Giraffe have unusually high heart rates for their size, at 150 beats per minute. When the animal lowers its head the blood rushes down fairly unopposed and a rete mirabile in the upper neck, with its large cross sectional area, prevents excess blood flow to the brain. When it raises again, the blood vessels constrict and direct blood into the brain so the animal does not faint. The jugular veins contain several (most commonly seven) valves to prevent blood flowing back into the head from the inferior vena cava and right atrium while the head is lowered. Conversely, the blood vessels
History of the location of the soul His medical anatomy is described through the use of Plato's corporeal ideals of the soul. The heart was the spirited, the liver the appetitive, and the brain the logical. Galen states in "On Respiration and the Arteries" "one must determine by dissection that the number and nature of the structures that connect the heart to the brain" and it was observed that when these nerves were cut in animals they would lose their voice and when veins were cut they would bleed, but retain their voice. Therefore the brain does not need the heart to feel or create sensations and