Answer the following questions in relation to blood vessels in the human body - Leaving Cert Biology - Question c - 2005
Question c
Answer the following questions in relation to blood vessels in the human body.
(i) Valves are present in veins. What is their function?
(ii) Why are valves not nee... show full transcript
Worked Solution & Example Answer:Answer the following questions in relation to blood vessels in the human body - Leaving Cert Biology - Question c - 2005
Step 1
Valves are present in veins. What is their function?
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Answer
The function of valves in veins is to prevent the backflow of blood. They ensure that blood flows in one direction toward the heart, counteracting the effects of gravity and low pressure in the venous system.
Step 2
Why are valves not needed in arteries?
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Answer
Valves are not needed in arteries because blood in the arteries is under high pressure, which is generated by the pumping action of the heart. This pressure is sufficient to keep the blood flowing consistently forward.
Step 3
Which has the bigger lumen (cavity), an artery or a vein?
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Answer
A vein has a bigger lumen compared to an artery. This larger cavity allows veins to accommodate varying volumes of blood as they are responsible for returning blood to the heart.
Step 4
The wall of capillaries is only one cell thick. How is this related to their function?
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Answer
The one-cell-thick walls of capillaries are crucial for their function, allowing for easy diffusion of substances in and out of the blood. This thin barrier facilitates the exchange of gases, nutrients, and waste products between blood and surrounding tissues.
Step 5
How does a portal vein differ from other veins?
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A portal vein differs from other veins in that it carries blood between two organs instead of directly back to the heart. This allows for the transport of nutrients and other substances between organs, such as from the digestive system to the liver.
Step 6
Name the following blood vessels:
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Answer
The vessels that carry blood from the aorta to the kidneys are known as renal arteries.
The vessels that supply the heart's muscle with blood are known as coronary or cardiac arteries.
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