Cardiovascular System

Cardiac Output varies with the demands of the body.

Provide at least 3 examples of reasons cardiac output may vary (increase or decrease).

Determine your "at rest" heart rate, and then extrapolate to beats per hour and beyond.

Your age: _________________

Number of beats in 15 seconds: _____________

Multiply by 4 to get number of beats per minute: _____________

Multiply your answer for per minute by 60 to get per hour: ________

How many beats would there be per year? ___________________

If your heart beat stayed constant how many beats would there be at 85 years old?

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To calculate cardiac output, you need to know your body surface area in square meters and your cardiac index (how much blood is pumped per minute for every square meter of body surface area).

To find your body's surface area, first use a conversion tool (Google) to determine your weight in kilograms and your height in centimeters.

1. Weight =___________ (kilos) Height = ______________ (cm)

On a nomogram, find your weight in the right column and your height in the left column.

Place a straight-edge on the nomogram so the weight and height are connected. The point where the straight-edge crosses the center column denotes your body's surface area in square meters.

2. What does the nomogram denote your body’s surface is? _______

How much blood the heart pumps for every square meter of surface area (cardiac index) varies with the age of the individual. For teens and adults, the average cardiac index is 2.5 - 4.0 liters/m2/minute.

We will use 2.75 liters/m2/minute for our measurement.

Multiply your body surface area by the cardiac index (2.75 l/m2/minute) to determine the liters of blood pumped by your heart in one minute (cardiac output).

1. Body surface area _____________ x 2.751/m²/minute = ___________liters per minute.

2. How does your volume per minute compare to a 2 liter beverage bottle? Is it more, less, about the same?

________________________________________________________

3. How much blood is pumped in an hour? In one day? ____________

How much blood does your heart pump in one beat?

This volume is called stroke volume.

How would you calculate stroke volume? (Answer: liters pumped per minute divided by beats per minute).

1. What is your stroke volume? _______________

2. Convert the stroke volume to milliliters.

_______liters per minute x 1000 = ____________ml per beat.