In this sub-unit of human physiology we will explore contents of:

• Arteries convey blood at high pressure from the ventricles to the tissues of the body
• Arteries have muscle cells and elastic fibres in their walls
• The muscle and elastic fibres assist in maintaining blood pressure between pump cycles
• Blood flows through tissues in capillaries
• Capillaries have permeable walls that allow exchange of material between cells in the tissue and the blood in the capillary
• Veins collect blood at low pressure from the tissues of the body and return it to the atria of the heart
• Valves in veins and the heart ensure circulation of blood by preventing backflow