Breathing and Gas Exchange in Human Biology

Thorax

Upper body part containing lungs and breathing structures.

Ribs

Protective cage around lungs and heart.

Intercostal muscles

Muscles controlling ribcage movement during breathing.

Diaphragm

Dome-shaped muscle separating thorax from abdomen.

Trachea

Windpipe carrying air to the lungs.

Bronchi

Two tubes branching from the trachea into lungs.

Bronchioles

Smaller branches from bronchi within the lungs.

Alveoli

Tiny air sacs for gas exchange in lungs.

Pleural membranes

Thin membranes surrounding lungs, reducing friction.

Ventilation

Process of moving air in and out of lungs.

Inhalation

. diaphragm contracts and moves downward

. intercostal muscles contract lifting the ribcage up and out. . . . . This increases the volume of the thorax and decreases the pressure inside it.

Exhalation

. diaphragm relaxes and moves upward

. intercostal muscles relax, ribcage moves down and in

. This decreases the volume of the thorax and increases the pressure inside it.

Gas Exchange

Oxygen and carbon dioxide exchange in alveoli.

Surface area

Alveoli's large area enhances diffusion efficiency.

Thin walls

Alveoli walls are one cell thick for diffusion.

Moist lining

Gases dissolve in moisture for easier diffusion.

Rich blood supply

Maintains concentration gradient for gas exchange.

Cilia

Hair-like structures clearing mucus in respiratory tract.

Tar

Substance from smoking damaging lungs and cilia.

Carbon monoxide

Gas reducing blood's oxygen-carrying capacity.

Nicotine

Substance causing blood vessels to narrow.

Coronary heart disease

Condition increasing risk due to smoking effects.

Emphysema

Lung condition reducing gas exchange efficiency.