Anatomy & Physiology Fundamentals Flashcards

Which cells produce pulmonary surfactant?

Answer: Type II pneumocytes

Type II alveolar cells synthesize and secrete surfactant, beginning around 24 to 28 weeks of gestation.

A lecithin/sphingomyelin (L/S) ratio of which value generally indicates fetal lung maturity?

Answer: 2:1 or greater

An L/S ratio of 2:1 or higher suggests adequate surfactant and a low risk of respiratory distress syndrome.

What is the main function of surfactant in the newborn lung?

Answer: Reduces surface tension and prevents alveolar collapse at end-expiration

Surfactant lowers alveolar surface tension, maintaining functional residual capacity and reducing work of breathing.

Why is nasal obstruction particularly dangerous for a newborn?

Answer: Newborns are obligate nose breathers

Newborns preferentially breathe through the nose and do not readily switch to mouth breathing, so blockage can cause distress.

What is the normal respiratory rate range for a healthy term newborn?

Answer: 30 to 60 breaths per minute

Term newborns normally breathe 30 to 60 times per minute, with rates sustained above 60 warranting evaluation.

Which description fits normal periodic breathing in a newborn?

Answer: Pauses of less than 20 seconds with no color change or bradycardia

Periodic breathing involves brief pauses under 20 seconds without cyanosis or bradycardia, unlike pathologic apnea.

Which mechanism contributes most to clearing fetal lung fluid after birth?

Answer: Absorption via epithelial sodium channels and lymphatics, aided by thoracic squeeze

Fluid is largely absorbed through epithelial sodium channels and lymphatics, with some expelled during vaginal delivery squeeze.