Do Now: 1. Where, specifically, is blood created? Which part of the long bone? 2. Which structures are primarily associated with growth? 3.

Transcription

1 Do Now: 1. Where, specifically, is blood created? Which part of the long bone? 2. Which structures are primarily associated with growth? 3. How could damage to these areas impact bone growth? WRITE AND ANSWER THE QUESTIONS ON PAGE 47 IN JOURNALS

2 Review of Class Rules Do NOT talk while Ms. Greco is talking (38 : 1) Phones should NOT be out unless Ms. Greco has given you permission to use them No swearing or inappropriate language Keep all hands, feet and objects to yourself No more food in the classroom Do NOT leave Ms. Greco s room a mess at the end of the class **Next class we will start a ticket rewards system

3 Turn in your homework 1. Explain how bones are classified 2. list five major parts of a long bone 3. how do compact and spongy bone differ in structure? 4. Describe the microscopic structure of compact bone 5. Describe the development of an intramembranous bone Shapes long, short, flat, irregular, or sesamoid (round) Epiphysis, diaphysis, periosteum, articular cartilage, spongy bone, compact bone, medullary cavity In compact bone, the osteocytes and layers of extracellular matrix concentrically clustered around a central canal form a cylinder-shaped unit called an osteon. In spongy bone, bone cells do not aggregate around central canals the osteocytes and layers of extracellular matrix concentrically clustered around a central canal form a cylinder-shaped unit called an osteon. Many of these units cemented together form the substance of compact bone. Each central canal contains blood vessels and nerve fibers surrounded by loose connective tissue. Membrane-like layers of unspecialized, or relatively undifferentiated, connective tissues appear at the sites of the future bones. Then, some of the partially differentiated progenitor cells enlarge and further differentiate into bone-forming cells called osteoblasts. Osteocytes surround osteoblasts, which eventually leads to the formation of bone

4 Endochondral Bones

5 Endochondral Bones Most bones of the skeleton Develop in the fetus from masses of hyaline cartilage shaped like future bony structures, they are subsequently replaced by bone tissue Primary Ossification Center: The first site of bone formation in the shaft (diaphysis) of a long bone

6 Endochondral Bones Epiphyseal Plate: A band of cartilage that remains between the diaphysis and the epiphysis ( 2 ossification centers) as spongy bone is deposited into them Contains layers young cells undergoing mitosis and producing new cells As cells grow, an extracellular matrix forms, cartilage plate thickens, lengthening the bone Osteoclasts: large multinucleated cells that break down the extracellular matrix After, bone-building osteoblasts invade the region and deposit new bone tissue

7 Homeostasis of Bone Tissue

8 Homeostasis of Bone Tissue Osteoclasts and osteoblasts are in a continuous cycle of remodeling intramembranous and endochondral bones Osteoclasts resorb bone matrix, osteoblasts replace Bone mass of an adult skeleton remains constant, even though 3-5% of it is exchanged each year

9 Factors Affecting Bone Development, Growth, and Repair

10 Factors Affecting Bone Development, Growth, and Repair Nutrition Vitamin D Calcium Hormones Growth Hormone secreted by pituitary gland Sex Hormones Physical Exercise Stimulates bone tissue to thicken and strengthen

11 Group Poster Activity (30min) In groups of 3-5: Create a poster that diagrams the stages of endochondral bone growth Summarize the major events and developing structures You may use colored pencils/crayons

12