Quantity of caffeine per drink

Coffee (8 oz)	100-200 mg depending on brand
Coca-Cola (20 oz)	57 mg
Pepsi (20 oz)	63 mg
Tea (20 oz)	25-50 mg depending on brand/style
Hershey Milk Chocolate Bar (1.55 oz)	10 mg

Physical responses to caffeine

The effects of caffeine can only be felt when the caffeine is present in sufficient amounts. For most people, from 32 to 200 mg of caffeine acts as a minor stimulant; these amounts have been shown to speed up reactions in simple routinized tasks in laboratory experiments. As noted above, the minor stimulant effect is experienced by some people as pleasant and by others as unpleasant. Steadiness of the hand has been shown to be worse after 200 mg of caffeine. More than 300 mg is enough to produce temporary insomnia. 480 mg has been known to cause panic attacks in panic disorder patients. Amounts of 5 to 10 g (5000-10,000 mg) of caffeine cause death.

Elimination of caffeine from the body

The two primary ways that chemicals are eliminated from the body are through filtration by the kidneys and metabolism by enzymes from the liver. Our bodies eliminate caffeine primarily by the functioning of the kidneys. The kidneys tend to filter out a constant proportion of a chemical, that proportion depending on the particular chemical and individual. In the "average person", about 13% of the caffeine in the body is eliminated each hour.

1. (4 pts) Is the rate of elimination of caffeine from the body linear or exponential? Explain your reasoning.

2. Suppose a person starts the day by drinking 3 cups of coffee containing 130 mg of caffeine each.

1. (4 pts) Let C = mg of caffeine remaining in the body and let t = hours since the 390 mg of caffeine was consumed. Write a function C(t) that expresses the amount of caffeine remaining in the body as a function of time.

C(t) = ____________________________________

2. (15 pts) Determine how much caffeine will be present in this persons body over a 24-hour period. Record those answers in the table below.

Hours after consumption	Amount of Caffeine present (3 decimal places)	Hours after consumption	Amount of Caffeine present (3 decimal places)
0		13
1		14
2		15
3		16
4		17
5		18
6		19
7		20
8		21
9		22
10		23
11		24
12

3. (4 pts) Rounding to the nearest hour, when will the caffeine be reduced to an amount that should no longer have any stimulant effect on the body? (Refer to the reading to determine what this amount typically is?)

3. (5 pts) The time it takes for the amount of a substance present to be reduced by half is called the half-life of the substance. This term is applied in many situations, including the elimination of drugs from the body and the decay of radioactive materials. What is the half-life of caffeine in the body? Round to the nearest whole number?

4. (4 pts) Choose a caffeinated beverage and use the internet to determine the amount of caffeine in one serving. List your information source.

Beverage: ____________________________________________________

# of ounces in one serving:____________ Amount of caffeine in one serving: ____________

Internet Source:____________________________________________________________________

5. Assume you have that drink at the start of our class.

   1. (1 pt) Class Start time: _______________ AM or PM (Online Classes use 9AM)

2. (5 pts) At what time will you have half of the original amount of caffeine in your system? Based on your drink, how much caffeine will be in your body at that time? Show your work.

3. (8 pts) Assume that you go to bed at 11:00 PM, will you still feel the effect of the caffeine when you go to sleep? (i.e. will the caffeine be reduced to an amount that it should no longer have any stimulant effect on your body?) Explain why or why not. Show your work.