Chapter 7 Skeletal System *You may want to attach paper to your study guide for further room for writing

Aids to Understanding Words Complete the Aids to Understanding Words You may just write what is in the parentheses You may also want to write “key words” or “clues”

Living Tissues of Bone Bone tissue Cartilage Dense connective tissue Blood Nervous tissue

Classifying Bones by Their Shape Long bones – long longitudinal axes, expanded at each end Thigh bones, forearms Short bones – cubelike, lengths/widths equal Wrists, ankles Flat bones - platelike, broad surfaces Ribs, scapula, bones of skull

Classifying Bones Irregular bones – variety of shapes, usually connected to other bones Vertebrae, facial bones Sesamoid (round) bones – small and nodular, embedded within tendons (muscle to bone), adjacent to joints Kneecap (patella)

Parts of a Long Bone Use the worksheet provided to label these parts AND write their functions (p.132 Fig.7.1) Epiphysis (proximal and distal) Diaphysis Periosteum Compact bone Spongy bone Medullary Cavity Red Marrow (spaces) *see sheet Yellow Marrow *see sheet

Bone Structure and Function Bones have projections called “processes” that provide attachment sites for ligaments and tendons Some bones have small holes to allow passage of blood vessels and nerve fibers Shape of bones helps them to fit together

Periosteum Vascular, fibrous tissue covering the bone Function – formation and repair of bone tissue Generally located on the diaphysis (shaft)

Compact Bone vs. Spongy Bone continuous matrix with no gaps typically form outer walls of long bones Spongy branching bony plates irregular connecting spaces lace-like appearance found in hollow tube of compact bone (long bone)

Osteocytes Osteocytes – bone cells Found in lacunae (bony chambers) Form concentric circles around the central canal Look at page 108 to refresh your memory *cellular matrix of bone is composed of collagen (resilience) and calcium phosphate (hardness)

Flashcard Time! Use the notecards provided to make flashcards for the following: Long bones * Short bones * Flat bones * Irregular bones * Sesamoid bones * *also list examples with the description

Flashcards Continued! Epiphysis Diaphysis Compact bone Spongy bone Medullary cavity Worth 10 points - due by the end of class!

Bone Development/Growth: Intramembranous Bone Broad, flat bones of skull - form during first weeks of embryonic development Membrane-like layers appear at future bone sites Tissues enlarge to form osteoblasts Osteoblasts deposit bony matrix  spongy bone  periosteum  compact bone (between periostem and spongy) Ossification – formation of bone

Bone Development/Growth: Endochondral Bones Most of the bones of the body – develop in fetus from masses of hyaline cartilage Models of cartilage grow rapidly and then begin to change Long bones - cartilage breaks down and disappears Periosteum forms  encircles diaphysis  blood vessels and osteoblasts form spongy bone

Ossification of Endochondral Bones Primary Ossification Center (diaphysis) first region of bone formation, development proceeds to ends of bone Secondary Ossification Center (epiphysis) Spongy bone forms in all directions Epiphyseal plate (cartilage) remains between centers

Epiphyseal Plate Epiphyseal plate contains dividing cells that lengthen the bone When the centers meet and the plate ossifies – lengthening is no longer possible Look at page 134, Fig. 7.5 What happens if the plate is damaged before it ossifies?

Ossification Complete when adult size is reached Homeostasis of bone tissue Life long process of bone remodeling Osteoclasts (cells that erode bone) reabsorb bone matrix Osteoblasts (bone-forming cells) replace bone matrix Hormones that control blood calcium help control the resorption and deposition (3-5% exchanged of bone calcium exchanged each year)

How is a fracture healed? Pages 136 - 137 Blood vessels rupture, and periosteum tears Blood spreads and develops a hematoma (blood clot) Vessels in surrounding tissues dilate – causing swelling and inflammation Osteoblasts and new blood vessles invade the hematoma and form spongy bone

Fracture Healing ( continued) Fibroblasts farther from a blood supply produce masses of fibrocartilage Phagocytes and osteoclasts remove the hematoma and other bone debris Fibrocartilage fills the gap between the ends of the broken bone The cartilaginous callus is replaced by bone tissue Phew! Smaller the fracture, faster the healing.

Factors Affecting Bone Growth/Development Nutrition Vitamin D for proper absorption of Calcium Hormonal secretions Growth hormones stimulate cell division Sex hormones stimulate ossification of ephiphyseal plates (Why sex hormones?) Physical exercise Provides stress needed to thicken and strengthen bones

Book Work! Page 171, Chapter Assessments #s 1-8 Save this paper! You will be adding to it!!!