Mechanisms Of Ventilation

Front 1

EQUATION: Boyle's Law

Back 1

P = 1/V

Front 2

Explain Boyle's law qualitatively.

Back 2

pressure and volume are inversely related

Front 3

Which of the 3 following forces causes a) contraction of the lungs and b) expansion of the chest cavity during a pneumothorax? Compliance, elasticity, surface tension.

Back 3

Ans: elastic recoil causes both

Front 4

transmural pressure, def

Back 4

the pressure across a structure (in Wilson's class, specifically the pressure accross the lungs (outside air or airway minus intrapleural pressure)

Front 5

transpulmonary pressure, def

Back 5

pressure accross the lungs (ie. pressure difference between the alveolar pressure and the intrapleural pressure); subtype of transmural pressure

Front 6

collapse of the upper respiratory tract occurs only during the combination of what 2 conditions?

Back 6

only in patients with loss of elastance (elastin) during forced expiration. Dynamic compression has the greatest effect on the bronchioles.

Front 7

Describe the 4 phases of a pressure-volume loop for a patient that is inspiring deeply.

Back 7

1 Difficult to overcome surface tension that keeps airways closed, 2 airway recruitment, surface tension is overcome, 3 further decrease in Pip (intrapulmonary pressure) opens additional airways, 4 lungs fully distended. IMAGE

Front 8

hysteresis, def

Back 8

inflation of the lungs follows a different curve than deflation of the lungs in a graph of V over P

Front 9

Why is ventilation greatest at the base of the lungs?

Back 9

Because the transmural pressure is most negative at the base (difference between intrapleural pressure and airway/outside pressure is greatest at the base). This is due to the accordian effect.

Front 10

In which zone of the lung is alveolar ventilation the highest? BLood flow?

Back 10

Both are highest in Zone 3 (base), but the difference in blood flow (Q) is greater between Zones 1 and 3 than the difference in alveolar ventilation (V)

Front 11

Describe the changes in intrapleural pressure and alveolar pressure during the normal breath cycle

Back 11

IMAGE

Front 12

What is the physiological basis for hysteresis (difference in compliance between inspiration and expiration)?

Back 12

water-water interactions are stronger than water-air interactions; the surface tension decreases compliance at the beginning of inspiration and increases compliance at the end of expiration

Front 13

What allows surface tension to be overcome during phase 1 of the Pressure-Volume loop in order to allow inspiration?

Back 13

dispersion of surfactant molecules

Front 14

What are the breathing patterns associated with fibrosis and COPD?

Back 14

FIBROSIS: short shallow breaths (low compliance, stiff lung). COPD: long deep breaths (high compliance)

Front 15

What is the effect of increased airway resistance on the time required for inspiration? On the tidal volume (volume of a normal inspiration)?

Back 15

Increased airway resistance increases the amount of time required for inflation, but only slightly decreases the end inspiratory volume (tidal volume)

Front 16

What is the effect of respiratory rate on tidal volume?

Back 16

increased respiratory rate decreases tidal volume

Front 17

Which contribute more to overall resistance, large airways or smaller airways?

Back 17

large airways contribute more to resistance (smaller airways have greater cross-sectional area)

Front 18

Which have greater turbulence, larger airways or smaller airways?

Back 18

larger airways have greater turbulence

Front 19

What is the effect of COPD on airway resistance at low volumes? At high volumes?

Back 19

increased resistance at all volumes, due to collapsed conducting airways

Front 20

What is the effect of parasympathetic vs. sympathetic stimulation on the lungs? What are the adrenergic/catecholaminic receptors involved? What are their respective mechanisms?

Back 20

PARASYMPATHETIC: bronchoconstriction (M3, inc IP3/Ca). SYMPATHETIC: bronchodilation (β2, inc cAMP).

Front 21

CLINICAL APPLICATION: What receptors in the lung do asthma inhalers work on?

Back 21

agonist for β2 adrenergic receptors.

Front 22

In addition to the ANS, what system regulates the resistance of the lungs?

Back 22

HUMORAL FACTORS (histamine)

Front 23

Effect of histamine on the lung?

Back 23

bronchoconstriction

Front 24

What is the effect of changes in compliance on TLC? On RV?

Back 24

decreased compliance reduces total lung capacity, increased compliance increases residual volume

Front 25

Name some factors that could compromise respiration (

Back 25

weak respiratry muscles, pain, decreased skeletal flexibility, dec compliance, posture

Front 26

What is the effect of laying down on respiration?

Back 26

impedes ventilation

Front 27

rate of air movement between 25% and 75% of vital capacity, term? volume of air moved, term?

Back 27

forced expiratory flow (FEF), forced expiratory volume (FEV)

Front 28

What are the two components of RV?

Back 28

residual volume: 1 anatomical dead space, 2 physiological dead space

Front 29

anatomical dead space vs. physiological dead space, def

Back 29

ANATOMICAL: airway volume. PHYSIOLOGICAL: part of lungs not participating in gas exchange

Front 30

4 methods to measure FRC? What specific value is measured by each?

Back 30

1 helium gas dilution (ventilated only), 2 whole body plethysmography (ventilated and unventilated), 3 Fowler's method (measures dead space), 4 Bohr's method (measures physiologic dead space)

Front 31

Describe the flow-volume relationship

Back 31

beginning part is effort dependent, later part is effort independent (effort increases flow at the beginning of expiration, but at the end of expiration no matter how hard you push, air will flow out at the same rate)

Front 32

2 general categories of pulmonary disorders?

Back 32

1 restrictive (ex. fibrosis), 2 obstructive (ex. COPD)

Front 33

CLINICAL APPLICATION: pulmonary fibrosis, physiological cause and effect on the following: compliance, TLC, max rate of expiration, degree of dynamic compression

Back 33

CAUSE: inhalation of particles (ex. anthracosis) causes inc fibrous connective tissue. EFFECTS: dec compliance, dec TLC, dec max rate of expiration, normal degree of dynamic compression

Front 34

What is the effect of fibrosis on a Flow-Volume curve?

Back 34

truncates it (dec lung volume)

Front 35

What is the relationship between elasticity, elastic recoil, and elastance?

Back 35

xxx

Front 36

give more detail on each of the methods for measuring FRC

Back 36

xxx