Systems effected
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The nervous system
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Caffeine affects many systems in your body. The central nervous system is the system that is mostly effected when consumes caffeine into their body. The action of caffeine is the antagonism of adenosine receptors. Caffeine affects the nervous system differently from the way adenosine does , even though it attaches itself to the same neural receptors. Caffeine causes your neurons to fire on rapidly. Caffeine continues to affect your brain as long as it remains in your blood. While the average half life of caffeine in the adult bloodstream is about four hours , the length of time can vary depending on the caffeine user. Caffeine has been shown to act on the part of the brain that is sensitive to levels of carbon dioxide in the blood , making it an ingredient in over the counter cold remedies. Caffeine makes your brain even more sensitive to levels of carbon dioxide in the blood , which causes increased depth of breathing and higher levels of oxygen blood. This makes caffeine an effective treatment for those who suffer from breathing problems but can also lead to hyperventilation if too much is consumed. (Hanes, 2013)
Adenosine receptor antagonism
In absence of caffeine and when a person is awake and alert , little adenosine is present in the central nervous system neurons. With a continued wakeful state , over time it accumulates and reversibly binds with adenosine receptors found in certain CNS neurons , resulting in a cellular response causing gradually increased drowsiness and ultimately sleep , a state necessary for metabolic removal of many substances toxic to neurons. (Hanes, 2013)
When caffeine is consumed , it reversibly binds with adenosine receptors without activating them, thus blocks(antagonizes) the interaction of adenosine with its receptor. The temporarily prevents or relieves drowsiness , and thus maintains or restores alertness. Caffeine is a receptor antagonist that all adenosine subtypes (A1, A2A, A2B, and A3 receptors). The caffeine molecule is structurally similar to adenosine , and is capable of binding to adenosine receptors on the surface of cells without activating them, thereby acting as a competitive inhibitor. Antagonism of these adenosine receptors stimulates the vagal nucleus , reducing heart rate , constricting blood vessels , and increasing the respiratory rate. It also promotes release of the neurotransmitters monoamines and acetylcholine, which awards caffeine with its stimulant effects. (fitday , 2012)
Adenosine receptor antagonism
In absence of caffeine and when a person is awake and alert , little adenosine is present in the central nervous system neurons. With a continued wakeful state , over time it accumulates and reversibly binds with adenosine receptors found in certain CNS neurons , resulting in a cellular response causing gradually increased drowsiness and ultimately sleep , a state necessary for metabolic removal of many substances toxic to neurons. (Hanes, 2013)
When caffeine is consumed , it reversibly binds with adenosine receptors without activating them, thus blocks(antagonizes) the interaction of adenosine with its receptor. The temporarily prevents or relieves drowsiness , and thus maintains or restores alertness. Caffeine is a receptor antagonist that all adenosine subtypes (A1, A2A, A2B, and A3 receptors). The caffeine molecule is structurally similar to adenosine , and is capable of binding to adenosine receptors on the surface of cells without activating them, thereby acting as a competitive inhibitor. Antagonism of these adenosine receptors stimulates the vagal nucleus , reducing heart rate , constricting blood vessels , and increasing the respiratory rate. It also promotes release of the neurotransmitters monoamines and acetylcholine, which awards caffeine with its stimulant effects. (fitday , 2012)
Urinary system
In large doses, caffeine acts as a diuretic , a substance that increases the volume and frequency of urination. According to the New York University Langone Medical centre , caffeine is one of many factors that can aggravate an overactive bladder by causing a sudden intense need to urinate. This increase of urine is due to both a diuresis ( increase in water excretion) and a natriuresis ( increase in saline excretion). It is mediated via proximal tubular adenosine receptor blockade. Because of this effect , some authorities have recommended air line passengers and athletes to avoid caffeine due to risk of dehydration , and the risk of extracellular fluid volume depletion. However, chronic users of caffeine develop a tolerance to these effects , and have no chronic increase in urinary output. (Hanes, 2013)
Excretory system(Gastrointestinal tract)
After consumption , caffeine enters the digestive system where it is absorbed into the blood stream. According to the university of Maryland Medical Center, caffeine stimulates the secretion of stomach acid , which can aggravate existing conditions like heartburn or ulcer. In the lower bowel caffeine increases muscle contractions known as peristalsis , which can result in more urgent or frequent bowel movements. (Hanes , 2013)
Cardiovascular system
Caffeine as a stimulant , speeds up cardiovascular functions such as heart rate and blood pressure. It binds to the receptors on the heart’s surface , causing it to beat more rapidly. Caffeine may cause temporary but dramatic increase in blood pressure. This increase in blood pressure can be dangerous for those who have hypertension or other cardiovascular diseases. For this reason , people with hypertension should limit caffeine consumption to 200 milligrams per day or less to prevent unnecessary spikes in blood pressure.(Hanes, 2013)
Excretory system(Gastrointestinal tract)
After consumption , caffeine enters the digestive system where it is absorbed into the blood stream. According to the university of Maryland Medical Center, caffeine stimulates the secretion of stomach acid , which can aggravate existing conditions like heartburn or ulcer. In the lower bowel caffeine increases muscle contractions known as peristalsis , which can result in more urgent or frequent bowel movements. (Hanes , 2013)
Cardiovascular system
Caffeine as a stimulant , speeds up cardiovascular functions such as heart rate and blood pressure. It binds to the receptors on the heart’s surface , causing it to beat more rapidly. Caffeine may cause temporary but dramatic increase in blood pressure. This increase in blood pressure can be dangerous for those who have hypertension or other cardiovascular diseases. For this reason , people with hypertension should limit caffeine consumption to 200 milligrams per day or less to prevent unnecessary spikes in blood pressure.(Hanes, 2013)