IB Bio Topic 6.4 - Gas Exchange

Ventilation

the muscular movement of fresh air into the alveoli of the lungs and removing stale air.

Gas Exchange

collective term for the exchange of gasses that occur at the alveoli of the lungs. It is based on two concentration gradients: one for oxygen and another for carbon dioxide.

Ventilation Rate (Breathing Rate)

the number of breaths (including inhalation and exhalation) taken per minute.

Alveoli

tiny air sacs in the lungs where gaseous exchange takes place

Type I Pneumocytes (Type 1 Pneumocytes)

extremely thin and flat alveolar cells, adapted for gas exchange due to their increased surface area

Type II Pneumocytes (Type 2 Pneumocytes)

secretes a solution containing surfactant, a water-based solution of phospho-lipoproteins

Surfactant

A solution responsible for the film of moisture in the alveoli, reducing surface tension and thus preventing the alveoli’s sides from sticking to each other

Inhalation (Inspiration)

Breathing in. External intercostals contract to lift the ribcage, whereas the diaphragm contracts to increase the volume of the thorax

Exhalation (Expiration)

Breathing out. Internal intercostal contract to lower the ribcage, whereas abdominal muscles contract to decrease the volume of the thoracic cavity

Antagonistic

Term for when muscles work together to move the same body part in opposite directions.

Tidal Volume

the amount of air which enters or leaves the lungs in a single breath at rest. The average is 500 ml

Lung Cancer

The most common form of cancer, most commonly caused by smoking. Consequences include shortness of breath, chest pain, and fatigue.

Emphysema

A disease that results in an inflammatory response in the lungs, which causes narrowing of small airways, breakdown of lung tissue, and decreased alveoli elasticity, decreasing the efficiency of ventilation and gas exchange