When climbing a mountain, the respiratory and circulatory systems undergo changes to adapt to decreasing oxygen levels (hypoxia). There are increases in heart rate, blood pressure, and cardiac output. After prolonged time at high altitude, the body further adapts through increasing red blood cell count and blood oxygen levels. Over days to weeks, the body's sensitivity to hypoxia increases, enhancing ventilation. Prolonged hypoxia can cause symptoms like fatigue, headaches, and in severe cases, tachycardia, pulmonary hypertension and death. The body aims to adapt and acclimate to restore oxygen levels, while oxygen therapy can also counteract hypoxia.

1. RESPIRATORY AND
CIRCULATORY SYSTEM
Changes at high altitude

2. CHANGES WHEN CLIMBING
A MOUNTAIN
 Hypoxia directly affects the vascular tone of the pulmonary and
systemic resistance vessels and increases ventilation and symphatetic
activity
 Increases in heart rate, myocardial contractility and cardiac output
 Increases in blood pressure

3. CHANGES WHEN REACHED
THE HIGHEST PEAK
 The system will adapt after prolonged stay
 Increases oxygen content of the blood because of an increase in
hematocrit associated with plasma level reduction, and an increase in
red blood cell mass due to erythropoiesis
 With exposure over days to weeks, sensitivity to hypoxia
increases, leading to further enhancement of ventilation ( ventilatory
acclimatization)

4. SYMPTOMS OF HYPOXIA
AND TREATMENT
 The symptoms may include fatigue, light-headedness , disorientation
, headaches
 In severe case, It may include tachycardia and pulmonary hypertension then
cyanosis and hypotension followed by death
 To counter the effects, the body should adapt: acclimitazation by which the body
restores the pO2 to standard level
 Oxygen enrichment also can counteract the effects of hypoxia by increasing the
concentration of oxygen in the air thus restored arterial pO2 level towards normal