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Giraffe Cardiovascular Adaptations to Gravity

The physiological systems of animals have adapted to Earth’s gravity over the past hundreds of millions of years. In general, gravitational adaptations of the cardiovascular system are more pronounced in terrestrial specieswith greater height and thus greater gravity-dependent gradients of blood pressure from head to feet. For example, dinosaurs (1), tree-climbing snakes (2), giraffes (3), and other tall animals have evolved mechanisms to provide adequate blood flow and nutrition to their brains while restricting blood flow and tissue swelling in

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Siphon mechanism in collapsible tubes: application to circulation of the giraffe head

Controversy exists over the principles involved in determining blood flow to the head of a giraffe, specifically over the role of gravity pressure (pgh) in the collapsible jugular vein in facilitating uphill flow in arteries. This study investigates pressures within vertically oriented models containing both rigid and collapsible tubes. An inverted U-tube was constructed (height = 103 cm) of thick rubber tubing in the ascending limb and collapsible dialysis tubing in the descending limb. Water flow was induced by a

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The Remarkable Cardiovascular System of Giraffes

Gravity affects the physiology of many animals, and the effect is, for good reason, most pronounced in tall species. The physiology—in particular, cardiovascular function—of giraffes has therefore captivated the interest of physiologists for centuries. Several studies document high mean arterial blood pressure of giraffes of about 200 mm Hg. This appears necessary to establish a cerebral perfusion pressure on the order of 100mmHg at the cranial end of the carotid arteries. Here, we discuss the unique characteristics of blood vessels,

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