Anatomy and physiology:   The respiratory system consists of the upper and lower airways, the lungs, and the thoracic cage.  Besides exchanging oxygen and carbon dioxide in the lungs and tissues, the respiratory system helps regulate the body's acid - base balance.

Respiratory system functions primarily to maintain the exchange of oxygen and carbon dioxide in the lungs and tissues and to regulate acid - base balance.  Any change in this system affects every other body system.  What's more changes in other body systems may also reduce the lungs ability to provide oxygen.  For instance, any acute disease heightens the body's oxygen demand and therefore increases the work of breathing.  Also a debilitating, acute disease makes a patient more susceptible to secondary infections which may also affect the lungs.  Even a mild illness can promote respiratory complications.

Respiratory tract:  The upper airways of the respiratory tract include the nose, mouth, nasopharynx, oropharynx, laryngopharynx, and larynx.  These structures warm and humidify inspired air, and provide for taste, smell and mastication.  The respiratory system is here protected from infection and foreign body inhalation by involuntary defense mechanisms: sneezing, coughing, gagging, and spasm.
  The lower airways of the respiratory tract include the trachea, bronchi, and the lungs.  These also employ coughing, and spasm as defense mechanisms.  Beginning at the bottom of the trachea, the bronchi split into right and left branches.  Growing progressively smaller, the right and left mainstem bronchi further divide into secondary and tertiary bronchi, then into bronchioles, and finally into alveoli.
 

Abnormal Respiration:  The following is a llist of terms designating various abnormalities of respiration.  They are not specific diseases, but are symptoms of disease or some other injurious conditious.

1.  Anoxia,  which means "lack of oxygen."  Certain tissues, such as the brain, may be permanently damaged because of a lack of oxygen.

2.  Asphyxia,  a term indicating an increase in carbon dioxide in the tissues accompanied by an oxygen deficiency.  Synonymous with suffocation.

3.  Dyspnea,  which means "difficult or labored breathing."

4.  Cheyne - Stokes,  respiration, which is a type of rhythmical variation in the depth of respiratory movements found in certain criticallly ill or unconscious patients.

5.  Suffocation,  which refers to any stoppage of respiration.  It can result, for example, from strangulation, inhalation of a foreign object, sleeping with the face buried in a pillow ( as infants somethimes do ), drowning or overinhalation of smoke.  Suffocation can refer also to the asphyxia that it causes.

6.  Cyanosis,  which refers to a bluish color of the skin and visible mucous membranes caused by an insufficent amount of oxygen in the blood.  Cyanosis may result from asphyxiation or suffocation, but it may also be caused by other factors.  Heart disease can caused a lack of circulation through the lungs with resulting insufficient oxygenation.