Trachte Respiratory Physiology

Question 1

What are the four key processes in respiration?

Answer 1

1. Ventilationv (air into lungs)
2. Diffusion (O2 to blood)
3. Perfusion (blood flow)
4. Gas transport (via hemaglobin)

Question 2

Define ventilation

Answer 2

Getting air into the lungs

Question 3

Define diffusion

Answer 3

getting oxygen into the blood

Question 4

Define perfusion

Answer 4

blood flow

Question 5

How do gases more across the blood gas interface?

Answer 5

via diffusion - high to low pressure

Question 6

Partial pressure of O2 in the alveoli?

Answer 6

150 mmHg

Question 7

Partial pressure of O2 in the venous blood?

Answer 7

40 mmHg

Question 8

Gases move across a barrier depending on these four things -

Answer 8

1. Cross sectional area of the barrier
2. Permeability of the barrier
3. Thickness of barrier
4. Pressure gradients

Question 9

Pulmonary fibrosis destroys this part of the gas/barrier interface

Answer 9

Permeability of barrier

Question 10

Emphysema destroys this part of the gas/barrier interface

Answer 10

Cross sectional area of the barrier

Question 11

How the the parts of the airway descend?

Answer 11

Trachea - L and R bronchi - Lobular bronchi - segmented bronchi - terminal bronchioles - respiratory bronchioles

Question 12

Conducting airway is composed of these parts of the airway

Answer 12

Trachea all the way through the terminal bronchioles. Movement of air occurs here.

Question 13

Is there gas exchange at the conducting airway?

Answer 13

No, just conduction of air.

Question 14

Where is the anatomic dead space?

Answer 14

The conducting airway

Question 15

What is one way we see increased anatomic dead space in humans?

Answer 15

When someone is on a respirator

Question 16

Muscle contraction during inspiration?

Answer 16

Diaphragm contracts by moving down

Intercostals contract and raise ribs

Question 17

Where does dust settle if you have an inhalation?

Answer 17

in the terminal bronchioles (NOT the alveoli)

Question 18

Blood flow in lungs?

Answer 18

Pulmonary artery to capillaries to pulmonary veins

Question 19

What damages the vascular walls in the lungs?

Answer 19

Increased capillary pressure (HTN, hypoxia) or increasing alveolar pressure (respirator)

Question 20

Are we as good as birds?

Answer 20

Nope. Humans aren’t as good as birds.

Question 21

______ reduce surface tension and prevent alveolar collpase

Answer 21

Surfactants

Question 22

Ventilation is defined as

Answer 22

the amount of air entering and leaving the lungs per minute

Question 23

Tidal volume is defined as

Answer 23

the amount of air inspired and expired in routine breathing

Question 24

What is a normal tidal volume? Alveoli volume?

Answer 24

500 mL

350 mL

Question 25

Vital capacity is defined as

Answer 25

The maximum volume of air that can be exhaled after a maximum inspiration

Question 26

Residual volume is defined as

Answer 26

the amount remaining in the lung after a maximal expiration

Question 27

Functional residual capacity is defined as

Answer 27

the amount remaining in the lungs after a typical exhalation

Question 28

How do you measure FRC?

Answer 28

You cannot directly, use helium/gas dilution test to calculate

Question 29

Regarding a gas dilution test - the more dilute the helium the _______ the lungs

Answer 29

Larger, have greater volume

Question 30

How do you calculate alveolar ventilation?

Answer 30

Va = VCO2/PCO2 (x K)

Question 31

How do you measure anatomic dead space?

Answer 31

breath O2, plot N and find midpoint (half maximal) concentration - transition from deadspace to alveolar ventilation

Question 32

Vd/Vt (volume dead space/tidal volume) =

Answer 32

(PaCO2 - PeCO2)/PaCO2

Question 33

Which portions of the lungs are best ventilated?

Answer 33

The lower portions

Question 34

What is the difference between anatomic and physiological dead space?

Answer 34

anatomic dead space is the amount of ventilation confined to the conducting airway Physiologic dead space is the amount of ventilation not exchanging with the blood

Question 35

Total lung volume =

Answer 35

vital capacity + residual volume

Question 36

What two ventilatory measures can you measure directly?

Answer 36

Tidal volume | vital capacity

Question 37

The process by which O2 (or other gases) move from higher to lower pressure

Answer 37

Diffusion

Question 38

Diffusion is _____ to surface area

Answer 38

proportional

Question 39

Diffusion is _____ ________ to barrier thickness

Answer 39

inversely proportional

Question 40

Example of less diffusion via less surface area?

Answer 40

Pneumothorax

Question 41

Example of less diffusion because of barrier thickness?

Answer 41

Some sort of interstitial disease

Question 42

What is the driving force for diffusion?

Answer 42

Pressure differences

Question 43

Carbon Monoxide and blood

Answer 43

So soluble that it is diffusion limited

Question 44

When is O2 diffusion limited?

