The authors would like to acknowledge David A. Miller for his contributions that remain unchanged from the first edition.
DEFINITIONS AND CONCEPTS
I. Breathing
A. A lay term, breathing is understood as the movement of air into and out of the lungs.
B. Physiologically, breathing is controlled by the metabolic needs of the body (i.e., oxygen and carbon dioxide levels in the blood) as perceived by the central nervous system (chemoreceptor input).
C. Breathing is also under voluntary control in conscious, alert individuals.
II. Ventilation
A. Ventilation is the aspect of breathing that refers to the actual movement of air into and out of the lungs.
B. Ventilation is determined by the volume of air moved (tidal volume) and by the ventilatory rate.
C. Individuals who are alert and spontaneously breathing vary the amount of air inhaled and exhaled with each breath, as well as the respiratory rate, responding to the control of the central nervous system over the ventilatory act.
D. Yawning and sighing are normal variations seen during the act of ventilation.
III. Respiration
A. Respiration refers to the following:
1. Actual use of oxygen at the cellular level, and
2. Removal from the cellular environment of these products:
B. Cellular respiration is dependent on two variables:
1. Perfusion of capillaries with oxygen and nutrient-laden blood in adequate amounts (Cellular uptake and use of oxygen normally are independent of oxygen delivery.)
2. Venous blood flow that removes cellular metabolic wastes to the heart, lungs, and kidneys
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a. For distribution to other cells, especially the following:
i. Alveoli
ii. Liver
iii. Kidneys
b. For further metabolism as needed and eventual removal from the body via these routes:
