The Skeletal System

1. The Skeletal System Honors A&P

2. Do Now: • How would your life be different if you had an exoskeleton (skeleton on the outside)?

3. Name the bones: Frontal Maxillary Mandible Vertebrae‘ Clavicle Humorous Sternum Rib Radius Ulna Coxal/pelvic girdle Sacrum/coccyx Carpals Metacarpals Phalanges Femur Patella Fibula Tibia Tarsals Metatarsals phalanges

4. Functions • Support • Structural support • Framework for attachment • Protection • Surrounds soft tissues and organs • Storage • Calcium and phosphate reserve • Energy reserves (triglycerides in yellow marrow) • Hematopoeisis • Rbc, wbc, and platelet production in red marrow • Hormone production • Osteocalcin – regulates bone formation • Leverage for movement • Change magnitude and direction of forces generated by skeletal muscles • Tendons connect muscle to bone

5. Classification of Bones • Axial vs. Appendicular skeletons • Long Bones • Longer than they are wide • Ex. Limb bones • Short Bones • Cube shaped • Ex. Carpals, tarsals • Sesamoid bones • Form in tendon • Ex. Patella & psiform • Flat Bones • Thin and broad • Ex. Ribs, sternum, scapulae, ribs, cranial bones • Irregular Bones • Complex shapes • Ex. Vertebrae and hips

6. What is NOT part of the Appendicular skeleton? • Hip • Scapula • Fibula • Coccyx • Clavicle

7. What is the tailbone called? • Sacrum • Coccyx • Patella • Scapula • Clavicle • Hyoid • Talus

8. What is the shin bone called? • Sacrum • Patella • Tibia • Fibula • Radius • Ulna • Talus • Calcaneous

9. What type of bone is a rib? • Long • Short • Flat • Irregular • Sesmoid

10. What type of bone is a phalange? • Long • Short • Flat • Irregular • Sesmoid

11. What type of bone is a patella? • Long • Short • Flat • Irregular • Sesmoid

12. What type of bones are the tarsals? • Long • Short • Flat • Irregular • Sesmoid

13. Features of Long Bones • Diaphysis • Central shaft of thick collar of compact bone • Medullary Cavity • Contains Yellow Bone marrow • Loose connective tissue • Compact bone • Dense/solid • Found in diaphysis • Epiphysis • Expanded ends covered w/ articularcartilage • Epiphyseal line in adults is remnant of epiphyseal plate • Spongy (cancellous) bone • Network of bony rods w/ spaces • Found in epiphysis • Periosteum • Covers outer surface of bone w dense irregular tissue • Inner layer osteoblasts and osteoclasts • Secured by Sharpey’s fibers (collagen) • Nutirent foramen (formina) • Opening in periosteum for bv, nerrves, and lymph vessles • Endosteum • Layer of osteoblasts that lines marrow cavity

14. Skeletal Cartilage • Skeletal Cartilage • Consists of mostly water • Avascular, no nerves • Surrounded by perichondrium (dense irregular) w/bv • Types • Hyaline • Most abundant • Articular cartilage , costal cartilage nasal cartilage, and respiratory cartilage • Elastic • External ear & epiglottis • Fibrocartilage • Highly copmressable • Mensci & vertebral discs • Growth • Flexible matrix to accomadate mitosis • Appositional growth – from perichondrium • Interstitial growth – from chondrocytes within

15. Microscopic Features of Compact Bone • Haversiansystem (aka osteons) • arranged in cylinders • Lamella • concentric matrix tube • Twister resistor • Haversian (central) canal • blood vessels and nerve fibers • Perforating canals (aka Volkmanns canals) • connect bv of periosteum to haversian canal • Osteocytes • reside in lacunae • Canaliculi • connect lacunae to central canal

