How Is A Birds Breathing System And Heart Different To That Of A Mammal?
The respiratory system of a bird is very different to that of a mammal. When a bird takes a breath in, the air does not go straight into lungs. Instead it passes through a circular pathway through a series of air sacs and tubes, then into lungs, and the out of the body through a second series of air sacs and tubes. This adaptation allows birds to replace all of the air in the lungs with each breath, not just some of the air. In humans, air is drawn in and out along the same pathway, so only an incomplete exchange of air is achieved. The hearts of birds are also different to those of mammals. In proportion to their body size, birds’ hearts are much larger and more powerful. This is because they have to supply the demands of flight muscles. Birds’ hearts also beat much faster than human hearts at rest. For example the heart of a sparrow beats at around 460 times per minute. Human hearts beat on average only 70 times per minute. However, the record belongs to the Hummingbird whose tiny he
