Respiratory System Flashcards
What is boyle’s law?
volume is inversely related to pressure
increase volume, decrease pressure
decrease volume, increase pressure
intra-alveolar pressure
pressure within the pleural sac
atmospheric pressure
the pressure exerted by the weight of the air in the atmosphere on objects on Earth’s surface
intrapleural pressure
pressure within the pleural sac
What are the nonrespiratory functions of the nervous system?
reroute for water loss and heat elimination
enhances venous return
helps maintain normal acid-base balance by altering the amount of H+ generating CO2 exhaled
enables vocalization
defends against inhaled foreign matter
removed, modifies, activates or inactivates various materials passing through the pulmonary circulation
resting inspiration (muscles and pressure gradient)
diaphragm contracts, increase volume and decrease pressure, gas moves in
intra alveolar pressure < atmospheric pressure
resting expiration (muscles and pressure gradient)
diaphragm resting, decrease volume and increase pressure, gas moves out
intra alveolar pressure > atmospheric pressure
ventilation
movement of gas into and out of lungs
respiration
exchange of gases in alveoli
maximal expiration (muscles and volume/pressure)
contract internal intercostals that lowers rib cage
decrease volume and increase pressure
maximal inspiration (muscles and volume/pressure)
contract external intercostals that lift the rib cage
increase volume and decrease pressure
lung compliance
how much effort is required to stretch of distend the lungs
What factors affect lung compliance?
elastin and surfactant
Surfactant definition and effects
surface active agent that lowers surface tension, mixture of lipids and proteins secreted by type II alveolar cells
1. increases pulmonary compliance, reducing the work of inflating the lungs
2. reduces the lungs’ tendency to recoil so that they do not collapse as readily
alveolar type I cell
exchange of gas occurs here
alveolar type II cell
secrets surfactant
law of la place
P = 2T/r
minute ventilation
the volume of air breathed in and out in 1 minute
minute ventilation (VE) equation
VE = TV x fb
tidal volume (TV)
the volume of air entering or leaving the lungs during a single breath
alveolar ventilation
takes into account dead space, how much gas is actually reaching the alveoli
alveolar ventilation (Va) equation
Va = fb x (TV - dead space)
dead space
area where there is no gas exchange (ie trachea)
newborn respiratory distress syndrome
premature babies do not produce enough pulmonary surfactant to reduce the alveolar surface tension to manageable levels
newborn respiratory distress syndrome breathing pattern
fast and short
What forces are keeping the alveoli open?
transmural pressure gradient
pulmonary surfactant (opposes alveolar surface tension)
What forces promote alveolar collapse?
elasticity of stretched elastin
fibers in lung connective tissue
alveolar surface tension
What factors increase the work of breathing?
- when pulmonary compliance is decreased
- when airway resistance is increased
- when elastic recoil is decreased
- when there is a need for increased ventilation
describe the upper zone (zone 1)
elevated ventilation
reduced perfusion
increase in V/Q ratio
describe the middle zone (zone 2)
ventilation almost equal to perfusion
normal, optimal ratio = 0.8
describe the lower zone (zone 3)
reduced ventilation
elevated perfusion
decrease in V/Q ratio
intrapleural fluid
secreted by the pleura, lubricates the pleural surfaces as they slide past each other during respiratory movements
In a relaxed state the diapgragm is…?
contracted
elastin
the protein that allows the lungs to be elastic
explain how gas moves
gas moves from areas of high pressure to low pressure
hypoxia
low oxygen in the tissues/organs
ischemia
low blood flow
hypoxemia
low oxygen content in the blood
shunt
lung is perfused but poorly ventilated, V/Q low for the entire lung
pulmonary edema
alveolus filled with fluid
will breathing in 100% oxygenated blood help pulmonary edema?
no because blood cannot be oxygenated when the alveolus is filled with blood
V/Q mismatch
lungs are ventilated but perfusion is inadequate or ineffective, V/Q high ratio for entire lung
emphysema
caused by smoking, less alveolar surface area
will breathing in 100% oxygenated blood help emphysema?
yes because less blood was oxygenated when blood was flowing to fast past it
what factors influence the rate of gas transfer between air and blood?
- partial pressure gradients of O2 and CO2
- surface area of the alveolar capillary membrane
- thickness of the alveolar capillary membrane
- diffusion constant
relaxed state
O2 binds to hemoglobin
taunt state
O2 unbinds to hemoglobin
what are the two ways that CO2 can be transported out of red blood cells?
- as HbCO2
- as HCO3- (bicarbonate and primary way)
Bohr effect
O2 curve shifts to the right
increase CO2 and increase H+ increase O2 release from Hb
change in molecular structure of Hb that reduces its affinity for O2
Haldane effect
Hb unloads O2 and uptakes CO2
CO2 curve shifts down
increased O2 released from Hb causes increased CO2 and H+ uptake by Hb
medulla
expiratory and inspiratory center
what structures are found in the pons?
pneumatic center that controls the rate and pattern of breathing, protects from lung overinflation and inhibits apneustic nerve if overinflation occurs
apneustic center controls the intensity of breathing and lower intensity during overinflation
phrenic nerve
autonomic control of the diaphragm
sympathetic activation
Contract more, more oxygen needed, stimulates the respiratory center
central inputs
H+ can activate the respiratory center but they don’t cross the blood-brain barrier
CO2 can cross the barrier and it stimulates ventilation
peripheral inputs
Carotid bodies and aortic bodies can deflect changes in blood
gas exchange pathway
O2 from lungs goes to RBC
in RBC oxygen binds to HB (HBO4)
O4 unbinds and goes to tissues
CO2 has a high concentration gradient and CO2 from tissues goes to the RBC
in RBC CO2 + H2O –> H2CO3 –> H+ + HCO3
HHB in RBC prevents any changes or alterations in pH
in RBC, Cl goes in and HCO3 goes out during chloride shift
CO2 goes back to the lungs in the form of HCO3
