Hello I am Olaf, the oxygen molecule and I want to take you around the body and show you my daily life, supporting the human respiratory system...
You can imagine my cycle around the body like a day at work, starting in the morning when I go to my work place. My state from floating around in the air changes because person x inhales my through his mouth. I am sucked into the trachea then, which is like like walking along a street.
This happens because of the change of pressure in the internal body system and the external pressure. The diaphragm moves downwards pushing the abdomen out and the rib cage moves upwards and outwards at the same time, so that the lungs have more space. Thus, there is an increased volume which decreases the pressure inside the lungs, causing the air to be inspired.
So I travel down the pathway from trachea to the lungs, starting with big tubes called bronchi, which separate into smaller tubes called bronchioles which end in little air sacs, called alveoli.
Arrived at the alveoli, now I have to cross the membranes to get to the blood stream, flowing through a network of little blood vessels called capillaries. This is like a crossing over a pedestrian crossing. I have to float through two cell walls, one of the alveoli and one of the capillary, having each two membranes, thus until arriving in the bloodstream crossing a total of four cell membranes, which is a relatively short way for me, making my day less complicated.
Now, I jump onto a red blood cell which will carry me through the stream, like a personal motor boat. Meanwhile I oxygenate the deoxygenated stream. Special about it is, that it is an artery stream, which I travel along in direction of the heart now, which can be imagined like travelling in the opposite direction of the traffic, because normally arteries lead away from the heart. To jump on the boat and to be bound to a hemoglobin molecule, I have to overcome the wall of the red blood cell, which is like opening the door of a car.
The red blood cell takes me to the heart, which is like a junction, where the direction of traffic changes. Now I am pumped together with the red blood cell into a new artery, which brings me to whatever location where engergy is needed. Arrived at any place in the body, I can mix with my colleagues, a few Mr Water and a particular Mr Glucose. Together, we can produce ATP.
This is basically the important bit of my work and afterwards I am really exhaused and I head of into direction of the outside world. Thus, another red blood cell picks me up via a vein. I have to cross its cell wall again then, binding to a carbohemoglobin that is connected to the cell. On the way back, we cross the juction at the heart again leading to another vein that belongs to the pulmonary system, which my day had started with, the circulation to the cells for energy having been the systematic circulation.
The vein takes me back to the lungs where I have to at first get off the blood cell by exiting through its membrane and then cross the four membranes of capillary and alveoli again, ending in the alveoli as a carbon dioxide compound.
Now, the only step that is left, before my final destination, returning to my home, the air, is to be pumped up by exhalation of person x again. Ventilation is activated by the diaphragm, a muscle which relaxes and pushes upward into a domed shape and the rib cage being pulled in and down. I am moves outside through the bronchioles, bronchi and trachea again, finally floating through the mouth and being released into the atmosphere.
This was my daily routine and the formation of O2 into CO2 in the human respiratory system.
Sources:
http://de.slideshare.net/sarahfree/oxygen-through-the-respiratory-system
https://prezi.com/9uqpc_zz4x1l/oxy-the-oxygen-molecules-journey-through-the-respiratory-system/
http://image.slidesharecdn.com/lecture7resp-141208082139-conversion-gate01/95/respiratory-system-7-638.jpg?cb=1418029376