Answer 44

Certain pulmonary diseases - not the norm

Question 45

What do you do if you need more O2 diffusion?

Answer 45

Increase CO. It is a perfusion/low limited process

Question 46

When does O2 reach equilibrium during diffusion?

Answer 46

1/3 through capillaries

Question 47

High altitude and diffusion?

Answer 47

Harder, because PaO2 is lower

Question 48

How do you measure diffusion capacity?

Answer 48

Carbon monoxide test | Diffusion capacity = Vco/(P1-P2)

Question 49

When do you do a diffusion capacity test?

Answer 49

To test for interstitial diseases

Question 50

Diffusion of gas through a tissue is proportional to

Answer 50

``` Area 1/thickness 1/molecular weight solubility pressure differential ```

Question 51

Diffusion limited gases

Answer 51

CO and O2 (in some disease states)

Question 52

Perfusion limited gases

Answer 52

O2, N2O and CO2

Question 53

What is a normal PO2

Answer 53

40 mmHg

Question 54

What is a normal PCO2

Answer 54

45/46 mmHg

Question 55

What is normal pulmonary pressure

Answer 55

25/8

Question 56

Why does pulmonary artery resistance decrease when there is an increase in pulmonary artery pressure?

Answer 56

Recruitment of additional capillaries to conduct BF | Distention of capillaries to allow more blood flow

Question 57

Radius and length in pulmonary capillaries

Answer 57

Radius is larger, Length is shorter | We want low pressure to keep lungs dry

Question 58

3 drugs that contract vessels and result in an increase in resistance

Answer 58

NE 5HT Histamine

Question 59

3 drugs that relax vessels and reduce resistance

Answer 59

Ach Iso Prostacyclin

Question 60

Fick Equation/Principle

Answer 60

O2 consumed = CO (CaO2 - CvO2)

Question 61

Pulmonary blood flow equation

Answer 61

VO2 / (CaO2 - CvO2)

Question 62

Why is there more flow to the base of the lung than the apex?

Answer 62

Gravity

Question 63

Zone 1 Characteristics

Answer 63

Palveoli > Parteriole > Pvenous NO FLOW Does not happen naturally, hemorrhage or positive pressure breathing typically

Question 64

Zone 2 Characteristics

Answer 64

Part > P alveoli > Pvenous Determined by pressure differences of artery and alveoli Apical region

Question 65

Zone 3 Characteristics

Answer 65

P art > Pvenous > Palveoli Flow dependent on arterial venous pressure differences (normal situation in the circulatory system) Midregions and base of lung

Question 66

P art > P alveoli > P venous

Answer 66

Zone 2

Question 67

P alveoli > P art > p venous

Answer 67

Zone 1

Question 68

P art > P venous > P alveoli

Answer 68

Zone 3

Question 69

How does alveolar hypoxia constrict blood vessels perfusing the hypoxic region of the lung?

Answer 69

Inhibiting voltage gated K channels = hypopolarize | Causes an increase in [Ca] leading to vasoconstriction

Question 70

What controls fluid movement in the lungs?

Answer 70

Starling forces

Question 71

Other functions for pulmonary circulation?

Answer 71

Reservoir for blood | Filter of blood (thrombi in legs can't get to brain) -- thats helpful

Question 72

Metabolic functions of the lungs

Answer 72

1. AGI to AGII via ACE 2. Inactivates bradykinin 3. 5HT removal from circulation 4. prostaglandin metabolism 5. PG and Leu synthesis

Question 73

Is pressure lower or higher than systemic in the pulmonary system?

Answer 73

Lower

Question 74

Resistance is extremely low and falls further upon increases in CO in the pulmonary system -- why?

Answer 74

recruitment and distension

Question 75

Causes of hypoxemia

Answer 75

Hypoventilation Diffusion limitation Shunt (R to L) Ventilation-perfusion mismatch

Question 76

Oxygen levels in air vs. blood

Answer 76

150 mmHg in humidified air 100 mmHg is alveoli 1-100 mmHg in tissues

Question 77

Why does the PCO2 increase when we hypoventilate?

Answer 77

Stimulates breathing, respiratory exchange

Question 78

PCO2 =

Answer 78

(VCO2/Va) x K

Question 79

PAO2 =

Answer 79

PIO2 - ([PACO2/R])

Question 80

What is a shunt?

Answer 80

Mixing of O2 depleted blood from the bronchial circulation and a small amount of blood from the thebesian veins of the heart

Question 81

Can O2 correct a shunt?

Answer 81

No.. Doesn't matter how much you oxygenate, still will be some mixture and will not maintain 100% O2 sats.

Question 82

If there is no perfusion but the alveoli are still ventilated...

Answer 82

PO2 and PCO2 approach that of the inspired gas

Question 83

If there is perfusion but no ventilation (obstruction to airflow)

Answer 83

the PO2 and PCO2 approach that of venous blood

Question 84

Does the apex or base of the lung have a higher ventilation to perfusion ratio?

Answer 84

Apex