Chapter 7 Learning Objectives

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Dec 6, 2023

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Unit 2 (7-11) Chapter 7 Learning Objectives 1. Compare and contrast compact and spongy bone. 1) Compact Bone: a. Dense and solid in structure. b. Found in the outer layer of bones. c. Provides strength and support, suitable for weight-bearing and protection. d. Contains fewer spaces and cavities. e. Contains blood vessels and nerves within its structure. f. Limited bone marrow. 2) Spongy Bone: a. Less dense, appearing spongy or porous. b. Located in the interior of bones. c. Provides some strength while reducing overall bone weight. d. Comprises a network of trabeculae with spaces in between. e. Contains significant amounts of red bone marrow. f. Offers flexibility to bones and helps distribute forces. 2. Identify the types and locations of cartilage within the skeletal system. 1) Hyaline Cartilage: a. Location: Found in several key areas throughout the body, including: 1. Articular cartilage: Covers the ends of long bones at joints, reducing friction and enabling smooth movement. 2. Costal cartilage: Connects the ribs to the sternum (breastbone). 3. Respiratory cartilage: Forms the framework of the larynx (voice box) and reinforces the walls of the respiratory passages. 4. Nasal cartilage: Supports and shapes the nose. 2) Elastic Cartilage: a. L ocation : Found in structures that require both strength and elasticity, such as: 1. External ear (auricle): Provides shape and flexibility to the outer ear. 2. Epiglottis: A flap-like structure in the throat that covers the trachea during swallowing to prevent food from entering the windpipe. 3) Fibrocartilage: a. Location : Found in areas subjected to heavy pressure and stress, such as: 1. Intervertebral discs : Situated between the vertebrae of the spinal column, providing cushioning and support. 2. Pubic symphysis: Connects the two pubic bones in the pelvic region. 3. Menisci of the knee : Wedge-shaped cartilages that cushion and stabilize the knee joint. 1

Unit 2 (7-11) 3. Describe the four major classes of bones as determined by shape. 1) Long Bones: a. Shape : Long bones are longer than they are wide and have a cylindrical shape. They typically have a shaft (diaphysis) with two ends (epiphyses). b. Examples : Femur (thigh bone), humerus (upper arm bone), radius, ulna, tibia, and fibula. 2) Short Bones: a. Shape : Short bones are roughly cube-shaped or have a similar length, width, and height. They are compact and dense. b. Examples : Carpals (bones of the wrist) and tarsals (bones of the ankle). 3) Flat Bones: a. Shape : Flat bones are thin, flattened, and often curved in shape. They have a layer of spongy bone sandwiched between two layers of compact bone. b. Examples : Skull bones (e.g., parietal and frontal), scapula (shoulder blade), sternum (breastbone), and ribs. 4) Irregular Bones: a. Shape : Irregular bones have complex, irregular shapes that don't fit into the other three categories. They can vary significantly in their shapes. b. Examples : Vertebrae (bones of the spine), pelvic bones (e.g., the sacrum), and some facial bones (e.g., the mandible or jawbone). 4. Describe the structural components of a long bone. 1) The structural components of a long bone include the diaphysis (shaft), epiphyses (ends), metaphysis (growth plate region), articular cartilage (hyaline cartilage covering the joint surfaces), periosteum (connective tissue covering the bone), endosteum (lining the medullary cavity), and nutrient foramen (openings for blood vessels and nerves). These components work together to provide support, mobility, and hematopoiesis (blood cell production) in long bones. 5. Compare the gross anatomy of other bones to that of a long bone. 1) Long Bones (e.g., Femur): a. Cylindrical shape with a diaphysis and epiphyses. b. Contains a medullary cavity with bone marrow. c. Primary functions include support, movement, and blood cell production. 2) Short Bones (e.g., Carpals): a. Cube-shaped or similar in length, width, and height. b. Composed of spongy bone surrounded by compact bone. c. Provide stability and support in joints, aiding fine motor movements. 2

Unit 2 (7-11) 3) Flat Bones (e.g., Sternum): a. Thin and often curved or flat. b. Consist of two layers of compact bone with spongy bone between. c. Primarily protect internal organs, offer muscle attachment, and house bone marrow. 4) Irregular Bones (e.g., Vertebrae): a. Complex and irregular shapes. b. Structure varies but may contain both compact and spongy bone. c. Serve diverse functions such as protection, support, and specific roles in the body. 6. Explain the general function of blood vessels and nerves that serve a bone. 1) Blood vessels in bones provide a nutrient-rich blood supply, oxygen, and remove waste, supporting bone growth, maintenance, and blood cell production. Nerves in bones transmit sensory signals (e.g., pain and pressure) and control muscle movement, enabling coordinated actions and detecting injuries. Both systems contribute to bone health, function, and adaptability. 7. Compare and contrast the structure and location of the two types of bone marrow. 1) Red Bone Marrow: a. Structure : Highly vascular, contains a rich network of blood vessels and appears red due to the presence of red blood cells. 2) Yellow Bone Marrow: a. Structure : Contains a higher proportion of fat cells and appears yellow or fatty. 8. Name the four types of bone cells and their functions. 1) Osteoblasts: These cells are responsible for bone formation. They synthesize and deposit bone matrix, including collagen, which forms the framework for new bone tissue. 2) Osteocytes: Osteocytes are mature bone cells embedded within the bone matrix. They maintain bone tissue and play a role in regulating calcium and phosphate levels. 3) Osteoclasts : Osteoclasts are responsible for bone resorption or breakdown. They help in remodeling bone tissue by breaking down old or damaged bone, releasing minerals into the bloodstream. 4) Osteoprogenitor Cells : These are precursor cells that can differentiate into osteoblasts. They play a role in bone repair and regeneration. 3

