KNOW YOUR BODY-BONES AND JOINTS

There  are  more than 200   bones   in our  body.All  together  they   form  the body's  hard skeleton   framework.As  we grow up  ,the bones grow  longer  thicker  .Bones  are composed    mainly  of  calcium,phosphorus  and a fibrous  substance  known  as collagen.Bones   give  a definite    shape  to  the  body.Each  bone  is made up  of ,hard  exterior  surrounding,but a spongy  ,lighter   interior .The  soft  organ are also  protected  under the  hard  shield of bones.Bones are  very    strong  but  they  can break .Long  bones  are  hollow  and the cavity  contains  marrow  ;This  is  a  soft pulpy tissue ,from  which red  and white blood  cells are  produced.Some  bones fit  together  ,others  slide over  each other.
The  place  where  the bones meet are  called joints  .So  joints  are the movable   connections .Our  knees ,spine ,shoulder and  elbows,are some joints  where  bones meet.In the limbs,the joints   are highly  mobile but  the movement  of  the spinal  column is limited.This  is  because  of the  vertebral   bodies that are linked together.There are several  different types  of  joints.For example ,the   finger joint  are hinge  joint  that  allows  only  bending and straightening.On  the other hand  the hip  is a ball   and socket  joint,  that  allows  a femur   a variety  of movements.The  human  hand  has 27  bones ,our  face has 14  bones.We  have over 230  movable  and semi moveable   joints in our body.There are 206  bones  in  our  Skeleton.