​What is Pathology -What could cause hypoxia or anoxia?

​What is Pathology -What could cause hypoxia or anoxia? 
Hypoxia or anoxia can be caused by a variety of factors. Hypoxia and anoxia can be caused by the following factors: a)  Inadequate oxygen supply (e.g., low oxygen concentration in air at high altitude) 
b) Airway obstruction (e.g., strangulation and drowning)
 c)  Inadequate blood oxygenation in the lungs (e.g., lung diseases) 
d) Inadequate oxygen transfer in the blood (e.g., anaemia) and insufficient blood perfusion in the tissues (ischemia resulting from heart failure) 
e) Cellular respiration inhibition—that is, blocked oxygen use (e.g., cyanide poisoning of respiratory enzymes)