NR 351 Exam 5

Chapter 38- Oxygenation and Perfusion

• Performs its functions through pulmonary ventilation, respiration and perfusion

• Normal functioning depends on:

• Integrity of the airway system to transport air to & from lungs

• Oxygenate venous blood; remove carbon dioxide from blood

• Properly functioning cardiovascular system to carry nutrients

• Upper airway

• Function: warm, filter, humidify inspired air

• Nose, pharynx, larynx, epiglottis

• Lower airway

• Function: conduction of air, mucociliary clearance, production of pulmonary 

surfactant

• Trachea, primary and secondary bronchi, and tertiary bronchioles

• Anatomy of lungs

• Located within thoracic cavity

• Right lung: three lobes and 10 bronchopulmonary segments

• Left lung: two lobes and 8 bronchopulmonary segments

• Lungs are composed of elastic tissue (alveoli, surfactant (low surfactant, alveoli 

collapse), pleura- fluid between lungs and sac)

• Pleural cavity- negative pressure

Pulmonary Ventilation- the movement of air into and out of the lungs 

• Inspiration- the active phase of ventilation- air into lungs

• Expiration- the passive phase of ventilation- air out of lungs

• Respiration- involves gas exchange between the atmospheric air in the alveoli and 

blood in the capillaries

• Perfusion- the process by which oxygenated capillary blood passes through body 

tissues

Process of Ventilation

• During Inspiration

• Diaphragm contracts and descends, lengthening thoracic cavity

• External intercostals muscles contract, lifting the ribs upward and outward

• Sternum is pushed forward, enlarging the chest from front to back

• Increased lung volume and decreased intrapulmonic pressure allow air to move from 

an area of greater pressure (outside lungs) to lesser pressure (inside lungs)

• Relaxation of these structures results in expiration

Gas Exchange- refers to the intake or oxygen and release of carbon dioxide

• Four factors

Change in surface area available

Thickening of alveolar-capillary membrane

Partial pressure

Solubility and molecular weight of the gas

• Atelectasis- incomplete lung expansion; obstruction of airway by foreign bodies

Transport of Respiratory Gases

• Oxygen is carried in the body via plasma and RBC’s

• Most oxygen is carried by RBC’s in the form of oxyhemoglobin

• Hemoglobin carries carbon dioxide in the form of carboxyhemoglobin

• Alterations in Respiratory function:

Hypoxia- inadequate amount of oxygen available to the cells (can be chronicheadache, chest pain, enlarged heart, clubbing)

Dyspnea- difficulty breathing

Hypoventilation- decreased rate or depth of air movement into the lungs

• Factors affecting Respiratory function

Levels of health- acute and chronic illnesses

Medications

Alteration in muscle function- obesity, scoliosis

Cardiovascular System- vital for exchange of gases

• Composed of the heart and blood vessels

Heart- cone shaped, muscular pump divided into four hollow chambers

Upper chambers: receive blood from the veins

Lower chambers: force blood out of the heart

• Alterations

Dysrhythmia or arrhythmia- abnormality to heart rhythm

Myocardial ischemia- decrease of oxygen to heart; impaired oxygen to tissues

Angina- temporary imbalance of oxygen to heart

Myocardial infarction- acute, coronary syndrome characterized by decrease in 

heart tissue

Heart failure- unable to pump sufficient blood supply