1. Unit 5: The Skeletal System Ch. 7

3. General Organization 206 bones* Axial Skeleton – down the center Axial Skeleton – down the center Skull Skull Cranium – 8 Cranium – 8 Facial – 14 Facial – 14 Middle Ear - 6 Middle Ear - 6 Vertebral Column Vertebral Column Cervical – 7 Cervical – 7 Thoracic – 12 Thoracic – 12 Lumbar – 5 Lumbar – 5 Sacrum, Coccyx Sacrum, Coccyx Thoracic Cage Thoracic Cage 12 pairs 12 pairs 7 true ribs 7 true ribs 5 False Ribs 5 False Ribs 2 floating ribs 2 floating ribs Appendicular Skeleton – the appendages Appendicular Skeleton – the appendages Pectoral Girdle Scapula – 2 Clavicle – 2 Upper Limbs Humerus – 2 Radius – 2 Ulna – 2 Carpals – 16 Metacarpals – 10 Phalanges – 28 Pelvic Girdle Coxal – 2 Lower Limbs Femur – 2 Patella – 2 Tibia – 2 Fibula – 2 Tarsals – 14 Metatarsal 10 Phalanges - 28

4. Types of Bones Long – cartoon bone Long – cartoon bone Expanded ends Expanded ends Longer than wide Longer than wide Humerus, femur, finger bones Humerus, femur, finger bones Short – boxy or cube-like Short – boxy or cube-like Carpals, tarsals Carpals, tarsals Flat – platelike Flat – platelike Ribs, scapula, sternum Ribs, scapula, sternum Irregular – variety of shapes Irregular – variety of shapes Vertebrae, many facial bones Vertebrae, many facial bones Sesamoid – found in joints for stability Sesamoid – found in joints for stability Patella (knee cap) Patella (knee cap) Wormian (sutural) – extra bones in skull where cranial bones meet Wormian (sutural) – extra bones in skull where cranial bones meet

5. Bone Structure: Macroscopic Structure – Long bone Macroscopic Structure – Long bone Epiphyses – expanded ends Epiphyses – expanded ends Articular Cartilge – hyaline; protection in joints Articular Cartilge – hyaline; protection in joints Diaphysis – shaft Diaphysis – shaft Medullary Cavity – hollow portion containing marrow Medullary Cavity – hollow portion containing marrow Periosteum – outer covering Periosteum – outer covering Endosteum – inner covering Endosteum – inner covering Types of bone Types of bone Compact – dense for strength Compact – dense for strength outer outer Osteons Osteons Spongy – light, airy Spongy – light, airy inner inner Reduce weight Reduce weight Trabeculae Trabeculae

6. Bone Structure: Microscopic – Compact Microscopic – Compact Osteon – Repeating unit Osteon – Repeating unit Bullseye Bullseye Osteonic (Haversion Canal) Osteonic (Haversion Canal) Central Central Blood vessels, nerves Blood vessels, nerves Lamellae – concentric circles of matrix Lamellae – concentric circles of matrix Osteocytes – mature bone cells Osteocytes – mature bone cells Lacunae Lacunae Canaliculi Canaliculi Transverse (perforating/ Volkmann’s) Canal Transverse (perforating/ Volkmann’s) Canal Connects osteonic canals Connects osteonic canals

8. Bone Structure: Spongy - cancellous Spongy - cancellous Trabeculae – bony plates Trabeculae – bony plates Osteocytes found here Osteocytes found here

9. Bone Growth and Development Skeletal Formation Animation Skeletal Formation Animation Skeletal Formation Animation Skeletal Formation Animation Ossification – formation of bone Ossification – formation of bone Osteoblast – deposit solid mineral matrix Osteoblast – deposit solid mineral matrix Turn into osteoclasts – mature bone cells Turn into osteoclasts – mature bone cells Endochondral Bone Formation Endochondral Bone Formation Most common; arise from hyaline cartilage Most common; arise from hyaline cartilage Periosteum forms; deposit bone underneath – outside of bone first Periosteum forms; deposit bone underneath – outside of bone first Primary ossification center – center of diaphysis Primary ossification center – center of diaphysis Ossification moves towards ends Ossification moves towards ends Secondary Ossification Center – Epiphyses Secondary Ossification Center – Epiphyses Mainly spongy bone develops Mainly spongy bone develops

