When climbing a mountain: 1) The cardiovascular control center activates the sympathetic nervous system, increasing heart rate and blood flow to working muscles. 2) Increased breathing and muscle pumping improves venous return, increasing stroke volume and cardiac output. 3) Blood flow shifts from other organs to the skeletal muscles and heart. When reaching high altitudes: 1) Decreased oxygen causes arterial chemoreceptors to increase breathing rate, restoring blood oxygen levels. 2) Increased ventilation lowers carbon dioxide levels, causing hypocapnia. Symptoms of high altitude sickness include cyanosis, nausea, headaches, breathlessness, fatigue, and increased blood pressure. Treatments include supplemental oxygen through ventil

1. ASSIGNMENT 4 & 5
CIRCULATORY AND RESPIRATORY
SYSTEM

2. QUESTION :
• A healthy person, male, aged 20-30 years old
wants to climb Mount Everest. Please describe
the changes in his circulatory and respiratory
system when he
a) is climbing the mountain
b) when he reached the highest peak
c) if he were to suffer from hypoxia/high altitude
sickness, what are his symptoms and what are
the possible treatment.
d) Bonus question: would it make any difference if
the climber is a female?

3. Please describe the changes in his circulatory
and respiratory system when he
a) Is climbing the mountain
- When he is climbing a
mountain, mechanoreceptors in his muscles
detect the change in the tension of the muscle
as a result of contraction. These
mechanoreceptors send afferent sensory
information to his brain, activating the
cardiovascular control center in the medulla
oblongata.

4. • the cardiovascular control center reduces the
activity of the parasympathetic nervous
systems and increases the activity of the
sympathetic nervous system, changing the
efferent signals going to the heart and the
arteriolar smooth muscle.
• At the onset of climbing, parasympathetic
activity decreases, causing an increase in
heart rate.

5. - At the same time, the increase in muscular
activity and breathing improves the function
of the respiratory and skeletal muscle
pumps, causing an increase venous return to
the heart.
- Because of the Frank-Starling effect, the
resulting increase in end-diastolic volume
causes an increase in stroke volume.

6. - During the initial stages of exercise, the
increase in cardiac output are a result of both
increases in heart rate and increases in stroke
volume.
- In principle, the increase in contractility
should cause an increase in stroke volume, but
the large increase in heart rate reduces the
time available for filling of the heart, and
limits end-diastolic volume.

7. - There are large changes in the patterns of blood
flow. These changes of blood flow are the result of
vasodilation of the arterioles leading to the skeletal
muscle and heart and vasoconstriction of the
arterioles leading to the other organs.

9. b) When he reached the highest peak
- At high altitude, the decrease in barometric pressure
reduces the amount of oxygen available in the
environment. Arterial chemoreceptors detect this
decline in blood oxygen pressure, send a signal to the
medulla to increase the rate and depth of
breathing, restoring blood oxygen. Because of the
increased ventilation rate, more carbon dioxide will
be lost at the lungs leading to hypocapnia, or lower
than normal blood pressure.

11. • c) if he were to suffer from hypoxia/high altitude
sickness, what are his symptoms and what are the possible
treatment.
Cyanosis
Nausea or
vomiting
Blood Pressure
increased
Headaches
Symptoms of hypoxia
breathless
Fatigue or
tiredness

12. Transport
ventilator
Treatment
for Hypoxia
Nasal cannula
Simple oxygen
facemask
Bag valve mask
Non-rebreather
mask
Bonus question : would it make any difference if the climber is a
female ?
Answer : No. It will not make any difference.