[Solved] Which of the following statements is/are true regarding vein

Which of the following statements is/are true regarding veins in human beings?

A. They mostly carry carbon dioxide rich blood to the heart.

B. They have thick walls.

C. They have valves which allow blood to flow in one direction.

D. They are superficially locked under the skin 

Answer (Detailed Solution Below)

Option 2 : A, C, D 

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10 Questions 10 Marks 10 Mins

Concept:

Human circulatory system:

• The organ system of human beings or other organisms which is responsible for the transport of materials inside the body is called the circulatory system.
• Our circulatory system consists of a muscular pumping organ called the heart, arteries, veins, capillaries, and blood.
• The heart has two atria and two ventricles.
• The heart acts as a pump to push out blood. 
• The arteries, veins, and capillaries act as tubes or pipes through which blood flows. These tubes which carry blood are called blood vessels.
• Arteries carry oxygenated blood away from the heart except the pulmonary artery carries deoxygenated blood.
• Veins carry deoxygenated blood away from the heart except the pulmonary veins carry oxygenated blood.

Explanation:

• The blood vessels carrying the blood from the body towards the heart are called veins.
  • ​Veins carry CO₂-rich blood from all parts of the body back to the heart. Hence, statement A is correct.
• Veins have thin walls whereas arteries have thick elastic walls. Hence, statement B is incorrect.
• Veins have valves to ensure blood flows only towards the heart. Hence, statement C is correct.
  • ​The one-way valves in veins prevent the blood from flowing backward & and help to force the blood to move towards the heart.
• They are situated superficially under the skin. Hence, statement D is correct.

Thus, the correct statements are A, C , and D.

Additional Information Open circulatory system:

• In an open circulatory system, the blood is not enclosed in the blood vessels and bathes the organs and tissues directly
• there is no distinction between blood and interstitial fluid
• Ex. Spiders, cockroaches, and prawns

Closed circulatory system:

• the heart pumps blood through vessels that are separate from the interstitial fluid of the body
• The blood vessels are found throughout the body and form the plumbing circuit of the body.
• Ex. Rabbit, Lion, Whale

Key Points 

• For double circulation, there are 2 circulatory pathways: 
  • Systematic circulation
  • Pulmonary circulation
• Systematic circulation 
  • It carries oxygenated blood from the heart to all parts of the body through a complex system of arteries and capillaries.
  • It also carries deoxygenated blood from these organs back to the heart through veins.
• Pulmonary circulation 
  • After the heart receives the deoxygenated blood from different parts of the body, it pumps blood to the lungs for expelling the CO2 and collecting oxygen.
  • After that, the oxygenated blood is sent back to the heart for systematic circulation.