16. Microscopic Features of Bone (cont’d) • Spongy Bone • Found in flat, short and irregular bones and epiphysis of long bones • Trabecule (rods create network) • Lamellae arrangemnet • No central haversiancancal • All 3 bone cell types • In flat bones, the spongy bone is called dipole • Chemical composition • Inorganic: 65% mineral salts –Hydroxyapatite • Calcium Phosphates account for hardness • Other 1/3 Osteoid - organic components • Cells, collagen, and ground substance

17. Bone Cytology • Osteogenic cells (osteoprogenitor) • bone stem cells • Osteoclasts • giant multinucleated cells that secrete acids and enzymes to dissolve bony matrix and release Ca (osteolysis) • Secrete lysosomal enzymes to digest organic matrix and HCl to make Ca soluable • Phagocytic digestion • Osteoblasts • produce new bone (osteogenesis) , collagen • promotes Ca deposits in bone matrix • Osteocytes • Mature bone cells occupy lacunae • Monitor and maintain bone matrix • Stimulate osteoblasts and osteoclasts • Periosteal and endosteal cells • Flat cells on bone surface

18. Compact Bone vs. Spongy Bone(Ground bone) (Cancellous bone) Note the absence of osteons in spongy bone

19. The outer covering of each bone, made from fibrous connective tissue, is called • Epiphysis • Diaphysis • articularcartilage • Periosteum • Endosteum

20. Which cells are responsible for building new osseous tissue? • Osteocytes • Osteoclasts • Osteoblasts • Osteogenic cells • Perisoteal cells • Endosteal cells • Macrophages

21. Which tissue type houses red bone marrow? • Compact bone • Periosteum • Diaphysis • Osteon • Spongy bone • Lamella

22. Which tissue type has lamellae? • Compact bone • Spongy bone • All of the above • None of the above

23. Spongy bone contains all of the following except • trabeculae. • collagen fibers. • true osteons. • hydroxyapatite

24. Do Now: • List 4 things in your car…. • Complete the following sentence for each item: • A ___(item)____ is like the skeletal system because_________________

25. Ossification (Osteogenesis): Bone Formation • Begins at 6 weeks (in utero) • Composed of fibrous membranes and hyaline cartilage • Flexible and resilient to accommodate mitosis • IntramembranousOssification • Bone develops within membranes of connective tissue • Cranial bones & clavicles • Mesenchymal cells form fiberous connective membranes

26. Endochondrial Ossification Bone replaces cartilage • Primary Ossification center – infiltrated w/bv causing mesenchymal cells to become osteoblasts • Bone Collar forms from osteoblasts • Chondroctyes within shaft enlarge and calcify and die… opening up a cavity • Periosteal bud (bv, nerves, osteoblasts, redmarrow elements) invades internal cavity • osteoclasts erode calcified matrix • osteoblasts secrete trabeculae • Diaphysis elongates – by hyaline cartilage followed by ossification • Epiphysis ossify from secondary ossification centers where spongy bone is retained

27. Bone Growth • Post-natal growth of long bones • Cells at epiphyseal plate rapidly divide pushing epiphysis away from diaphysis • Cartilage is replaced by bone on diaphysis side, and requires continues remodeling • Epiphyseal plate closure occurs at about 18 in females and 21 in males • Growth in width (thickness) • Osteoblasts in periosteum secrete bone on external surface as osteoclasts remove bone on the endosteal surface • Hormonal Regulation • Growth hormone (hGH) stimulates growth at epiphyseal plate • Sex hormones promote gender specific development of the skeleton

28. Which of these statements is not true about intramembranous bones? • They begin with a cartilage model. • They form between flat sheets of connective tissue. • Skull bones are formed in this way. • Osteoblasts deposit new bone along blood vessels within the layers

29. When cartilage is produced at the epiphyseal side of the metaphysis at the same rate as bone is deposited on the opposite side, bones • become shorter. • become thicker. • become more porous and weaker. • grow wider. • grow longer.

30. Intramembranous ossification • is the most common way bones are formed. • begins within a connective tissue membrane. • is responsible for long bone formation. • begins with a cartilaginous precursor.

