Embryology

Question 1

Embryonic (4-7wks)

Answer 1

Trachea up to tertiary bronchioles

Question 2

Pseudoglandular (5-16 wks)

Answer 2

Up to terminal bronchioles

Question 3

Cannalicular (wks 16-26)

Answer 3

Alvelolar ducts and capillaries

Question 4

Saccular (wks 26 - birth)

Answer 4

Alveolar ducts to terminal sacs

Pneumocytes develop

Question 5

Alvelolar (wks 32 to 8 years)

Answer 5

Adult alveoli (secondary septation)

Question 6

Pulmonary hypoplasia

Answer 6

Poorly developed bronchial tree

Associated with congenital diaphragmatic hernia and bilateral renal agenesis

Question 7

Brochogenic cyst

Answer 7

Abnormal budding of the foregut and dilation/ cyst of terminal or large bronchi

Question 8

Type I cells

Answer 8

Line the alveoli

Squamous, thin for optimal diffusion

Question 9

Type II cells

Answer 9

Secrete pulmonary surfactant –> decrease alveolar tension

Increase compliance, decreases lung recoil

Precursors to Type I and II cells

Question 10

Surfactant

Answer 10

Composed of dipalmitoylphosphatidylcholine

Synthesis begins at week 26, but mature levels not reached until week 35

Question 11

Club cells

Answer 11

Contain secretory granules that degrade toxins

Act as reserve cells

Question 12

NRDS

Answer 12

Caused by surfactant deficiency
Causes buildup of hyaline membrane
Screening test for fetal lung maturity: lecithin:sphingomyelin ratio (should be >2, if less than 1.5- NRDS is likely)

Can happen as a result of C-section delivery (decreased release of fetal glucocorticoids)

Tx: maternal steroids before birth; artificial surfactant for infant

Therapeutic supplemental oxygen –> dangerous; can result in retinopathy, intraventricular hemorrhage, and bronchopulmonary dysplasia

Question 13

Conducting zone

Answer 13

Large airways up to terminal bronchioles –> warms and filters air, but does not participate in gas exchange (dead space- air, but no blood perfusion)

Cartilage and goblet cells up to bronchi

Question 14

Respiratory zone

Answer 14

Respiratory bronchioles, alveolar ducts and alveoli

Gas exchange

Question 15

Lung relations

Answer 15

Right- 3 lobes

Left- 2 lobes + Lingula

Question 16

Aspiration

Answer 16

Most commonly affects right lobe
Upright: inferior segment of inferior right lobe
Supine: superior segment of inferior right lobe

Question 17

Pulmonary artery to bronchus- RALS

Answer 17

Right Anterior

Left Superior

Question 18

Intercostal n., a., and v.

Answer 18

Run inferior to the corresponding ribs

To avoid –> during thoracocentesis, needles are inserted superior to a rib

Question 19

Diaphragm structures

Answer 19

T8: IVC (vena cava- eight letters)
T10: esophagus, vagus (CN 10 + esophagus)
T12: aorta, thoracic duct, azygos vein (red, white and blue)

Question 20

Diaphragm innervation

Answer 20

C 3, 4, and 5- keep diaphragm alive

Question 21

IRV

Answer 21

Amount you can inspire beyond a normal breath

Question 22

Tidal volume

Answer 22

Normally 500mL

Amount that you can inspire (and expire) just with normal breathing

Question 23

Expiratory reserve volume

Answer 23

amount you can expire beyond normal expiration

Question 24

Residual volume

Answer 24

Amount that remains in lung (cannot be expired)

Question 25

Capacity

Answer 25

sum of 2 or more physiologic VOLUMES

Question 26

Inspiratory capacity

Answer 26

IRV + TV

Question 27

Functional residual capacity

Answer 27

ERV + RV

Question 28

Vital capacity

Answer 28

Everything but RV (IRV + TV + ERV) | Max inspiration + expiration

Question 29

Total lung capacity

Answer 29

Everything | IRV + TC + ERV + RV

Question 30

Physiologic dead space

Answer 30

V_dead = V_tidal * (PaCO2 - PeCO2)/ PaCO2 where PeCO2 is the expired air PCO2 V-dead = Taco Paco Peco Paco

Question 31

Minute ventilation

Answer 31

Volume of gas entering per minute V_E = V_T * RR

Question 32

Alveolar ventilation

Answer 32

Volume of gas that reaches ALVEOLI (per unit time); discounts the dead space V_A = (V_T - V_D) * RR

