Animals: Circulatory System - Blood Vessels

Animals: Circulatory System - Blood Vessels

• Blood vessels form an intricate network throughout the body, comprised of: arteries, veins, and capillaries.

• Arteries carry oxygenated blood (with the exception of the pulmonary artery) away from the heart and have thick, strong and elastic walls to withstand high blood pressure.

• The arteries divide into smaller vessels known as arterioles, which further subdivide into tiny capillaries.

• Capillaries are the smallest of the blood vessels and function to allow substances to be exchanged between the bloodstream and cells. Their walls are only one cell thick, which allows efficient diffusion of oxygen, nutrients, and waste products.

• Deoxygenated blood (apart from the pulmonary vein) is returned to the heart via veins, which have thinner walls than arteries and have valves to prevent the backflow of blood.

• Arteries have a narrow lumen (the inside of the vessel), which helps maintain high blood pressure whilst veins have a wider lumen and lower blood pressure.

• Blood in capillaries is at a lower pressure than in arteries but higher than in veins. This helps to push out oxygen and nutrients into the cells, but prevent large amounts of blood from being lost through the thin capillary walls.

• The structure of each type of blood vessel is correlated to its function in the body. Understanding these differences helps to explain how blood is transported and how substances are exchanged efficiently in the circulatory system.

• Cardiovascular diseases, such as atherosclerosis, occur when there’s damage to the blood vessels. In the case of atherosclerosis, the artery walls thicken due to accumulation of fatty acids, leading to restricted blood flow. This emphasises the importance of a healthy circulatory system.

• In summary, blood vessels play a crucial role in the complex circulatory system, carrying nutrients, oxygen, and waste materials to and from the heart and rest of the body.