03b: Buffers, Immuno, Perfusion

Question 1

Normal arterial blood pH is (X), meaning there’s (Y) concentration of H+.

Answer 1

X = 7.4
Y = 40 nM

Question 2

Normal body pH range is (X), meaning normal H+ range is (Y).

Answer 2

X = 7.38-7.42
Y = 42-38 nM

Question 3

Tolerated pH range in our body is (X), meaning tolerated H+ range is (Y).

Answer 3

X = 6.8-7.8
Y = 158-16 nM

Question 4

List the sources of acids in our body.

Answer 4

1. Oxidation of fuel (CO2 production forms H2CO3)

2. Metabolism (H2SO4, H3PO4, uric acid)

Question 5

Body produces volatile and fixed acids. What’s the difference?

Answer 5

Volatile (respiratory) acids can be excreted via lungs; non-volatile are products of metabolism and are “fixed” in body until kidney excretion

Question 6

Optimal buffering occurs when pH value is (smaller/larger) than pKa.

Answer 6

Equal!

Question 7

List some good body buffers, with pKa near (X).

Answer 7

X = 7.4;

1. Phosphate buffer system (6.8)
2. Proteins, esp with His (7-7.8); Hb
3. H2CO3 system (6.1)

Question 8

Buffer is substance that (minimizes/maximizes) change in (X) by doing what?

Answer 8

Minimizes;
X = pH

Donating/accepting protons

Question 9

Acids (donate/accept) protons and bases (donate/accept) protons.

Answer 9

Donate; accept

Question 10

Isohydric principle states that:

Answer 10

when several buffers are in solution, they’re all in equilibrium with the H+

Question 11

Isohydric principle: the (X) of each buffer will dictate (Y) ratio.

Answer 11

X = pKa
Y = base concentration to weak acid concentration

Question 12

At pH 7.4, your H+ concentration is (X). If you drop to 6.4, how does that concentration change?

Answer 12

X = 40 nM

One pH drop means H+ conc increased by factor of 10, so 400 nM is new conc

Question 13

Under normal circumstances, based on Davenport Diagram with PaCO2 of (X), pH of (Y), and H+ conc of (Z), what’s the concentration of HCO3- ?

Answer 13

X = 40 Torr
Y = 7.4
Z = 40 nM

24 mM

Question 14

Most common cause of community acquired pneumonia is infection via:

Answer 14

Streptococcus pneumoniae (Gram positive bac)

Question 15

Innate immune defense against respiratory pathogens: first line of defense consists of:

Answer 15

1. Intact epithelium within lung

2. Alveolar macrophages

Question 16

T/F: We inhale bacterial pathogens on a regular basis.

Answer 16

True

Question 17

T/F: Complement is part of humoral innate immune system, crucial to lung protection from bacteria.

Answer 17

Partially false - it is humoral, but complement levels within normal lung fluid are not sufficiently high

Question 18

List the three actions of alveolar macrophages, when encountering bacterial pathogen.

Answer 18

1. Ingest/kill bacteria
2. Secrete pro-inflamm cytokines
3. Secrete mediators to recruit neutrophils

Question 19

T/F: Neutrophils are not present in normal lung.

Answer 19

True

Question 20

Phagocytic cells that combat bacterial infection such as pneumonia.

Answer 20

Macrophages and neutrophils

Question 21

T/F: During pneumonia, macrophages and monocytes act as phagocytic cells, combating bacteria in lung.

Answer 21

False - not monocytes (which are only in peripheral blood)

Question 22

NETS are formed when neutrophil extrudes (X). Which functions do these NETS serve?

Answer 22

X = its DNA

1. Engulf/trap pathogens
2. Proteins (associated with nucleic acid) have antimicrobial activity

Question 23

Aside from neutrophils, a(n) (X)-staining material is found in the alveoli during inflammatory response. It’s composed of (Y) from (blood/air/ISF). List the pros/cons of it.

Answer 23

X = pink
Y = proteins; blood

Pros: Ab to bacteria (opsonization)
Cons: fluid interferes with normal gas exchange (hypoxia, dyspnea)

Question 24

List the mechanisms of immune system that may lead to lung injury following infection.

Answer 24

1. Excess cytokines
2. Excess ROS/RNS production
3. Proteolytic enzyme release
4. Epithelial barrier disruption (excess inflammation)
5. NET attacks normal cells

Question 25

T/F: Excess production of ROS shouldn’t cause damage if the mediators stay within the phagolysosome.

