Lab 8 Review

FEV

A pulmonary function test for obstructive disorders

Describe Boyle's law and how inhalation and exhalation follow from this law Identify the muscles involved in quiet inhalation and those additionally required for forced inhalation. Which spirometry measurements indicate the extent of quiet and forced inhalation?

According to Boyle's law, the pressure of a gas is inversely proportional to its volume. During inhalation, therefore, air is pushed into the lungs by the greater pressure of the atmosphere. When thoracic volume decreases during exhalation, the intrapulmonary pressure rises above the atmospheric pressure and air is pushed out of the lungs. Normal (unforced) ventilation is regulated by action of the diaphragm and the external intercostal muscles. Forced inhalation recruits other muscles such as the scalenus, sternocleidomastoid, and pectoralis major muscles. Quiet inhalation is measured as tidal volume whereas forced inhalation can be measured from normal exhalation as inspiratory capacity.

Residual Volume (RV)

Amount of air remaining in the lungs after a maximum exhalation

obstructive disorders

Category of pulmonary disorders in which the alveoli are normal but there is an abnormally high resistance to air flow

When a person lungs are ventilated by a tank of gas, the technique is known as intermittent positive pressure breathing (iPPB) Analyzing this term, explain how this technique inflates the lungs for inspiration and deflates the lungs for expiration.

Intermittent positive pressure breathing (IPPB) must be used whenever surgery requires that an opening be made into the thoracic cavity. With the chest open, the lungs will collapse due to higher atmospheric pressure. Consequently, positive pressure must be used during open chest surgery to force air into the lungs during inspiration in order to ventilate the alveoli. The expiration phase is passive as the IPPB device intermittently stops the positive pressure inflow and the lungs collapse clue to the higher atmospheric pressure

Inspiratory capacity

Maximum amount of air that can be inspired after a normal expiration

Can you measure the residual volume and total lung volume by spirometry? Explain. Also, explain how the residual volume, vital capacity, and total lung capacity change with age

No, because residual volume cannot be exhaled and total lung capacity includes the residual volume. These volumes can be estimated however by multiplying an age dependent factor times the vital capacity.

Explain how quiet exhalation is accomplished, and compare this to forced exhalation. Which spirometry measurements indicate quiet and forced exhalation?

Quiet exhalation is generally passive. Relaxation of the diaphragm and external intercostal muscles causes the thorax to resume its original volume and the air pressure inside the lungs rises resulting in exhalation. The amount of air inhaled or exhaled quietly is the tidal volume. During forced exhalation, the internal intercostal and abdominal muscles contract, decreasing the thoracic volume to a lower level than that achieved in normal exhalation. The amount of air forcefully exhaled is the expiratory reserve volume (ERV)

vital capacity

The total volume of air that can be exhaled after maximal inhalation.

Does your chest expand because your lungs inflate, or do your lungs inflate because your chest expands? Explain.

Your lungs inflate because your chest expands. Contraction of the diaphragm and intercostal muscles must occur first, increasing the volume of the thoracic cavity. According to Boyle's law, this increased volume creates a pressure lower than that of the atmosphere. As a result, atmospheric air exerting greater pressure pushes into the lower pressure area that exists in the alveoli of the lungs causing them to inflate.

bronchitis and asthma

examples of obstructive disorders

Distinguish between obstructive and restrictive pulmonary disorders. Explain how spirometry aids in their diagnosis

obstructive disorders are seen when there is an abnormally high resistance to airflow through the bronchioles due to such conditions as bronchoconstriction or mucus. In obstructive disorders, the vital capacity is normal but since airflow is affected the FEV1 is low. Restrictive disorders occur when the alveoli are adversely affected by disease. In restrictive disorders, vital capacity is reduced but the FEV1 may be normal.

Expiratory Reserve Volume (ERV)

the volume of additional air that can be forcibly exhaled after a normal exhalation