Blood Vessels

Blood Vessels:

Blood vessels transport substances around the body.

5 types of blood vessels you need to know about are:

• Arteries
• Arterioles
• Capillaries
• Venules
• Veins

Arteries:

Arteries carry blood from the heart to the rest of the body. The walls of arteries are thick and muscular and they have an elastic tissue that can stretch and recoil as the heart is beating. The inner lining of arteries (endotherlium) is folded and this allows the arteries to expand. All arteries except the pulmonary artery transports oxygenated blood around the body.

Arterioles:

Arterioles are smaller than arteries but they are similar because they also have a layer of smooth muscle. The smooth muscle allows them to contract and expand as blood flows through, therefore it controls the amount of blood reaching the tissues.

Capillaries:

These are the smallest of the blood vessels, only one cell thick. Here, substances like glucose and oxygen are exchanged between the cells. Capillaries are adapted for efficient diffusion because they are so thin. Arterioles branch into capillaries.

Venules:

Capillaries connect to venules, the have very thin walls that can contain some muscular tissue as well.

Veins:

Veins are responsible for taking all the blood back to the heart to be oxygenated again. Veins carry blood under a low pressure, they have a wider lumen (inner layer) and have very little elastic or muscle tissue present. Veins also contains valves within them which flip back and stop blood flowing in the wrong direction. All veins (except for the pulmonary vein…