREE
DIAPHRAGM
Fig. 36.10a, p. 602
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alveolar sac
bronchiole
alveolar sac (sectioned)
alveolar duct
alveoli
pulmonary capillary
Fig. 36.10b, p. 602
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Normal (Passive) Exhalation

• Muscles of inhalation relax
• Thoracic cavity recoils
• Lung volume decreases
• Air flows down pressure gradient and out of lungs

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Inhalation

• Diaphragm flattens
• External intercostal muscles contract
• Volume of thoracic cavity increases
• Lungs expand
• Air flows down pressure gradient into lungs

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Control of Breathing

• Medulla oblongata sets main rhythm centers in
  pons fine-tune it
• Magnitude of breathing depends on concentration
  of oxygen and H
• Brain detects H, increases breathing
• Carotid bodies and aortic bodies detect drop in
  oxygen, increase breathing

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INWARD BULK FLOW OF AIR
OUTWARD BULK FLOW OF AIR
Fig. 36.12a, p. 604
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GAS EXCHANGE AND TRANSPORT

• O2 and CO2 diffuse from high to low
• Oxygen - hemoglobin in RBCs
• 98 of O2 bound to heme groups of hemoglobin
• Carbon Dioxide- 10 dissolves in blood
• 30- binds to hemoglobin
• 60-transported as bicarbonate ions (
  HCO3-)

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• Carbon monoxide- CO has a high affinity for
  hemoglobin
• binds 200X faster than O2
• competition occurs
• cells cant use CO
• CO poisoning

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Effects of Smoking

• Shortened life expectancy
• Increased rates of cancers
• Increased rate of heart disease
• Impaired immune function and healing
• Detrimental to fetus

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Bronchitis

• Irritation of the ciliated epithelium that lines
  the bronchiole walls
• Air pollutants, smoking, or allergies can be the
  cause
• Excess mucus causes coughing, can harbor bacteria
• Chronic bronchitis scars and constricts airways

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Emphysema

• An irreversible breakdown in alveolar walls
• Lungs become inelastic
• May be caused by a genetic defect
• Most often caused by smoking