IB Biology - 6.4. Gas exchange

Ventilation

Ventilation

Exchange of air between the atmosphere and the lungs, activated by breathing.

Gas exchange

The exchange of oxygen and CO2 between bloodstream and the alveoli via passive diffusion.

Respiratory system diagram

You should be able to label it

Alveoli

Are the body's gas exchange surfaces, formed in clusters at the ends of the smallest bronchioles.

Pneumocytes type I

Extremely thin alveolar, permeable and adapted for gas exchange.

Pneumocytes type II

Secrete a solution containing surfactant, which creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension.

Lung cancer causes

Smoking, passive smoking, air pollution, radon gas, asbestos and silica.

Lung cancer consequences

Difficulties with breathing, chest pain, persistent coughing, loss of appetite, weight loss, coughing blood, fatigue, death.

Emphysema

Respiratory disease, caused by smoking or air pollution. Consequences are loss of elasticity in lungs, reduced surface area for gas exchange and difficulty to exhale air. Inflammatory response.

Cell respiration

Production of ATP at the cellular level.

Necessity of a ventilation system

We are large organisms, we are land-borne, large concentration gradient.

Mechanics of ventilation

Tumor

Abnormal growth of tissue that develop at any stage of life in any part of the body.

Physiological respiration

Involves the transport of oxygen to cells within the tissues, where energy production occurs.

Pneumocytes

Alveolar cells. Are the cells that line the alveoli and comprise of the majority of the inner surface of the lungs

Surface tension

The elastic force created by a fluid surface that minimizes the surface area (via cohesion of liquid molecules)

Breathing

Active movement of respiratory muscles that enables the passage of air into and out of the lungs. Boyle's law.

Inspiration

Increase volume of the chest.

Expiration

Decrease the volume of the chest.

Diaphragm

Muscles contract, causing the diaphragm to flatten and increase the volume of the thoracic cavity.

External intercostals

Contract, pulling ribs upwards and outwards (expanding chest).

Influence of exercise

Increase ventilation rate and tidal volume.

Spirometry

Measuring the amount (volume) and speed (flow) at which air can be inhaled or exhaled.

Total lung capacity

Volume of air in the lungs after a maximal inhalation.

Vital capacity

Volume of air that can be exchanged by the lungs via a maximal inhalation and exhalation.

Residual volume

Volume of air that is always present in the lungs (20% of total lung capacity).

Tidal volume

Volume of air that is exchanged via normal breathing.

Asthma

Chronic inflammation of the airways to the lungs.

Pneumothorax

Abnormal collection of gas in the pleural space that causes an uncoupling of the lung from the chest wall