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I begin my journey in a capillary, the movement in here is very slow due to an apparent low pressure, and the walls are only one cell thick to allow substances to diffuse out of the blood

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Introduction

I begin my journey in a capillary, the movement in here is very slow due to an apparent low pressure, and the walls are only one cell thick to allow substances to diffuse out of the blood e.g. oxygen and are very thin. In front and behind me I can see other red blood cells like myself. They have no nucleus to allow more space to carry oxygen, and are small biconcave disc- shaped cells filled with a red pigment called haemoglobin. As I squeeze through the capillary walls, I see in the distance a cauliflower-shaped sac, as I got closer it was revealed to me that this 'bunch of grapes' was an alveoli, as I looked round there were thousands of them branching off from the trachea - the 'flexible hose of a vacuum'. The windpipe as it is more commonly called is held open by rings of cartilage, and the alveoli are situated at the end of each bronchiole - a narrow tube. The alveoli have a high concentration of oxygen. The haemoglobin now associates with the oxygen that is diffusing through the thin moist walls to form a loosely bonded compound called oxyhaemoglobin. ...read more.

Middle

Digestion starts in the mouth, our teeth begin breaking up the food, then we swallow it and pass it through to the oesophagus (also known as the gullet), it is a circular tube with muscles in its walls. The function of the gullet is to pass food down to your stomach, it does this by the muscles in the walls contracting and squeezing behind the food to push it along. In front of the food the muscles relax. This movement of food down the gut is called peristalsis. The food now has reached the stomach, which has muscular walls to churn up the food and mix it with gastric juices that the stomach itself produces. After 2-3 hours of churning, the food is a runny liquid. A ring of muscle opens to let the food squirt out a little at a time, it passes into the small intestine. From here it travels down the duodenum part of the small intestine, the digestion is completed here and the food is absorbed into the bloodstream. The small intestine is well designed for absorption because the inner surface is covered in tiny finger like projections called villi, this creates ...read more.

Conclusion

I travel through the liver and proceed along the hepatic vein leading on to the vena cava. At the vena cava, we branched off towards a muscle in the arm. When I reached the muscle , my red blood cell diffused oxygen and its glucose supply via the partialtly permeable membrane. I then watched a chemical reaction take place, as the glucose and the oxygen react to produce carbon dioxide and energy by the process of respiration. This process took nplace in the mitochondria which is in the cell cytoplasm. The cells used the energy for all the chemical reactions in the body. The bi-product carbon dfioxide diffused into the plasma ; a yellow coloured watery liquid in the blood in which the cells float in. I have now attached myself to a particle of carbon dioxide, icarry on my journey back towards the right side of the heart with deoxygenated blood, I enter the right atrium via the vena cava, the blood coming back from the body is travelling very slow because of the lack of energy. The right atrium contracts and pushes bood through the tricuspid valve into the right ventricle (a chamber), i then get pushed up through the semi-lunar valve out of the pulmonary artery. ...read more.

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