How does caffeine stimulate the body?

Question

scientific explanation if posssible. will give ten points to best answer

Answer 1

The attraction to caffeine - medically known as a trimethylxanthine (a xanthene alkaloid) - probably stems from the energizing, and stimulating effects it has on the brain.

. Although it is taken in a variety of ways, many of which are pleasurable to the taste buds, pure caffeine in its isolated form actually has the appearance of a white, crystalline power, and tastes very bitter.

Before being used for commercial production, or sold in its natural state, caffeine is taken from, or found in, a variety of sources:

Tea

The coffee tree

Guarana berries

Kola nut

Cocoa

Yerba mate

Essentially a central nervous system stimulant, caffeine is used medically to stimulate cardiac function and as a mild diuretic (to produce urine production and help with water excretion from the body by inhibiting the reabsorption of sodium and water from the kidneys). However, its main use, as alluded to earlier, is as a recreational energy booster, which increases feelings of alertness.

Answer 2

it stimulates the mind, not the body, it is similar in effect to adrenaline, a netural substance from the adrenal gland in the brain.

it tells your brain to get into gear and start working at a higher capacity, this speeds up the heart rate and gets oxygen flowing around the body quicker, thus releasing stored energy

Answer 3

Caffeine stimulates body by inhibiting adenosine. Adenosine is an inhibitory neurotransmitter, believed to play a role in promoting sleep and suppressing arousal, with levels increasing with each hour an organism is awake. The caffeine molecule is structurally similar to adenosine. It binds to adenosine receptors on the surface of cells without activating them, and blocks them from the effect of adenosine. By doing so, caffeine allows for continued stimulation of neurons that otherwise would not fire.

Answer 4

It increases heart rate, constricts blood vessels and up to 1000mg can give cardiac arrest

Answer 5

What are the short term effects of caffeine on the body?

Caffeine increases heartbeat, respiration, basal metabolic rate, gastroenteric reflexes, and the production of stomach acid and urine; and it relaxes smooth muscles, notably the bronchial muscle. All of these changes vary considerably among people and may depend upon the individual's sensitivity to this drug, his/her metabolism, or upon whether the consumer habitually uses or rarely uses caffeine. How long caffeine's effects last is influenced by the person's hormonal status, whether he/she smokes or takes medications, or has a disease that impairs liver functioning.

Subjectively, people report that caffeine gives them a "lift." They feel less drowsy, less fatigued, more capable of rapid and sustained intellectual effort. They also report improved performance of some manual tasks such as driving. However, caffeine may restore only those abilities or feelings the person had before fatigue or boredom set in. Studies have also shown that caffeine decreases reaction time to both visual and auditory stimuli; it does not significantly alter numerical reasoning (arithmetic skills) or short-term memory; and it can diminish performance of manual tasks that involve delicate muscular coordination and accurate timing.

How long does it take to feel caffeine's effects?

Caffeine is rapidly absorbed through the stomach and small intestine into the bloodstream, where it takes about 15-45 minutes to reach peak levels. The level of caffeine in the blood reaching the brain determines the potency of its effects on the body. Usually the central nervous system is maximally stimulated within 30-60 minutes. Caffeine is metabolized by the liver and eventually its metabolites are excreted in urine, although caffeine can also be secreted in saliva, s***n, and breast milk.

Caffeine will continue to have an effect on the body as long as it remains in the blood. The time required for the body to eliminate one-half of the total amount of caffeine consumed (or caffeine's half-life) varies from several hours to several days, but for the average non-smoking adult it is about 3-4 hours.1, 2 Several factors can lengthen caffeine's half-life, such as some medications, liver diseases, pregnancy, and the level of enzymes in the liver needed for caffeine metabolism. The half-life of caffeine in a pregnant women is 18-20 hours; the half-life in women taking oral contraceptives is up to 13 hours. Other factors, such as smoking can shorten caffeine's half-life. Half-life in a newborn baby may be as long as 30 hours.

What are the symptoms of caffeine overdose?

Caffeine stimulates the central nervous system and can produce a variety of effects elsewhere in the body. The symptoms of a caffeine overdose ("caffeinism") will vary, according to individual differences and the amount consumed. Doses ranging from 250 to 750 mg (2 to 7 cups of coffee or tablets of NoDoz) can produce restlessness, dizziness, nausea, headache, tense muscles, sleep disturbances, and irregular heart beats. Doses of over 750 mg (7 cups of coffee) can produce all of the above as well as a reaction similar to an anxiety attack, including delirium, drowsiness, ringing ears, diarrhea, vomiting, light flashes, difficulty breathing, convulsions (extreme overdose). These amounts of caffeine may come from a single dose or from multiple doses at short intervals. Besides caffeine's effects, the essential oils of coffee may cause gastrointestinal irritation and diarrhea, and the high tannin content of tea can result in constipation.

How does caffeine affect sleep?

Studies of the effect of caffeine on sleep have shown that one strong cup of coffee, drunk 30-60 minutes before going to sleep, can cause restlessness and difficulty falling asleep, increased body movements, a tendency to be awakened more readily by sudden noises, and a decreased quality of sleep.

