Chapter 17 Flashcards
List 4 major functions of the respiratory system.
1) exchange of gases btw the atmosphere +
blood
2) homeostatic regulation of body pH
3) protection from inhaled pathogens +
irritating substances
4) vocalization
Explain the function of the pleural cavity.
fluid in the cavity that allows for the parietal and visceral layers to slide past each other with a reduced amount of friction
Explain the function of the pleural sac.
(a double membrane) that surrounds the lung
Explain the function of the external intercostals.
help with inspiration by pulling the ribcage out
Explain the function of the diaphragm.
brings the floor of the thoracic cavity down during inspiration
Explain the function of the type I alveolar cells.
gas exchange
Explain the function of the type II alveolar cells.
produce surfactant
Explain the function of connective tissue.
elastin + collagen –> close association w/ capillaries
List the pathway for the pulmonary circulation from high flow to low flow.
1) right ventricle
2) pulmonary trunk
3) pulmonary arteries
4) lungs
5) pulmonary veins
6) left atrium
Explain mathematically the relationship between atmospheric pressure and the partial pressures of individual gases.
- partial pressure of N2 –> higher in
atmosphere - partial pressure of O2 –> higher in
atmosphere - partial pressure of CO2 –> higher in alveoli
- partial pressure of H2O –> higher in alveoli
Explain the relationship between the pressure of a gas and the volume in which it is contained.
PV = nRT
V = 1/P –> inverse relationship
What is the equation to find partial pressure of a gas?
P(atm) x (% of gas in atmosphere)
What is Boyle’s Law?
P1V1 = P2V2
Define + describe lung volumes.
- how much air is moved
respiratory cycle = 1 inspiration followed by 1
expiration
Define lung capacity.
sums of 2 or more volumes
What is used to measure lung volume?
spirometer
What are the 4 lung volumes.
1) V(T) = tidal volume
2) IRV = inspiratory reserve volume
3) ERV = expiratory reserve volume
4) RV = residual volume
What are the 4 lung capacities?
1) inspiratory capacity = V(T) + IRV
2) vital capacity = V(T) + IRV + ERV
3) total lung capacity = V(T) + IRV + ERV + RV
4) functional residual capacity = ERV + RV
When does inspiration occur?
when alveolar pressure decreases
When does expiration occur?
when alveolar pressure increases
Explain how pressures and lung volumes change during normal breathing, and how that affects airflow in the respiratory system.
Alveolar Pressure:
- begins at 0 = atmospheric pressure
- inspiration –> goes negative, then back to 0 (when the pressure btw atmosphere and alveoli are equal)
- expiration –> goes positive, then back to 0
Intrapleural Pressure:
- normally negative pressure (-3 mm Hg)
- inspiration –> starts around -3 and ends around -6 (pressure drops)
- expiration –> lung pressure decreases (pressure goes back to the normal value)
Volume of Air Moved:
- inspiration –> volume increases
- expiration –> volume decreases
Explain the role that subatmospheric intrapleural pressure plays in normal breathing.
subatmospheric pressure in pleural cavity keeps the lungs inflated
Graph the alveolar + intrapleural pressure changes that occur during one respiratory cycle.
Compare + contrast compliance and elastance in respiratory physiology.
compliance –> ability to stretch
- high compliance = stretches easily
- low compliance = requires more force
elastance –> ability to return to resting volume when stretching force is released
Explain the role of surface tension in respiratory physiology.
easier to expand the alveoli when the water molecules are not trying to stick to one another
Explain the role of surfactants in respiratory physiology.
- reduces surface tension –> so that the alveoli fluid doesn’t promote collapse
- helps increase compliance
- smaller alveoli have more surfactants than
larger alveoli
- smaller alveoli have more surfactants than
Map the factors affecting airway resistance, with emphasis on local and reflex control mechanisms involved in bronchodilation and bronchoconstriction.
R = Ln/r^4
bronchodilation –> decreases resistance
- sympathetic: epinephrine binds to B2
receptors on smooth muscle
- local control –> CO2
- long distance control –> epinephrine
bronchoconstriction –> increases resistance
- parasympathetic: Ach binds to muscarinic receptors on smooth muscle
- local control –> histamine + leukotrienes
- long distance control –> parasympathetic
neurons
What is the formula to find total pulmonary ventilation?
ventilation rate x tidal volume (Vt)
What is the formula to find alveolar ventilation?
ventilation rate x
(tidal volume - dead space volume)
Explain why gas composition in the alveoli remains relatively constant during normal breathing.
the amount of oxygen entering the alveoli equals the amount of oxygen leaving to enter the blood
Explain how alveoli change with hyper- and hypoventilation.
- hyperventilation –> increasing alveolar
ventilation –> oxygen partial pressure increases + CO2 partial pressure decreases - hypoventilation –> decreasing alveolar
ventilation –> oxygen partial pressure decreases + CO2 partial pressure increases
Explain the local control mechanisms by which ventilation and alveolar blood flow are matched.
ventilation perfusion matching –> perfusion of blood past alveoli is matched to alveolar ventilation to maximize gas exchange
What is the normal alveolar partial pressure of oxygen?
100 mm Hg
What is the normal alveolar partial pressure of carbon dioxide?
40 mm Hg
What happens when the alveoli do not have good exchange?
- pressure of CO2 increases and pressure of
O2 decreases - blood going to that area of the lungs is not getting oxygenated
In systemic arteries, what happens when the pressure of CO2 increases?
dilation
In systemic arteries, what happens when the pressure of CO2 decreases?
constriction
In systemic arteries, what happens when the pressure of O2 increases?
constriction
In systemic arteries, what happens when the pressure of O2 decreases?
dilation
In pulmonary arteries, what happens when the pressure of CO2 increases?
weak response of constriction
In pulmonary arteries, what happens when the pressure of CO2 decreases?
weak response of dilation
In pulmonary arteries, what happens when the pressure of O2 increases?
weak response of dilation
In pulmonary arteries, what happens when the pressure of O2 decreases?
constriction
In bronchioles, what happens when the pressure of CO2 increases?
dilation
In bronchioles, what happens when the pressure of CO2 decreases?
constriction
In bronchioles, what happens when the pressure of O2 increases?
weak response of constriction
In bronchioles, what happens when the pressure of O2 decreases?
weak response of dilation
