Download The Human Respiratory System Answer Sheet

THE HUMAN RESPIRATORY SYSTEM – Answer Sheet
The Upper Respiratory Tract
Air enters the body either by the
mouth
or by the
nose
the latter case, it moves through nasal passages coated with mucous
that have fine hair-like
cilia
. In
and lined with cells
projecting into the airways. The mucous traps
dust
,
bacteria
, and other foreign materials. The constant
motion of the cilia then carries this mucous away from the lungs toward the pharynx, where it is
swallowed
. (Sneezing and coughing can also expel some of this foreign material from
the body.) The air is
warmed
and
moistened
as it goes through the
nasal passages. This conditioning helps protect the delicate tissues of the lungs and the ciliated cells.
After leaving the nasal passages or the mouth cavity, the air passes into the pharynx which
connects with two passages, the
tissue, the
epiglottis
are reinforced by rings of
trachea
and the
esophagus
. A flap of
, prevents food from entering the trachea. The walls of the trachea
cartilage
inspired (breathed in) enters the
which hold it open at all times. Most of the air that is
larynx
, the enlarged upper portion of the trachea. To
get into the larynx, the air passes through the
glottis
varying degrees. The larynx contains the
formed from folds of mucous membrane.
vocal cords
, a slit which can open or close to
- thin strong fibers of tissue
The Lower Respiratory Tract
The trachea continues down into the
thoracic cavity
or chest cavity. Like the nasal
passages, its walls are lined with cells, some that have cilia and others that secrete mucous.
At its lower end, the trachea divides into two
then divides into smaller and smaller
bronchi
bronchioles
. Each
bronchus
. The very small bronchioles lack
the supporting rings of cartilage present in the trachea. These small bronchioles finally lead to
terminal
and sacs called
bronchioles
alveoli
, each of which ends in a group of alveolar ducts
. The air passages perform two tasks. The bronchi and
bronchioles conduct air in and out, and the alveoli are involved in the exchange of
and
carbon
dioxide
between the air and the blood.
** Each lung is enveloped by a double layer of membrane,
pleural
membrane.
oxygen
pleura
or