RS Lec 3

Question 1

static properties of lungs (def.)

Answer 1

-mechanical properties when no air is flowing (needed to maintain lung + chest wall @ certain volume)

Question 2

things that make up static properties of lung

Answer 2

• intrapleural pressure (Pip)
• transpulmonary pressure (Ptp)
• static compliance of lung
• surface tension of the lung

Question 3

dynamic properties of lungs (def.)

Answer 3

-mechanical properties when the lungs are changing volume and air is flowing in and out (necessary to permit airflow)

Question 4

things that make up dynamic properties of lung

Answer 4

• alveolar pressure (Palv)
• dynamic lung compliance
• airway +tissue resistance

Question 5

boyle law

Answer 5

-fixed amount of air at constant temp – pressure is inversely proportional to V

Question 6

↓V leads to ↑ Palv=

Answer 6

expiration

Question 7

↑V leads to ↓ Palv=

Answer 7

inspiration

Question 8

difference is pressure generated …

Answer 8

air moves via bulk flow from high pressure to low pressure

Question 9

Palv < Patm

Answer 9

inspiration (increase in thoracic volume)

Question 10

Palv > Patm

Answer 10

expiration (decrease in thoracic volume)

Question 11

Bulk flow (F)

Answer 11

-F= (Palv- Patm)/R

Question 12

lung pressures that affect INS, EXP

Answer 12

• intrapleural pressure (Pip)
• alveolar pressure (Palv)
• transpulmonary pressure (Ptp)

Question 13

pleurae (def.)

Answer 13

-thin double-layered envelope between intrapleural fluid

Question 14

visceral pleura (def.)

Answer 14

-covers external surface of lung

Question 15

parietal pleura (def.)

Answer 15

-covers thoracic wall + superior face of diaphragm

Question 16

intrapleural fluid (10 ml) reduces

Answer 16

-friction of lungs during breathing (thin space- 5 to 35 um)

Question 17

lung volume determined by interaction between…

Answer 17

• lung + thoracic cage via intrapleural space

Question 18

tendency of lungs

Answer 18

collapse due to elastic recoil

Question 19

tendency of chest wall

Answer 19

-outward due to elastic recoil

Question 20

at equilibrium (tendency of lungs/chest wall)

Answer 20

-inward elastic recoil (lungs) balances outward recoil (chest)

Question 21

Intrapleural pressure (Pip) (3)

Answer 21

• pressure within pleural cavity
• changes with breathing but always subatmospheric due to opposite recoil
• relative vacuum

Question 22

if Pip = Palv

Answer 22

-lungs would collaspe

Question 23

alveolar pressure (Palv) (3)

Answer 23

• pressure of air inside the alveoli, dynamic element in producing airflow
• when airways are open Patm = Palv

Question 24

difference between alveolar pressure + atmospheric pressure

Answer 24

-controls gas-exchange between lungs + atmosphere

Question 25

transpulmonary pressure (Ptp)

Answer 25

- force responsible for keeping the alveoli open, difference between Palv and Pip - static parameter, does not cause airflow but determines lung volume

Question 26

Inspiration actions

Answer 26

- diaphragm + INS intercostal contracts - thorax expand - Pip more subatmospheric - increase Ptp - lungs expand - Palv subatmospheric (flow from high to low) - air flow in alveoli

Question 27

expiration actions

Answer 27

- diaphragm + INS intercostal stop contracting - chest wall recoil inward - Pip back to regular subatmospheric value - Ptp back to preINS value - lungs recoil - Palv increases (compressed air) > Patm - air flow out of lungs

Question 28

airway resistance is generally

Answer 28

small

Question 29

resistive forces (airflow)

Answer 29

- inertia of RS (negligible) - friction (1. lung tissue past itself, 2. lung +chest wall (IP fluid ↓ friction) - frictional resistance to flow of air through airways (80%)

Question 30

airflow resistance sensitive to

Answer 30

-changes in radius when flow is not laminar

Question 31

laminar airflow

Answer 31

- little energy lost to resistance | - happens in smallest airways

Question 32

transitional airflow

Answer 32

- produces vortices- resistance increases | - happens in most of bronchial tree (intermediate airways)

Question 33

turbulent airflow

Answer 33

- resistance to airflow is the highest - happens in large airways - linear air velocities is high

Question 34

laminar flow (poiseuille's law)

Answer 34

- proportional to viscosity of gas, length of tube | - inversely proportional to r^4

Question 35

resistance in airways in upper air passages/large airways

Answer 35

0.6

Question 36

resistance in airways small airways (#)

Answer 36

0.3

Question 37

terminal bronchioles arranged in parallel

Answer 37

- lower aggregate R - parallel: 1/R= 1/R1 + 1/R2 +... - in series: R= R1 +R2 +...

Question 38

small airways determine airflow resistance because they are easily occluded by...

Answer 38

- smooth muscle contraction in walls - edema occurring in walls of alveoli + bronchioles - mucus collecting in lumen of bronchioles