Essential Book Of Anatomy & Histology In Human Being

Humans are vertebrates animals having a vertabral column or backbone. They rely on a sturdy internal frame that is centered on a prominent spine. The human skeletal system consists of bones cartilage ligaments and tendons and accounts for about 20 percent of the body weight.The living bones in our bodies use oxygen and give off waste products in metabolism. They contain active tissues that consume nutrients require a blood supply and change shape or remodel in response to variations in mechanical stress.The cell is defined as a distinct entity by having a thin skin or plasmalemma/cell membrane separating off from the outside a soft viscous almost fluid cytoplasm in which are suspended a number of firmer recognizable structures - organelles and inclusions - and one or more nuclei. The nucleus likewise is a mass of material enclosed in nuclear membranes.