Various body functions and processes work to promote health and survival homeostasis is affected by illness disease and injury you help patients and residents meet their basic needs your care promotes comfort healing and recovery therefore you need to know the bodys normal structure anatomy and function physiology they will help you understand signs symptoms and the reasons for care and procedures you will give safe and more effective care. The eye has three layers o the sclera the white of the eye is the outer layer it is made of tough connective tissue o the choroid is the second layer blood vessels the ciliary muscle and the iris make up the choroid the iris gives o the retina is the inner layer it has receptors for . In the human body the simplest functioning unit is the cell which is the basic unit of life there are many different types of cells in the body and when cells with the same function or origin are organized in groups the formation of tissue results in turn combinations of tissues form organs such as the heart lungs brain and skin. Body structures functions has been completely updated and now includes great new features such as a review of medical terminology case studies to promote critical thinking and complete coverage on the effects of aging a new chapter on infection control has been added to give more coverage to this critical topic in health care what people are saying write a review user review flag as