2. Climbing mountain
• Increase in metabolic demand (oxygen requirement,
substrates in skeletal muscles increase, removal of
metabolites and CO2)
• Ventilation rate and breathing frequency increase –
increases oxygen consumption
• Increase in pulmonary ventilation – increase in tidal
volume and respiratory rate – increase in oxygen
uptake and CO2 output.
• Haemoglobin fully saturated with O2 throughout
climbing the mountain
• Blood flow increase – cardiac output increase
• Decreased pH and increased body temperature –
more oxygen is unloaded into muscle.
• Heart rate and stroke volume increase.
3. At highest peak – High-altitude hypoxia
• Blood Po2 drops
▫ Detected by arterial chemoreceptors, send signal to
medulla
▫ Medulla send effector signal to increase rate and depth
of breathing, restoring blood Po2 .
• Increased ventilation rate, more CO2 in lungs –
causes hypocapnia.
▫ PCO2 provides primary drive to breathe.
▫ Low blood PCO2 will cause difficult in breathing
▫ low [H+], causes alkalosis
Longer-term exposure to high altitude – alkalosis triggers
the kidney to excrete HCO3- to regulate blood pH
4. • Increase in red blood cell numbers (polycythemia)
▫ High red blood cells numbers in blood volume causes
increased blood viscoscity
• Increase in levels of 2,3-DPG in red blood cells
▫ Decrease the oxygen affinity of the blood.
▫ But the effect is canceled out by respiratory alkalosis,
no net change in haemoglobin oxygen affinity at high
altitude.
• Pulmonary arterioles vasoconstrict
▫ Reduced perfusion (process of a body delivering blood to a capillary bed in its biological
tissue) of lungs
▫ Reduces oxygen uptake from the environment
▫ May cause pulmonary edema (accumulation of fluids
in the lungs) – reduce efficiency of gas exchange.
6. hypoxia/high altitude sickness
Symptoms:
• Headaches
• Fatigue or tiredness
• Breathlessness or shortness of breath
• Palpitations may be seen in the initial phases of
hypoxia. As hypoxia progresses, the heart rate may
quickly fall by a significant degree. In severe cases,
abnormal heart rhythms or arrhythmias may develop.
• Raised blood pressure in initial phases of hypoxia is
followed by lowered blood pressure as the condition
progresses.
• Light headedness
• Nausea and vomiting
7. • Skin and nail beds may turn bluish, a condition
called cyanosis. (Blood that is low in oxygen is
a dark bluish-red colour)
• Euphoria or sensation of dissociation from self
• Confusion, memory loss and cognitive
problems
• Disorientation and uncoordinated movement
• Severe hypoxia can lead to loss of consciousness,
seizures or convulsions, coma and even death.
• Breathing may become slow and shallow and the
pupils of the eyes may not be responsive when
light is shone on them.
8. Treatment – supply oxygen
• Breathing assistance (mechanical ventilation)
• Controlling the heart rate and rhythm
• Fluids, blood products, or medications to raise
blood pressure if it is low
• Medications or general anesthetics to calm
seizures
9. Female climbers
• Female have significantly smaller lung volumes and
maximal expiratory flow rates than males
• They also have more reproductive hormones,
estrogen and progesterone
▫ can influence ventilation, substrate metabolism,
thermoregulation, and pulmonary function during
exercise.
• Therefore, during climbing, female have higher
breathing frequency, and perhaps greater
chance of getting hypoxemia compared to men.
