When the giraffe bends its head to drink water from the ground, there is a risk

Question

When the giraffe bends its head to drink water from the ground, there is a risk of increasing the arterial pressure in its brain even further (due to gravitational forces). An important recent finding was that the internal jugular vein (IJV) of the giraffe contains at least seven (7) valves, more than any other species (by comparison, the human IJV contains only one). Briefly explain the role of venous valves and how an increased number of valves within the IJV would affect the giraffe’s mean arterial pressure when it lowers its head. [2 marks].

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Explanation / Answer

The greatest challenges of the giraffe against gravitional activity on its circulatory system is when it lower its head to drink and raise its head again,generally in humans with there is sudden increase in the MAP there is auto regulation, but in giraffe when it drinks the water by lowering the head then blood could enters the jugular vein from the inferior vena ceva or regurgitate from the jugular veins in to the cranial veins, the main function of the jugular vein valves is to prevent regurgitation of blood from the inferior vena cava and right atrium into the jugular vein in head down position,the anatomical structure of the valves is such that they are closed when the head is in the down position, their effectiveness in preventing regurgitation will depend on their capacity to with stand the hydrostatic pressure generated by venous return and the column of blood in the jugular veins and on their number position, structure due to this valve system in the ijv the sudden increase in the mean aterial pressure when it put its head down to drink will not cause any damage to the brain.

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