Respiratory System Physiology

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Respiratory System Physiology

• RESPIRATORY SYSTEM PHYSIOLOGY
• FOUR steps in the Respiratory System Process
• Pulmonary Ventilation Moving air into and out of
  the lungs (Breathing)
• External Respiration Gas exchange between the
  pulmonary blood and the alveoli O2 and CO2
• Respiratory Gas Transport Moving O2 and CO2 to
  and from the lungs and body tissue.
• Internal Respiration Gas exchange BETWEEN blood
  and tissue cells.
• Mechanisms of Breathing
• Boyles Law of Pressure Pressure is directly
  related to volume
• The mechanics of breathing depends on changes in
  PRESSURE which depend on changes in VOLUME.
• The HIGHER the volume, the LOWER the pressure
• The HIGHER the pressure, the LOWER the volume

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Respiratory System Physiology

• TWO PHASES OF BREATHING
• INSPIRATION Moving air INTO the lungs.
• Contracting our diapragm and intercostal muscles
  increases the size of our THORACIC cavity and
  lungs which cling to them by pleural fluid.
• This DECREASES air pressure in lungs to create a
  partial vacuum, and SUCKS air into the lungs.
• This process stops when INTRAPULMONARY pressure
  in the lung equals the atmospheric pressure
  outside the lung.
• EXPIRATION Moving air out of the lungs.
• As muscles relax, the lungs decrease in VOLUME
  and air pressure in them INCREASES.
• Gases flow easily out of the lungs until pressure
  equalizes
• ATELECTASIS is the term for a collapsed lung,
  which results from air entering the PLEURAL
  space, separating it from the lung.
• Air may enter the pleural space through a chest
  wound or also from a rupture of the visceral
  (pulmonary) pleura.

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Respiratory System AnatomyNon Respiratory Air
Movements

• COUGH Taking a deep breath, closing the glottis
  and forcing air superiorly from the lungs against
  the glottis. The glottis THEN opens suddenly and
  a BLAST of air rushes upward. Coughs act to
  clear the lower respiratory passageways.
• SNEEZE Similar to cough except that expelled
  air is directed through NASAL cavities instead of
  through ORAL cavity. The UVULA becomes depressed
  and closes the oral cavity off from the pharynx,
  routing the air through nasal cavities. Sneezes
  clear upper respiratory
• CRYING Inspiration followed by a release of air
  in a number of short breaths. Primarily an
  emotionally induced mechanism.
• HICCUPS Sudden inspirations resulting from
  spasms of the diaphragm believed to be initiated
  by irritation of diaphragm or phrenic nerves,
  which serve the diaphragm. The sound occurs when
  inspired air hits vocal folds of a closed
  glottis.
• YAWN Very deep inspiration, taken with jaws
  wide open. Ventilates all alveoli. Formerly
  believed to be triggered by the need to increase
  the amount of O2 in blood Theory questioned now

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Respiratory System Volumes Capacities

• RESPIRATORY VOLUMES
• TIDAL VOLUME (TV) Amt of air inhaled or exhaled
  with each breath. Adult Male AVG 500 ml
• INSPIRATORY RESERVE VOLUME (IRV) Amt of air
  that can be forcefully INHALED after a normal
  tidal volume inspiration Adult
  Male AVG 3100 ml
• EXPIRATORY RESERVE VOLUME (ERV) Amt of air that
  can be forcefully EXHALED after a normal tidal
  volume exhalation
  Adult Male AVG 1200ml
• RESIDUAL VOLUME (RV) Amt of air remaining in
  lungs after a forced exhalation (Allows gas
  exchange to go on continuously even between
  breaths and helps keep the alveoli inflated.
  Adult Male
  AVG 1200ml

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Respiratory System Volumes and Capacities

• RESPIRATORY CAPACITIES
• VITAL CAPACITY (VC) The maximum amt of air
  that can be expired after a maximum inspiratory
  effort. VC TV IRV ERV RV Adult
  Male AVG 4800 ml
• DEAD SPACE VOLUME The amt of air that enters
  the respiratory tract BUT remains in the
  conducting zone passageways and NEVER reaches the
  alveoli.
  Adult Male
  AVG 150 ml
• Respiratory Capacities are measured with a
  SPIROMETER. As a person breathes, the volumes of
  air exhaled can be read on an indicator, which
  shows the changes in air volume inside the
  apparatus.
• Pneumonia shows a decrease in IRV and VC because
  INSPIRATION is obstructed.
• Emphysema shows a decrease in ERV because
  EXPIRATION is hampered and shows an increase in
  Residual Volume

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Respiratory System Disorders

• CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)
• Chronic Bronchitis and Emphysema Major causes
  of disability and death in the U.S.
• 82 of ALL COPDS are caused by SMOKING
• FREATURES OF COPDS
• Patients almost ALWAYS have a history of SMOKING
• Dyspnea Difficult or labored Breathing Air
  Hunger
• Coughing frequent Pulmonary Infections are
  common
• Most victims are HYPOXIC, retain CO2 and
  respiratory acidosis, and unltimately develop
  respiratory failure.
• Patients arent BORN with these (No genetic
  predisposition)

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Respiratory System Disorders

• Emphysema Chronic inflammation causes FIBROSIS
  of the lungs and makes them less elastic. This
  causes the airways to collapse during EXPIRATION
  and obstruct out flow air..Patients use an
  incredible amt of energy to EXHALE, and they are
  always exhausted.
• Chronic Bronchitis Mucosa of the lower
  respiratory passages becomes severely inflamed
  and produces excessive amts of MUCUS . Pooled
  mucus impairs ventilation and gas exchange and
  increases risk of lung INFECTIONS, including
  PNEUMONIAS.

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Respiratory System Disorders

• DEVELOPMENTAL DISORDERS
• CYSTIC FIBROSIS (CF) Over secretion of a thick
  MUCUS that clogs the respiratory passages. It
  puts the child at risk for fatal respiratory
  INFECTIONS and it impairs FOOD DIGESTION by
  clogging ducts that deliver pancreatic enzymes
  and bile to the small intestine.
• ASTHMA Chronically Inflamed, Hypersensitive
  bronchial passages that respond to many irritants
  with dyspnea, coughing, and wheezing.
  Respiratory passageways are narrowed by
  bronchiole spasms
• LUNG CANCER See pp 420-421 A Closer Look