Anatomy and Physiology unit 5 assignment 3

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Investigating homeostatic responses to exercise

Homeostatis is the term used to describe constant regulation of the body’s internal conditions, this includes regulating the body’s temperature, blood sugar level, level of Carbon dioxide level and PH. For the body to work these things have to be maintained at a constant level by physiological processes, this enables the enzymes in the body to be able to work efficiently and effectively without being denatured due to unstable conditions. Homeostatis is extremely important in the body as it enables the body to be able to function without you becoming unwell, if homeostatis wasn’t carried out it could potentially lead to death if untreated. A negative feedback loop is the main process used in order to maintain homeostatis. Negative feedback is a reaction that counteracts the original stimulus such as if the levels of blood glucose increased, the body would have to produce insulin in order to bring the blood glucose levels back down to a safe level. Here is an example of the process of a negative feedback loop using increase in carbon dioxide:

During exercise, the level of carbon dioxide in the blood may increase, this is due to the rate of cellular respiration, when we exercise we carry out more cellular respiration at a faster pace as the body requires more energy to carry out more muscle contractions that take place during exercise. This means that levels of glucose and oxygen decrease while carbon dioxide and energy increase.

Body temperature may also rise slightly due to the excess energy that turns into heat as a waste product. The way that the body reacts to these changes is through negative feedback loops, as shown above.

When there is excess carbon dioxide in the blood, the chemo-receptors pick up the change and this triggers the brain to react in different ways, one way is that the heart begins to pump more quickly to get de-oxygenated blood to the lungs so that gas exchange can take place more quickly, another reaction is in the example above, we begin to breathe more so that more waste carbon dioxide leaves the body and is replaced with oxygen. If the level of carbon dioxide exceeds a level which is safe for the body’s internal functioning, the PH level can drop causing the acid level in the blood to reach unsafe levels, this can lead to acidosis which is a poisoning of the blood, if untreated this can lead to death.

When the temperature of the body (internal) increases during exercise, this is detected by thermoreceptors found in the hypothalamus however when the temperature externally increases this is detected by the thermoreceptors found on the skin. Internally, the temperature of the blood and internal environment should never exceed 37.5 degrees Celsius and should never drop lower than 36.5 degrees Celsius, a drop to low would lead to hypothermia and going too high would lead to hyperthermia although increase in temperature can also be caused by fever. When the internal temperature increases, the thermoreceptors tell the hypothalamus to trigger responses, the hypothalamus works with the skin, sweat glands, and blood vessels. Some of the responses to heat increase include, sweating and vasodilation. Vasodilation is the dilating of blood vessels so that they are closer to the surface of the skin, this means they can radiate the heat from the blood through the skin which gives the ‘flushed’ appearance after periods of exercise. Sweating is the boy’s way of releasing heat by evaporation, sweat is made up of mainly water which we produce and consume more of when exercising anyway. If the internal body temperature doesn’t decrease, this can lead to hyperthermia (also known as heat stroke), the symptoms of this include, excessive sweating, fainting, nausea and eventually this can lead to death.

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In the reaction to the increase in blood temperature the stimulus is the increase in temperature, the receptor is the thermoreceptor, the effectors are the blood vessels and sweat glands and the responses are vasodilation and sweating.

When exercising blood glucose can decrease as it is required for cellular respiration more than usual, this change is detected by the pancreas which sends glucagon into the blood stream telling the liver to convert stored glycogen into glucose which will increase blood sugar levels. The stimulus is the decrease in glucose, the receptor is the pancreas, the coordinator is the glucagon, the ...

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