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					Respiratory Physiology
           4 distinct events
 Pulmonary ventilation: air is moved in and
  out of the lungs
 External respiration: gas exchange between
  blood and alveoli
 Respiratory gas transport: CV system
  transports oxygen and carbon dioxide between
  lungs & tissues
 Internal respiration: gas exchange between
  blood & tissue cells
    Definition: Cellular respiration: actual use of
     oxygen & production of carbon dioxide in the cells
Pulmonary Ventilation
External Respiration
Internal Respiration
Cellular Respiration
Mechanics of Breathing
 Pulmonary ventilation:
   Moving air into and out of the lungs
   Breathing
      Inspiration = moving air into the lungs
      Expiration = moving air out of lungs
      Pressure Relationships
 Intrapulmonary pressure
   Pressure within the alveoli (lungs)
   Changes with phases of breathing
   Always equalizes itself with atmospheric
 Intrapleural pressure
   Pressure between the pleural membranes
    (within intrapleural space)
   Always 4 mmHg less than intrapulmonary
 Any conditions that causes intrapulmonary
 pressure to equal intrapleural pressure will
 cause the lungs to collapse
   This means they lose the ability to move air
    since there is NO more pressure difference
   Atelectasis – term for lung collapse
   pneumothorax – air in the intrapleural space
    due to trauma – causes lung collapse
       Pulmonary ventilation
 Question: Why does breathing happen?
 ONLY acceptable answer: The RULE:
  Volume changes lead to pressure changes
  which lead to the flow of gases to equalize
  the pressure
 Boyle’s law: Pressure
  & Volume vary inversely
 Main inspiratory muscles
   Diaphragm & external intercostals
 Thoracic dimensions change to increase
  volume of thoracic cavity by 0.5 liters
 Intrapulmonary pressure drops 1-3 mmHg
  and air rushes info normal quiet inspiration
 A deep forced inspiration requires
  activation of accessory muscles
 A passive process dependent on natural
  lung elasticity
 The lungs recoil, volume decreases,
  alveoli compress, intrapulmonary pressure
  rises, gas outflows to equalize the
  pressure with atmospheric pressure
 Forced expiration requires contraction of
  muscles of the abdominal wall
        Respiratory Sounds
 Bronchial sounds: produced by air rushing
  through trachea & bronchi
 Vesicular sounds: produced by air filling
 Wheezing: whistling sound
 Rales: rasping sound
      Physical factors influencing
 Pulmonary ventilation can be influenced
 by 4 physical factors
     Respiratory passage resistance
     Lung compliance
     Lung elasticity
     Alveolar surface tension forces
Respiratory passage resistance
 Friction as air moves
  through passages
    Smooth muscle
    Local accumulations of
     mucus, infectious
     material, and tumors
     will cause the air flow
     to be reduced
    Add this: Disorders
     such as asthma
           Lung compliance
 The ease with which lungs can readily
 Affected by the elasticity of the lungs and
  the thoracic cage
 Diminished by 3 main factors:
   Fibrosis of the lung tissue
   Ossification and/or muscle paralysis impairs
    flexibility of the thoracic cage
   Blockage of the passageways
Lung fibrosis
           Lung Elasticity
 Essential for normal expiration
 Emphysema: tissue becomes less elastic
 and more fibrous
  Alveolar Surface Tension Forces
 Surface tension – molecules of liquid hold
  together with hydrogen bonds
 Surfactant – substance which interferes
  with cohesion of water molecules so less
  energy is needed to expand the lungs
 IRDS – Infant Respiratory Distress Syndrome – read
  & know imbalance
  page 424
Type II Cells
Gas Exchanges in the
            Gas Exchanges
 Occur:
   Between the blood and the alveoli AND
   Between the blood and the tissue cells
   Takes place by simple diffusion
   Depends on partial pressures of oxygen &
    carbon dioxide that exist on opposite sides of
    the exchange membrane
   Diagrams on page 416-417 of text
                Henry’s law
 Each gas will dissolve in a liquid in
  proportion to its partial pressure and
  solubility coefficient of the liquid
   CO2 = .57
   O2 = .024
   N2 = .012
 Solubility increases with increasing
  partial pressure
 Solubility decreases with increasing
        Hyperbaric Conditions
 Hyperbaric
  oxygen chambers
  – designed to
  force greater
  amounts of
  oxygen into
  patient’s blood
 Treats tetanus,
  migraines, slow
  healing wounds,
  burns/skin grafts
            Life Applications
Write down the basics for each one:
     Oxygen toxicity
     Nitrogen narcosis
     Decompression sickness
     High altitude sickness
                  Oxygen Toxicity:
 Exposed to 100 percent oxygen at normal air pressure for 48
    Free radicals (highly reactive form of oxygen molecule)
      destroys proteins and membranes in the epithelial cells.
 Fluid accumulates in the lungs.
 Gas exchange in the alveoli slows down – have to breathe more
  to get enough oxygen.
 Volume of exchangeable air decreases by 17 percent.
          Nitrogen Narcosis
 With increasing dive depth,
   partial pressure of nitrogen (PN2)↑
   more N2 becomes dissolved in the blood.
   high N2 concentration impairs the conduction
    of nerve impulses and mimics the effects of
    alcohol or narcotics.
