Week 3: The Cardio-Respiratory System – The Lungs

Lungs Size

The lungs have a capacity of about 4-6 litres, comparable to the size of a basketball.

Surface Area

A larger surface area in the lungs allows for more efficient oxygen exchange.

Surface Area Measurement

The surface area of the lungs is between 50-100 square meters, roughly half a tennis court.

Gas Exchange

The primary function of the lungs is to exchange oxygen into the system and carbon dioxide out of the system.

pH Regulation

The lungs help regulate blood pH, preventing it from becoming too acidic.

Pathogen Protection

The lungs filter out inhaled pathogens to protect the body.

Vocalization

The lungs enable speech by forcing air through the vocal cords.

External Respiration

The process of moving gases from the environment to the cells of the body.

Respiratory System Anatomy

is divided into upper and lower parts, including structures like the nasal cavity and trachea.

Intercostal Muscles

Muscles located between the ribs that assist in breathing.

Diaphragm

A large muscle at the bottom of the rib cage that plays a crucial role in respiration.

Alveoli

Small sacs in the lungs that facilitate gas exchange, increasing surface area for efficiency.

Pleural Cavity

The space between the two pleural membranes that contains liquid to reduce friction during lung movement.

Boyle's Law

Describes how pressure and volume are inversely related in gases, crucial for lung function.

Dalton's Law

States that the total pressure of a gas mixture is the sum of the partial pressures of its individual gases.

Tidal Volume

The amount of air inhaled or exhaled with each breath, typically around 0.5-1 litres at rest.

Inspiratory Reserve Volume

The additional volume of air that can be inhaled after a normal inhalation, around 2.5-3.5 litres at rest.

Expiratory Reserve Volume

The additional volume of air that can be exhaled after a normal exhalation, around 1-1.5 litres at rest.

Forced Vital Capacity (FVC)

The maximum amount of air that can be forcibly exhaled after taking the deepest breath possible.

Minute Ventilation

The total volume of air inhaled and exhaled per minute, calculated as tidal volume multiplied by breathing rate.