10. Bone Growth and Development Epiphyseal Disk – growth plate Epiphyseal Disk – growth plate Area between the two ossification centers that remains cartilage Area between the two ossification centers that remains cartilage Does not ossifiy until adulthood Does not ossifiy until adulthood 4 layers of cells 4 layers of cells Cartilage cells continue to divide, mature, ossify and die Cartilage cells continue to divide, mature, ossify and die Move toward ends of bone Move toward ends of bone Intramembranous Ossification – bone formation between two sheets of connective tissue Intramembranous Ossification – bone formation between two sheets of connective tissue Generally in flat bones of skull Generally in flat bones of skull

12. Factors Affecting Bone Growth Diet – what you eat Diet – what you eat Minerals such as calcium, phosphates Minerals such as calcium, phosphates Vitamin D – needed for proper absorption of calcium Vitamin D – needed for proper absorption of calcium Rickets/ osteomalacia – lack of vit. D; soft bones Rickets/ osteomalacia – lack of vit. D; soft bones Dehydrocholesterol – inactive form; activated by sunlight in the skin Dehydrocholesterol – inactive form; activated by sunlight in the skin Vitamin A & C Vitamin A & C Vit. A – bone resorption Vit. A – bone resorption Lack causes retardation in development Lack causes retardation in development Vit. C – collagen synthesis Vit. C – collagen synthesis Hormones – chemical messengers from glands Hormones – chemical messengers from glands Human Growth Hormone – pituitary; stimulates growth of epiphyseal disk Human Growth Hormone – pituitary; stimulates growth of epiphyseal disk Dwarfism, gigantism, achondroplasia, acromegaly Dwarfism, gigantism, achondroplasia, acromegaly Thyroid hormone – thyroid; replace cartilage with bone Thyroid hormone – thyroid; replace cartilage with bone Male and Female Sex Hormones Male and Female Sex Hormones Physical Stress – exercise Physical Stress – exercise Tug of tendons cause bones to thicken and strengthen Tug of tendons cause bones to thicken and strengthen

14. Skeletal Functions: Support and Protection Support and Protection Body Movement – lever actions Body Movement – lever actions 1 st class – EF, F, RF 1 st class – EF, F, RF Triceps Triceps 2 nd class – F, RF, EF 2 nd class – F, RF, EF Mandible Mandible 3 rd Class – F, EF, RF 3 rd Class – F, EF, RF Bicep Bicep Blood Cell Formation – Hematopoiesis Blood Cell Formation – Hematopoiesis Marrow – hematopoietic tissue Marrow – hematopoietic tissue Found in medullary cavity of long bones (young); spongy bone spaces (older) Found in medullary cavity of long bones (young); spongy bone spaces (older) Red – blood cell formation Red – blood cell formation Yellow – fat storage Yellow – fat storage Can be converted back and forth as needed Can be converted back and forth as needed

15. Skeletal Functions: Hemocytoblast – blood stem cell Hemocytoblast – blood stem cell Erythrocyte – red blood cell Erythrocyte – red blood cell Leukocyte – white blood cell Leukocyte – white blood cell Thrombocyte – platelet Thrombocyte – platelet Inorganic Salt Storage Inorganic Salt Storage Electrolytes needed for a variety of physiological functions Electrolytes needed for a variety of physiological functions Ca ++ needed for nerve impulse conduction, skeletal muscle contraction Ca ++ needed for nerve impulse conduction, skeletal muscle contraction Negative Feedback Negative Feedback Blood Ca levels too high: Thyroid releases Calcitonin  osteoblast activity; deposit calcium in bone Blood Ca levels too high: Thyroid releases Calcitonin  osteoblast activity; deposit calcium in bone Blood Ca levels too low: Parathyroid release parathyroid hormone  Osteoclast activity; dissolve bone, release minerals into blood Blood Ca levels too low: Parathyroid release parathyroid hormone  Osteoclast activity; dissolve bone, release minerals into blood