week 2 mechanics of respiration cont

Question 1

Flow-Volume Loop

Answer 1

slide 31

Question 2

Compliance is a measure of

Answer 2

the distensibility of the lungs

Question 3

Compliance =

Answer 3

change in lung volume/ change in lung pressure

Cpulm = change of Vpulm / change of Ppulm

Question 4

The extent of lung expansion is dependant on

Answer 4

increase of transpulmonary pressure

Question 5

Normal static compliance is?

Answer 5

70-100 ml of air/cm of H2O transpulmonary pressure

Question 6

is Compliance reduced by?

Answer 6

by higher or lower lung volumes, higher expansion pressures, venous congestion, alveolar edema, atelectasis & fibrosis

Question 7

Compliance increased

Answer 7

with age & emphysema secondary to alterations of elastic fibers

Question 8

Lung Volumes Changes Related To

Answer 8

Transpulmonary Pressure

Question 9

pressure-volume curve

Answer 9

slide 36

Question 10

Elastic Lung Tissue

Answer 10

1. Elastin & Collagen fibers of lung parenchyma
2. Natural state of these fibers is contracted coils
3. Elastic force generated by the return to this coiled state after being stretched and elongated
4. The recoil force assists to deflate lungs

Question 11

Surface Air-fluid Interface

Answer 11

1. 2/3 of total elastic force in lung
2. Surface tension of H2O
   Complex synergy between air & fluid holds alveoli open
3. Without air in the alveoli a fluid filled lung has only lung tissue elastic forces to resist volume changes
4. Surfactant in the alveoli fluid reduces surface tension, keeps alveoli from collapsing

Question 12

normal pt I:E ratio

Answer 12

1:2

Question 13

copd or emphysema I:E ratio

Answer 13

1:3

Question 14

Surface Tension Elastic Forces

Answer 14

The net effect on the lung to simultaneously

attempt to collapse alveoli by water tension

Question 15

surfactant does what to the alveoli?

Answer 15

keeps them open. Surfactant lowers the surface tension of the alveoli fluid. reduces work of breathing.

Question 16

surfactant is produced by what cell type?

Answer 16

Type II pneumocyte

Question 17

DPPC-Dipalmitoyl phosphatidyl choline

Answer 17

1. DPPC opposes water self-attractant elastic force to reduce alveolar surface tension
2. Reduction of surface tension greater when film compressed closer as DPPC repel each other more

Question 18

Total Ventilation or Minute Ventilation

Answer 18

Total volume of air conducted into lungs per minute
Single breath = Tidal Volume (VT)
VT varies with age, sex, body position & activity
Normal VT is 0.5 L
Minute ventilation = VT * freq
6 L/min. = 0.5 L * 12 breaths/min.

Question 19

Alveolar Ventilation

Answer 19

Volume of fresh air entering alveoli each minute (70% of total ventilation or minute ventilation)

Alveolar ventilation is always less than total ventilation

Anatomical dead space and its portion of tidal volume (30%) affect amount of gas exchanged in alveoli

Alveolar O2 concentration steady state achieved when supply matches demand

Question 20

Anatomic Dead Space = how much also what is it

Answer 20

150/500

Dead Space = ventilated but not perfused

Question 21

dead space is roughly how many ml/kg

Answer 21

2 ml/kg

Question 22

Wasted Ventilation is

Answer 22

The concept of physiologic dead space (VPD) describes a deviation from ideal ventilation relative to blood flow

Question 23

what does wasted ventilation include?

Answer 23

anatomical dead space plus any portion of alveolar ventilation that does not exchange O2 or CO2 with pulmonary blood flow (alveolar dead space)

Question 24

Ventilation/blood flow (V/Q) mismatch

Answer 24

where blood flow blocked ( clot or emboli)

Question 25

Airway Closure is

Answer 25

The base of lung during exhalation does not have all of gas compressed out Small airways in region of respiratory bronchioles collapse Gas trapped in distal alveoli

Question 26

who have airway closing issues?

Answer 26

Airway closure occurs at very low lung volumes in normal young subjects in the lowermost lung regions Occurs in normal elderly lungs at higher volumes & can be present at FRC Frequently develops in patients with chronic lung disease

Question 27

Laminar flow is

Answer 27

parallel streams of flow

Question 28

Velocity in center of airway twice as fast than at edges of tube T/F

Answer 28

true

Question 29

Poiseuille Law describes

Answer 29

resistance to flow through a tube Pressure increases proportionally to flow rate & gas viscosity Smaller airway radius & longer distances increase flow resistance

Question 30

decreasing the radius of the tube will do what to the resistance?

Answer 30

it will double the resistance

Question 31

Turbulent Flow occurs at ___ flow rates or air velocity

Answer 31

higher

Question 32

an increase in what will make turbulence more probable

Answer 32

density, velocity & airway resistance

Question 33

Chief Site of Airway Resistance is at ?

Answer 33

Major resistance is at the medium-sized bronchi

Question 34

Most of pressure drop occurs at what division? | also slide 57

Answer 34

seventh

Question 35

Factors Determining Airway Resistance

Answer 35

1. Lung Volume 2. Bronchial Smooth Muscle 3. Density & Viscosity Of Inspired Gas

Question 36

As lung volume is reduced -

Answer 36

airway resistance increases

Question 37

Contraction of airways increases

Answer 37

resistance

Question 38

Bronchoconstriction caused by

Answer 38

PSN, acetylcholine, low Pco2, direct stimulation, histamine, environmental, cold

Question 39

what is most likely to cause bronchospasm?

Answer 39

antibiotics and rocc

Question 40

Density & Viscosity Of Inspired Gas

Answer 40

Changes in density rather than viscosity have more influence on resistance

Question 41

Work of Breathing

Answer 41

Work is required to move the lung & chest | Work represented as pressure * volume (W=P*V)

Question 42

O2 cost of quiet breathing is

Answer 42

5% of total resting oxygen consumption

Question 43

Hyperventilation increases O2 cost to

Answer 43

30% | High O2 cost in obstructive lung disease limits exercise ability