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Pleura cavity
Visceral pleura
Parietal pleura
Function (3)
 - Pleura cavity = btwn visceral and parietal pleurae
- Visceral pleura = inner lung lining
- Parietal pleura = outer lung lining, lines the thoracic wall and sperior aspect of the diaphragm
- Functions:
- a) reduce friction
- b) create pressure gradient
- c) compartmentalization (preventing spread of infection)
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Upper resp system
- 3 parts
- function (2)
- nose
- nasal cavity
- pharynx
- function: a) filter and b) humidify incoming air
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Lower resp system
- 5 parts
- larynx
- trachea
- bronchi
- bronchioles
- alveoli
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Tracheobronchial epithelium
- smooth muscles in walls of airway increase gradually and control conductance of airaways
- conductance: the ability to allow flow; inverse of resistance
- tracheobronchial tree: a system of tubes conveying air to the respiratory system; has 24 orders of braches; ends in alveoli where gas xchange occurs
- cartilage rings support the trachea and smaller airways to bronchioles, preventing collapse
- elevator effect: cilia pushes mucus and forieng particles up airway
- functions: a) warms, b) humidifies, c) filters
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Respiratory membrane cells
1) type I alveolar cells
2) type II alveolar cells
3) alveolar macrophages (dust cells)
4) capillary endtothelium
- type I alveolar cells: simple squamous epithelium
- type II alveolar cells: cuboidal cells; produce surfactant
- alveolar macrophages or dust cells: patrol epithelium; engulf foreign particles
- capillary endothelium
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Compliance
- definition
- factors (3)
Surfactant (produced from what cell type?)
- compliance: how easily lungs can be inflated
- factors:
- a) elastin (stretch) and collagen fibers (resist stretch)
- b) water content
- c) surface tension (* increase ST = increase compliance)
- - Surface tension in alveoli reflects the attraction of H2O molecules via H-bond. Surfactant interrupts the H-bond thus reduce suraface tension - such reduction in surface tension makes it easier to inflate the alveoli
- - Surfactant is produced from type II alveolar cells
- - inflation pressure stimulates release of surfactant from type II cells
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What (3) factors affect alveolar-capillary diffusion? (mvt of O2 and CO2)
- 1) permeability (thickness)
- 2) surface area
- 3) concentration gradient for the gas (obstruction can lead to stale air, limiting [gradient])
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Lung ventilation
- definition
- (2) factors
- lung ventilation: the act of driving air in and out of the lungs
- factors:
- a) action of respiratory (intercoastal) muscles - chest compliance (affecting volume)
- b) lung compliance (how easiliy lungs can be inflated; alveoli to change size)
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Respiratory muscles (5)
- principle resp muscles
- accessory muscles of inhalation
- accessory muscles of exhalation
- principle resp muscle: (1) diaphram (and external intercoastal muscles)
- accessory musclles of inhalation: (2) scalene, (3) sternocleidomastoid
- accessory muscle on exhalation: (4) internal intercoastal (pulls chest space = smaller, (5) abdominal muscles (3 of them; forces diaphragm upwards; diaphragm bounces back b/c its passive)
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tidal volume*
- air inhaled or exhaled in oen quiet breath
- (hard to measure) (~0.5L)
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inspiratory reserve volume
air in excess of tidal inspiration that can be inhaled with max effort (~3L)
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expiratory reserve volume
- air in excess of tidal expiration that can be exhaled with max effort
- (minus residue volume)
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residual volume
air remaining in lungs after max expiration, keeps alveoli inflated
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vital capacity
- amount of air that can be exhaled with max effort after max inspiration; assess strength of thoracic muscles and pulmonary function (during exercise)
- max inhalation to max expiration (minus residual volume)
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inspiratory capacity
- max amount of air that can be inhaled after a normal tidal expiration
- max inhalation to tidal expiration
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functional residual capacity
- amount of air in lungs after a normal tidal expiration
- tidal expiration to residual volume
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total lung capacity
max amount of air lungs can contain (~5-6L)
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forced expiratory volume (FEV)*
- % of vital capacity exhaled/timehealth adult 75 to 85% in 1 sec
- (vital capacity, max exhaled after max inspiration)
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minute respiratory volume (MRV)
- TV x resp rate (at rest)e.g. 500mL x 12 breaths/min = 6L/min or 6000mL/min
- max 125-170L/min
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partial pressure
Pa02 or PO2 normal value
Normal O2 saturation
- partial pressure: pressure of just O2 gas/all gases OR pressure of a gas in a gas mixutre is similar to concentration fo that gas in that gas mixture
- Pa02 or PO2 normal value: >80 mm Hg
- Normal O2 saturation: 95-97%
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Normal partial pressure PaCO2
When you exhale you remove CO2 from your blood and also (increase/decrease) the amount of carbonic acid, (raising/lowering) your blood pH
- Normal partial pressure PaCO2: 35-45 mm Hg
- When you exhale you remove CO2 from your blood and also decrease the amount of carbonic acid,
- raising your blood pH (basic)
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Two types of chemoreceptors
central chemoreceptors
peripheral chemoreceptors
- central chemoreceptors: measure PCO2 and pH in cerebrospinal fluid; increase resp when PCO2 increases or pH decreases
- peripheral chemoreceptors:
- a) measures PO2 in arterial blood;
- b) increases resp when PO2 <60 mm Hg;
- c) more sensitive than central chemorecept. (starts faster)
- d) not as powerful
- Both can adapt to stimulus and become less sensitive with prolonged exposure
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