Question 33

Compliance

Answer 33

Change in volume / Change in pressure The higher, the easier it is to fill

Question 34

Hemoglobin

Answer 34

Two forms: Taut in tissues, Relaxed in Respiratory areas Tight- deoxygenated; low affinity for O2 --> good for releasing/ unloading O2 (e.g. tissues) Relaxed- oxygenated; high affinity for O2 --> exhibits cooperatively (in lungs) Acts as a buffer for H+ (which is released- along with CO2- when more O2 is binding; Haldane effect)

Question 35

Methemoglobinemia

Answer 35

Oxidized form of Hb (Fe 3+); doesn't bind O2 as readily, but binds cyanide S&S: cyanosis with chocolate colored blood Can be induced using nitrates (+ thiosulfate) Can be corrected with methylene blue

Question 36

Carboxyhemoglobin

Answer 36

Carbon monoxide Causes left shit and decreased O2 binding Tx: 100% oxygen

Question 37

Cyanide vs. CO poisoning

Answer 37

Both present very similarly, but cyanide poisoning will be associated with an acrid (bitter almond) smell on breath Both will present with brightly colored venous blood, due to decreased oxygen extraction

Question 38

Things that shift curve right

Answer 38

``` Altitude CO2 Exercise 2,3 BPG Acid Temperature ```

Question 39

Fetal hemoglobin

Answer 39

curve shifted left

Question 40

Oxygen content of blood

Answer 40

O2 content = (1.34 * Hb * SaO2) + .003*PaCO2 Where PaCO2- is determined by plasma O2 concentration (generally unchanged) SaO2: affected by poisoning (e.g. CO) Hb: affected by anemia/ polycythemia

Question 41

Perfusion limited

Answer 41

Normal- O2, CO2, N2O The amount of O2 exchange with blood is dependent on the blood flow (the O2 immediately diffuses through capillaries)

Question 42

Diffusion limited

Answer 42

Pathologic- seen in emphysema, fibrosis Diffusion is slow, so it is the limiting factor in gas exchange (blood leaves lungs without being oxygenated)

Question 43

Diffusion

Answer 43

Proportional to the area (cross-sectional area- more area, more oxygen can diffuse), and partial pressure gradiant Inversely proportional to the thickness of the alveolar wall (increased in pulmonary fibrosis)

Question 44

Pulmonary vascular resistance

Answer 44

Gradient in pressure between pulmonary artery and left atrium divided by the cardiac output Resistance is inversely proportional to the r^4 (radius of the vessel) Resistance is directly proportional to the length of the vessel

Question 45

Alveolar gas equation

Answer 45

PA_O2 = 150 - Pa_CO2/ 0.8

Question 46

Things that cause decreased O2 delivery to tissue (hypoxia)

Answer 46

Decreased cardiac output Hypoxemia Anemia CO poisoning

Question 47

Thing that cause hypoxemia (decreased PaO2)

Answer 47

Normal A-a gradient (10-15) High altitude Hypoventilation Abnormal A-a gradient V/Q mismatch Diffusion limitation Right to left shunt

Question 48

Things that cause ischemia (decreased blood flow)

Answer 48

Impeded arterial flow (emboli) | Decreased venous drainage (HF)

Question 49

V/Q mismatch

Answer 49

V/Q= infinity: ventilation present, but perfusion is not: "dead space"; normal in upper portion of lung, but pathologic with emboli --> 100% O2 helps because there is not blockage of ventilation V/Q = 0; ventilation is not present, but perfusion is: "shunt"; 100% does not help because there is a ventilation block (e.g. aspiration)

Question 50

V/Q through body

Answer 50

Gas floats, liquid sinks so V/Q is high at the apex (more V) and low at the base (more Q) With exercise --> more vasodilation of capillaries so V/Q approaches 1

Question 51

CO2 transport

Answer 51

Carried as HCO3- in the plasma Haldane effect: in lungs, O2 binding to Hb causes release of H+ and HCO3- (converted to CO2) Bohr effect: in peripheral tissue, high CO2 content causes, release of O2 and uptake of HCO3- + H+ into blood

Question 52

High altitude

Answer 52

Hyperventilation due to decreased PO2 Increased 2,3 BPG (to favor unloading to tissue) Increase in mitochondria Increase in renal excretion of HCO3- (to compensate for respiratory alkalosis --> this is what acetazolamide treats Can lead to pulm HTN and RVH --> due to pulmonary vasoconstriction

Question 53

Response to exercise

Answer 53

Increased CO2 production Increased O2 consumption Increased ventilation rate and increased perfusion (due to opening of capillaries at the apex) NO CHANGE to PaO2 or PaCO2 (this is a function of the PLASMA) increased venous CO2 content and venous O2 content (because more is being extracted/ released from the peripheral tissue)