The wide variation in caffeine's effects on sleep may be related to whether the person is a habitual, heavy user or a non-user of caffeine. Non-users report greater difficulty with sleep after consuming caffeine. Heavy users may also experience sleep disturbances; however, their increased tolerance to the effects of caffeine affects their perceptions of disturbed sleep. Often they sleep for shorter periods of time, but have grown accustomed to this pattern.

If you use caffeine and are having trouble sleeping, you may want to try cutting back on your total daily intake or avoid consumption 5-7 hours before you plan on sleeping, to allow time for the caffeine to be metabolized.

Caffeine and Health Problems

HEARTBURN - In some people, coffee has been shown to relax the sphincter muscles at the lower end of the esophagus, allowing the stomach contents to "back up" into the esophagus; this is called heartburn. Caffeine alone has no effect on the sphincter muscles, so other substances in coffee apparently cause the heartburn.

ULCERS - Caffeine can increase the secretion of both acid and pepsin in the stomach, which could exacerbate an existing ulcer. However, since both "regular" and decaffeinated coffees have also been shown to stimulate the gastric mucosa and increase stomach acid secretion, caffeine is probably not the only component of coffee responsible.

FIBROCYSTIC BREAST DISEASE - In the late '70's and '80's, several well-publicized studies linked caffeine consumption with benign fibrocystic breast disease (FBD). More recent investigations, however, have not supported these findings. Individual women may notice a decrease in palpable breast lumps, the symptoms of FBD, when they limit their caffeine intake, although research has not shown a direct association.

HEART PROBLEMS - Caffeine has been shown to cause cardiac arrhythmias (irregular heartbeats) in certain individuals; often persons with heart disease are told to avoid caffeine altogether. However, no evidence shows that caffeine is a causative factor in the development of heart disease. Also see "Has coffee drinking been linked to heart disease?" in this section.

HEART DISEASE - The relationship between coffee drinking and heart disease has been investigated in numerous studies but strong, independent risks associated with coffee drinking have not been clearly documented. Researchers at Johns Hopkins Medical Institute recently found heavy coffee drinkers (defined as five or more cups per day) were two to three times more likely to have coronary heart disease than were nondrinkers (NEJM, October 16, 1986). This relationship was true even when accounting for other important risk factors such as age, smoking habits, serum cholesterol and blood pressure.

However, the study did not control for the effects of diet, sedentary lifestyle or high levels of occupational stress. Nor did it indicate the exact quantity in ounces of coffee consumed, the type of coffee (regular or decaffeinated), the brewing method, or the use of cream or sugar.

If coffee drinking does increase the risk of heart disease, it may do so through its effect on cholesterol. A few studies have linked heavy coffee consumption to elevated total serum cholesterol, although caffeine alone does not seem to be responsible. Perhaps it's not even the coffee, but a high saturated fat diet among heavy coffee drinkers that's increasing the risk of heart disease. Increased coffee consumption by men has been associated with increased calorie consumption from fat and increased cholesterol intake. (Adapted from DNS ALERT, Cornell Cooperative Extension, Dec. 1986)

Addiction and Withdrawal

Caffeine is addictive according to several definitions of 'addiction'. It causes withdrawal symptoms after cessation of heavy use (most commonly headaches) and regular users develop tolerance and experience cravings when ceasing use. Regular users can also become emotionally and mentally dependent upon their daily caffeine (coffee, soda, etc).

Withdrawal Symptoms

Caffeine has the potential to produce tolerance, which means that increased amounts of the drug are needed to achieve a consistent effect. Withdrawal symptoms can occur when use of caffeine is stopped abruptly. Users may experience fatigue, and most commonly, headaches. Primary withdrawal effects last for only a few days though mild withdrawal effects can last as long as a week or two.

craving

tiredness, lethargy

confusion and inability to focus

headaches, which may not respond to painkillers, but may abate with the intake of caffeine

Answer 6

Caffeine increases heartbeat, respiration, basal metabolic rate, gastroenteric reflexes, and the production of stomach acid and urine; and it relaxes smooth muscles, notably the bronchial muscle. All of these changes vary considerably among people and may depend upon the individual's sensitivity to this drug, his/her metabolism, or upon whether the consumer habitually uses or rarely uses caffeine. How long caffeine's effects last is influenced by the person's hormonal status, whether he/she smokes or takes medications, or has a disease that impairs liver functioning.

Subjectively, people report that caffeine gives them a "lift." They feel less drowsy, less fatigued, more capable of rapid and sustained intellectual effort. They also report improved performance of some manual tasks such as driving. However, caffeine may restore only those abilities or feelings the person had before fatigue or boredom set in. Studies have also shown that caffeine decreases reaction time to both visual and auditory stimuli; it does not significantly alter numerical reasoning (arithmetic skills) or short-term memory; and it can diminish performance of manual tasks that involve delicate muscular coordination and accurate timing.