  Symptoms of nitrogen narcosis
include (don’t need to memorize):
 Wooziness          slowing of reaction
 Giddiness
                     fixation of ideas
 Euphoria
                     impairment of
 Disorientation      complex reasoning.
 loss of balance    These effects are
 loss of manual      exacerbated by
  dexterity           cold, stress, and a
                      rapid rate of
   Decompression Sickness (the
 As pressure ↑, solubility of gases ↑
 Larger quantities of N2 forced into the
  body fluid/blood (but not used up by the
 Ascending rapidly causes N2 gas to
  become less soluble and “bubble” out of
  the blood too fast to be exhaled
     Decompression sickness
 Gas collected in joint spaces (pain)
 Can cause air embolisms in blood which
  can lead to heart attack & stroke
 Treatment:
   Hyperbaric chamber
   Take back down to depth & bring up slowly so
    can exhale gas
Internal & External
    Factors influencing internal &
        external respiration
 Partial pressure gradients and gas solubilities
   Oxygen = has low solubility but steep partial
    pressure gradient (104 mmHg in alveoli – 40
    mmHg in blood = 64 mmHg pressure
   Carbon dioxide = has solubility ~20x greater
    than oxygen but partial pressure gradient is
    only 5 mmHg
    Factors influencing internal &
        external respiration
 Partial pressure gradients and gas solubilities
   Due to the ratios of solubility coefficients and
    pressure gradients:
   ~Equal amounts of gases are exchanged
   pH is not affected
      H2O + CO2 = H2CO3 (carbonic acid)
   Factors influencing internal &
       external respiration
 Thickness of respiratory membranes
   0.5 to 1.0 micrometers
   Hypoxia = oxygen deprivation
   Add this: Thickness – edematous (swollen)
    tissue can be caused by congestion and
    Factors influencing internal &
        external respiration
 Surface Area
   50-70 square
    meters for gas
   Emphysema
      Walls of alveoli
       break down
      Less surface
       area to volume
Control of Respiration
 The phrenic & intercostal nerves transmit
 impulses to the respiratory muscles
   Irritation to phrenic nerve is responsible for
    hiccups (spasm of diaphragm muscle)
 Neural centers are located in medulla &
           Breathing Terms
 Eupnea = normal respiration rate
   Approx 12-15 breaths per min
 Hyperpnea = higher than normal rate
 Apnea = No rate
 Dyspnea = general term for abnormal rate
 Physical factors, conscious control,
 emotional factors, and chemical factors all
 influence rate & depth of breathing.
 Slow & shallow respiration
 Not adequate expiration so
 CO2 is not vented out of the body
 Production of excess acid
      H2O + CO2 = H2CO3 (carbonic acid)
 Respiratory acidosis results
 Deep & rapid respiration
 Too much CO2 is vented out of the body
 Not enough acid production
     H2O + CO2 = H2CO3 (carbonic acid)
 Respiratory alkalosis results
 Treatment: trap the CO2 and
 rebreathe it till breathing returns to
End of Quiz #2 Material
          Chronic Bronchitis
 Symptoms: inflammation of mucosa –
 chronic mucus production
   Impairs ventilation and gas exchange
   Reduction of airway diameter
 “blue bloater” – hypoxia leads to cyanosis
  – CO2 retention leads to hyperinflation of
  chest wall
 Causative factors: cigarette smoking
 Normal

 Bronchitis
     Obstructive Emphysema
 “pink puffer”
   Gas exchange adequate until end stage so
    stay oxygenated and pink
   Breathing is very labored due to lack of
    alveolar recoil
   Membranes thicken so decrease in diffusion
 Barrel chest from hyperinflation of lungs
 Alveolar walls collapse = loss of surface
  area so less gas diffusion
 Causative factor: cigarette smoking
       4 features in common
 Both emphysema and chronic bronchitis
   Smoking history
   Dyspnea = air hunger due to dysfunctional
   Coughing & pulmonary infections
   Will develop respiratory failure, hypoxia,
               Lung Cancer
 Basic Info
   1/3 of all cancer deaths are due to lung
   90% have a smoking history
   Metastasizes very rapidly due to vascularity of
                   3 types
 Know the descriptions (what they look like
 & where specifically they form) of these 3
 types of lung cancers from page 420
   Squamous cell carcinoma
   Adenocarcinoma
   Oat cell (small cell) carcinoma
Squamous cell carcinoma
Oat cell carcinoma
 Resection of diseased portion of lung
 Radiation therapy
 Chemotherapy
Lung Resection
           Cystic Fibrosis
• Genetic disorder – recessive
• Causes oversecretion of thick mucus that
  clogs respiratory passages
• Impairs food digestion by clogging ducts
  that secrete enzymes
Sudden Infant Death Syndrome
• Caused by heart rhythm abnormality or
  problem in neural control of respiration
• Chronically inflamed hypersensitive
  bronchial passageways
• Bronchoconstriction of passageways in
  response to allergen, temperature
  changes, & exercise
• Can be managed with medication
Developmental Aspects
 Read through the Developmental
  Aspects section of your notes