Outline

1. Outline Chapter 20 page 402-415 Diversity of Skeletons • Hydrostatic Skeleton • Exoskeletons • Endoskeletons Human Skeletal System • Axial Skeleton • Appendicular Skeleton Human Muscular System • The Muscles • Muscle Contraction

2. Hydrostatic Skeleton Functions • Supports body form • Provides resistance for the contraction of muscles to act against Source • Some organisms use their fluid-filled gastrovascular cavity • Others use their fluid-filled coelom

3. Locomotion in an Earthworm

4. Exoskeletons and Endoskeletons Exoskeleton - External Skeleton • Molluscs - composed of calcium carbonate • Arthropods - composed of chitin Endoskeleton - Internal Skeleton • Echinoderms and vertebrates • Mineralized bone and cartilage • Grows as the animal grows • Does not limit space for internal organs • Supports greater weight

5. Exoskeleton

6. The Vertebrate Endoskeleton

7. Human Skeletal System Functions • Supports and protects the body • Permits movement • Provides resistive foundation for muscles to act against Bones store calcium and phosphate ions Certain bones produce red blood cells

8. Bone Growth and Renewal Cartilage structures in early development act as models for future bones • Calcium salts deposited in matrix by cartilage cells and later by osteoblasts • Endochondral ossification Osteoclasts • Break down bone • Remove worn cells • Deposit calcium in the blood • Work with osteoblasts to heal broken bones

9. Anatomy of a Long Bone Gross • Main shank • Thick outer cylinder of compact bone • Medullary cavity in center • Spongy bone at ends Details • Compact bone • Unit of structure called osteon • Concentric lamellae arranged around central canal • Osteocytes lie in lacunae at lamellar boundaries • Spongy bone • Numerous bars and plates separated by irregular spaces • Spaces filled with red bone marrow

12. The Human Skeleton

13. The Axial Skeleton Lies in the midline of the body Consists of • The skull • The vertebral column • The sternum, and • The ribs

14. The Skull Formed by cranium and facial bones • Major bones are named after • The lobes of the brain, and • The facial bones • Foramen magnum • Opening at base of skull • Where spinal cord connects to brain • Bones of cranium surround sinuses

15. The Skull

16. Vertebral Column Vertebral column • Supports the head and trunk • Protects the spinal cord and roots of spinal nerves Segments (from superior to inferior) • Cervical - Neck • Thoracic - Thorax • Lumbar - Small of back • Sacral - Sacrum • Coccyx - Tailbone Intervertebral disks of fibrocartilage act as padding

17. Rib Cage Protects the heart and lungs, and assists breathing Support by the thoracic vertebrae • Twelve pairs of ribs • True ribs • Connect directly to sternum • Seven pairs • “False” ribs • Do not connect directly to sternum • Five pairs

18. The Rib Cage

19. The Appendicular Skeleton Consists of • The bones within the pectoral and pelvic girdles • The attached limbs Pectoral girdle – Bones of the shoulder • Anterior • Supports the arms and hands Pelvic girdle - Bones of the pelvis • Posterior • Supports the legs and feet

20. Bones of the Pectoral Girdle,the Arm, and the Hand

21. Bones of the Pelvic Girdle,the leg, and the Foot

22. Classification of Joints Fibrous Joints • Immovable • Between cranial bones Cartilaginous Joints • Slightly Movable • Between vertebrae Synovial Joints • Freely Movable • Bones separated by a cavity Ligaments bind bones together at joint

23. The Knee Joint

24. Human Muscular System Skeletal muscles • Attached to the skeleton by cable-like fibrous connective tissue called tendons • Arranged in antagonistic pairs • Can only contract, cannot push • When one muscle contracts, it stretches its antagonistic partner A muscle at “rest” exhibits tone (minimal contraction) A muscle in tetany is at maximum sustained contraction

25. Antagonistic Muscles