The Amazing Giraffe
December 21, 2022
The Giraffe is an amazing Mammal. Huge in many aspects, with a very long neck but also an interesting anatomy to make everything work inside that big body.
A giraffe heart weighs on average 11 kilograms and is composed of have two halves, the right and the left, which are each responsible for moving blood around the body. The right ventricle of the heart pumps blood a relatively short distance to the lungs, but the left ventricle of the heart has incredibly thick, well-muscled walls and small chamber radius giving each heartbeat enough power to push blood around the body.
The giraffe has one of the highest blood pressures of any mammal. It reaches pressures of up to 280/180 mm Hg, which is twice that found in humans (120/80 mmHg). This is because the giraffe’s head is on average 2 meters above its heart and the heart must combat the forces of gravity to ensure that the brain gets adequate blood flow and oxygen. To allow for adequate blood flow, the giraffe’s heart has an altered electrical rhythm, which allows more time for the left ventricle to fill with blood between each heartbeat.
So why don’t they pass out when they lower their heads to drink? Their jugular veins have valves that block the return flow of the blood, and the blood vessels have elastic walls that dilate and shrink to manage the change in blood flow. These one-way valves and the elasticity of the veins prevent blood from flowing too quickly to the brain when the giraffe lowers to drink.
