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HKDSE_Biology
Transport in Organisms (Lab. Schedule)
Class:______ Names:___________________________
Date:_______________
Aim:
To examine a pig’s heart
Procedure:
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Distinguish between the dorsal & ventral sides of the heart. Note that the thin-walled veins arise from
the dorsal side while the thick-walled pulmonary artery arises from the ventral side.
Place the heart with the ventral side upwards (facing you).
Identify the atria, ventricles & the major blood vessels associated with the heart.
Dissect the heart to study its internal structures starting from the bottom (the tip) with the help of
scalpel, scissors, forceps & a seeker.
Examine the dissected heart & note structures inside.
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Ventral view / dorsal view* of a dissected pig
heart (delete as appropriate)
Bicuspid valve
Left atrium
Aortic / semilunar valve
Vena Cava
Right atrium
Tricuspid valve
Right ventricle
Interventricular septum
Papillary muscle
Left ventricle
Questions:
1. Compare the relative thickness of the wall between atria & ventricles. Account for this difference.
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2.
Compare the relative thickness of the wall between right ventricle & left ventricle. Account for this
difference.
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3.
Name the valve that prevents the backflow of blood from left ventricle to left atrium.
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4.
Name the valve that prevents the backflow of blood from pulmonary artery to right ventricle.
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5.
Will the blood in left ventricle be mixed with that in right ventricle? What is the importance of this
feature?
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6.
Which heart chamber first receives blood coming from the liver?
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7.
Which heart chamber first receives blood coming from the lungs?
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8.
Are the heart tendons elastic or inelastic? What is their function?
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-- End of Experiment –
HKDSE_Biology
Transport in Organisms (Lab. Schedule) (Answer)
Aim:
To examine a pig’s heart
Questions:
1. Compare the relative thickness of the wall between atria & ventricles. Account for this difference.
A. The wall of ventricles is thicker because ventricles must generate a greater force to pump blood (over a
greater distance) to different parts of the body. The atria only pump blood to ventricles (which is close
to the atria).
2.
A.
Compare the relative thickness of the wall between right ventricle & left ventricle. Account for this
difference.
The wall of left ventricle is thicker because left ventricle must generate a greater force to pump blood
over a much longer distance (over the whole body except the lungs). Right ventricle pump blood to
lungs only (which are very close to the heart).
3.
A.
Name the valve that prevents the backflow of blood from left ventricle to left atrium.
Bicuspid valve / Atrio-ventricular valve
4.
A.
Name the valve that prevents the backflow of blood from pulmonary artery to right ventricle.
Semilunar valve
5.
A.
Will the blood in left ventricle be mixed with that in right ventricle? What is the importance of this
feature?
No, it will not. This feature ensures that the oxygenated blood in the left chambers does not mix with
the deoxygenated blood in the right chambers. In this way all organs (except the lungs) are supplied
with fully oxygenated blood.
6.
A.
Which heart chamber first receives blood coming from the liver?
It is the right atrium.
7.
A.
Which heart chamber first receives blood coming from the lungs?
It is the left atrium.
8.
A.
Are the heart tendons elastic or inelastic? What is their function?
They are inelastic. They prevent the valves between atria and ventricles from being turned into the
atria during ventricular contraction.