Respiratory

Question 1

Embryonic stage

Answer 1

• Weeks 4-7
• Lung bud → trachea → mainstem bronchi → secondary (lobar) bronchi → tertiary (segmental) bronchi
• Errors at this stage can lead to TE fistula

Question 2

Pseudoglandular stage

Answer 2

• Weeks 5-16
• Endodermal tubules → terminal bronchioles
• Surrounded by modest capillary network
• Respiration impossible, incompatible with life

Question 3

Canalicular stage

Answer 3

• Weeks 16-26
• Terminal bronchioles → respiratory bronchioles → alveolar ducts
• Surrounded by prominent capillary network
• Airways increase in diameter
• Respiration capable at 25 weeks

Question 4

Saccular stage

Answer 4

• Weeks 26-birth
• Alveolar ducts → terminal sacs
• Terminal sacs separated by primary septae
• Pneumocytes develop

Question 5

Alveolar stage

Answer 5

• Weeks 32-8 years
• Terminal sacs → adult alveoli (due to secondary septation)
• In utero, breathing occurs via aspiration and expulsion of amniotic fluid → ↑ vascular resistance through gestation
• At birth, fluid gets replaced with air → ↓ pulmonary vascular resistance

Question 6

Bronchogenic cysts

Answer 6

• Caused by abnormal budding of the foregut and dilation of the terminal or large bronchi
• Discrete, round, sharply defined and air-filled densities on CXR
• Drain poorly and cause chronic infections

Question 7

Club cells

Answer 7

• Non-ciliated
• Low columnar/cuboidal with secretory granules
• Secrete component of surfactant
• Degrade toxins
• Act as reserve cells

Question 8

Zone of respiratory tree that has least airway resistance

Answer 8

Terminal bronchioles

Question 9

Where do cartilage and goblet cells extend to on respiratory tree

Answer 9

End of bronchi

Question 10

Where do cilia extend to on respiratory tree

Answer 10

Respiratory bronchioles

Question 11

Inspiratory capacity

Answer 11

IRV + TV

Question 12

Functional residual capacity

Answer 12

• RV + ERV
• Volume of gas in lungs after normal expiration
• Includes RV (cannot be measure on spirometry)

Question 13

Vital capacity

Answer 13

• TV + IRV + ERV

- Maximal volume of gas that can be expired after a maximal inspiration

Question 14

Physiological dead space

Answer 14

• Anatomic dead space of conducting airways plus alveolar dead space
• Apex of healthy lung is larges contributor of alveolar dead space
• Volume of inspired air that does not take part in gas exchange

Question 15

Physiologic dead space

Answer 15

• Approximately equivalent to anatomic dead space in normal lungs
• May be greater than anatomic dead space in lung diseases with V/Q defects

Question 16

Pathologic dead space

Answer 16

• When part of respiratory zone becomes unable to perform gas exchange
• Ventilated but not perfused

Question 17

What determines the combined volume of the lungs

Answer 17

The elastic properties of both chest wall and lungs

Question 18

Hysteresis

Answer 18

Lung inflation curve follows a different curve than the lung deflation curve due to need to overcome surface tension forces in inflation

Question 19

How does fetal hemoglobin has an increased affinity for O2

Answer 19

Has a decreased affinity for 2,3-BPG

Question 20

Perfusion limited

Answer 20

• O2 (normal health), CO2, N2O
• Gas equilibrates early along the length of the capillary
• Diffusion can only be ↑ if blood flow ↑

Question 21

Diffusion limited

Answer 21

• O2 (emphysema, fibrosis), CO

- Gas does not equilibrate by the time blood reaches the end of the capillary

Question 22

Haldane and Bohr effects

Answer 22

HALDANE EFFECT:

• Occurs in lungs
• Oxygenation of Hb promotes dissociation of H+ from Hb
• This shifts equilibrium toward CO2 formation
• Therefore, CO2 is released from RBCs

BOHR EFFECT:

• Occurs in peripheral tissue
• ↑ H+ from tissue metabolism shifts curve to right, unloading O2

Question 23

Response to high altitude

Answer 23

• ↓ atmospheric O2 → ↓ PaO2 → ↑ ventilation → ↓ PaCO2 → respiratory alkalosis → altitude sickness
• Chronic ↑ in ventilation
• ↑ erythropoietin → ↑ hematocrit and Hb (chronic hypoxia)
• ↑ 2,3-BPG, binds Hb so that Hb releases more O2
• Cellular changes (↑ mitochondria)
• ↑ renal excretion of HCO3- to compensate for respiratory alkalosis (can augment with acetazolamide)
• Chronic hypoxic pulmonary vasoconstriction results in pulmonary hypertension and RVH

