Anatomy of the Respiratory System and Fetal Development

Comprehensive vocabulary flashcards covering fetal lung development phases, neonatal respiratory parameters, placental anatomy, adult respiratory structures, and immune responses.

Embryonic period

The phase occurring at the 26th week after fertilization where lungs appear as small buds from the esophagus, including the tracheal cartilage and mainstem bronchi.

Pseudoglandular period

Occurs between the 6th and 16th week of development where all lung segments (segmental, subsegmental) are present and goblet cells appear in the trachea.

Canalicular period

Occurring between the 17th and 26th week of gestation, featuring the proliferation of terminal bronchioles and high vascularization of the lungs.

Terminal sac period

Starts at week 26 until full term (40 weeks) where the entire acinus develops and Type I and II alveolar cells become visible.

Alveolar period

Starts at 32 weeks and continues through childhood, during which alveolar-capillaries increase to about 300 million.

Newborn Lung Compliance

The average value is about $0.005\,L/cm\,H_2O$.

Newborn Airway Resistance

The average value is about $30\,cm\,H_2O/L/sec$.

Cotyledons

The 15 to 20 anatomical segments that consist the placenta.

Umbilical Arteries

The two vessels responsible for carrying deoxygenated blood from the fetus.

Umbilical Veins

The vessels through which oxygenated fetal blood returns to the fetus from the chorionic villi.

Amniocentesis

A procedure used to diagnose fetal abnormalities, lung maturity, bilirubin levels, and genetic disorders during early pregnancy.

Meconium

The first stool of an infant, described as a thick and sticky, usually greenish to black material.

Respiratory Distress Syndrome (RDS)

A condition occurring in babies born before their Type II alveolar cells are mature enough to produce adequate pulmonary surfactant.

Vibrissae

Hair follicles found in the vestibule of the nose that act as filters for air entering the body.

Turbinates

Structures in the nose responsible for the humidification and warming of inspired air.

Pharyngotympanic tubes

Tubes that connect the nasopharynx to the middle ear to equalize pressure.

Glottis

The space between the true vocal cords, which is the narrowest part of the airway in adults.

Valsalva’s Maneuver

A movement where the glottis is closed tightly to prevent air from leaving during physical work like lifting or pushing.

Conducting Zone

Includes airway generations 0–19, extending from the trachea to the terminal bronchioles.

Respiratory Zone

Includes airway generations 20–28 and is the primary site of gas exchange.

Mucociliary Escalator

The mechanism where cilia move in an upward wavelike motion through the sol layer to push the gel layer and particles toward the larynx.

Cellular Immunity

Sensitized lymphocytes responsible for tissue rejection and the destruction of infected or abnormal cells.

Humoral Immunity

Circulating antibodies involved in allergic reactions and defenses against environmental antigens like pollen and animal dander.

Mast Cells

Cells located in the lamina propria that release substances such as histamine and heparin, altering bronchial airway diameter.

Type I Pneumocytes

Squamous cells forming 95% of the surface area of the alveolar epithelium.

Type II Pneumocytes

Granular cells forming 5% of the alveolar epithelium and the source of pulmonary surfactant.

Arterioles

Known as resistance vessels, they supply nutrients to respiratory bronchioles and regulate blood distribution.

Veins

Known as capacitance vessels, they can hold large amounts of blood with little pressure.

Lymphatic vessels

Vessels that help remove excess fluid and protein molecules; they are found more in the lower lobes and more on the left side.

Sympathetic Nervous System

The 'fight or flight' division of the ANS that increases heart rate and blood pressure and relaxes bronchial smooth muscles.

Parasympathetic Nervous System

The division of the ANS that decreases heart rate and blood pressure and constricts bronchial smooth muscles.

Apices

The tops of the lungs, located at about the level of the first rib.

Hilum

The center of the mediastinal border where mainstem bronchi, blood vessels, and nerves enter the lungs.

Pneumothorax

A condition where air enters the potential space between the visceral and parietal pleurae.

Empyema

A condition characterized by the presence of pus in the pleural cavity.

Diaphragm

The major muscle of ventilation that receives motor innervation from the phrenic nerves.