lung mechanics

Question 1

how does a gas move

Answer 1

high to low P

Question 2

what muscles are involved in inspiration

Answer 2

diaphragm, intercostals, accessory muscles (scalene and SCM)

Question 3

what point are lungs at after normal exp.

Answer 3

FRC

Question 4

muscles for forced expiration

Answer 4

abs and internal intercostals

Question 5

function of pleaura (2)

Answer 5

1. transmit pressure

2. allow movement

Question 6

what is typical pleural pressure at FRC

Answer 6

-5

Question 7

when does pleural pressure become positive

Answer 7

forced expiration

Question 8

what happens to lung volumes as pleural pressue become more neg.

Answer 8

volumes increase

Question 9

what happens to alveolar elastic in emphysema and fibrosis

Answer 9

emphysema - destroyed

fibrosis - increased

Question 10

formula for compliance

Answer 10

change in V/change in P

Question 11

how does lung compliance change with volumes?

Answer 11

less compliant at very high or low volumes

Question 12

what can create stiff chest wall

Answer 12

obesity, burns, binders, drugs, mulitrib fractures

Question 13

what 3 things determine lung vol.

Answer 13

1. chest wall compl.
2. lung compliance
3. resp. muscle strength

Question 14

what is formula for laPlaces law for spheres

Answer 14

P=(2xsurface tension)/radius

Question 15

take away from laPlace

Answer 15

the smaller the radius, the higher the pressure – gas wants out

Question 16

what does surface tension on surfactant depend upon?

Answer 16

surface area

Question 17

what is purpose of surfactant

Answer 17

helps stabilize the sphere size so doesn’t get too big

Question 18

** what are 3 purposes of sufactant

Answer 18

1. stabilizes small alveoli
2. less tension = less breathing work
3. keeps lungs dry

Question 19

where in the lung are alveoli most compliant

Answer 19

at the base