Skeleton

SKELETON

Constructed from 206 bones,the human skeleton is strong ,flexible framework that supports and shapes the body and produces movement when pulled by muscles. The skeleton also protects soft,internal organs,such as the brain and lungs. bones which make up 20 percent of the body's mass ,are connected to each other at joints and are held together by strong straps of tissue called Ligaments.

1. SKULL

                                                                                     The bone in the  skull protect the brain, provide a framework for the face, and anchor the muscles that produce facial expression The skull consists of 22 bones , 21 of which are locked together by immovable joints called sutures . only the lower jaw (mandible)can move .

Mandible moves to open the mouth for eating,breathing,and speaking.

2. CHEST 

                    

The bones of the chest (thorax)consist of the sternum (breastbone), the ribs, and part of the backbone . Together , they form a protective "cage"that protects the lungs and the heart .

3. FOREARM

The Forearm is made up of two parallel bones -the ulna and the radius . The ulna curves round the humerus to form the elbow's point , while the radius form a joint with the carpals (wrist bone). Radius is the outer bone in the forearm . Ulna is the inner bone of the forearm.

4. ELBOW 

     

The bones of the upper arm and forearm meet at the elbow. this joint act like a door hinge allowing the arm to bend or straighten. The forearms bones can rotate at the elbow , enabling the palm of the hand to face upwards and downwards.

5. KNEE 

The Knee joint between the femur(thigh bone) and the tibia (shin bone) is the strongest and most complex joint in the body. this hinge joints allow the leg to bend or straighten and supports the body's weight during activities such as running, jumping, or kicking.                               Femur (thigh bone )is the longest bone in the body .                                 Tibia (shin bone) forms joint with the femur and ankle bones.

6.PELVIS 

This strong, bowl -shaped structure consists of the two curved hip bones (pelvic girdle) and the sacrum. The pelvic supports the abdominal organs and attaches the thigh bones to rest of the skeleton.                       Sacrum anchors the backbone to the pelvic girdle .                                   Hip joints is where the ball shaped head of the femur fits into the cup shaped socket in the hip bone.

7. HAND 

       

Hinged at the wrist,the hand consists of 27 bone and many movable joints (knuckles), which enable it to perform a wide range of tasks. The human thumb is opposable , which means that it can be rotated to touch the tips of each of the other fingers.

8.FOOT 

Each foot consists of the ankle, sole, and toe bones , which supports and move the body's weight . These bones also provide a flexible platform that pushes the body off the ground during movement and absorbs the shock on landing.                                                                                          Phalanges are the 14 slender bones that form the toes .                            Tarsals are the seven bones that form the ankle , heel, and apart of the arch of the foot.

9. TOES 

       

The phalanges of the toes are much shorter and less flexible than those of the fingers. the phalanges enables the body to stay upright and to stand on tiptoe. they also help to propel the body forwards during movement .                                                                                                     Metatarsals are the five long bones that connect the toes to the middle part of the foot .           

 

       

 

                    

cells and its kind

CELLS

The Body is constructed from trillions of tiny living units known as Cell.

There are more then 200 different type of cell -and each has its own shape,size and specific job to do .

Typically ,cells of the same type work together in units called Tissues.

Each individual cell is surrounded by a thin membrane that regulates the movement of nutrients and other substances in and out of the cell .

Cells multiply by continually dividing into two identical "offspring". this division allows the body to grow and to replace cells that are damaged or worn out.

1. NERVE CELLS

Found in the Brain,spinal cord ,and nerves ,nerves cells, or neurons , carry and process high speed electrical signals ,called nerve impulses. these impulses coordinate body processes and enable us to feel,think and move .

2.WHITE BLOOD CELL 

                     A macrophage "reaches out" to capture bacteria (blue)which it will digest.

Circulating in blood ,and in a clear fluid known as lymph, white blood cells help defend the body against disease. The cells include macrophages and neutrophils,which eat bacteria and other germs ,and also lymphocytes,which release germ disabling antibodies.

3.EPITHELIAL CELLS 

Epithelial cells lock together to form the protective,pitted lining of the stomach.

Tightly packed together ,these cells provide a barrier to stop harmful chemicals and germs reaching body tissues. they cover the body,forming the outer layer of skin, and line hollow organs such as the stomach,lungs and bladder.

4.BONE CELLS 

Bone matrix is made of hard calcium salts and more flexible collagen fibres. 

Spiky osteocyte lives in a lacuna,or space,in the bone matrix.

Osteocytes are bone cells that help to keep the bone in good condition .At first,they lay down bone , but later become stranded within a bony space. They keep in touch through tiny threads and pick up supplies from nearby blood vessels.

5.LIVER CELLS 

Also known as hepatocytes , liver cells enable the liver to perform many hundreds  of roles to control blood composition and keep the body stable. these include processing and storing nutrients (foods) , and removing poisons.

6. FAT CELLS 

A spherical fat cell is filled mostly with a droplet of energy rich fat.

 As their name suggests, fat cells specialize in storing fat .They group together to form adipose tissue,which serves as an energy store, cushions organs such as the kidneys,and insulates the body under the skin .