Transcript Guided Notes for the Respiratory System

Guided Notes for the
Respiratory System
Part One
1. The cardiovascular and respiratory
systems share responsibility for
supplying the body with oxygen and
disposing of carbon dioxide. The
respiratory organs oversee the gas
exchanges that occur between the
blood and the external environment.
2. The organs of the respiratory system
include the nose, pharynx, larynx,
trachea, bronchi, and the lungs. Since
gas exchanges with the blood happen
only in the alveoli, the other structures
are really just conducting passageways
that allow air to reach the lungs.
However, they purify, humidify, and
warm incoming air.
3. During breathing, air enters the nose
by passing through the external
nares, or nostrils. The olfactory
receptors for the sense of smell are
located in the mucosa, in the slitlike
superior part of the nasal cavity,
below the ethmoid bone.
3. (continued) The function of the
respiratory mucosa is to warm the air
as it flows past. In addition, the
sticky mucus produced by the
mucosa’s glands moistens the air and
traps incoming bacteria and foreign
debris.
4. The nasal cavity is surrounded by a
ring of paranasal sinuses, located in
the frontal, sphenoid, ethmoid, and
maxillary bones. They produce
mucus, which drains into the nasal
cavities.
5. The pharynx, commonly called
the throat, serves as a
common passageway for food
and air.
6. If the pharyngeal tonsils become
inflamed and swollen, it forces the
person to breathe through the mouth.
In this situation, air is not properly
moistened, warmed, or filtered before
reaching the lungs.
7. The larynx, or voice box, is formed
by 8 rigid hyaline cartilages and a
spoon-shaped flap of elastic cartilage
called the epiglottis. The epiglottis
protects the superior opening of the
larynx. When we swallow, the larynx
is pulled upward and the epiglottis
tips, forming a lid over the larynx.
This routes food into the esophagus
posteriorly.
8. If anything other than air enters
the larynx, a cough reflex is
triggered to expel the substance
and prevent it from entering the
lungs.
9. The trachea is lined with ciliated
mucosa. The cilia beat continuously
and in a direction opposite to that of
incoming air. They propel mucus
away from the lungs to the throat,
where it can be swallowed or spat
out.
10. The trachea is rigid because its
walls are reinforced with c-shaped
rings of hyaline cartilage. The solid
portions of the rings support the
trachea walls and keep it patent, or
open, in spite of the pressure
changes that occur during breathing.
11. The right and left primary
bronchi are formed by the division
of the trachea. The right primary
bronchus is wider, shorter, and
straighter than the left.
12. Each lung is divided into
lobes by fissures. The left lung
has 2 lobes, and the right lung
has 3 lobes.
13. The surface of each lung is covered
with a visceral serosa called the
pulmonary, or visceral, pleura, and
the walls of the thoracic cavity are
lined by the parietal pleura. These
pleural membranes produce pleural
fluid, which allows the lungs to glide
easily over the thorax wall during
breathing movements and causes the
pleural layers to cling together.
14. After the primary bronchi enter the
lungs, they subdivide into smaller and
smaller branches (bronchii), finally
ending in the smallest of the
conducting passageways, the
bronchioles.
15. The terminal bronchioles lead
into respiratory zone structures,
even smaller conduits that
eventually terminate in alveoli.
16. The respiratory zone is the only site
of gas exchange. All other
respiratory passages are conducting
zone structures, which serve as
conduits to and from the respiratory
zone.
17. The walls of the alveoli are
composed largely of a single, thin
layer of squamous epithelial cells.
The external surfaces of the alveoli
are covered with a “cobweb” of
pulmonary capillaries.
18. Gas exchanges occur by simple
diffusion through the respiratory
membrane. Oxygen passing from the
alveolar air into the capillary blood
and carbon dioxide leaving the blood
to enter the gas-filled alveolus.