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24 pts
9.2 – The Mammalian Circulatory System
1. Who was William Harvey and what did he establish? (2 points)
During the 17th century, William Harvey established that mammals have a cyclic
circulatory system and disproved the fact that many people thought that blood was
absorbed by the skin. He established that blood will travel in only one direction through
the circulatory system (flowing away from the heart in arteries, and back towards the
heart in veins). He never found a place where blood stops flowing from the heart and
begins to make its return.
2. What is cardiac circulation? (1 point)
The mammalian heart is a closed, complete, double loop system. The blood vessels are
organized into three primary cycles. The route that is taken by blood within the heart is
called cardiac circulation.
3. What is the difference between pulmonary and systemic circulation? How much
blood is found in each type of circulation at any given moment? (2 points)
The path of the blood from the heart to the lungs and back is called pulmonary
circulation (10% of the volume of blood in your body is found in this type of circulation).
The path of the blood from the heart to the rest of the body is called systemic
circulation.
Systemic circulation includes all of the blood vessels other than those
associated with the lungs (90% of the volume of blood in your body is found in this type of
circulation).
4. What are the three main components of a circulatory system? (3 points)
 The transport vessels (arteries, veins, capillaries), which conduct fluid from one area
to another;
 The transport medium (blood), which is the specialized fluid tissue that carries
substances around the body;
 The pumping mechanism (the heart).
5. Make a simple flow chart to show how blood flows away and back to the heart.
Use the second last paragraph on page 305 to help you. (2 points)
Blood travels from the heart to an artery to and arteriole and then to a capillary network
where gases, food, hormones and wastes are exchanged across the capillary wall and the
interstitial fluid bathing each cell of the body. The capillaries then empty into venules and
progressively larger veins that carry blood back to the heart.
6. Check out figure 9.7 on page 306. Summarize the graph in a few sentences.(2
points)
As vessels get smaller and smaller, friction increases and blood pressure drops. This
means that blood moves very slowly through the capillaries. The aorta and arteries contain
the greatest pressure as they are immediate to the heart. The capillaries have very little
blood pressure and the veins have the least amount of total blood pressure.
7. List three interesting facts about arteries. (3 points)
 3 different structural layers
 Outer layer has elastic fibres.
 Middle layer is made up of circular bands of elastic fibres and smooth muscle.
 Inner layer is a single layer thick to reduce the friction as blood rushes through it.
8. If you were to extend the arteries, veins and capillaries from end to end, what
distance would they stretch? (1 point)
The arteries, veins and capillaries in your body would stretch a distance of approximately
160 000 km.
9. List three interesting facts about veins. (3 points)
> Compared to an artery, a vein has a thinner wall and a larger inner circumference.
> Veins are not as elastic as arteries, but have greater capacity.
> Veins contain 2x as much blood as the arterial system.
> Blood travels very slowly in the veins.
> Due to the fact that veins can’t contract they contain little flaps (one-way valves) which
help keep blood moving towards the heart. They must be able to overcome the pull of gravity.
> Muscle contraction will help push blood back via veins to the heart.
10.Why may Mrs. LeBlanc suggest that you jiggle your feet if you are feeling sleepy
during the Biology 11 exam? (1 point)
Movement assists the flow of blood and speeds the delivery of oxygen around the body,
especially to the brain!
11. List three interesting facts about capillaries. (3 points)
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Smallest of the blood vessels.
Reach every corner of the body.
Single cell walls
8 micrometers thick just large enough for one red blood cell to pass through single file.
Regulates the movement of fluids and other materials into and out of the blood stream.
Blood is contained in the capillary network and doesn’t escape into the body’s cells
directly.