Respiratory phys. Lung Vol and Capacity 2 of 2

Question 1

List the muscles involved in ventilation

Answer 1

1. inspiration
   
   1. diaphragm- 60-75%
   2. external intercostals
      
      1. movement of rib cage
   3. scalens
      
      1. movement of ribcage
2. expiration
   
   1. quiet brething
      
      1. passive process
   2. forced exhalation
      
      1. internal intercostal muscles
      2. abdominal muscles

Question 2

when the external intercostals contract where do the ribs move?

Answer 2

upward. think about bucket handle

Question 3

define compliance

3-what does a high and low compliant lung mean

Answer 3

1. ability to stretch ; distensibility of the system
2. expressed as a change in volume
   
   1. results from a given force or pressure exerted on the lung
   2. delta V/ delta P
3. compliant lungs
   
   1. high compliance
      
      1. lung stretches easily
      2. has less elastic tissue
   2. low compliance
      
      1. lung requires more force from the inspiritory muscles
      2. has elastic tissue

Question 4

define elastance

Answer 4

1. ability to resist being deformed, or recoil to resting position
2. spring back to shape after stretching
3. compliance =elastance

Question 5

define hysteresis

explain

Answer 5

slopes of the pressure-volume relationship in an isolated lung for inspiration and expiration are different. but when the lung is filed with water, the slope is the same.

explanation for the different curves lies in surface tension at the liquid-air interface of the air-filled lung. compare to a water filled lung(left slope).

lung volume is greater during expiration than inspiration. To maintain a specific volume

Question 6

Define when the lung is higher/lower in compliance during ventilation

Answer 6

Compliance is higher during expiration than during inspiration

Question 7

what is the pressure at FRC?

Answer 7

-5

Question 8

what is the greatest force in lung recoil?

Answer 8

surface tension

Question 9

which location has the most and least resistance in the lungs?

Answer 9

first 8 segments of bronchioles have highest resistance

respiratory zone has lowest reistance

Question 10

describe the compliance with respect to PV loop.

what is compliance determined by?

Answer 10

1. varies witth inhalation and exhalation- consider where the slope is steepest
   
   1. increase around FRC
   2. decreses around TLC and RV
2. compliance is detrmined by
   
   1. connective tissue of lung
      
      1. elastin and collagen
   2. surface tension

Question 11

describe the lung chest wall interaction

Answer 11

1. lung tissue cannot expand/contract on its own
2. no direct attachment between lungs and chest wall
3. attached via interpleural space with a negative pressure compared to outside and inside the lungs

Question 12

what determines lung volume (interaction).

discuss the static nature of the two

Answer 12

interaction of lung and chest wall ultimately determine lung volume

1. lungs
   
   1. collapse due to an inward elastic recoil
2. chest wall
   
   1. outward elastic recoil
   2. for lung volumes-what are the % values?
      
      1. RV-60%
      2. TLC 75%

Question 13

Describe the intrapleural cavity

1. pressure
2. origin of the pressure

Answer 13

1. intrapleural space normally has a negativepressure at rest (end of Vt)
2. intrapleural pressure results from pulling apart of the two plural membranes
   
   1. these are the static forces from the lung tissue(inward) and the chest wall(outward)

Question 14

describe the cause of a collapse lung in a pneumothorax, with respect to the lung tissue and the chest wall

Answer 14

The negatibve pressure in the intrapleural cavity keeps the lung tissue and chest wall in contact with each other.

destuction of this pressure: pneumothrax, hemothorax, hydrothorax

• leads to a similar pressure as external and lungs, allowing the lung tissue and chest wall to act indepently of each other

Question 15

draw the PV compliance of chest wall, chest wall + lungs and lungs.

explain

1. explain compliance in each curve
   
   1. what happens when volume = FRC?
   2. what happens when the volume = less than FRC?
   3. what happens when the volume = more than FRC
2. what is the cause of the two forces

Answer 15

1. slope of each curve = compliance
   
   1. reltaive contributions of both forces shift depending on the volume ofthe lungs
      
      1. volume =FRC=end of tidal volume
         
         1. airway pressure = 0
         2. the chest wall force cancels out the lung tissue force
      2. volume= less than FRC
         
         1. forced exhalation, the chest wall will force the lungs open
      3. volume = more than FRC
         
         1. tidal volume, the lung tissue will force the chest wall closed
2. forces explained
   
   1. expanding
      
      1. elasticity (inverse of compliance) of chest wall provides an expanding force
   2. collapse
      
      1. elasticity of the lungs provides a collapsing force

Question 16

compare compliance and elasticity

Answer 16

they are inversly related.

1. compliance - something is easily manipulated
   
   1. too high = disease
   2. too low = disease
2. elastic- something returns to its shape pre-deformation
   
   1. chest wall- expanding force
   2. lung tissue - collapsing force

example

1. ephmysema - high compliance low elasticity

Question 17

explain how disease changes compliance with respect to a PV slope and the two forces

Answer 17

emphysema and fibrosis effect the lung tissue and chest wall

1. normal
   
   1. FRC
      
      1. the opposing forces of the lungs and chest wall are matched
2. emphysema
   
   1. associated with a loss of elastic fibers
   2. increased compliance
      
      1. steeper slope
   3. equilibrium is now obtained ata higher lung volume
      
      1. as the lungs expand, the collapsing force becomes GREATER
   4. Patients breathe at higher lung volumes and have BARREL-SHAPED chest
3. fibrosis
   
   1. associated with stiffening of the lung tissues
   2. decreased compliance
   3. flatter slope
   4. the collapsing force of the lungs is greater than the expansion force of the chest wall.
   5. FRC is lower for these patients, struggle to take deep breathes

Question 18

what is generated with a liquid-air interface?

where?

contribution?

