TRANSPORT IS ESSENTIAL FOR LIFE#4

Cells must import and export materials in order to maintain life-sustaining activities.In the human body, the oxygen is absorbed by the blood stream in the lungs, being then transported to the cells where an elaborated change process takes place. Oxigen plays a vital role in the breathing processes and in the metabolism of the living organisms. Probably, the only living cells that do not need oxygen are some anaerobic bacteria that obtain energy from other metabolic processes.
The nutrient compounds, inside of the cell, are oxidized through complex enzymatic processes.
This oxidation is the source of energy of most of the animals, mainly of mammals.
The products are carbon dioxide and water (exhaled air has a relative humidity of 100%), which are eliminated by the human body through the lungs. Transport in our bodies is so important, because without it our body wouldn't be able to function propertly.Water is of major importance to all living things; in some organisms, up to 90% of their body weight comes from water. Up to 60% of the human body is water, the brain is composed of 70% water, and the lungs are nearly 90% water. Lean muscle tissue contains about 75% water by weight, as is the brain; body fat contains 10% water and bone has 22% water. About 83% of our blood is water, which helps digest our food, transport waste, and control body temperature. Each day humans must replace 2.4 litres of water, some through drinking and the rest taken by the body from the foods eaten.