31. Osteocytes maintain contact with the blood vessels of the central canal through • periosteum. • interstitial lamellae. • concentric lamellae. • canaliculi.

32. Bone Homeostasis • Remodeling • Every week recycle 5-7% of bone mass • Spongy bone 3-4 years • Compact bone 10 years • Bone deposit occurs at injured or stressed sites • Vit C, D,A, Ca, P, Mg, Mn are needed • Bone resorption – osteoclasts • Wolf’s Law – bone grows or remodels in response to the demands placed on it • Long bones thickest in middle where bending stress • Bony projections where muscles attach • Inactivity (even brief) causes atrophy (degeneration) • Prenatal Requirements • Prenatal – minerals absorbed from mother (often loses bone mass) • Consume Ca and P from diet • Vitamin D3 allows absorption of Ca and P • Vitamin A and C needed for osteoblast activity

33. Homeostasis and Mineral Storage • Calcification – deposition of calcium salts, regulated by hormones • 99% Ca deposited in skeleton • Ca+ ions used Nervous & Muscular System • Ca absorbed from intestine under control of vitamin D • Ca ion conc.regulated • Parathyroid hormone (PTH) • elevate Ca levels in body fluids (bones become weaker) • Calcitonin • depresses Ca levels in body fluids (bones become stronger)

34. Injury and Repair • Fracture – any crack or break in a bone • Healing can take from 4 months to over a year! • Fracture hemotoma – large blood clot closes injured bv • External and internal calluses – thickenings resulting from mitotic divisions

35. Classification of Fractures • Displaced (not aligned) or Non-displaced (normal position) • Complete (through) or incomplete • Linear (parallel) or transverse (perp to bone) • Compound (open sticking through skin) or simple (closed)

36. Types of Fractures Comminuted – 3 or more fragments Compression – crushed (vertebrae) Spiral – due to twisting (athletes) Depression – skull Greenstick – children (partial break/bend) http://www.youtube.com/watch?v=usn8ltc1FWU&playnext=2&list=PL27A7948A76FDD768

37. Fracture Repair • Reduction – realignment of broken bone ends • Closed – physician positions bones and immobilizes • Open – bones secured w/pins or wires • Hematoma forms • Bv rupture and hemmorhage, clot forms, bone cells die • Fibrocartilage callus forms • Capillaries grow into hemotoma, phagocytic cells clean area • Fibroblasts secrete collagen • Chondroblasts secrete matrix, psteoblasts form spongy bone • Bony callus forms • Trabeculae appear, endochondrial ossification • Bone remodeling occurs • Excess removed, compact bone replaces shaft walls

38. What is a complete break of a bone and it sticking through the skin? • Dislocation • Greenstick • Compound Fracture • Sprain • Simple Fracture

39. Aging and Skeletal System • Reduction in bone mass occurs between ages 30 -40 • Women lose ~8% skeletal mass per decade • Men lose ~3% per decade • Epiphyses, vertebrae, and jaws most vulnerable • Osteoperosis – decrease in estrogen increases osteoclast activity (so does smoking); other causes include lack of Ca+ in diet, inactive lifestyle, and certain medications

40. Which of the following factors is NOT believed to affect bone growth? • Exercise and gravity • Genetic factors • Stimulation by hormones such as growth hormone, testosterone, thyroid hormone, and estrogen • Increased intake of protein • Diet deficiencies in vitamins D and C, and minerals such as calcium

41. How would increasing the proportion of organic molecules to inorganic components in the bony matrix affect the physical characteristics of bone? • The bone would be less flexible. • The bones would be more brittle. • The bones would be more flexible. • The bones would be less compressible. • The bones would be stronger.

42. Mary is 50 years old. During a checkup, a bone scan reveals that portions of her skeleton show signs of osteoporosis. Her physician suggests hormone therapy after reviewing the test results. What hormone is prescribed for Mary? • Parathyroid hormone • Calcitonin • Estrogen • Growth hormone

43. Bone Markings

44. Bone Markings