1. The Skeletal System

2. Types of skeletons  Exoskeleton: outside the body Arthropods (lobster)  Endoskeleton: Inside the body Vertebrates such as humans

4. Regions of the skeleton  Axial skeleton- consists of the skull, backbone, and rib cage  Appendicular skeleton consists of the bones of the forelimbs and hind limbs, shoulder girdle and pelvic girdle

5. Functions of the skeleton  Provides support  Gives the body shape  Protects fragile organs-brain & heart  Movement (working w/ muscular system)  Stores minerals-calcium  Site of blood cell formation Blood cells are formed in bone marrow, deep within the bone. Bone is living!

6. Composition of Skeletal System The skeletal system consists of bones and special types of connective tissues,  206 bones - light, but strong  Cartilage – flexible, but strong Babies skeleton (350 ‘bones’) Why is this a benefit at this age? Eventually replaced by bone. Adults: Nose, ears, ribs, throat made of cartilage Ends of long bones are cartilage

8. Composition of Skeletal System continued  Tendons: Connect muscle to bone. Ex: achilles’ tendon  Ligaments: Connect bone to bone Ex: ACL (anterior crutiate ligament)

10. Composition continued  Joints - where bones meet  Types: Immovable - ex. bones in the skull Slightly movable - ex. vertebrae Freely movable - ex. knee, elbow, shoulder

11. Types of Bones  5 basic types of bones: long = compact short = spongy except surface flat = plates of compact enclosing spongy irregular = variable sesamoid = develop in tendons or ligaments (ex.patella)  Sutural bones = in joint between skull bones

14. Skeletal disorders  Arthritis- inflammation of the joints  Osteoporosis- bones become thinner, more porous, easily broken

15. miscellaneous  Your skeleton is replaced every two years  Osteocyte – “bone cell”  Bone is 5 times stronger than a steel bar of the same weight.  The knee is the body’s largest joint

17. The Muscular System

18. Types of Muscles  Skeletal Attached to bones Voluntary - we consciously control  Smooth In internal organs and blood vessels Involuntary - we do NOT consciously control  Cardiac Heart muscle Involuntary

19. Functions of Muscles  Movement  Posture  Joint stability  Heat production

20. Muscular System Composition  656 different muscles Usually work in pairs (one relaxes while the other retracts) Some remain partially contracted at all times (muscle tone) Allows us to keep our head up even when relaxed Regular exercise increases muscle tone

21. Muscle Miscellaneous  40% of our body weight  Cells are specialized to contract (shorten) when stimulated  The number of muscle cells you have never changes.  Repetitive muscle activity increases the size of the cells, not the number.