Download Part 1: External Anatomy of Heart 5. Insert your index finger into the

Part 1: External Anatomy of Heart
5. Insert your index finger into the right atrium and your thumb into the left atrium.
Squeeze. What is the name of the muscle? What is its function?
Septum. The function is to prevent mixing between the oxygenated and
deoxygenated blood.
Part 2: Internal Anatomy of Heart
Right side of heart
4. Pull the two sides apart and look for three flaps of membrane. These membranes form
the tricuspid valve between the right atrium and the right ventricle. The membranes
are connected to flaps of muscle called the papillary muscles by tendons called the
chordae tendinae or "heartstrings." Explain the function of the tricuspid valve.
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To prevent backflow of blood from the right ventricle to right atrium
During the ventricular systole went the pressure in ventricle is higher than in
atrium
This causes the closing of the tricuspid valves
5. Insert your probe into the pulmonary artery. To which chamber do you probe goes to?
(This is the chamber that the blood from which the blood flows into the pulmonary
artery)
right ventricle
Left side of heart
2. Locate the bicuspid valve between the left atrium and ventricle. This will have two
flaps of membrane connected to papillary muscles by tendons. Explain the function of
the valves.
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To prevent backflow of blood from the left ventricle to left atrium
During the ventricular systole went the pressure in ventricle is higher than in
atrium
This causes the closing of the bicuspid valves
3. Insert a probe into the aorta and observe where it connects to the left ventricle. State
the chamber which the probe appears. (This is the chamber that the blood from which
the blood flows into the aorta)
left ventricle
4. Compare the thickness of the wall of the right ventricle and the left ventricle. Which
is thicker? Explain why one wall is thicker than the other?
 The left ventricle has thicker wall
 The left ventricle pumps blood to the rest of the body which can be long
distance from the heart
 whereas right ventricle pumps blood to lungs which is of a short distance
from heart
 Left ventricle has to have thicker wall to pump hard to produce high
pressure to allow blood to travel to the rest of the body
Aorta and Pulmonary Artery
1.
Compare the thickness of the aorta and pulmonary artery. Which is thicker? Why?
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2.
Aorta is thicker than pulmonary artery
The blood travelling through aorta is from left ventricle hence is of higher
pressre than blood travelling through pulmonary artery
Aorta is thicker to withstand the high pressure
Make an incision up through the aorta and examine the inside carefully for small
membranous pockets. These form the aortic semilunar valves which prevents blood
from flowing back into the left ventricle. What is the function of the valves?
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Prevents backflow of blood from aorta into left ventricle
During diastole when the pressure in ventricle drops
This causes the semilunar valves to close hence preventing backflow
Part 3: Tracing the Flow of blood
Right heart
Deoxygenated blood enters the right atrium (chamber) through the superior vena cava and
inferior vena cava .It passes through the tricuspid valve and enters the right ventricle
(chamber). Blood leaves through the semilunar valve and goes into the
Pulmonary (vessel) artery, to the lungs (organ) to pick up oxygen.
Left heart
Oxygenated blood from the lungs enters the left atrium (chamber) through the pulmonary
vein (vessel) . Blood flows through the Bicuspid valve into the left ventricle (chamber). It
leaves through the semilunar valve, entering the aorta (vessel).
The heart really does feed itself first, because the first branches off the aorta are the right and
left coronary arteries (vessels).