Lecture 31 + 32

Question 1

Equations for lung compliance?

Answer 1

C = 1/ E

compliance is inverse to elasticity

C = delta V / delta P

Question 2

What forces need to be overcome for inflation of lungs?

Answer 2

1. airway resistance
2. frictional forces
3. elasticity of lungs
4. inertia of the air

Question 3

The inflation deflation hysteresis is due to what?

Answer 3

surface tension

surface tension contributes significantly to lung compliance

Question 4

what is the equation for surface tension?

Answer 4

P = 2T / R

increased radius = decreased pressure
decreased radius = increased pressure

Question 5

high compliance in lungs?
what does the graph look like?
clinical examples?

Answer 5

lungs inflate easily and has little recoil

graph will move to the left

typical of emphysema and COPD

Question 6

Low compliance in lungs?
graph?
clinical?

Answer 6

lungs inflate with difficulty due to large recoil

moves to the right

seen in pulmonary fibrosis and RDS

Question 7

Functional Residual Capacity

Answer 7

the lung volume at which the inwardly directed lung recoil is exactly balanced by the outwardly directed chest wall recoil

no active muscle input

sets ventilatory tone

Question 8

dynamic compliance

Answer 8

respiratory rate does not affect lung volume if resistance is normal

breathing rate does affect lung volume if resistance is high

Question 9

taut vs relaxed state

Answer 9

taut state is the structure for deoxygenated hemoglobin

relaxed state is the structure for oxygenated hemoglobin

Question 10

2,3 BPG?

Answer 10

This molecule promotes the formation of the taut state, thus decreasing O2 affinity for Hb

unloading of 02 into the tissues

Question 11

low levels of 2,3 BPG?

what does it look like on a graph

Answer 11

curve moves to the left

Question 12

high levels of 2,3 BPG?
graph?
normal seen in what group of people?

Answer 12

decreases affinity of Hb of oxygen
promotes more oxygen release
negative allosteric effector

seen in those who live in higher altitudes

Question 13

hexokinase deficiency?

Answer 13

reduced levels of 2,3 BPG (lethal)

left shift on the binding curve

increased 02 affinity

Question 14

pyruvate kinase deficiency

Answer 14

elevated 2,3 BPG levels

right shift on the binding curve

decreased 02 affinity

Question 15

explain the Bohr effect

Answer 15

As the pH decreases, Hb 02 affinity decreases

decrease in pH = curve moves to right
increase in pH = curve moves to left

Question 16

carbonic anhydrase

Answer 16

converts CO2 to carbonic acid

lowers PH, lower O2 affinity