Download Heart Lab

Names__________________________
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Heart Lab
I. External
This is a sheep's heart. Since sheep are mammals, this heart is a lot like yours.
1. How many chambers does a mammal’s heart have? _____________
Find the top chambers (right and left atria). They are very small and are gray or brown
in color. Now locate the bottom chambers (right and left ventricles). The ventricles
make up 95% of the heart. They are hard to see because they are covered with fat, but
they are usually gray or brown in color.
2. Why do the ventricles have bigger muscles than the atria?(Think
function)____________________________________________________
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3. Why is the left ventricle stronger than the right? (Hint: see pages 202-203)
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Find the fat deposits on the heart. As we age, more fat builds up.
4. Why might this be unhealthy?__________________________________________
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5. What can we do to keep fat buildup to a minimum?_________________________
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Find the small blood vessels on the surface of the heart. These are called coronary
blood vessels.
6. What do you think their purpose is?(See Sec. 11.11) ________________________
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7. Shade in the coronary blood vessels
in this diagram. One of these
is blocked. So don't shade in
the parts that blood can't get to.
8. What do you think will happen
to the part of the heart that
can't get its blood supply?
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9. What is this health problem called? (Hint:
It is very common and you have heard
these two words!)
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10. Find the major blood vessels leading into and out of the chambers. This is
difficult. There are 2 arteries and 3 veins, but these branch into other blood vessels so it
may look like more than 5. Also, the butcher may have cut off one or more of the blood
vessels so you may just see a hole. See if you can guess which are veins (enter into the
atria) and which are arteries(exit out the ventricles). Make a quick sketch of the
top(where the holes are) of the heart and label which holes you think are the vein
holes(in to the heart) and which holes you think are the artery(away from heart) holes.
11. Using p. 202-3, draw a view of the heart major blood vessels. Label the pulmonary
artery, aorta, pulmonary vein, superior vena cava(top vein returning to right atrium from
body), and inferior vena cava(bottom vein returning to right atrium from body).
II. Internal
Notice how much thicker the ventricle walls are than the atria walls. Rholl may need
to help you find the walls.
12. Why are the ventricle walls so much thicker?(Think function)
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Find the one-way valves that separate each atria from its ventricle. They look like
flaps of skin with strings attached to them.
13. Which direction do they allow the blood to flow.
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14. Some people's heart valves wear out and need to be replaced by artificial valves.
Look at the sheep's valves. Which part of the valves(flaps of skin or strings?) do you
think would most likely "break"?
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There are also valves leading out of each ventricle to the aorta and pulmonary artery.
See if you can find these valves.
15. Why wouldn't a heart with no valves work? _____________________________
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See if you can find the same 5(?) major blood vessels you identified yesterday.
Remember arteries lead out of the ventricles and veins lead into the atria.
16. How many did you get right yesterday in problem number 10? _____________
17. Now label the 5 major blood vessels again on the following drawing.(aorta,
pulmonary artery, pulmonary vein, superior vena cava, and inferior vena cava)