Respiratory Cycle DSA

Question 1

Diaphragm

Answer 1

• Innervated by phrenic nerve
• Contracting, flattens into abdomen
• Increases volume of thorax

Question 2

Contraction of inspiratory

muscles

Answer 2

• Increase in thoracic volume

Question 3

Muscles that elevate rib cage

Answer 3

• External intercostals

Question 4

Scalene

Answer 4

– raise 1st and 2nd rib

Question 5

Sternomastoids

Answer 5

– raise sternum

Question 6

Muscles of Expiration, passive or active?

Answer 6

Mostly passive – recoil when

inspiratory muscle relax

Question 7

Muscles that compress rib cage

Answer 7

• Abdominals – displace diaphragm
• Internal intercostals – decrease AP diameter, increase
intra-abdominal pressure

Question 8

Residual Volume (RV)

Answer 8

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

“getting the wind knocked out of you”

Question 9

Tidal Volume (VT)

Answer 9

is the amount of
air inspired or expired in a single
breath, can vary

500ml

Question 10

Inspiratory Reserve Volume (IRV)

Answer 10

volume of air breathed above tidal
volume (VT)

3000ml

Question 11

Expiratory Reserve Volume (ERV)

Answer 11

volume of air that can be forced out
in addition to tidal volume (VT).

1100-1200 ml

Question 12

Vital capacity (VC)

Answer 12

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

4600-4700 ml

Question 13

What is VC influenced by?

Answer 13

influenced by posture, ability of diaphragm to
contract/relax, strength of respiratory muscles, thoracic wall
expansibility, resistance to air flow, lung elasticity, disease

Question 14

Inspiratory capacity (IC) –

Answer 14

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

3500ml

Question 15

Functional residual capacity (FRC)

Answer 15

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

2300-2400 ml

Question 16

Total Lung Capacity (TLC)

Answer 16

– maximal
volume to which lungs can be
expanded with greatest effort

TLC = IC + FRC = VC + RV
= ERV + RV + IRV + VT

5800-6000 ml

Question 17

Nitrogen-Washout Technique:

Answer 17

Determines FRC
Individual breaths 100% O2 through one-way valve, all expired gas is
collected, monitored until N2 reaches zero.

Total volume of all gas expired is determined, and multiplied by % of N2
in mixed expired air (80%).

Question 18

Helium (He) dilution:

Answer 18

Inhalation of a known concentration
(C1) of helium [insoluble in blood]
from a known volume (V1)

Change in concentration (C2) allows
for determination of V2 = FRC

Question 19

Body plethysmography:

Answer 19

Enclosed rigid box
Breath against shutter
• Pressure in lungs change
• Pressure in box changes
proportionally in opposite
direction

Question 20

Intrapleural pressure

Answer 20

less than atmospheric pressure, near -5 cm H2O

Question 21

During Inspiration, Ppl

Answer 21

Decreases to near -8 cm H2O

Question 22

As thoracic cavity increases in size, alveolar pressure and pleural pressure

Answer 22

Ap: decreases

Pp: increases

Question 23

Respiratory Cycle: Mid Inspiration

Answer 23

Volume is increasing
Pa is decreasing
Ppl is decreasing
Air is flowing into lungs

Question 24

Respiratory Cycle: end of inspiration

Answer 24

volume has reached peak increase?

Question 25

Respiratory cycle Mid Expiration

Answer 25

Volume is decreasing?

Question 26

Respiratory cycle End Expiration

Answer 26

Volume has returned to resting
Pa decreases to zero
Ppl returns to resting

Question 27

Respiratory Cycle summary

Answer 27

1. rest
2. mid inspiration
3. end inspiration
4. mid inspiration
5. rest

Question 28

Dead space

Answer 28

areas of lung that receive air but not blood

Question 29

Anatomic dead space

Answer 29

space in respiratory system other than alveoli

Question 30

Physiological dead space

Answer 30

basically alveolar dead space, in healthy individuals almost zero

Question 31

alveolar dead space

Answer 31

alveoli receive air but not blood

Question 32

At end of inspiration, anatomical dead space:

Answer 32

has entered the lungs