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In these three units seen this year, resistance has a very important role. Resistance is something that slows down or opposes the passage of a substance or a force. On one hand, in electricity, we can see the resistance in the electric current where resistors are put to reduce current flow. On the other hand, in the circulatory system, the small surface area of the capillaries have a similar function as a resistor, because it avoids fast blood flow for gas exchange: Given to the capillaries being narrow, the red blood cells get stuck, and there the gas change occurs. Finally, in rates of reaction, the redaction of temperature, the increase of surface area and the lack of a catalyst also slows down a chemical reaction and resit it from occurring at a high rate or speed.

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Both units consist in the measure of the time taken to achieve a point. For example, in one side the speed taken by running to arrive to a place, and in the other side the time taken for the product to be created.

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Diffusion results in molecules moving from a region of high concentration to a region where they are less concentrated. This action is the one used for gas exchange in the circulatory system, where oxygen moves into the body cells, which have a low concentration of oxygen, from the red blood cells that have a higher concentration of oxygen. Additionally, diffusion is also used for gas exchange in the respiratory system.  Carbon dioxide travels from the deoxygenated blood that has a high concentration of CO2, to the alveoli that has a low carbon dioxide concentration by diffusion.

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The law of conservation of mass and the law of conservation of energy likewise state that energy or in a chemical reaction mass can not be created or destroyed.

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Gas exchange in the respiratory system and the circulatory system

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Gas exchange in the respiratory system and the circulatory system

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In the respiratory system and in the circulatory system multiple gas exchanges occur. On one hand, in the respiratory system, the lungs diffuse oxygen to the blood, and the blood diffuses carbon dioxide to the lungs, for them to remove this toxic gas from the body through exhalation. On the other side, oxygenated blood diffuses oxygen to the body cells, and the body cells diffuse the waste product of respiration to blood.

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The circulatory system can be compared to the circuit in electricity. Firstly, a relationship between these two actions is that the blood or the electrons always flow in the direction. The heart of the circulatory system can be compared to the battery in the electric circuit, because they both pump charged things, in one side charged electrons and in the other side blood charged with oxygen. Additionally, once the oxygenated blood and the charged electrons pass through either the bulb or the body cells, they eventually discharge and flow back to the heart or the battery.

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In the circulatory system, the different blood vessels transport blood around the body at different pressures. The reason for veins having a low pressure and arteries a high pressure can be illustrated by the gas laws. According to the formula P.V/T, the higher the volume of the tube where blood is transported, the pressure increases, and the narrower the tube is, the pressure decreases.