Chapter Two Review

vertical

Contraction of the diaphragm increases the ________ dimension of the thorax

In advanced emphysema, the diaphragm is pulled down and stretched relatively flat by the flaring of the rib cage. In normal inspiration, contraction of the diaphragm causes the central tendon to pull down, causing air to enter the lungs (Boyle's law dictates that a drop in alveolar pressure causes air to flow in). When the diaphragm of an individual with advanced emphysema contracts, it pulls the ribs closer together because they were distended by the barrel chest. As a result, the alveoli are compressed, causing an increase in alveolar pressure and causing air to leave the lungs. Thus, the inspiratory movement of the diaphragm causes expiration. The single inspiratory avenue left to the individual is to elevate the sternum and clavicle using clavicular breathing.

Emphysema results in a breakdown of the alveolar wall, resulting in enlargement of alveolar clusters and consequent enlargement of the thorax known as barrel chest. The result of this condition is that the diaphragm is pulled down at rest. Discuss the implications of the muscular action of inspiration and expiration on this altered system.

the spinal cord

What passes through the vertebral foramen?

transverse

contraction of the accessory muscles of inspiration increases the _____ dimension of the thorax

decreases

contraction of the muscles of expiration _______ the volume of the thorax

pressure

force distributed over area

7

how many cervical vertebrae are there?

5

how many lumbar vertebrae are there?

5

how many sacral vertebrae (fused) are there?

12

how many thoracic vertebrae are there?

negative

pressure causes air to enter a chamber that has expanded until the pressure is equalized