exam 1

• respiratory system: organ system that takes in air and expels it from the body
• respiration refers to ventilation of the lungs (breathing)
• functions of the respiratory system:

  1. gas exchange ~ O2 and CO2 exchanged between blood and air
  2. communication ~ speech and other vocalizations
  3. olfaction ~ sense of smell
  4. acid-base balance ~ influences of pH of body fluids by eliminating CO2
  5. blood pressure regulation ~ assists with synthesis of angiotension II, a hormone that regulates blood pressure
• organization of respiratory organs: nose, pharynx, larynx, trachea, bronchi, lungs
• conducting zone: passages that serve only for airflow (no gas exchange); nostrils through major bronchioles; anatomical dead space
• respiratory zone: regions that participate in gas exchange; alveoli and nearby structures
• upper respiratory tract: airway from nose through larynx
• lower respiratory tract: regions from trachea through lungs
• types of alveoli cells:

  1. squamous (type 1) alveolar cells
  2. thin, 95%, gas exchange
  3. great (type 2) alveolar cells
  4. round/cuboidal, 5%, repair type 1 cells, secrete pulmonary surfactant
• pulmonary surfactant: mixture of phospholipids and proteins that coats the alveoli and prevents them from collapsing during exhalation
• respiratory membrane: thin barrier between the alveolar air and blood

  contains 3 layers:

  1. squamous alveolar cells
  2. endothelial cells of blood capillary
  3. their shared basement membrane
• each alveolus is surrounded by a basket of capillaries supplied by the pulmonary artery
• pleura: serous membrane that lines thoracic wall and forms surface of lung

  • visceral pleura: forms surface of the lung
  • parietal pleura: adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm
  • pleural cavity: potential space between pleurae
  • pleural effusion: pathological seepage of fluid into the pleural cavity
• respiratory muscles

  1. diaphragm: prime mover of respiration
  2. contraction = flattens diaphragm = enlarges thoracic cavity = pulling air into lungs
  3. relaxation = diaphragm bulges = compressing lungs = expelling air
  4. 2/3 of airflow
  5. internal and external intercostal muscles: contribute to enlargement and contraction of thoracic cage
  6. located between ribs
  7. 1/3 of airflow
• voluntary control of breathing

  • voluntary control over breathing originates in the motor cortex of frontal lobe of the cerebrum
  • sends impulses down corticospinal tracts to respiratory neurons in spinal cord, bypassing brainstem
  • breaking point: when CO2 levels rise to a point where automatic controls override one's voluntary will
• boyle's law

  • increase volume/space = decrease pressure = inhalation = external intercostals
  • decrease volume/space = increase pressure = exhalation = internal intercostals
• atmospheric (barometric) pressure: the weight of the air above us

  intrapulmonary pressure: air pressure within lungs
• intrapleural pressure: the slightly negative pressure that exists between the two pleural layers that allows thoracic cage expansion
• expiration: passive process achieved mainly by elastic recoil of thoracic cage; exhaling

  inspiration: passive process achieved by expanding the thoracic cage; inhaling
• pneumothorax: presence of air in pleural cavity

  • thoracic wall is punctured
  • inspiration sucks air through the wound into the pleural cavity
  • potential space becomes an air-filled cavity
  • loss of negative intrapleural pressure allows lungs to recoil and collapse
• atelectasis: collapse of part of all of a lung
• resistance to airflow factors:

  1. bronchiole diameter: increase or decrease of bronchiole diameter
  2. pulmonary compliance: the ease with which the lungs expand, or more exactly, the change in lung volume relative to a given pressure change
• bronchoconstriction: decrease in diameter of bronchus or bronchiole; decreases airflow

  • histamine, parasympathetic nerves, cold air, and chemical irritants
• bronchodilation: increase in diameter of bronchus or bronchiole; increase airflow

  • epinephrine and sympathetic stimulation
• alveoli cells --> alveolus --> alveoli --> alveolar sac
• air consists of

  • 78.6 % N
  • 20.9% O
  • 0.04% CO2
  • 0%-4% H2O vapor
• ventilation: blood flow matches airflow

  perfusion: airflow matches bloodflow
• bronchioles have smooth muscle to change how much airflow comes through
• in the lungs, CO2 enters air alveolus and O2 leaves air alveolus
• in the heart, CO2 leaves the tissue and O2 enters the tissue
• nasal cavity

  1. heats
  2. humidifies
  3. filters
• the more partial O2 pressure, the more O2 bound to hemoglobin
• pH effects how fast O2 is transported
• respiratory cycle: one complete breath, in and out
• charles's law: the volume of a given quantity of gas is directly proportional to its absolute temperature
• henry's law: concentrations move from high to low
• Dalton's law: total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases
• physiological (total) dead space: the sum of anatomical dead space and any pathological dead space that may exist
• respiratory volumes

  • tidal volume (TV): amount of air inhaled and exhaled in one cycle during quiet breathing
  • inspiratory reserve volume (IRV): amount of air in excess of tidal volume that can be inhaled with maximum effort
  • expiratory reserve volume (ERV): amount of air in excess of tidal volume that can be exhaled with maximum effort
  • residual volume (RV): amount of air remaining in the lungs after maximum expiration; the amount that can never be voluntarily exhaled
• respiratory capacities

  Vital capacity (VC): the amount of air that can be inhaled and then exhaled with maximum effort; the deepest possible breath (VC = ERV + TV + IRV)

  inspiratory capacity (IC): maximum amount of air than be inhaled after a normal tidal expiration (IC = TV + IRV)

  functional residual capacity (FRC): amount of air remaining in the lungs after a normal tidal expiration (FRC = RV + ERV)

  total lung capacity (TLC): maximum amount of air the lungs can contain (TLC = RV + VC)