The Skeletal System

1. The Skeletal System

2. Supports the body • Protects internal organs • Aids in movement • Stores minerals • Make blood cells The Skeleton

3. 206 bones • Bone is living tissue • Contains living bone cells, blood vessels and nerves. • Bone marrow stores fat and makes blood cells • Bone starts out as cartilage and ossifies into bone. The Skeleton

4. Spongy bone Haversian canal compact bone Compact bone Periosteum Bone marrow Spongy bone Osteocyte Artery Periosteum Vein Figure 36-3 The Structure of Bone Section 36-1

5. Elastic ligaments hold bones together at joints. • Cartilage protects bones at joints. • Hinge joints – elbow and knee • Ball and socket joint – shoulder and hip • Pivot joint – neck • Gliding joint – wrist and ankle Joints

6. Muscle Tendon Femur Patella Bursa Ligament Synovial fluid Cartilage Fat Fibula Tibia Section 36-1

7. Arthritis – inflammation of joints • Osteoporosis – mineral loss; weakening • Sprains – ligaments are stretched or torn. Skeletal Disorders

8. Muscular System

9. The only tissue that contracts. • Three types: • Skeletal = attached to bones; voluntary • Cardiac = in the heart; involuntary • Smooth = make up digestive tract, blood vessels and other organs; involuntary Muscular Tissue

10. Section 36-2

11. Protein fibers called actin and myosin slide over each other. • This requires lots of energy. • Muscle cells have lots of mitochondria, like nerve cells. Muscle Contraction

12. Muscles contract when nerves tell them to. Muscle Contraction

13. Inelastic tendons attach muscle to bone. • Muscles can only pull, not push. • Muscles work in opposing pairs to move a bone. • One muscle bends the joint and another muscle straightens the joint. Movement

14. Section 36-2 Movement Movement Biceps (relaxed) Biceps (contracted) Triceps (contracted) Triceps (relaxed)

15. Regular exercise keeps the muscles in a partial state of contraction called muscle tone. • This is important to survival. Muscle Tone

16. Integumentary System Hair, skin, nails

17. First line of defense against disease. • Helps regulate body temperature. • Aids in waste removal (excretion). • Protects against UV radiation. Skin

18. Section 36-3

19. UV radiation can cause mutations in skin cells resulting in abnormal growth. • The tendency towards skin cancer is hereditary. Skin Cancer

20. Hair provides protection from UV radiation and filters particulates from the nose, ear and eyes. • Hairs as well as attached skin cells are used as forensic evidence. • Nails grow from the base called the root. • Some nails get invaded by a fungus and look nasty. Hair and Nails