Respiratory system

Question 1

Trachea

Answer 1

Contains rings of cartilage the help it maintain its shape
The tunnel that leads to the thoracic cavity
Contains cilia, which beat in rhythmical waves to carry foreign particles and mucus away from the lungs

Question 2

Alveoli

Answer 2

Functional units of the lung
Very thin walls, usually a single cell in thickness
Covered by a thin film of water, and surrounded by a dense layer of capillaries
Site of Oxygen and CO2 exchange in the lungs