N

• Nerve - a collection of fibres made up of neurons with a protective sheath through which sensory stimuli and motor impulses pass between the brain or other parts of the central nervous system and other parts of the body

• Nervous system - the system of cells, tissues, organs that regulate the body's responses to internal and external stimuli

• Neuritis - inflammation of a nerve

• Neurones - nerve cells that conduct impulses

• Neutron - an electrically neutral subatomic particle

• Niche - special area of demand for a product or service

• Nucleus - part of a cell that contains hereditary factors or central part of an atom made up of protons and neutrons

• Nutrition - the process by which a living organism assimilates food and uses it for growth and repair