Respiratory System pt 1 Flashcards
what are the levels of gas exchange
external and internal respiration
what are the parts to external respiration
- pulmonary (air in and out of lungs thru bulk flow)
- O2 and CO2 exchange bw air spaces in lungs and blood by diffusion
- CO2 and O2 transport bw lungs and body tissues via heart and circulatory system
- O2 and CO2 exchange bw blood and tissues
describe internal respiration
cellular respiration in mitochondria (oxidative phosphorylation mechanism)
draw out a flowchart of air to lungs and blood with main transport steps
….
describe bulk flow
transport mechanism to let air move in and out of lungs
describe inspiration
pressure in lungs < atmospheric pressure so air comes in by suction
describe expiration
pressure in lungs > atmospheric pressure which makes air go out
what is the direction air moves (gradient)
high to low pressure
why does ventilation happen
due to pressure gradients bw alveoli and outside air (atmosphere)
what is FRC
- functional residual capacity
- volume of air in lungs bw breaths
what are the types of pulmonary pressures
- atmospheric
- intrapleural
- intra-alveolar
- transpulmonary
describe atmospheric pressure (P atm)
- ↓ as altitude ↑
- ↑ underwater
describe intrapleural pressure (P ip)
- pressure inside pleural sac (membrane that folds on itself in lungs to make a sac)
- always - under normal conditions bc lungs would collapse
- changes with phase of respiration but always negative during normal breathing bc of elasticity in lungs and chest wall
describe intra-alveolar pressure (P alv)
- pressure of air in alveoli (air sacs in lungs at end of “tree branches”)
- changes with phase of respiration
- neg during inspiration
- pos during expiration
describe transpulmonary pressure (P alv - P ip)
- distending pressure force across lung wall
- ↑ in this leads to ↑ in distending pressure across lungs
- makes alveoli to expand and ↑ volume
draw out arrows to represent the direction of elastic forces at FRC for lung, pleural sac, and chest wall
elastic recoil of lung pushes inward (volume of air at functional residual capacity)
elastic recoil of lung pushes outward
pleural sac has forces pushing in both directions
net force is 0
what is pneumothorax
- when air collects outside lung but inside the pleural cavity
- can happen from puncture wound to chest
define spontaneous pneumothorax
- caused by disease rather than trauma
- diseases like pneumonia and emphysema damage pleura next to bronchus/alveolus causing air to enter intrapleural space
- results in lung collapsing
define boyle’s law
for given amt of gas in airtight container, pressure is inversely related to volume
why may there be resistance to air flow in the body
- airway radius
- presence of mucous
how can we calculate flow rate
(Patm - Palv)/R where R is airflow resistance
what are some factors affecting intra-alveolar pressure
- quantity of air in alveoli
- volume of alveoli
what are the determinants of intra-alveolar pressure
- lung expansion
- lung recoil
- quantity/volume factors
what happens to alveolar volume during lung expansion
- increase in volume which leads to decrease in P alv
- pressure gradient drives air into lungs (inspiration)
what happens to alveolar volume during lung recoil
- decrease in volume which leads to increase in P alv
- pressure gradient drives air out of lungs (expiration)
label the respiratory muscles
….
what are the inspiratory muscles; expiratory muscles
insp: external intercostal muscles, diaphragm
exp: internal intercostal muscles, abdominal muscles
what are the mechanisms of passive and active expiration
- passive: elastic recoil of lungs
- active: abdominal and internal intercostal
the internal and external intercostal muscles run in __________ directions. why is that important?
different; confers 2 different functions (external expand ribcage and increase volume of thoracic cavity to bring air to lungs; internal decrease volume of thoracic cavity and abdominal muscles, pushing air out of lungs)
draw out the respiratory muscles and how they are affected during inspiration and expiration
insp: external intercostals and diaphragm contracts, chest wall and lungs expand, expansion of ribs moves sternum upward and outward
exp: external intercostals and diaphragm relax, chest cavity and lungs contract, ribs and sternum depress
what triggers inspiration
neural stimulation of inspiratory muscles and contraction(?) of external intercostals which allows for passive recoil of chest wall
what are the factors affecting pulmonary ventilation
- lung compliance
- airway resistance
describe lung compliance; why is it better to have larger lung compliance
- ease that lungs can be stretched with;
- smaller change in transpulmonary pressure needed to bring in a given volume of air and easier to inspire
what can affect lung compliance, why?
- elasticity (more elastic = less compliant)
- lung surface tension (↑ surface tension = ↓ lung compliance)
define surfactant
fluid that can ↓ surface tension (detergent-like)
how can the lungs overcome surface tension
- surfactant secreted from type 2 cells in alveolar walls
- ↑ lung compliance
what are the factors affecting airway resistance
- passive forces (short-term)
- contractile activity of smooth muscle (long-term)
- mucus secretion
define distension
airways open from pulling of tissues moving away from airways
simply describe passive forces
changes in transpulmonary pressure during respiratory cycle
what does expiration do as a passive force
↑ resistance b/c of recoil
what does inspiration do as a passive force
transpulmonary pressure ↑ which pulls outward on airways that makes airways expand and ↓ resistance
describe inspiration as a tractive force
causes distension (airways pulled open as tissues move away from airways)
what does expiration do as a tractive force
↑ resistance due to removal of tractive forces (airways closing down a little bit)
define bronchoconstriction
smooth muscle constriction happens which ↓ bronchiole radius
define bronchodilation
smooth muscle relaxes which causes causes bronchiole radius to ↓
how can bronchiolar smooth muscle impact airway resistance
thru bronchoconstriction and bronchodilation
describe the extrinsic control of bronchiole radius
- neural and hormonal
- in ANS (parasymp. and sympathetic)
- epinephrine causes bronchodilation
describe the intrinsic control of bronchiole radius
- thru local chemical signals (histamine and CO2)
how do the parasympathetic and sympathetic systems help with extrinsic control of bronchiole radii
- sympathetic: relaxation of smooth muscle
- parasympathetic: contraction of smooth muscle
how does histamine play a role with intrinsic control of bronchiole radii
- bronchoconstriction
- released during asthma and allergies
- ↑ mucous secretion
how does CO2 play a role with intrinsic control of bronchiole radii
- bronchodilation (at ↑ levels)
- bronchoconstriction (at ↓ levels)
describe tidal volume
amt of air taken in and out of lungs in a single, unforced breath
describe inspiratory reserve volume
volume that you can still breathe in after normal breathing in
describe expiratory reserve volume
volume you can still expire after breathing out
describe residual volume
- volume left after expiratory reserve volume
- measurable by helium dilution method
what is tlc
- total lung capacity
- volume of air in lungs after maximum inspiration
what is frc
- functional residual capacity
- volume remaining after resting tidal volume (ERV+RV)
what is vc
- vital capacity
- maximum volume expired after maximum inspiration (VT+IRV+ERV)
what is ic
- inspiratory capacity
- VT+IRV
