Chapter 2 Bones Muscles and Skin Section 1

Chapter 2: Bones, Muscles, and Skin Section 1 – The skeletal system

l The skeleton of a newborn baby is made up of more than 300 (our book says 275) parts, most of which are made of cartilage. Over time, most of this cartilage turns into bone, in a process called ossification. As the baby grows, some of its bones fuse together to form bigger bones. By adulthood, your skeleton contains just 206 bones.

Five Functions! 1. 2. 3. 4. 5. Provides the body with shape and support Enables you to move Protects organs Produces blood cells Stores minerals

How many vertebra do we have? l 24… ¡ ¡ ¡ l 7 cervical vertebra (top) 12 thoracic vertebra (mid) 5 lumbar vertebra (bottom) Or 26 if you include the Sacrum and Coccyx ¡ As a baby, the sacrum is 5 separate bones and the coccyx is 3 -5 separate bones

Skull/cranium Mandible Clavicle Sternum Humerous Ribs Vertebra Pelvic Gridle Radius Ulna Carpals Metacarpals Phalanges Femur Patella Tibia Fibula Tarsals Metatarsals Phalanges Human Skeleton

Bones – strong and living l Skeleton means ‘dried up body’ or ‘mummy’ l Math Question: if a person weighed 150 pounds, how much of that weight would come from bones? (20% of body weight is bone) 20% x 150 lbs = 30 lbs 20 100 = x 150 x = 30 lbs

What happens if you break a bone? Your bones are tough stuff — but even tough stuff can break. Like a wooden pencil, bones will bend under strain. But if the pressure is too much, or too sudden, bones can snap. l When a bone breaks it is called a fracture. There's more than one way to break or fracture a bone. A break can be anything from a hairline fracture (a thin break in the bone) to the bone that's snapped in two pieces like a broken tree branch. l

Structure of bones Spongy bone Outer membrane Bone marrow Compact bone Blood vessels Canals

l What does marrow do? ¡ l Bone marrow produces blood cells What is cartilage? Where is it found? ¡ A flexible connective tissue that is more flexible than bone Hyaline cartilage: this is the connective tissue that gives structure to the nose and trachea and the ear lobes. It also covers the ends of bones at joints to smooth the surfaces so that jarring does not occur during movement. White fibrous cartilage: is found between the vertebrae of the spine. It acts as a shock absorbed to protect the bones of the vertebrae from damage when, for example, someone jumps up and down. Yellow elastic cartilage: forms the pharynx and the epiglottis, two structures inside the back of the throat.

Joints of the skeleton l Two different kinds of joints: ¡ ¡ l Immovable Moveable Four types of moveable joints: ¡ ¡ Ball and socket – shoulder Pivot – neck Hinge – knee Gliding – wrist GLIDING JOINT

Ligaments hold bones together

l What should a person do to help build and maintain a healthy skeleton? ¡ Balanced diet l ¡ including dairy (or calcium) Regular exercise l What skeletal condition can happen to people as they get older? ¡ Osteoporosis l Bones begin to lose minerals

Skeletal system injuries l Fracture: a break in a bone l Sprain: ligaments are stretched too far – possible torn l Dislocation: bone comes out of it’s joint

How does an x-ray work? l X-rays are passed through the body. Solid areas in the body (ex: bone) absorb the xrays. Areas that are less solid allow the xrays to pass through.