Phys 3

Question 1

How do we change the radius of the tube? What does decrease/increasing the radius do to resistance? What is radius changes used for?

Answer 1

1. Smooth muscle in the airway walls
2. a. increase resistance
   b. decrease resistance
3. Directing air to the alveoli with lots of blood (?)

Question 2

Perfusion

Answer 2

• Q

- from right ventricle (5L/min)

Question 3

Alveolar Ventilation

Answer 3

• volume of air reaching the alveoli

- 4L/min

Question 4

J=_________________

Answer 4

=((S.A) X D X (P1-P2)) / distance

J: diffusion rate in ml/min
D: diffusion coefficient for each gas
(P1-P2): pressure gradient across alveolar membrane
S.A.: surface area available for diffusion (corresponds to # of alveoli in lungs)
Distance: thickness of alveolar barrier

***must be calculated for each gas independently

Question 5

What is J for O2? CO2?

Answer 5

1. 250 ml/min (air to blood)

2. 200 ml/min (blood to air)

Question 6

What is the role of collagen in the interstitial space?

Answer 6

it increases the diffusion distance and decrease the diffusion of the gases across the barrier (can increase with pathology; such as interstitial lung disease)

Question 7

What two things can change within the lungs?

Answer 7

surface area and distance

Question 8

Which weighs more/which is more soluble in water: O2 or CO2?

Answer 8

1. CO2

2. O2

Question 9

What is the safety margin for RBCs?

Answer 9

They spend .75 seconds in the pulmonary capillary, but typically pick up the O2 by .25 seconds. This gives them an extra .5 seconds to pick up the O2 if anything happened to go wrong.

Question 10

What is the safety margin for RBCs during heavy exercise?

Answer 10

• they don’t have one!!
• they only get the .25 seconds in the capillary
• also true in patients with lung disease

Question 11

What is the simples correction factor ever?

Answer 11

DLO2= 1.23 X DLCO

Question 12

Which has a larger safety margin: CO2 or O2?

Answer 12

CO2 by a LOT

Question 13

Acute neonatal respiratory distress syndrome

Answer 13

• caused by immaturity of the lungs and deficient surfactant production
• treatment with exogenous surfactant improves condition

Question 14

LaPlace’s Law

Answer 14

Pressure=2T/r
T= tension
r= radius

Question 15

Large/small alveoli have a _1/2__ radius, so the pressure is __3/4__.

Answer 15

Large/small alveoli have a large/small radius, so the pressure is low/high.

**Problem: the air wants to go towards the lower P, and this can collapse the small alveoli

Question 16

What is the role of surfactant?

Answer 16

It reduced T in the smallest alveoli more than in the larger alveoli, which helps to lower their pressure. It removes the gradient, so the air stays in the small alveoli. It is stored in intracellular lamellar bodies, and secreted into alveolus. (basically, it reduces water’s attraction to itself)

Question 17

What is surfactant composed of?

Answer 17

1. Phospholipids
2. Dipalmitoylphosphatidylcholine
3. Multiple proteins (SPA, SPB!!!, SPC, SPD)

Question 18

O2 vs. CO2

1. Partial pressure in lungs
2. Partial Pressure in venous blood
3. Gradient for diffusion at the start of the capillary

Answer 18

1. 104 vs. 40 mmHg
2. 40 vs. 45 mmHg
3. 60 vs. 5 mmHg

Question 19

SP-A

Answer 19

• regulates DPPC secretion and function

- SP-D has similar function/may modify SP-A

Question 20

SP-B

Answer 20

• important in adjusting surface tension

- SP-C has similar function; both are lipophilic

Question 21

What 2 things promote surfactant production? What inhibits it?

Answer 21

1. Prostaglandins promote secretion
2. ## ATP and stretch
3. SP-A and DPPC inhibit secretion (negative feedback)

Question 22

COPD results in the destruction of ___

Answer 22

alveoli (destroys SA for GE)

Question 23

Interstitial fibrosis

Answer 23

deposition of collagen into the interstitial space

Question 24

Sympathetic innervation causes…

Answer 24

broncho-dilation

Question 25

Parasympathetic innervation causes…

Answer 25

broncho-constriction