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
The Tell-Tale Brain The Tell-Tale Brain The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human is a 2010 nonfiction book by V. S. Ramachandran that explores, from a neurological viewpoint, the uniqueness of human nature. Ramachandran explores various aspects of visual perception and cognition to argue that humans are unique among species. For example, he notes that although animals show cortical remapping after the loss of a limb, the plasticity seen in the human brain (after amputation) is much more dramatic. Ramachandran discusses seven main concepts which define the human aspect of self and how each may be disrupted by a