1. UNIT 4
The Metric System

2. Key Terms
Gram
Liter
Meter

3. Metric System First proposed in 1670 by Gabriel Mouton
Adopted in 1801 by French National Assembly
Official standard for scientific and industrial measurement in 92% of world
Measured in units of 10
Utilizes concept of decimal point
(continues)

4. Metric System
Provides simple, flexible, accurate way to measure length, volume, and weight
Medication dosages may be
In micrograms
In milligrams
In grams
Per kilogram of body weight
(continues)

5. Metric System Volume of medication may be in Other measurements
Milliliters
Cubic centimeters
Other measurements
BP measured in millimeters of mercury (mm Hg)
Wound and lesion size measured in centimeters
Organs measured in grams
(continues)

6. Metric System Laboratory results measured in: Micrograms Milligrams
Grams per deciliter
Units per liter

7. Basic Rules Whole numbers designated by Arabic numbers
Decimal fractions used for numbers less than 1
Prefixes written in lowercase
Abbreviations are same for singular or plural

8. Metric System Uses 14 prefixes Each prefix based on multiple of 10
Medical field uses seven most common prefixes

9. Metric Prefixes Micro- One millionth Milli- One thousandth Centi-
One hundredth
Deci-
One tenth
Deka-
Ten
Hecto-
One hundred
Kilo-
One thousand

10. Fundamental Units
Meter
Length
Liter
Volume
Gram
Mass/Weight

11. Length Meter is fundamental unit of length
1 meter = inches or 3.28 feet
1 inch = approximately 2.5 centimeters

12. Length Meter (m) Length 1 millimeter (mm) 0.001 meter
1 centimeter (cm)
0.01 meter
1 decimeter (dm)
0.1 meter
1 meter (m)
1 meter
1 dekameter (dam)
10 meters
1 hectometer (hm)
100 meters
1 kilometer (km)
1,000 meters

13. Volume Liter is fundamental unit of volume 1 liter = 1.056 quarts
1 liter = 0.26 gallon
1 liter = 2.1 pints
1 mL = 1 cc
(continues)

14. Volume Liter is fundamental unit of volume (cont’d)
Amount of space occupied by 1 milliliter is equivalent to 1 cubic centimeter
1 mL water = 1 g in weight
15 mL = 1 tablespoon

15. Volume Liter (L) Volume 1 milliliter (mL) 0.001 liter
1 centiliter (cL)
0.01 liter
1 deciliter (dL)
0.1 liter
1 liter (L)
1 liter
1 dekaliter (daL)
10 liters
1 hectoliter (hL)
100 liters
1 kiloliter (kL)
1,000 liters

16. Weight Gram is fundamental unit of solids, mass, or weight
1 cc or 1 mL of water = 1 g
1 g = approximately 15 grains
1 g = oz

17. Weight Gram (g) Weight 1 milligram (mg) 0.001 gram 1 centigram (cg)
1 decigram (dg)
0.1 gram
1 gram (g)
1 gram
1 dekagram (dag)
10 grams
1 hectogram (hg)
100 grams
1 kilogram (kg)
1,000 grams

18. Common Equivalents 2 ½ cm = 1 inch 1,000 mL or cc = 1 liter
1,000 mcg = 1 mg
1,000 mg = 1 g
1,000 g = 1 kg
1 kg = 2.2 lb

19. Conversions Set up proportion using metric equivalents
Assign x as value of unknown factor
Solve proportion as learned in Unit 3

20. Moving the Decimal
If converting from larger to smaller, multiply by decimal value of smaller unit (move decimal right)
If converting from smaller to larger, divide by decimal value of smaller unit (move decimal left)

21. Dosage Based on Body Weight
Some medications are ordered as mg/kg
Weight of patient must be expressed in kg

22. Calculating Dose Convert weight to kg Calculate dosage based on weight
Determine number of doses per day
Calculate amount of medication per dose