Vein

Definition

A vein is a blood vessel that carries deoxygenated blood towards the heart. They are an essential part of the circulatory system, working alongside arteries and capillaries.

5 Must Know Facts For Your Next Test

1. Veins have valves that prevent backflow of blood, ensuring it flows in one direction towards the heart.
2. The walls of veins are thinner and less elastic compared to arteries because they operate under lower pressure.
3. Veins can be classified into superficial veins, which are close to the skin's surface, and deep veins, which are located deeper within the body.
4. The largest vein in the human body is the inferior vena cava, which carries blood from the lower half of the body to the heart.
5. Infections or inflammation of veins can lead to conditions such as phlebitis or thrombophlebitis.

Review Questions

• What is the primary function of a vein in the circulatory system?
• How do valves within veins contribute to proper blood circulation?
• What distinguishes superficial veins from deep veins?

Related terms

Artery: A blood vessel that carries oxygenated blood away from the heart under high pressure.

Capillary: The smallest type of blood vessel where gas and nutrient exchange occurs between blood and tissues.

Lymphatic Vessel: A structure similar to a vein that transports lymph fluid throughout the lymphatic system.