Respiratory Cycle + Lung Volumes DSA

Question 1

What is the general rule for one letter abbreviations?

Answer 1

capital letters = air

lower letters = blood

Question 2

What does v with a line above it mean?

Answer 2

mixed venous (blood from all the organs/tissues mixed together)

Question 3

What does F stand for?

Answer 3

fractional concentration of gas (would specify what gas you are referring to)

Question 4

What is the abbreviation for arterial?

Answer 4

a

Question 5

How do you calculate munite ventilation?

Answer 5

V(dot) = Vt * f

(tidal volume times respiratory rate)

Question 6

What is the nitrogen-washout technique?

Answer 6

determines FRC

person breaths 100% O2 through one-way valve –> all expired gas collected until N2 reaches 0

total vol of all gas expired is measured and multiplied by % of N2 on mixed expired air (80%)

Question 7

What is the abbreviation for blood flow?

Answer 7

Q

Question 8

How is alveolar ventilation calculated/ what is it?

Answer 8

V(dot)_A = (V_T - V_DS)*f

Question 9

What is ERV?

Answer 9

expiratory reserve volume

volume of air that can be forced out in addition to tidal volume

*doesn’t include residual volume

*requires activation of expiratory muscles

Question 10

What does a positive transpulmonary pressure mean?

Answer 10

the lungs are “open” or partially inflated

Question 11

What is IC?

Answer 11

inspiratory capacity

capacity of air that can be maximally inspired following a normal exhale

IC = Vt + IRV

Question 12

What is residual volume?

Answer 12

RV

volume of air that cannot be forced out, no matter how hard one tries

cannot be determined by spirometry

Question 13

What is the abbreviation for alveolar?

Answer 13

A

Question 14

What is the function of FRC?

Answer 14

helps prevent collapse of lungs, reduces workload, dilutes toxic inhaled gases

Question 15

What is physiologic dead space?

Answer 15

anatomic dead space plus alveolar dead space

Question 16

What is FRC?

Answer 16

functional residual capacity

amount of air that remains in the lungs following a normal expiration

FRC = ERV+RV

Question 17

What is inspiratory reserve volume?

Answer 17

IRV

volume of air breathed above tidal volume

Question 18

What is intrapleural pressure at rest?

Answer 18

-5 cm H2O

Question 19

What are the abbreviations for atmospheric pressure?

Answer 19

P_ATM or P_B

Question 20

What is VC?

Answer 20

vital capacity

amount of air that can be maximally inspired following a max expiration

VC = IRV + V_T + ERV

Question 21

As the volume in the thorax goes up, what happens to the intrapleural pressure?

Answer 21

goes down!

(think PV=nRT)

Question 22

What is Helium dilution?

Answer 22

used to measure FRC

inhale known concentration of helium (insoluble in blood) from known volume -> change in concentration allows for determination of FRC

Question 23

What is alveolar volume?

Answer 23

amount of air that actually gets to the alveoli and participates in gas exchange

V_A = V_t - V_DS

Question 24

What is normal atmospheric pressure?

Answer 24

0 cm H20

Question 25

What is transpulmonary pressure?

Answer 25

Pressure "across" the lungs P_ALV -P_IP

Question 26

What is Vdot?

Answer 26

airflow or volume per unit time

Question 27

What is body plethysmography?

Answer 27

used to measure FRC enclosed in box --\> breath against shutter --\> pressure in lungs change --\> pressure in box changes proportionally

Question 28

At the end of expiration, what muscles are activated to hold the thorax at volume?

Answer 28

none! no effort is required to hold the thorax at rest

Question 29

What is the rough estimate for anatomic dead space?

Answer 29

V_DS volume in mL = weight in lbs

Question 30

What is alveolar dead space conceptually?

Answer 30

alveoli that are getting air, but not blood