RESP 1330: Exercise Physiology and High Altitude Effects

When a person begins moderate exercise, when does alveolar ventilation first increase?

• After 30–60 seconds of activity
• Immediately, within a few seconds
• Only after lactic acid builds up
• Once heart rate doubles

During strenuous exercise, how does skeletal muscle oxygen consumption compare with rest?

• About 50% at rest and drops with exertion
• Roughly 10–15% at rest, rising above 90% during heavy exercise
• Remains stable regardless of workload
• Mainly unchanged as brain and heart take priority

A student jogging uphill suddenly shows a widened alveolar–arterial PO₂ difference. What mechanism explains this?

• Decreased CO₂ production
• Ventilation–perfusion mismatch in working muscles
• Enhanced central chemoreceptor activity
• Reduced renal compensation

A runner collapses on a hot day, confused and not sweating. What should be done first?

• Replace lost electrolytes
• Rapidly cool the body
• Slowly give IV fluids
• Increase PaCO₂

A healthy person at high altitude begins to hyperventilate. Which receptors cause this response?

• Baroreceptors
• Central chemoreceptors
• Peripheral chemoreceptors
• Proprioceptors

What happens to cardiac output during heavy exercise?

• It may double
• It may increase 4–8 times
• It decreases as oxygen demand rises
• It remains unchanged

Which blood flow changes occur during exercise?

• Visceral vessels dilate and muscle vessels constrict
• Capillaries in working muscles dilate while non-working muscles constrict
• All vascular beds dilate equally
• Cerebral vessels constrict sharply

During maximal exercise, oxygen diffusion capacity rises because of:

• More alveoli are recruited
• Pulmonary capillaries open and distend
• Hemoglobin affinity decreases
• Peripheral chemoreceptor activity increases

Which symptom set is most consistent with heat stroke?

• Sweating, dizziness, and bradycardia
• Headache, absence of sweating, confusion
• Cool skin, shallow breathing, slow pulse
• Fatigue, mild fever, and tachypnea

Why is heat stroke life-threatening without rapid cooling?

• Plasma volume falls severely
• Hyperthermia damages proteins and organs
• PaO₂ falls below critical levels
• Parasympathetic tone disappears