The primary purpose of the respiratory system is gas exchange, which involves the
transfer of oxygen & carbon dioxide from the atmosphere to the blood.
The upper respiratory tract (nasal cavity, pharynx, adenoids, tonsils, epiglottis, larynx,
trachea)
The lower respiratory tract (bronchi, bronchioles, alveolar ducts, alveoli)
Respiratory Physiology
Ventilation: moving gases into & out of the lungs
Pulmonary circulation: movement of blood from the heart to the lungs
Diffusion: movement of molecules from an area of higher concentration to an area of
lower concentration
Inspiration (active process): movement of air into the lungs
Expiration (passive process): movement of air out of the lungs
Oxygen transport: lungs & cardiovascular system involved
Carbon dioxide transport: diffuses into red blood cells & is hydrated into carbonic acid
VENTILATION
Requires movement of the chest wall & diaphragm
RESPIRATORY CYCLE
During inspiration, the diaphragm contract & the ribcage expands whereas during
expiration, the diaphragm relaxes & the ribcage recoils
EFFECTS OF AGING
-Decline of respiratory structure & function in middle adulthood
-these changes cause a reduction in oxygen diffusion capacity & producing lower arterial
oxygen saturations
-Elderly may have a lower tolerance for vigorous activities & need more rest
PHYSIOLOGICAL FACTORS AFFECTING OXYGENATION
Airway obstruction: blockage restricts delivery of inspired oxygen to alveoli
Restrictive defects: caused by restriction in expansion of the thoracic walls or
diaphragm.
reduces the volume of air that can be inspired
Mixed defects: both restrictive & obstructive
Functional Residual Capacity: volume of air present in the lungs at the end of passive
expiration
Anemia: low level of hemoglobin in blood
Toxic inhalant: causes a functional anemia
High altitude: atmospheric O2 concentration is lower, thus inspiratory O2 concentration
falls
Increased metabolic rate: results in increased tissue oxygen demand & CO2 production
NURSING PROCESS: ASSESSMENT
