ANP1115 Lecture 8 Respiratory System Part 2

Respiratory Zone

The area where terminal bronchioles branch into respiratory bronchioles, including alveoli.

Alveolar Membrane

The air-blood barrier composed of the alveolar wall, capillary wall, and basal laminae.

Type I Cells

Squamous epithelial cells in the alveoli that provide a thin barrier for gas exchange.

Surfactant

A substance secreted by type II cells that reduces surface tension in alveoli, preventing collapse.

Pulmonary Ventilation

The process of inspiration and expiration that involves the movement of air into and out of the lungs.

Tidal Volume

The amount of air taken in or expelled during normal, quiet breathing, approximately 500 ml per breath.

Intrapulmonary Pressure

The pressure within the alveoli of the lungs, which rises and falls with breathing.

Intrapleural Pressure

The pressure within the pleural cavity, typically about 4 mm Hg less than intrapulmonary pressure.

Transpulmonary Pressure

The difference between intrapulmonary pressure and intrapleural pressure; it keeps the lungs inflated.

Dead Space

Air that fills passageways without participating in gas exchange, approximately 150 ml.

Alveolar Surface Tension

A measure of the attraction between liquid molecules at the liquid-gas interface, crucial for lung function.

Lung Compliance

The ease with which the lungs can be distended, determined by lung tissue distensibility and surface tension.

Ventilation-Perfusion Coupling

The relationship between the amount of air reaching alveoli and the blood flow in pulmonary capillaries.

Dalton’s Law of Partial Pressures

The principle stating that the total pressure of a gas mixture equals the sum of the partial pressures of each gas.

Functional Residual Capacity

The volume of air remaining in the lungs after a normal expiration, consisting of expiratory reserve volume and residual volume.

Respiratory Capacities

Combinations of two or more lung volumes that describe overall lung function.

Alveolar Ventilation Rate (AVR)

A measure of effective lung ventilation, considering the volume of air that enters the alveoli per minute.

Infant Respiratory Distress Syndrome (IRDS)

A condition in premature infants characterized by insufficient surfactant production, leading to alveolar collapse.

Cough

A forceful expulsion of air from the lungs through the glottis to clear foreign particles and mucus.

Hiccups

Spasmodic contractions of the diaphragm triggered by irritation of the phrenic nerve.

External Respiration

The exchange of gases between the air in the alveoli and the blood in the pulmonary capillaries.

Internal Respiration

The exchange of gases between the blood and the tissues at the cellular level.

Physiologic Dead Space

The sum of anatomical dead space and any non-functional alveoli, affecting gas exchange efficiency.