Question 24

Response to exercise

Answer 24

• ↑ CO2 production
• ↑ O2 consumption
• ↑ ventilation rate to meet O2 demand
• V/Q ratio from apex to base becomes more uniform
• ↑ pulmonary blood flow due to ↑ cardiac output
• ↓ pH during strenuous exercise (secondary to lactic acidosis)
• No change in PaO2 and PaCO2, but ↑ in venous CO2 content and ↓ in venous O2 content

Question 25

Epistaxis of anterior segment of nostril

Answer 25

Kiesselbach plexus

Question 26

Epistaxis of posterior segment of nostril

Answer 26

Sphenopalatine artery, branch of maxillary artery

Question 27

Homan sign

Answer 27

- Dorsiflexion of foot → calf pain | - DVT

Question 28

When do cyanosis and hypercapnia occur in chronic bronchitis

Answer 28

- Cyanosis is due to early onset hypoxemia due to shunting | - Late onset dyspnea and CO2 retention (hypercapnia

Question 29

What is associated with peribronchial cuffing

Answer 29

Asthma

Question 30

Hypersensitivity pneumonitis

Answer 30

Mixed type III/IV hypersensitivity reaction to environmental antigen → dyspnea, cough, chest tightness, headache. Often seen in farmers and those exposed to birds.

Question 31

Caplan syndrome

Answer 31

Rheumatoid arthritis and pneumoconioses with intrapulmonary nodules

Question 32

What causes the initial damage in acute respiratory distress syndrome

Answer 32

Initial damage due to release of neutrophilic substances toxic to alveolar wall, activation of coagulation cascade and oxygen derived free radicals

Question 33

Causes of acute respiratory distress syndrome

Answer 33

- Sepsis - Pancreatitis - Pneumonia - Aspiration - uRemia - Trauma - Amniotic fluid embolism - Shock "SPARTAS"

Question 34

Obstructive sleep apnea in adults

Answer 34

Excess parapharyngeal tissue

Question 35

Obstructive sleep apnea in children

Answer 35

Adenotonsillar hypertrophy i

Question 36

Obesity hypoventilation syndrome

Answer 36

Obesity → hypoventilation → ↓ PaO2 and ↑ PaCO2 during sleep ↑ PaCO2 during waking hours (retention)

Question 37

Nonheritable causes of pulmonary arterial hypertension

Answer 37

- Drugs (eg amphetamines, cocaine) - Connective tissue disease - HIV infection - Portal hypertension - Congenital heart disease - Schistosomiasis

Question 38

Physical findings of pleural effusion

Answer 38

- ↓ breath sounds - Dull to percussion - ↓ fremitus - No tracheal deviation or might also be away from side of lesion (if large)

Question 39

Physical findings of atelectasis (bronchial obstruction)

Answer 39

- ↓ breath sounds - Dull to percussion - ↓ fremitus - Tracheal deviation toward side of lesion

Question 40

Physical findings of simple pneumothorax

Answer 40

- ↓ breath sounds - Hyperresonant to percussion - ↓ fremitus - No tracheal deviation

Question 41

Physical findings of tension pneumothorax

Answer 41

- ↓ breath sounds - Hyperresonant to percussion - ↓ fremitus - Tracheal deviation away from side of lesion

Question 42

Physical findings of consolidation (lobar pneumonia, pulmonary edema)

Answer 42

- Bronchial breath sounds; late inspiratory crackles - Dull to percussion - ↑ fremitus (this indicates denser or inflamed lung tissue) - No tracheal deviation

Question 43

Sites of metastases from lung cancer

Answer 43

- Adrenals - Brain - Bone (pathologic fracture) - Liver (jaundice, hepatomegaly)

Question 44

Lung metastases

Answer 44

- Usually multiple lesions - More common than primary neoplasms - Breast - Colon - Prostate - Bladder cancer

Question 45

Antibodies produced by small cell (oat cell) carcinoma are against

Answer 45

- Presynaptic Ca2+ channels (Lamber-Eaton myasthenic syndrome) - Neurons (paraneoplastic myelitis, encephalitis, subacute cerebellar degeneration)

Question 46

Small cell (oat cell) carcinoma stains for

Answer 46

- Chromogranin A | - Neuron-specific enolase

Question 47

Adenocarcinoma stains for

Answer 47

Mucin

Question 48

Bronchioalveolar subtype (adenocarcinoma in situ)

Answer 48

- CXR often shows hazy infiltrates similar to pneumonia - Better prognosis - Grows along alveolar septa → apparent "thickening" of alveolar walls - Tall columnar cells containing mucus

Question 49

Large cell carcinoma secretes

Answer 49

β-hCG

Question 50

Bronchial carcinoid tumor stains for

Answer 50

Chromogranin A