FIRST AID FOR THE USMLE ACTUAL
QUESTIONS AND ANSWERS FULL
SOLUTION STUDY GUIDE
●● Pulmonary Hypoplasia
What is it caused by?
Associated symptoms?
Answer: *What is it caused by?*
- congenital lung malformation due to poorly development bronchial tree
with abnormal histology usually involving the right lung
*Associated symptoms?*
- associated with congenital diaphragmatic hernia, bilateral renal
agenesis (Potter Syndrome)
●● Bronchogenic Cysts
What is it caused by?
Associated symptoms?
Answer: *What is it caused by?*
- abnormal budding of foregut and dilation of terminal or large bronchi
- on CXR --> appears as discrete, round, sharply defined and air filled
densities on CXR
,*Associated symptoms?*
- chronic infections 2/2 poor drainage
●● Compare and contrast histology of conducting airways vs respiratory
airway
Answer: *Compare and contrast histology of conducting airways vs
respiratory airway*
*Conducting airways:*
- responsible for humidifying and filtering the air
- from the nasal cavity to terminal bronchioles
- lined by pseudostratified columnar epithelium (aka "respiratory
epithelium")
- cilia are an important component and allow for mucus and foreign
particles to be swept away
*Respiratory airways:*
- responsible for gas exchange
- confined to alveolar ducts and alveoli
- simple squamous epithelium
●● What are the different kinds of pneumocytes that exist in the lung?
,For each, where are they found in the lung. What is their histologic
appearance and what role do they play in lung physiology?
Answer: *What are the different kinds of pneumocytes that exist in the
lung?*
- Type I cells
- Type II cells
- Club cells
For each, where are they found in the lung. What is their histologic
appearance and what role do they play in lung physiology?
*Type I*:
- 97% of alveolar surfaces, 10% cell population
- squamous cells (flat and thin), for optimal gas diffusion
- non-proliferative
*Type II*:
- 5% of alveolar surface, 12% cell population
- cuboidal and clustered
- secrete *surfactant* --> to lower surface tension and prevent alveolar
collapse
- surfactant is stored in *lamellar* bodies
, - *precursors* for new alveolar cells (type I and II)
*Club Cells (formerly Clara Cells)*
- aka bronchiolar exocrine cells located in terminal bronchioles
- *non-ciliated*
- low columnar/cuboidal
- located in the terminal bronchioles and secrete component of surfactant
- *degrade toxins*
- act as reserve cells
●● What is collapsing pressure?
Why is surfactant important for alveoli?
What is surfactant a mixture of? What is the most important component?
Around what week of gestation does surfactant synthesis begin? When
are mature levels of surfactant reached?
Answer: *What is collapsing pressure?*
CP = 2(surface tension)/radius
QUESTIONS AND ANSWERS FULL
SOLUTION STUDY GUIDE
●● Pulmonary Hypoplasia
What is it caused by?
Associated symptoms?
Answer: *What is it caused by?*
- congenital lung malformation due to poorly development bronchial tree
with abnormal histology usually involving the right lung
*Associated symptoms?*
- associated with congenital diaphragmatic hernia, bilateral renal
agenesis (Potter Syndrome)
●● Bronchogenic Cysts
What is it caused by?
Associated symptoms?
Answer: *What is it caused by?*
- abnormal budding of foregut and dilation of terminal or large bronchi
- on CXR --> appears as discrete, round, sharply defined and air filled
densities on CXR
,*Associated symptoms?*
- chronic infections 2/2 poor drainage
●● Compare and contrast histology of conducting airways vs respiratory
airway
Answer: *Compare and contrast histology of conducting airways vs
respiratory airway*
*Conducting airways:*
- responsible for humidifying and filtering the air
- from the nasal cavity to terminal bronchioles
- lined by pseudostratified columnar epithelium (aka "respiratory
epithelium")
- cilia are an important component and allow for mucus and foreign
particles to be swept away
*Respiratory airways:*
- responsible for gas exchange
- confined to alveolar ducts and alveoli
- simple squamous epithelium
●● What are the different kinds of pneumocytes that exist in the lung?
,For each, where are they found in the lung. What is their histologic
appearance and what role do they play in lung physiology?
Answer: *What are the different kinds of pneumocytes that exist in the
lung?*
- Type I cells
- Type II cells
- Club cells
For each, where are they found in the lung. What is their histologic
appearance and what role do they play in lung physiology?
*Type I*:
- 97% of alveolar surfaces, 10% cell population
- squamous cells (flat and thin), for optimal gas diffusion
- non-proliferative
*Type II*:
- 5% of alveolar surface, 12% cell population
- cuboidal and clustered
- secrete *surfactant* --> to lower surface tension and prevent alveolar
collapse
- surfactant is stored in *lamellar* bodies
, - *precursors* for new alveolar cells (type I and II)
*Club Cells (formerly Clara Cells)*
- aka bronchiolar exocrine cells located in terminal bronchioles
- *non-ciliated*
- low columnar/cuboidal
- located in the terminal bronchioles and secrete component of surfactant
- *degrade toxins*
- act as reserve cells
●● What is collapsing pressure?
Why is surfactant important for alveoli?
What is surfactant a mixture of? What is the most important component?
Around what week of gestation does surfactant synthesis begin? When
are mature levels of surfactant reached?
Answer: *What is collapsing pressure?*
CP = 2(surface tension)/radius
