Anatomy of the Respiratory System and Fetal Development

Comprehensive vocabulary flashcards based on the Anatomy of the Respiratory System and Fetal Development worksheet.

Embryonic period (fetal lung development)

The 26th week after fertilization where lungs appear as small buds from the esophagus, tracheal cartilage forms, and bronchi branch into two on the left and three on the right.

Pseudoglandular period

Occurs between the 6th - 16th week of development where all lung segments, goblet cells, and mucous glands appear, reaching approximately 20 generations of airways.

Canalicular period

Occurs between the 17th and 26th week of gestation; Thermal bronchioles proliferate, primitive bronchioles appear, lymphatic vessels develop (week 20), and lungs become highly vascularized.

Terminal sac period

Starts at week 26 and continues until full term (40 weeks); the entire acinus develops, Type I and II alveolar cells become visible, and surfactant begins to appear.

Alveolar period

Starts at 32 weeks and continues through childhood; alveolar-capillaries increase to about 300 million and respiratory acini are developed by the 34th week.

Newborn Lung Compliance and Resistance

The average lung compliance is $0.005\,L/cm\,H_2O$ and the airway resistance is approximately $30\,cm\,H_2O/L/sec$.

Sufficient Air-Blood Interface

By the 26th week of gestation, the air-blood interface and the quantity of pulmonary surfactant are usually sufficient to sustain life.

COTYLENDONS

The 15 to 20 segments that anatomically compose the placenta.

UMBILICAL ARTERIES

Two vessels that carry deoxygenated blood from the fetus to the placenta.

UMBILICAL VEINS

Vessels through which oxygenated fetal blood flows out of the chorionic villi and returns to the fetus.

Fetal Po2 Factors

Three reasons for maternal and fetal Po2 differences: the placenta is an actively metabolizing organ, placenta permeability varies for respiratory gases, and the presence of fetal and maternal vascular shunts.

Infant Lung Fluid Removal

Mechanisms include being squeezed out during birth ($1/3$), absorption by pulmonary capillaries ($1/3$), and removal by the lymphatic system ($1/3$) within the first 24 hours.

Amniocentesis

A procedure used to diagnose fetal abnormalities, assess lung maturity, bilirubin level (Rh incompatibility), creatine level (kidney function), genetic disorders, and meconium presence.

Meconium

The first delta stool; a thick, sticky, greenish to black material. If found in amniotic fluid, it indicates fetal asphyxia and possible Meconium aspiration.

Respiratory Distress Syndrome (RDS) Risk

Affects about 50% of babies born between 26-28 weeks and 25% of babies born between 30-31 weeks due to immature TYPE 2 alveolar cells and inadequate surfactant.

VIBRASSAE

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

Turbinates

Bony structures whose major role is the Humidification and Warming of inspired air.

Pharynx Divisions

The three parts of the pharynx: Nasopharynx, Oropharynx, and Laryngopharynx.

Pharyngotympanic tubes

Located in the lateral walls of the nasopharynx, they connect the nasopharynx to the middle ear to equalize pressure.

Larynx Functions

Acts as a passageway for air, protects against aspiration of solids and liquids, and generates sounds for speech.

Glottis

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

Valsalva’s Maneuver

Undifferentiated movement where laryngeal walls and vocal cords move to the midline, closing the glottis tightly to stop air escape during physical work.

CONDUCTING Zone

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

RESPIRATORY Zone

Includes airway generations 20-28 and serves as the site of gas exchange.

Tracheobronchial Tree Layers

The three layers consist of the EPITHLIAL LINING, LAMINA PROPRIA, and CARTILAGINOUS LAYER.

Mucociliary Escalator

Mechanism where cilia move through the sol layer and strike the gel layer 1500 times per minute, moving mucus toward the larynx at a rate of $2\,cm/min$.

Factors slowing the Mucociliary Escalator

Cigarette Smoke (ciliary paralysis), Dehydration, Positive pressure ventilation (dry air), Endotracheal suctioning, high oxygen concentrations, pollutants, and General anesthetics.

Cellular vs. Humoral Immunity

Cellular involves sensitized lymphocytes for tissue rejection; Humoral involves circulating antibodies for allergic reactions (e.g., pollen or animal dander).

Mast Cell Degranulation Substances

Chemicals released include Histamine, Leukotrienes, Heparin, Platelet activating factor (PAF), and Eosinophilic chemotactic factor of anaphylaxis (ECF-A).

TYPE I vs. TYPE II Pneumocytes

Type I (squamous) form 95% of alveolar surface area; Type II (granular) form 5% and are the source of Pulmonary surfactant to decrease surface tension.

Pulmonary Arterioles and Veins

Arterioles (resistance vessels) regulate blood distribution to alveoli; Veins (capacitance vessels) hold large blood volumes with little pressure.

Pulmonary Lymphatic Vessels

Remove excess fluid and protein; they are found more in the lower lobes than upper lobes and more in the left lung than the right.

Sympathetic vs. Parasympathetic Effects

Sympathetic increases HR/BP and relaxes bronchial smooth muscle; Parasympathetic decreases HR/BP and constricts bronchial smooth muscle.

Hilum

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

Pleural Pathology (Pneumothorax/Hemothorax/Empyema)

Refers to air, blood, or pus (respectively) entering the potential space between the visceral and parietal pleurae.

Sternum Parts

The three components of the sternum: Manubrium, Body, and Xiphoid process.

Diaphragm Innervation

The major muscle of ventilation receives its primary motor innervation from the Phrenic nerves.

Accessory Muscles of Inhalation

Includes Scalene muscle, Stenocleidomasteroid muscle, Pectoralis major muscles, Trapezius muscles, and External intercostal muscle.

Internal intercostal muscles

Accessory muscles of exhalation located beneath the external intercostals, not in the abdomen.