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A blood vessel carrying blood back towards the heart.
These are the bones that form the spine (vertebral column). There are 7 cervical vertebrae in the neck, 12 thoracic vertebrae at the back of the chest, 5 lumbar vertebrae in the small of the back, then the sacrum (formed by the fusion together of 5 sacral vertebrae), and finally two coccygeal vertebrae forming the lower end of the vertebral column. There is a canal along the length of the vertebral column, and the upper two thirds of this is occupied by the spinal cord, down to the level of the intervertebral disc between L1 and L2 vertebrae.
A tube carrying a fluid within the body. Usually, we use the term in relation to blood vessels, which carry blood: vessels carrying blood away from the heart are called arteries, and vessels carrying blood back towards the heart are called veins. The arterial and venous vessels are linked by the capillaries - the smallest blood vessels. However, the term vessel is also applied to the tubes carrying lymph: lymphatic vessels.
Closely-packed projections from the already-folded lining of the small intestine. Their purpose is to increase the surface area of the lining to facilitate absorption of digested materials into the body. The cells forming the epithelium that covers each villus have microvilli on their outer surface for the same reason.
These are dietary substances required in small quantities by the body for continued health - they are chemicals that the body is unable to manufacture for itself. The main vitamins for human health are summarised in a table.