19.
The primary function of the larynx is to control the volume of air passing through
the air passageways to and from the alveoli. The larynx also produces selected
vibration frequencies in the moving column of air. The epiglottis of the larynx acts like a
trap door to prevent food items from entering the lower air passageways. (para 7-27)
20.
The vocal folds are used to control the size of the opening between them, called
the rima glottidis.
Valsalva's maneuver is used to provide support for a strenuous effort with the
upper members. When Valsalva's maneuver ends with a sudden opening of the rima
21.
A column of air may be chopped into bits of speech. The frequencies of the
vibrations are the pitch, varied by a change in the tension of the vocal cords.
22.
A variety of situations may occlude a bronchus: A foreign object may be
aspirated. The wall of the tube may constrict in a bronchial spasm. The lining of the
tube may become swollen with fluid and close the passageway. (para 7-32b)
23.
The air in the passageways does not take part in actual respiration. Therefore, it
24.
External respiration is the exchange of gases between the air and the blood. It
takes place in the alveoli, which are small, spherical sacs. Adjacent to the walls of the
alveoli are numerous blood capillaries. The wall of the alveolus contains a special
chemical known as surfactant. To make the transfer of gases possible, the inner
25.
The pleural cavities help to provide lubrication for the expansion and contraction
26.
Respiratory reflexes are controlled by the respiratory center in the medullary
portion of the hindbrainstem. One of the major influences upon this center is the level of
27.
Providing nourishment and oxygen to the tissues of the lung is the nutrient blood.
Actually involved in the exchange of gases is the functional blood. (para 7-39)
28.
Functional blood is brought to and from the lungs by the pulmonary cycle of the
cardiovascular system. This cycle includes the right ventricle, the pulmonary arch, the
right and left pulmonary arteries, the capillaries in the vicinity of the alveoli, the
pulmonary venous system, and the left atrium. (para 7-39)
MD0007
7-30