Chapter 4 Flashcards
Measurement Systems, Units, and Equivalencies
What are the three main measurement systems used in medicine?
Household (U.S. Customary) System
Metric (International) System
Apothecary System
What is the basic unit of volume in the metric system?
Liter (L)
How many milliliters (mL) are in 1 liter (L)?
1,000 mL
What is the basic unit of weight in the metric system?
Gram (g)
Convert 1 kilogram (kg) to grams (g).
1 kg = 1,000 g
How many grams (g) are in 1 milligram (mg)?
1,000 mg = 1 g
What is the smallest unit of measurement in the metric system used in pharmacy?
Microgram (mcg or µg)
How many micrograms (mcg) are in 1 milligram (mg)?
1,000 mcg = 1 mg
In the household system, how many teaspoons (tsp) are in one tablespoon (Tbsp)?
3 tsp = 1 Tbsp
Convert 1 cup (c) to ounces (oz) in the household system.
1 cup = 8 oz
What is the abbreviation for tablespoon in the household system?
Tbsp or T
What is the basic unit of length in the metric system?
Meter (m)
Convert 1 meter (m) to centimeters (cm).
1 m = 100 cm
What is the household abbreviation for pound?
lb
How many ounces (oz) are in one pound (lb) in the household system?
16 oz = 1 lb
In the apothecary system, what is the basic unit of weight?
Grain (gr)
What is the apothecary unit of volume?
Fluid dram (fl ʒ)
How many fluid drams (fl ʒ) are in one fluid ounce (fl ℥)?
8 fluid drams = 1 fluid ounce
What are milliequivalents (mEq) used for in pharmacy?
To express the concentration of electrolytes (e.g., sodium, potassium, calcium).
What is the meaning of the abbreviation “IU” in pharmacy?
International Unit – used to measure the potency of biologics like insulin or vitamins.
What are some common abbreviations used in the household system?
Teaspoon = tsp
Tablespoon = Tbsp
Ounce = oz
Pound = lb
Cup = c
Pint = pt
Quart = qt
Gallon = gal
What are the key rules for expressing measurements in the metric system?
Use decimals, not fractions (e.g., 1.5 mL, not 1½ mL).
Always include a leading zero for values less than 1 (e.g., 0.25 mg).
Do not include trailing zeros (e.g., 2.5 mL, not 2.50 mL).
How many milliliters (mL) are in one cubic centimeter (cc)?
1 mL = 1 cc
What is the standard abbreviation for milliliter?
mL (Note: cc is not recommended for use due to potential for error).
How many teaspoons (tsp) are in one ounce (oz)?
6 tsp = 1 oz
In the household system, how many tablespoons (Tbsp) are in one ounce (oz)?
2 Tbsp = 1 oz
Convert 1 gallon to quarts (qt).
1 gallon = 4 quarts
How is specific gravity defined?
The ratio of the density of a substance to the density of water.
In the apothecary system, what is the abbreviation for grain?
gr
What is the conversion for teaspoons to milliliters (mL) in the household system?
1 tsp = 5 mL
How many milligrams (mg) are in one gram (g)?
1,000 mg = 1 g
What are the common prefixes used in the metric system?
Kilo = 1,000
Centi = 1/100
Milli = 1/1,000
Micro = 1/1,000,000
In the metric system, how many grams are in a kilogram?
1,000 grams = 1 kilogram
What are the common equivalents in the household system for weight?
16 oz = 1 lb
2,000 lb = 1 ton
What are the points to remember about the household system?
Uses fractions and Arabic numerals (e.g., ½ tsp).
Household flatware should not be used to measure medication.
Use a measuring device for accurate dosing.
What are the points to remember about the metric system?
A system of “place values” with the gram, liter, and meter as base units.
Leading zeros should always be used (e.g., 0.25 mL).
Do not use trailing zeros (e.g., 2.5 mg, not 2.50 mg).
What are the points to remember about the apothecary system?
Uses lowercase Roman numerals for numbers below 10.
Fractions are written for numbers less than 1 (e.g., ½ = ss).
Do not combine Roman and Arabic numerals in the same measurement.
How many fluid ounces (fl ℥) are in a pint (pt) in the household system?
1 pint = 16 fluid ounces