Answer 18

surface tension forces. law of LaPlace

in the alveoli, these act as main recoil property(50%). assisting to collapse the lung

This is the greatest component of lung recoil

surface tnesion>elastic

Question 19

acts against the inward recoiling of the lung.

1. properties
2. function

Answer 19

surfactant

1. properties
   
   1. proteins and phospholipids (dipalmitoylphosphatidylcholine)
   2. secreted by Type 2 pneumocytes
2. function
   
   1. lowering surface tension forces in alveoli
      
      1. disrupts cohesive forces between water molecules
      2. lowers lung recoil and increases compliance
   2. [higher] in smaller ALVEOLI
      
      1. lowering surface tension in small alveoli more than big alveoli
      2. prevent atelectasis, collapsing of lung

Question 20

describe the opposing force to the one listed

1. chest wall
2. surfactant

Answer 20

1. chest wall- compliance force, pulling lungs out ward
   
   1. elastic tissue- lungparynchema, pulling lung inward
2. surfactant- disrupting cohesive forces in surface tension, acting greater in smaller alveoli. balances out the recoil in smaller alveoli, to the same as larger alvoeli
   
   1. surface tension- greates force of lung recoil (50%), also greatest affects in smaller alveoli

Question 21

draw a PV curve featuring inflation deflation of the lungs under two conditions

1. normal
2. Hyaline membrane disease

Answer 21

bottom curev=lungs at postmortem from infant with HMD.

• decreased lung compliance
• increased critical opening and closing pressures

Question 22

mathematically explain the pressure gradient between the oropharynx and the alveoli

Answer 22

Question 23

describe three forms of flow

1. label
   
   1. location
   2. proportion
   3. relationships

Answer 23

1. laminar airflow
   
   1. parallel to the walls of the airways- small airways, alveoli
   2. occurs at low airflow rate
   3. flow proportional to change in pressuure
2. turbulent flow
   
   1. disorganized flow, trachea and large airways
   2. 3. turbulent flow proportional to squareroot of change in pressure
3. transitional flow
   
   1. in between laminar and turbulent
   2. most common for the respiratory system

Question 24

list location of highest and lowest resistance in the airway

Answer 24

upper airway- HIGHEST, 20-40%=nose-glottis

lower respiratory tract-LOWEST

1/Rtotal= 1/r +1/r…. this means the location with the greatest cross sectional area has the least resistance

Question 25

graph resistance as the air moves from the conducting zone to the respiratory zone

describe the governing law, changein the radius from 1->2

Answer 25

poiseuilles law = resistance is proportional to length of system, the viscocity and inversely proportional to the radius

16fold

Question 26

graph two lines, one airway resistance the other conductance. both dependent on lung volume.

Answer 26

airway resistance decreases with increasing lung volumes

conductance is the reciprocal aof resistance =1/R

patients with increasing AWR at higher lung volume= increase in FRC

Question 27

changes in airway diameter/radius by smooth muscle are manipulated by

Answer 27

1. parasympathetic stimulation
   
   1. contraction
   2. airway diameter decreases
   3. resistance is increased
2. sympathetic stimulates B2 receptors
   
   1. airway diameter is increased
   2. resistance is decreased
   3. B2 agonist = albuterol

Question 28

regulation of airway resistance is manipulated by several features

categorizes 7contrictors and 5 dilators

Answer 28

Question 29

list thte pressures when inhaling vs exhaling

1. atomospheric
2. Ppl
3. Paatmo

Answer 29

1. atomosphere = 760
2. intrapleural
   
   1. negative during normal breathing and maximal inhalation
   2. positive during forced exhalation
3. albeolar
   
   1. negative for inhalation
   2. positive for exhalation

Question 30

define PL

Answer 30

transpulmonary pressure = Pa-PL

Question 31

draw the following graphs for a breathing cycle

Answer 31

Question 32

explain forced expiration

why don’t the lungs collapse?

Answer 32

forced expiration increases the abdominal pressure- by use of the abdominal rectus and …

in this example the intrapleural pressure increases to +20, but the lung does not collapse because the transmural pressure is still positive. compare to COPD

Question 33

describe the forces at play in the alveolus of a person with COPD

Pa

Pl

Ppl

Paw

Pta

Answer 33

COPD lung compliace is increased due ot loss of elasticity

1. during forceful expiration, intrapleural pressure is raised to the same degree as a normal person; however alveolar and airway pressures are lower due to a loss of elasticity
   
   1. you can see that he transmural pressure is posistive, keeping the lung from collapsing. But the gradient accross the airway is less that normal lung.
2. COPD affected individuals expire slowly with pursed lips to raise airway pressure and prevent airway collapse

Question 34

explain work of breathing. Diagram and explain the graph

Answer 34

breathing requires work to overcome opposing forces, the work for breathing is only a total of 1-2% of total respiratory O2.(nothing)

components

1. elastic component= 65%
   
   1. work to overcome
      
      1. elastic recoil forces of the chest wall
      2. surface tension of the alveoli
2. resistive (non-elastic)component
   
   1. is work to overcome tissue and airway resistance
      
      1. airflow resitance=28%
      2. viscous resistance (lobe friction)=7% ( not included in most graphs)

Question 35

diagram the change in work of breathing for people with fibrosis and COPD

Answer 35

1. restictive (fibrosis)
   
   1. increased elastic work due an decrease in compliance
   2. breathe more shallowly and rapidly
2. obstructive diseases
   
   1. increased work is due to an increase in airway resistance
   2. breathe more slowly and deeply

patients with high work of breathing may develop respiratory muscle fatige and can result in respiratory failure