Blood Vessels

Blood Vessels

Types of Blood Vessels

  • The main types of blood vessels in the human body are arteries, veins, and capillaries.
  • These vessels connect to form a closed system of tubs where blood flows continuously.


  • Arteries carry blood away from the heart to the body’s tissues. Their walls are thick and muscular, which manage the high pressure exerted by the heart’s contractions.
  • The major artery is the aorta, which branches out to smaller arteries, arterioles, and eventually capillaries.
  • Arteroiles, the small branches of arteries, play a big role in controlling blood flow into specific areas.


  • Capillaries are the smallest and thinnest blood vessels, only one cell thick, which allows exchange of substances between the blood and body’s cells.
  • The primary function of capillaries is to permit the exchange of oxygen, nutrients, and waste products between the blood and the body tissues.
  • Blood in the capillaries is brought close to body cells due to the vast network of capillaries.
  • Each capillary is so tiny—only big enough to allow red blood cells to pass through in single file.


  • Veins carry blood back to the heart after the oxygen has been used up.
  • They have thinner walls than arteries, less elastic, and contain valves to prevent the backflow of blood.
  • Veins branch into smaller vessels known as venules before connecting with capillaries.
  • The largest veins are the vena cava—the inferior vena cava carries blood from the lower body, and the superior vena cava carries blood from the upper part of the body.

Blood Vessel Functions

  • Blood vessels play a significant role in the regulation of blood flow and blood pressure.
  • They also help to maintain the body’s temperature, delivering nutrients to the body’s cells, and removing waste products.
  • In times of injury, blood vessels constrict to direct more blood to the site for healing.

Ensure to understand the structure and functions of different types of blood vessels to prompt the comprehensive understanding of the circulatory system as a whole.