Respiratory Physiology II

Question 1

State the alveolar gas equation

Answer 1

Question 2

What is the A-a gradient?

Answer 2

The difference between the oxygen content in the alveoli (A) and the oxygen content in the blood (a)

Question 3

There are five causes of hypoxemia. Which ones are associated with changes in the A-a gradient?

Answer 3

A-a gradient is normal in hypoxic mixture and hypoventilation

A-a is increased by diffusion limitation, V/Q mismatch, and shunt

Question 4

Hypoxemia is defined as a PaO2 < ______

Answer 4

80

Question 5

How do you go about determining the A-a gradient?

Answer 5

You use the alveolar gas equation to calculate A and draw a blood gas to determine a

Question 6

When breathing room air, what is a normal A-a gradient?

Answer 6

< 15 mmHg

Question 7

What are some scenarios that increase the A-a gradient?

Answer 7

Age

Vasodilators (reduce the lungs ability to perform hypoxic vasoconstriction)

Right to left shunt (atelectasis, pneumonia, bronchial intubation, intracardiac defect)

Diffusion limitation (anything that thickens the alveolocapillary membrane)

Question 8

How can you calculate the degree of shunting?

Answer 8

You can estimate that shunt (the amount of blood moving through without undergoing gas exchange)

increases 1% for every 20mmHg increase in the A-a gradient

Question 9

What’s the difference between lung volumes and lung capacities?

Answer 9

Capacities are the combination of two or more volumes

Question 10

INSPIRATORY RESERVE VOLUME

DEFINITION

NORMAL VALUE

Answer 10

Volume of gas that can be forcibly inhaled after a tidal inhalation

3000ml

Question 11

TIDAL VOLUME

DEFINITION

NORMAL VALUE

Answer 11

volume of gas that enters and exits the lungs during tidal breathing

500ml

Question 12

EXPIRATORY RESERVE VOLUME

DEFINITION

NORMAL VALUE

Answer 12

volume of gas that can be forcibly exhaled after a tidal exhalation

1100ml

Question 13

RESIDUAL VOLUME

DEFINITION

NORMAL VALUE

Answer 13

volume of gas that remains after a forced exhalation

gas that CANNOT be exhaled

1200ml

Question 14

CLOSING VOLUME

DEFINITION

NORMAL VALUE

Answer 14

volume above residual volume when the airways start to collapse

Conveyed as a percentage of the total lung capacity

for young people it’s around 30%

Old people around 55%

Question 15

TOTAL LUNG CAPACITY

DEFINITION

NORMAL VALUE

Answer 15

IRV + TV + ERV + RV

5,800ml

Question 16

VITAL CAPACITY

DEFINITION

NORMAL VALUE

Answer 16

IRV + TV + ERV

4,500 ml

Question 17

INSPIRATORY CAPACITY

DEFINITION

NORMAL VALUE

Answer 17

IRV + TV

3500mL

Question 18

FUNCTIONAL RESIDUAL CAPACITY

DEFINITION

NORMAL VALUE

Answer 18

RV + ERV

volume of the lung at end-expiration

2300 mL

Question 19

CLOSING CAPACITY

DEFINITION

NORMAL VALUE

Answer 19

absolute volume of gas contained in the lungs when the small airways close

RV + CV

Variable

Question 20

What are the weight-based calculations for Vt, VC, and FRC?

Answer 20

Vt: 6-8 ml/kg

VC: 65-75 ml/kg

FRC: 35 ml/kg

BASED ON IBW NOT ACTUAL WEIGHT

Question 21

How do lung volumes differ in females?

Answer 21

25% smaller

Question 22

Lung volumes are _____ when sitting and ____ when supine

Answer 22

larger

smaller

Question 23

Patients with obstructive lung disease have increased:

Answer 23

residual volume

closing capacity

total lung capacity

Question 24

Spirometry cannot measure ______

Answer 24

residual volume

so it also can’t measure total lung capacity or FRC

also can’t measure closing volume or capacity

Question 25

Functional Residual Capacity is:

Answer 25

the volume of air in the lungs at the end of expiration

Question 26

At the point of FRC, the lungs are in a state of:

Answer 26

static equilibrium The inward elastic recoil is exactly equal to the outward elastic recoil

Question 27

\_\_\_\_\_\_\_ is the volume of air that prevents hypoxemia during apnea

Answer 27

FRC

Question 28

How can we determine how long a patient can remain apneic before becoming hypoxemic?

