Veins

Definition

Veins are blood vessels that carry deoxygenated blood towards the heart. They have valves to prevent backflow and rely on skeletal muscle contractions to aid blood flow.

5 Must Know Facts For Your Next Test

1. Veins have thinner walls compared to arteries and contain less smooth muscle.
2. The largest veins in the body are the superior and inferior vena cava, which return blood to the right atrium of the heart.
3. Venous valves are crucial for preventing the backflow of blood, especially in the limbs.
4. Veins can expand more than arteries due to their thin walls, allowing them to hold a larger volume of blood.
5. Varicose veins occur when veins become enlarged and valves fail, leading to pooling of blood.

Review Questions

• What is the primary function of veins in the cardiovascular system?
• How do venous valves contribute to proper blood circulation?
• Why are veins able to hold a larger volume of blood compared to arteries?

Related terms

Arteries: Blood vessels that carry oxygenated blood away from the heart under high pressure.

Capillaries:

Microscopic blood vessels where exchange of gases, nutrients, and waste occurs between blood and tissues.

Valves (in veins): Structures within veins that ensure unidirectional flow of blood toward the heart by preventing backflow.