ASSIGNMENT 4 & 5

CIRCULATORY AND RESPIRATORY SYSTEM

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 mountainb) when he reached the highest peakc) 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?

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.

• 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.

- 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.

- 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.

- 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.

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.

• c) if he were to suffer from hypoxia/high altitude sickness, what are his symptoms and what are the possible treatment.

Symptoms of hypoxia Headaches

Fatigue or tirednessbreathless

Blood Pressure increased

Nausea or vomiting

Cyanosis

Bonus question : would it make any difference if the climber is a female ?

Answer : No. It will not make any difference.

Treatment for Hypoxia Nasal cannula

Simple oxygen facemask

Non-rebreather mask

Bag valve mask

Transport ventilator