Embryologic Cardiopulmonary Development

Vocabulary flashcards covering embryologic cardiopulmonary development, fetal stages, germ layers, intrauterine structures, pulmonary stages, surfactant, fetal circulation, and baroreceptors/chemoreceptors.

Ovum Stage

The first stage of fetal development from conception to the completion of implantation (12 to 14 days), characterized by rapid cell division and attachment or implantation.

Embryo Stage

The second stage of fetal development from the end of the ovum stage until the embryo measures roughly 3 cm from head to rump (54 to 56 days), forming 3 germ layers and being most vulnerable to teratogenesis.

Fetus Stage

The third stage of fetal development lasting 210 to 214 days, characterized by the continued growth of organ systems.

Endoderm Layer

The embryonic germ layer that develops into the digestive system, liver, pancreas, and inner layers of the lungs.

Mesoderm Layer

The embryonic germ layer that develops into the circulatory system, skeletal system, and muscular system.

Ectoderm Layer

The embryonic germ layer that develops into hair, nails, skin, the nervous system, and epithelial layers of the lungs.

Neonate

The developmental period of a human from delivery through the first month of life.

Infant

The developmental period of a human from 1 month to 1 year of life.

Child

A pediatric patient above 1 year of age.

Placenta

The organ of respiration for the fetus that provides nutrients and oxygen, attaches to the uterine wall, and connects to the fetus via the umbilical cord.

Umbilical Vein

The single large vessel in the umbilical cord that carries oxygenated blood from the placenta to the fetus.

Umbilical Arteries

The two small vessels in the umbilical cord that carry deoxygenated blood from the descending aorta of the fetus back to the placenta.

Whartons Jelly

A gelatinous substance inside the umbilical cord that prevents the vessels from collapsing on themselves.

Amniotic Fluid

Fluid inside the amnion sac (about 1 liter at term) that is constantly absorbed and replenished, allowing fetal movement, providing protection, and aiding in thermoregulation.

Polyhydramnios

An excessive amount of amniotic fluid, which can be associated with swallowing issues/disorders or chromosomal issues like Down syndrome and Trisomy 18.

Oligohydramnios

An insufficient amount of amniotic fluid, which indicates a defect in the fetal renal system.

Embryonal Stage

The first stage of pulmonary development (first 7 weeks gestation) where major anatomical structures like the trachea and major bronchi develop, with lung development starting at 24 days.

Pseudoglandular Stage

The stage of lung development (7 to 16 weeks gestation) where remaining conducting airways and preacinar arteries develop, and lungs begin to look like glands.

Canalicular Stage

The pulmonary development stage (weeks 17 through 26) where terminal and respiratory bronchioles multiply, lungs vascularize, alveoli begin to develop, and minimal viability outside the womb is reached (~22-23 weeks).

Saccular Stage

The stage of lung development (26 to between 34 and 36 weeks) marked by increased complexity of saccules and microcirculation, with lungs completely formed by 24 to 26 weeks.

Alveolar Stage

The pulmonary development stage where true alveoli are present (between 32 to 34 weeks) and continue to increase in number until around age 8.

Laplace's Law

The mathematical relationship represented by $P = \frac{2T}{r}$, which states that as the radius ($r$) of the alveoli decreases, the surface tension ($T$) increases, raising the risk of collapse.

Surfactant

A substance found on the alveolar wall composed of phospholipids (mainly PC and PG), neutral lipids, and proteins that lowers surface tension and reduces muscular effort during breathing.

Type II Pneumocytes

Specialized cells that produce surfactant in the lungs starting at 24 weeks gestation.

Phosphatidylglycerol (PG)

A specific phospholipid component of surfactant whose presence indicates mature surfactant, usually appearing around 35 weeks gestation.

Lecithin-to-Sphingomyelin Ratio (L/S ratio)

A test on amniotic fluid used to measure fetal surfactant and determine lung maturity, where a 2:1 ratio generally indicates maturity around 35 weeks gestation.

Fetal Lung Fluid

Fluid produced and secreted by the fetus (about 20-30\,ml/kg at term) that maintains airway patency, shapes potential air spaces, and equates to functional residual capacity (FRC) when evacuated at delivery.

Transient Tachypnea of the Newborn (TTN)

Also known as RDS type II, a condition caused by the retention of fetal lung fluid, commonly occurring in babies delivered by Caesarean section.

Ductus Venosus

A fetal blood vessel shunt that directs blood to the inferior vena cava and closes as soon as the umbilical cord is clamped.

Foramen Ovale

An opening between the fetal heart atria that shunts blood from the right atrium to the left atrium, closing as soon as systemic blood pressure changes after birth.

Ductus Arteriosus

A fetal vascular shunt that diverts blood to the aorta, closing within 96 hours after birth as smooth muscle constricts (20% closed at 24 hours, 80% at 48 hours, 100% at 96 hours).

Fetal Hemoglobin (HgF)

A form of hemoglobin in the fetus that has a higher affinity for oxygen than adult hemoglobin (HgA), binding oxygen at lower partial pressure and remaining unaffected by 2,3 BPG.

Baroreceptors

Stretch receptors located in the bifurcation of the carotid arteries and the aortic arch that respond to pressure changes and are stimulated by bradycardia and hypotension.

Chemoreceptors

Sensory organs located in the carotid and aortic bodies that are sensitive to PaO2, PaCO2, and pH, regulating ventilation and aiding in the initiation of the first breath.