Answer 25

True

Question 26

Exchange of O2 and CO2 in lungs is determined by which 4 things?

Answer 26

1. V/Q
2. RER
3. Gas tensions (in inspired air and mixed venous blood)
4. Chemical processes in blood

Question 27

Hypoxemia is defined as (X). At sea level, it can be a result of which four things?

Answer 27

X = Low arterial PO2

1. Shunt
2. Inadequate (hypo-) ventilation
3. Diffusion issue
4. V/Q mismatch

Question 28

Hypoventilation is simply defined as (X). What’s the most common causes for it?

Answer 28

X = reduced/deficient alveolar ventilation

Usually diseases outside lung (i.e. neuromuscular disorders)

Question 29

Give some diseases/scenarios that cause diffusion impairment, leading to hypoxemia.

Answer 29

Thickening of blood-gas barrier (i.e. fibrosis, asbestosis, infection)

Question 30

An example of a natural shunt is from coronary venous blood to (X), via (Y) (arteries/veins).

Answer 30

X = LV
Y = Thebesian
veins

Question 31

Intrapulmonary shunt differs from extra pulmonary shunt in which way?

Answer 31

Intrapulm: blood perfuses unventilated alveoli
Extrapulm: Blood completely bypasses lung

Question 32

Patent ductus arteriosus is example of (intra/extra)-pulmonary shunt. Give example of the other kind of shunt.

Answer 32

Extrapulmonary;

Pulmonary edema (fluid-filled alveoli) could cause intrapulmonary shunt

Question 33

T/F: Breathing 100% O2 doesn’t significantly raise PaO2.

Answer 33

False - it does, but the CONTENT of O2 is only raised minimally

Question 34

Normal blood flow to lung is (X) and resting alveolar ventilation is (Y). Thus, normal V/Q ratio is (Z).

Answer 34

X = CO = 5 L/min
Y = 4 L/min
Z = 4/5 = 0.8

Question 35

T/F: There’s a fairly homogenous V/Q ratio in each alveolus.

Answer 35

False - non-homogeneity (regional differences)

Question 36

Blocked respiratory tube would result in (low/high) V/Q ratio.

Answer 36

Low (low V)

Question 37

In (low/high) V/Q ratio, you’d except alveolar gas P to reflect composition of inspired gas. Why?

Answer 37

High;

Not enough perfusion to deplete O2 or enrich alveolar gas with CO2

Question 38

Gravity causes (less/more) negative IP pressures at apex of lung. And (smaller/greater) alveolar distending pressures.

Answer 38

More; greater

Question 39

T/F: Alveoli at apex of lung have greater distending P, thus greater compliance.

Answer 39

False - greater distending P, so larger volumes, so decrease in compliance/distensibility

Question 40

(Ventilation/perfusion) greatest at apex of lung. And base?

Answer 40

Both greatest at base

Question 41

Mean pulmonary artery pressure is (X), with (increasing/decreasing) BP at lower levels of arterial tree.

Answer 41

X = 15 mmHg (or 20 cm H2O)

Increasing (increase hydrostatic P due to gravity)

Question 42

In severe disease states, such as (high/low) (X) P, zone (1/2/3) of lung is useless for gas exchange and considered part of (Y) dead space.

Answer 42

Either high Alv P or low arterial P (hemorrhage);
Zone 1
Y = alveolar

Question 43

In Zone (1/2/3) of lung, (X) behaves like starling resistor.

Answer 43

2;

Pulmonary venues

Question 44

Greatest distending pressures for vessels in Zone (1/2/3) of lung. Vascular resistance and perfusion here is (high/low)

Answer 44

Zone 3;

Lowest resistance, highest perfusion

Question 45

High V/Q ratio at (apex/base) of lung. Low V/Q ratio at (apex/base) of lung.

Answer 45

Apex; base

Question 46

You’d except higher PCO2 levels in areas with (low/high) V/Q ratio, such as (apex/base).

Answer 46

Low; base

Question 47

You’d except higher PO2 levels in areas with (low/high) V/Q ratio, such as (apex/base).

Answer 47

High; apex

Question 48

You successfully correct your patient’s hypoxemia with 100% O2. If you notice a large increase in the A–a difference, it is indicative that hypoxemia is caused by:

Answer 48

R to L shunt