1. The Musculo-skeletal System

2. Functions of the Skeletal System
1. Provides shape and support Backbone – center of the skeleton; all bones of the body are connected to this column Vertebrae – 26 small bones that make up the back 2. Enables you to move – muscles pull on bones to make the body move

3. Functions, con’t. 3. Protects your internal organs
Skull protects brain, sternum and ribs protect heart and lungs
4.      Produces blood cells in marrow
5.      Stores certain materials (calcium, phosphorus) until your body needs them

4. Bones – strong and living
Strong but lightweight
Made of phosphorus and calcium, tightly packed together
Bone growth
Bones contain cells and tissues, such as blood and nerves
Made of living cells, constantly making new bone
New bone tissue forms to fill gaps in broken bones

5. Structure of bones   
1. Covered by a thin, tough membrane with blood vessels and nerves 2. Compact bone – no open spaces; rigid and dense 3.  Spongy bone – has open spaces; able to absorb shock 4.  Marrow - red bone marrow makes red blood cells, yellow marrow stores fat

6. How Bones Form
Cartilage – connective tissue that is more flexible than bone
Infants born with much of skeleton formed by cartilage
Cartilage is replaced by bone until you stop growing
Ends of long bones remain covered by cartilage

7. Joints of the Skeleton
Joints – A place where two bones come together, allows bones to move in different ways
Immovable Joints – bones of the skull, ribs to sternum
Moveable Joints – allow bones to move
Bones in moveable joints held together by ligaments

8. Taking care of your bones
Well-balanced diet – dairy products, meats, whole grains, and leafy green veggies
Exercise – weight bearing exercise helps bones grow stronger and denser
Osteoporosis – weakening of the bones due to mineral loss
Fracture – break in the bone
Sprain – ligament is stretched too far or torn
Dislocation – bone moves out of joint; may also cause ligaments and tendons to overstretch

9. The Muscular System
A.    Involuntary muscles – not under conscious control; responsible for activities like breathing and digesting food B.     Voluntary muscles – under conscious control

10. 3 Types of Muscles 1. Skeletal attached to skeleton by tendons
appears banded, or striated
voluntary
react quickly, but tire quickly
2. Smooth
walls of stomach and blood vessels
appears smooth
involuntary
react more slowly, tire slowly
3. Cardiac
found in the heart
characteristics in common with smooth and skeletal muscle
striated, but does not get tired

11. Types of Muscle (con’t)

12. Muscle Action Mitochondria in muscles provide energy for contraction
Muscles can only contract (become shorter and thicker) and relax
Must work in pairs – one contracts, the other relaxes

13. Levers in the Human Body
Lever – a rigid bar that pivots around a fixed point called a fulcrum.
Force applied = effort force
Force resisting the motion of the lever = load
Increased work = mechanical advantage
m/technology/simplemach ines/levers/

14. Taking Care of Your Muscles
Exercise makes muscle cells grow wider, making muscle get thicker (stronger)
Resistance exercise – strengthens skeletal muscles
Endurance exercise (aerobic exercise) increases heart strength
Warming up makes muscles and joints more flexible
A muscle strain, or a pulled muscle, can occur when muscles are overworked or overstretched
A cramp is when an entire muscle contracts strongly and stays contracted