9. (a)
(i) Cardiac muscle may be described as a contractile tissue - Leaving Cert Biology - Question 9 - 2004
Question 9
9.
(a)
(i) Cardiac muscle may be described as a contractile tissue. Explain the meaning of the underlined term.
(ii) Which chamber of the heart has the greatest a... show full transcript
Worked Solution & Example Answer:9. (a)
(i) Cardiac muscle may be described as a contractile tissue - Leaving Cert Biology - Question 9 - 2004
Step 1
Explain the meaning of the underlined term.
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Answer
The term 'contractile' refers to the ability of cardiac muscle to shorten or contract. This unique property enables the heart to pump blood effectively by allowing the muscle fibers to tighten during each heartbeat.
Step 2
Which chamber of the heart has the greatest amount of muscle in its wall?
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Answer
The left ventricle has the greatest amount of muscle in its wall. This is necessary to generate the high pressure required to pump oxygenated blood throughout the body.
Step 3
Describe how you dissected a mammalian heart in order to investigate the internal structure of atria and ventricles.
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To dissect a mammalian heart, I first identified the dorsal and ventral sides, ensuring the ventral side was facing up. I placed the heart on a board, using a scalpel to carefully cut through the pericardial sac and opened the heart to view the internal structure. I ensured to wear safety goggles and gloves for protection throughout the dissection.
Step 4
Draw a labelled diagram of your dissection to show the location and structure of the bicuspid and tricuspid valves.
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The diagram should illustrate both the bicuspid valve located between the left atrium and left ventricle, as well as the tricuspid valve between the right atrium and right ventricle. Each valve should be properly labelled to highlight their structures.
Step 5
State the procedure that you followed to expose a semilunar valve.
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To expose the semilunar valve, I either cut the aorta or the pulmonary artery at their base, allowing visibility of the valve structure beneath.
Step 6
What is the function of a semilunar valve?
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The function of a semilunar valve is to prevent the backflow of blood into the ventricles. It allows blood to flow from the ventricles into either the aorta or the pulmonary artery during contraction and closes to keep blood from returning during relaxation.
Step 7
Where in your dissection did you find the origin of the coronary artery?
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In the dissection, I found the origin of the coronary artery at the aorta, near the semilunar valve, where it branches off to supply blood to the heart muscle itself.
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