Inside the Human Body - First to Last

Having watched the first part of Inside the human body last week, i set out to watch the next episode in the series with high expectations, and thankfully i wasn't disappointed. The episode that captures the talents of the human body to stay alive, from our first breath to our last, was vividly captured through the use of case studies and computer generated images.

Key facts that i took away from the episode included the key role of the human heart, that does more than simply pump blood around the body. According to Michael Mosley, the presenter, the human heart beats roughly 70 times a minute, pumping nearly 5 litres of blood around the body, in nearly 96 000 km of circulation. The episode, that opened with the birth of a child, showed how the human boy adapts immediately to the environment. In the mothers body, the lungs (in the baby) do not need to do any work, as oxygen is pumped into the body through the mothers blood. Thus the heart effectively has a hole to allow the blood in the baby, to bypass the lungs. However immediately after the baby is born, the body begins to circulate blood around the body and the pressure of the moving blood forces a flap to close over the hole, which may fuse to close the hole permanently.

Not only does the body adapt to changes internally (the use of lungs), but it also reacts instantly to the outside environment, especially the heat and the cold. For example, in the episode, a response to low oxygen levels, described as the dive reflex, allows divers to stay underwater for longer without having to take a breath. This is achieved by the body prioritizing the areas that need blood supply, primarily the brain and the heart. Thus within a few minutes the body begins to shut down blood flow to the extremities, beginning with fingers and toes and moving inwards. However, in a hot environment the body begins to release excessive amounts of water, in the form of sweat, to help cool the body, and this helps firefighters to move into fires for a short period of time.

Finally having watched the second episode (first to last), i have high aspirations for the remaining two episodes as well!