Respiratory Physiology Flashcards
Inhalation
- diaphragm contracts down
- rib cage lifts up and out
- increases volume
- increases intrapulmonic pressure
- increases negative pressure in intrapleural space
Exhalation
- diaphragm relaxes up
- rib cage goes down and in
- decreases volume
- decreases intrapulmonic pressure
- decreases negative pressure in intrapleural space
Does restful breathing use diaphragm or rib cage?
Diaphragm
Vigorous breathing
uses rib cage
What does surfactin do?
keeps alveoli from collapsing
What are the three types of work related to cpmpliance and inhalation?
- compliance: energy converted to air movement
- tissue: energy used to move tissues around (wasted)
- airway: energy used to overcome drag on respiratory tree linings
Tidal volume
regular amount of air per breath. 500mL
Inspiratory reserve volume
amount of air inhaled after tidal volume. 3000mL
Expiratory reserve volume
amount of air exhaled after tidal volume. 1000mL
Vital capacity
expiratory reserve + tidal volume + inspiratory reserve. 4500mL
residual volume
amount of air still left in lungs after complete exhalation. 1000mL
total lung volume
vital capacity + residual volume. 5500mL
What is spirometry?
Ventilation studied by measuring lung volume and volume changes over time.
How much air does a normal person get out in 1 sec?
90% to 100% of vital capacity out in 1 sec
What are abnormal factors that decrease vital capacity?
kyphosis, scoliosis, respiratory paralysis, pulmonary congestion, reduced compliance.
What are normal factors that increase vital capacity?
large body size, tall, greater muscle strength, vigor
What is measured in clinical assessment of lungs?
vital capacity and time
forced vital capacity
time it takes to get vital capacity out
forced expiratory volume
amount of vital capacity exhaled in 1 sec`
Minute respiratory volume
total new air into respiratory system per minute (tidal volume X respiratory volume
What is the respiratory volume at rest in a normal person?
500ml X 12bpm = 6 liters/min
Minute alveolar volume
amount of air arriving at alveoli
Anatomical dead space
ventilated air wasted filing up larger airways that do not participate in gas exchange.
How much is anatomical dead space?
150ml
What is alveolar volume?
12 X (500-150) = 4.2l/min
how is tidal volume related to respiratory rate?
inversely
Diffusion
regulated by the concentration of gaseous species
What does atmospheric air consist of?
79% N2
21% O2
0% CO2
Is CO2 or O2 more soluble?
CO2 is 20 X more soluble
What is P02 and PCO2 in atmospheric air?
PO2 = 160mm Hg
PCO2 = 0mm Hg
Diffusion is a function of what 3 factors?
- concentration gradients (partial pressures)
- solubility of gases in liquid (water)
- nature of any barriers (lung histology)
What are the 4 basic components of respiratory membrane?
- type I pneumocyte
- basement membrane of type 1 cell
- basement membrane of endothelium
- type I campillary cell (endothelium)
What would decrease gas exchange?
- additional fluids in alveoli, scarring of wall, thickening of wall, or destruction of wall.
When air is humidified in alveoli, it goes from __ to ___ mm HG?
3.7 mm HG to 47 mm Hg in alveoli
What is Hentry’s Law?
Dissolved gas = PP X solubility
Diffusion of gas is eual to ____?
D = change in P (P is determined by ventilation)
Are partial pressures the same in lungs and atmosphere?
No, because new air is being mixed with old air.
What is the partial pressure in the lungs and in the atmosphere?
lungs: O2: 105 and CO2: 40
atmosphere: O2: 160 and CO2: 0
Why are partial pressures different in the lungs and atmosphere?
- dead space
- 10 breaths to fully exchange air (mixing old and new air)
What factors affect PP in lungs (and thus diffusion)?
- Mixing
- humidification of incoming air
- absorption of 02 into the blood
- production of CO2 from the blood
- ventilation, which exchanges air on a cyclical basis
which factor of PP in lungs is most important and why?
Ventilation because it exchanges air on a cyclical basis.
- rate and depth of breath
- main physiological factor
How does ventilation change during exercise?
Increases in order to maintain normal alveolar P (105 mmHg)
What is the resting and exercising consumption rate of O2?
resting = 250ml/min exercising = 1000ml/min
If you increase the consumption rate of O2, what will happen to ventilation?
Ventilation will decrease
What is the resting and exercising production rate of CO2?
resting = 200ml/min exercising = 800ml/min
If you decrease alveolar pp of CO2, what will happen to alveolar ventilation?
It increases
What is the ventilation perfusion ratio?
V/Q - balance between rate of blood flow past alveoli and the rate of ventilation.
What does V/Q = 0 represent?
no ventilation
physiological shunt
- happens when ventilation to alveolar area is cut-off
- blood to affected area treated as if it bypassed lungs (deoxygenated)
- it will join oxygenated blood from normal areas.
What happens when V/Q = infinity?
No blood flow
Physiological dead space
- volume of lungs that does not participate in gas exchange
- created by alveolar area that is cut-off
- work of breathing is wasted
What is normal V/Q?
.8
What is the V/Q in the three areas of the lungs?
upper - high
middle - middle
lower - low
If O2 is decreased (hypoxia), why is vasoconstriction happening?
to preserve overall V/Q
If an alveolar area is not working and O2 is not being delivered, what happens to blood flow?
It is redirected to better ventilated area and minimizes physiological shunt
How is 02 transported by the blood?
3% as dissolved gas
97% as bound to hemoglobin
