1. UNIT 4: THE RESPIRATORY SYSTEM
 Watch the video and complete the text. Work in pairs.
The respiratory system moves air through the nose, pharynx, larynx,
trachea and bronchus, to the alveoli when the gas exchange between
________________ and carbon dioxide occurs.
Nares are the openings to the nose. The nasal cavity is lined with cilia,
mucous membranes and blood capillaries. The air is filtered by cilia,
moistened by mucous membranes and warmed by blood.
Air moves into the _____________ or throat, the common passageway for
food and air. Air continues on to the larynx.
The epiglottis is a flap tissue in front of the larynx, closes off the larynx
when swallowing to prevent _______________ from entering.
The larynx or voice box contains the vocal folds.
The _______________ or windpipe connects the larynx to the bronchial
tree. The cartilaginous rings of the trachea prevent the trachea from
collapsing.
____________ are spongy tissues with alveoli and blood capillaries.
Breathing occurs because of the expansion and contraction of the lungs.
The bronchi carrying the air subdivide into smaller branches, called
bronchioles. At the end of each bronchiole are the alveolar sacs.
The alveolar sacs are surrounded by ____________ capillaries and contain
millions of single layer alveolar cells where the gas exchange takes place.
Oxygenated air goes from the nose to the pharynx, larynx, trachea,
bronchus and alveoli. By the process of diffusion, oxygen in the air moves
from the __________ to the capillaries. Carbon dioxide moves from the
capillaries to the alveoli. This process is called respiration.
http://www.youtube.com/watch?feature=player_embedded&v=HiT621PrrO0
SCIENCE – Y6 UNIT4: THE RESPIRATORY SYSTEM Worksheet 4