Respiratory Physiology and Physics Flashcards

This flashcard set covers the mechanics of breathing, physical laws governing lung function, and the physiological components of the respiratory system based on the lecture transcript.

Inspiration

The process where the diaphragm and intercostal muscles contract, forcing the diaphragm down and increasing the volume of the thoracic cage, which decreases air pressure and allows air to flow into the lungs.

Expiration

The process where the diaphragm and intercostal muscles relax, causing the rib cage to move downward and inward and the diaphragm to become dome shaped, which decreases thoracic volume and increases air pressure to flow air out of the lungs.

Intrapulmonary pressure

The pressure that exists inside the lungs.

Intrapleural pressure

The pressure located between the pleura.

Transpulmonary pressure

The pressure measured across the wall of the lungs.

Boyle's Law

A law stating that the initial pressure times the initial volume is equal to a change in pressure times a change in volume ($P_1V_1 = P_2V_2$), meaning pressure and volume in the lungs are inversely related.

Alveoli

Small balloon-like structures attached to the branches of bronchial passages that serve as the exact site for oxygen and $CO_2$ gas exchange.

Compliance

The ease with which the lungs can be inflated, formally defined as the pulmonary volume change per unit of pressure change.

Elasticity

Also known as elastic recoil, this is the ability of the lungs' elastic tissues to return to a resting state during expiration.

Surface tension

A phenomenon created when gases in the air mix with liquids or fluids within the lungs and surrounding lung tissue, measured in dynes per centimeter.

Emphysema

A condition where the elastic recoil of the alveoli is compromised, making it difficult to exhale and often requiring forced expiration.

Dyne

A unit of force equivalent to the force required to accelerate a mass of $1\,g$ at a rate of $1\,cm/s^2$.

Type 1 pneumocytes

Simple squamous epithelium cells that create a thin air-blood barrier, making them ideal for filtration and diffusion of gases.

Type 2 pneumocytes

Simple cuboidal cells that secrete surfactant to reduce surface tension and break up the cohesive properties of water.

Surfactant

A lipoprotein complex that coats the alveoli, reducing surface tension by a factor of about 15 and increasing lung compliance to make expansion easier.

Dipomatoyl phosphatidylcholine (DPPC)

The main ingredient of surfactant that possesses the ability to lower surface tension.

Law of Laplace

A principle stating that the pressure required to keep an alveolus open is equal to two times the surface tension divided by the alveolar radius, expressed as $P = \frac{2T}{R}$.

Infant Respiratory Distress Syndrome (IRDS)

A condition in premature infants where small alveolar radii and lack of surfactant create high surface tension and elastic recoil, making it difficult to take the first breath.

Non-invasive NAVA

A ventilator device that uses an electrode to read signals from the phrenic nerve to allow the machine to assist breathing based on the brain's signals to the diaphragm.