Physiology Respiratory Sukowski 2

Question 1

What are the dynamic properties of ventilation (3)

Answer 1

1. Elastic recoil of lungs and chest wall
2. Resistance to air flow
3. Three patterns of airflow through tubes (laminar, transitional, turbulent)

Question 2

Factors that determine airway resistance (3)

Answer 2

1. Viscosity
2. Lung volume
3. State of contraction of bronchial smooth muscle

Question 3

Elastic recoil

Answer 3

(1/compliance) of lung and chest wall (due to ST and tissue elastic elements). Also involved in static recoil at FRC

Question 4

Where was Resistance to airflow come from?

Answer 4

4/5 (80%)- airway resisstance due to MEDIUM SIZED BRONCHI

20% due to airways <2 mm in diamter

1/5 Tissue resistance

Question 5

When is air flow laminar

Answer 5

very small airways ,

Pressure upstream> Pressure downstream

Slow rate,
flow rate higher at center of tube than elsewehre, flow is proprotional to difference

Question 6

When is air flow Turbulent

Answer 6

IN very large airways with high velocity

Re number >2000
Re# = 2rvd/n

movement of gas i random

flatter velocity profile?

Question 7

When is air flow TransitionalI

Answer 7

In most airways esp at branch points

where tue divdies

faster rate than lamina,
Flow is proportional to square of pressure difference

Question 8

What does astham do to flow rate?

Answer 8

Poiusellies law! Decrease in radius –> Increas resistnae!!!

Question 9

What is flow like in trachea?

Answer 9

Problby turbulent during exercise

Question 10

Hihg density gas vs high viscocity flow

Answer 10

High density - turbulent

High viscosit = laminar

Question 11

Which airway part has most resistance?

Answer 11

medium sized bronchi

Question 12

Viscoscity and AWR

Answer 12

increase in viscosicty elevates AWR for laminar flow but

REDUCES AWR for Turbulent flow (Re=2rd/n)

Question 13

Lung volume and AWR

Answer 13

1. Bronchi are pulled open by radial traction (interdependence) as lung expands to large volume (AWR decreases due to increased radius)
2. At low lung volums, small airways at base of lung close and trap air. These small airways are “silent zone” - contribute littel to overall AWR
3. Considerable small airway disease can be prsent but remain undetected by usual AWR measurements bc medium-sized airways contribuet the predominate AWR
4. Patients with inc. AWR (emphysema or asthma= OBSTRUCTIVE DISEASE) breathe at large lung volume (top of ung) to minimize AWR and reduce work of breahting

Question 14

State of contraction of bronchial SM

Answer 14

1. Bronchoconstrcition
   - PS (Ach)
   - Effrent reflexes provoked by irritants
   - Decrease PACO2 –> Vasocconstriction
   - Histamine constricts SM of alveolar ducts

2. Bronchodilation
Symp
NE
E
Isoproteneralol

Question 15

What are two reasons why IP falls during inspriation

Answer 15

1. increase lung volume, and increases static recoil
2. Fall in IP pressure necessary for inspriation to occur

Also needsto overcome AWR + Static recoil

Question 16

Do pts with severe COPD brathe with high lung voluem or low?

Answer 16

HIGH! –> to have low resistance, otherwise will be too hight and cannot stay alive

Question 17

Flow rate

Answer 17

limited and effort independent

Question 18

Compression, nost closure of larger airwasy

Answer 18

Transmural PRessure= Pinside- Poutside

Pressure holding champber of airwayopen

Question 19

Why does max flow rate decerase with decreaasing lung volume

Answer 19

1. difference between alveolar P and intrapleural P lessens causing a decreased driving pressure
   DF decreases, decrease elastic recoil
2. As the volume decreases, there is less radial traction on the airways causing a progressive increase in AWR

Question 20

Forced INSPIRATion and flow rate

Answer 20

the harder you inspire, the lower hte IP pressure, the higher the flow rate

Question 21

Mechanism of Dynamic Compression of Larger Airways with Forced Expiration

Answer 21

Compressino of larger airways duing forced expriation. When Transmural P (pressure difference across airway) beomes negative (inside-outside) airways will collapse

As forced expriation contineus, equal presure poitn will move inwards (towards lungs) b/c you are exhaling air and airway pressue rapidly falls due to AWR increaseing as lung ovlume decreases

Question 22

What happens to large airways during forced expriation

Answer 22

they will COMPReSSS not close

This causes a linear diminution of the flow rate that is effort independent

Question 23

What happens to equal pressure point (iintrapleurla P) as forced expiration continues

Answer 23

Equal pessure point will move inwards towards teh lung

Question 24

Whawt happens to small airways during gentle expiration towards RV

Answer 24

dependent small airways are closed, witha gentle expiration toward RV

Traps air int eh distal avleoli

Question 25

What are factors that exaggerate the Flow-Limiting Mechanism

Answer 25

Any condition that would increase AWR or Decrease Lung Recoil or both 1. Increase of Peripheral airwasy (magnifies the presure drop and decreases intrabronchial P during expiration; emphysema with dec. radila traction on airways) 2. Low lung volume --> Increase AWR and Decrease Lung recoil (reducing driving pressure - alveolar P - Intrap P) 3. Inc lugn compliance (decrease recoil)

Question 26

Why is it harder to inflate and defate empysemic lung

Answer 26

increase ARD Total lung volume is larger than for normal (eg 9.5 L vs 7L) while Vital capacity is less than for normal (3.5 vs 4.5 L)

Question 27

What are three causes of Uneven Ventilation in Different Lung Units at any given vertical level

Answer 27

1. decreased cmpliance 2. increased AWR 3. Incompeltel diffusion in airways of respriatory zone 9enlarged space as in emphysema)

Question 28

Uneven ventilation with restrictive disease

Answer 28

B- decrease comlaince (stiff lugn with high recoil) = rapid but small chagne in volume

Question 29

C- Obstructuve disease and uneven ventilation

Answer 29

increase AWR= slow to fill and empty; may not complete filing, small volume due to long tie cosntant

Question 30

what diseases ahve increases in AWR in larger airways with lon time constants

Answer 30

Obstructive disease of emphysema, bronchitis, and asthma

Question 31

What diseases have increase in AWR in small airways and alveoli with logn time constants

Answer 31

fibrosis in small airways alveoli with unequal ventiatliona dn tehrefore, long tiem constraits Normal, parallel, series (semphysema) collagteral

Question 32

Work done on lung equation

Answer 32

Pressure x volume

Question 33

What does work of lugn need to overcome

Answer 33

1. Elastic forces (lugn recoil; collagen/elastin and ST) Static: at FRC, before brething Dynamic: during breathign 2. Viscious forces - 80% due to AWR (medium-sized pulmoanry airways) - 20% due to tissue resistance (friction) total work of breathing restful vs exercise

Question 34

Restrictve lung work

Answer 34

mroe negative IP P at FRC Requires more qork than normalt o move the same volume of air due to STIFFNESS of lung (fibrosis RAPID, SHALLOW BREATHS

Question 35

Obstructive Lung Work

Answer 35

less negative IP Pat FRC Requires mroe work than normal (esp. during expriation), b/c of high AWR (emphysema, bronchitis) Slow, deep breaths