Answer 28

FRC / VO₂

Question 29

Conditions that reduce the FRC tend to reduce _____ or \_\_\_\_\_

Answer 29

Outward lung expansion Lung compliance

Question 30

What are some causes of decreased FRC in the OR?

Answer 30

Question 31

What factors increase closing volume?

Answer 31

Question 32

What's the difference between CaO2 and DO2?

Answer 32

CaO2 is the carrying capacity of the blood DO2 is the delivery of oxygen to tissues per minute

Question 33

Most oxygen forms a reversible bond with hemoglobin. The remainder dissolves into the blood according to _______ law

Answer 33

Henry's

Question 34

How can you calculate the carrying capacity of the blood?

Answer 34

Question 35

What is this number?

Answer 35

Question 36

What is this number?

Answer 36

Question 37

\_\_\_\_\_ is the driving mechanism of DO2

Answer 37

Cardiac Output

Question 38

What is the equation for DO2?

Answer 38

Question 39

What is the calculation for VO2?

Answer 39

Fick's Equation!

Question 40

What causes a decreased p50?

Answer 40

Question 41

What causes increased p50?

Answer 41

Question 42

Most hemoglobinopathies effect the oxyhemoglobin dissociation curve by causing a shift to the:

Answer 42

Left

Question 43

What is the Bohr Effect?

Answer 43

An increase in PaCO2 and a decrease in pH cause hemoglobin to release oxygen

Question 44

What is 2,3 - DPG?

Answer 44

It's a by-product of RBC glycolysis THINK: RBCs are in glycolysis when there *isn't enough oxygen* DPG causes a right shift, making it easier for oxygen to be released It makes sense that in chronic hypoxic states, 2,3-DPG is VITAL to adapting

Question 45

Why is it significant that banked blood is low in 2,3-DPG?

Answer 45

Banked blood is shifted to the left. It will not released oxygen as easily, reducing DO2

Question 46

Why is fetal blood always shifted to the left?

Answer 46

Because HgB F does not have 2,3-DPG

Question 47

Where is ATP stored in the body?

Answer 47

It isn't! ATP cannot be stored, so the supply must be continuously replenished

Question 48

What is the byproduct of glycolysis?

Answer 48

Question 49

What happens after glucose is broken down into pyruvic acid?

Answer 49

Question 50

The primary purpose of the Kreb's cycle is to:

Answer 50

Produce large amounts of H+ ions in the form of NADH

Question 51

In oxidative phosphorylation, _____ is the final electron accepter

Answer 51

Oxygen

Question 52

What are the end products of oxidative phosphorylation?

Answer 52

34 ATP Water

Question 53

What is the Hamburger shift?

Answer 53

The shifting of Cl- into venous blood cells to keep the cell electrically neutral after bicarb is transferred to the plasma

Question 54

What is carbonic anhydrase? Where is it found?

Answer 54

Facilitates formation of carbonic acid out of water and CO2 It is present inside of erythrocytes, NOT in the plasma

Question 55

Why is venous hematocrit always higher than arterial hematocrit?

Answer 55

When Cl ions shift into the cells, water moves osmotically with them Venous erythrocytes are always a little larger, and therefore take up a greater percentage of the blood volume

Question 56

Solubility of CO2 and O2 is a function of ______ law

Answer 56

Henry's

Question 57

In the presence of oxygenated hemoglobin, the CO2 dissociation curve shifts to the \_\_\_\_\_

Answer 57

Right Blood has less affinity for CO2 and it is therefore “released”

Question 58

In the presence of deoxygenated Hgb, the CO2 dissociation curves shifts to the \_\_\_\_\_\_

Answer 58

left When there's not as much O2, the blood “loves” CO2