BiologyConcept 27.4

Jose Juan Ucles Rodrigo DuarteRicardo MolinaKevin Luttmann

The skeleton functions in support and movement

Vocabulary1. Vertebra2. Cartilage3. Marrow

4. Joint5. Ligament6. Arhtritis

7. Osteorporosis

Definitions1. Vertebra: Segment of the backbone; encloses and

protects the nerve cord.

2. Cartilage: Type of connective tissue softer than bone.

3. Marrow: Specialized tissue found in bone; yellow bone marrow consists of stored fat that serves as an energy reserve; red bone marrow makes cells that develop into blood cells.

4. Joint: Area where one bone meets another.

5. Ligament: Strong fibrous connective tissue that holds together the bones in movable joints.

6. Arthritis: Group of skeletal disorders characterized by inflamed joints.

7. Osteoporosis: Disorder in which bones become thinner, more porous, and more easily broken.

Anatomy of the SkeletonThe skeleton provides a strong framework that holds your body up and maintains its shape. The skeleton also protects soft organs and provides attachment sites for your muscles.

The human skeleton consists of 206 bones.

Bones as Living Organisms

  Your  bones  are  organs made up of  living  connective tissue. Within  this  very  dense  connective tissue,  a material known asbone matrix surrounds the bone cells. Bone matrix consists of flexible fibers of the protein collagen and a hard mineral made of calcium and phosphate. The collagen keeps the bone flexible and non-brittle, while the hard mineral helps the bone withstand forces that push on it.A sheet of fibrous connective tissue covers most of the outside surface of the bone .In addition to covering the ends of bones, cartilage is found in the tip of your nose and the outer portion of your ears. When you were a newborn, much of your skeleton was made up of cartilage. As you grew, this cartilage was gradually  replaced  by  bone  as  minerals  circulating  in  the  blood  accumulated  in  the  developing  bone.  Bones continue  to  grow  in  length  in  women  until  about  age  18,  and  in men  until  about  age  21. Many  bones  contain specialized tissues called marrow. The shafts of long bones, such as the arm bone (humerus), have a central cavity containing yellow bone marrow. Yellow bone marrow consists of stored fat and serves as an energy reserve for the body.

How joints workAn area where one bone meets another bone is called a joint. Some joints connect bones in a way that allows little or no movement. Such joints are called immovable joints. By being unable to move, these bones better protect the soft organs that lie beneath them. Yet, if all your bones were fused together in one continuous skeleton, you would not be able to move. Movable joints allow you to bend, twist, and rotate your limbs, neck, and torso. The bones in a movable joint are held together by a strong, fibrous connective tissue called a ligament.Movable joints can be classified by the way in which the bones come together. The different structures of the joints allow your body to move in a variety of ways.

Skeletal DisordersSince bones consist of living tissue, they can repair themselves by building new tissue. If properly set using a cast or splint, a bone will usually return to its normal shape and strength.Besides fractures, bones and joints can be affected by disorders of the skeletal system. Arthritis refers to a group of skeletal disorders that involve inflammation of the joints. One out of every three adults in the United States suffers from arthritis or a related joint disorder.

Osteoporosis is a disorder in which bones become thinner, more porous, and more easily broken.

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