12.1-2: The Blood Vessels
There are three main types of blood vessels:
a) Arteries carry blood away from the heart. Artery walls have thick muscles to help blood flow.
b) Veins carry blood back to the heart. Veins have less muscle in their walls than arteries. They have
valves to prevent blood from flowing backwards. Skeletal muscles surrounding the veins also help to
keep blood moving forward.
c) Capillaries are spread throughout the body and are only one cell thick. Nutrients, gases and wastes in
the capillaries diffuse between the circulatory system and the body cells.
Definitions:
Blood Pressure:
Systolic Pressure
Diastolic Pressure:
Sphygmomanometer:
Blood Pressure
The blood pressure in a normal healthy individual is 120.80 mm Hg (systolic/diastolic). Higher than
normal blood pressure may indicate a disorder of the circulatory system, such as; artery damage, heart
attacks, strokes, and kidney failure.
Cardiac fitness can be determine using the following equations
Cardiac output = Heart rate X Stroke volume
Definitions:
Cardiac Output:
Hear Rate:
Stroke Volume:
The average person’s cardiac output is 4900mL/min at rest. Cardiovascular exercise strengthens the
circulatory system and increases the stroke volume.
Learning Check:
1. What is each type of blood vessel called? [k/u]
a) Vessels that carry blood to the heart
b) Thin vessels throughout the body where diffusion occurs
c) Vessels that carry blood from the heart
2. a) What causes blood to move through the arteries? [k/u]
b) What keeps blood moving through the veins? [k/u]
3. a) What is systolic blood pressure? [k/u]
b) What is diastolic blood pressure? [k/u]
4. When the average person is running, will their cardiac output be higher or lower than 4900 mL/min?
Why? [app]
5. a) A person has arresting cardiac output of 4900 mL/min and a heart rate of 90 beats per minute.
What is the person’s stroke volume? [app]
b) An athlete has a normal cardiac output, but a very low heart rate. Why might this be?