Unit 2 (7-11) 9. Describe the composition of bone's matrix. 1) Organic Matrix : This component makes up about one-third of the bone's matrix and consists primarily of collagen fibers. Collagen provides flexibility and tensile strength to the bone, making it resistant to bending or stretching. 2) Inorganic Matrix (Mineralized Matrix): This component makes up about two-thirds of the bone's matrix and consists mainly of hydroxyapatite crystals, which are primarily composed of calcium and phosphate ions. These mineral crystals provide hardness and rigidity to the bone, making it strong and capable of resisting compression. 10. Explain bone matrix formation and resorption. 1) Bone Matrix Formation: Bone matrix formation, or bone deposition, is the process by which bone tissue is created and strengthened. Osteoblasts, specialized bone-forming cells, are responsible for this process. They secrete collagen and other proteins, creating an organic matrix. Calcium and phosphate ions are then deposited into this matrix to form hydroxyapatite crystals, which provide hardness. Over time, these organic and inorganic components accumulate, forming new bone tissue. This process is essential for bone growth, repair, and maintenance. 2) Bone Matrix Resorption: Bone matrix resorption is the process of breaking down and removing existing bone tissue. Osteoclasts, specialized bone-resorbing cells, are responsible for this process. They release enzymes and acids that dissolve the mineralized matrix, releasing calcium and phosphate ions into the bloodstream. This resorption is crucial for bone remodeling, where old or damaged bone is replaced with new bone tissue. It also plays a role in regulating calcium levels in the body, as released calcium can be used for various physiological functions. 11. Compare the structure of compact bone and spongy bone. 1) Compact Bone: a. Dense and solid. b. Forms the outer layer of most bones. c. Composed of osteons (Haversian systems) with a central canal. d. Few spaces or cavities. e. Well-suited for weight-bearing and protection. 2) Spongy Bone: a. Less dense, with a spongy or honeycomb-like appearance. b. Located in the interior of bones. c. Composed of trabeculae (thin bony plates) with spaces between them. d. Contains numerous cavities filled with bone marrow. e. Provides flexibility and helps distribute forces. 4

Unit 2 (7-11) 12. Compare interstitial and appositional growth of cartilage. 1) Interstitial Growth of Cartilage: a. Occurs within the cartilage matrix. b. Cartilage cells (chondrocytes) within lacunae divide and secrete new matrix. c. Expands cartilage from within. d. Common in developing cartilage, such as during childhood growth. 2) Appositional Growth of Cartilage: a. Occurs on the cartilage's surface. b. Stem cells in the perichondrium (connective tissue covering) differentiate into chondroblasts. c. Chondroblasts secrete new matrix on the outer surface. d. Increases cartilage thickness and diameter. e. Common in adulthood, contributing to cartilage maintenance and repair. 13. Identify bones that are produced by intramembranous ossification. 1) Flat Bones of the Skull: The bones of the skull, including the frontal, parietal, occipital, and temporal bones, are formed through intramembranous ossification. 2) Clavicles (Collarbones): Both clavicles are formed through intramembranous ossification. 14. Differentiate between intramembranous ossification and endochondral ossification. 1) Intramembranous Ossification: a. Occurs in flat bones of the skull, clavicles, and some facial bones. b. Bone forms directly from mesenchymal or connective tissue membranes. c. No cartilage precursor is involved. d. Osteoblasts within mesenchymal tissue secrete bone matrix, which eventually mineralizes. e. Results in the formation of flat bones. f. Typically occurs during fetal development and early infancy. 2) Endochondral Ossification: a. Occurs in long bones, most of the skeleton, and the base of the skull. b. Bone forms from a hyaline cartilage precursor model. c. Cartilage model is gradually replaced by bone tissue. d. Begins with chondrocyte proliferation in the cartilage model, followed by cartilage calcification and invasion by blood vessels and osteoblasts. e. Results in the formation of long and most other types of bones. f. Continues throughout childhood and adolescence, responsible for bone growth and repair. 5

Unit 2 (7-11) 15. Define bone remodeling. 1) Bone remodeling is a continuous and dynamic physiological process in which old or damaged bone tissue is broken down (resorption) and replaced with new bone tissue (formation) to maintain bone health, adapt to mechanical demands, and regulate mineral levels in the body. 16. Explain the effect of mechanical stress on bone remodeling. 1) mechanical stress on bones triggers a dynamic balance between bone formation and resorption, ultimately leading to bone adaptation and increased strength to meet the mechanical demands placed on the skeleton. This is a fundamental principle in bone physiology and is crucial for overall bone health and integrity. 17. Identify the hormones that influence bone growth and bone remodeling, and describe their effects. 1) Growth Hormone (GH): Promotes bone growth during childhood by stimulating the proliferation of chondrocytes (cartilage cells) in the epiphyseal plates of long bones. It also enhances the activity of osteoblasts, leading to increased bone formation. 2) Thyroid Hormones (Thyroxine and Triiodothyronine ): Stimulate bone growth and development, particularly during infancy and childhood. They also help maintain bone health by regulating metabolic processes. 3) Parathyroid Hormone (PTH): Increases blood calcium levels by stimulating bone resorption, releasing calcium from bone tissue into the bloodstream. PTH indirectly influences bone remodeling by regulating calcium levels. 4) Calcitonin: Secreted by the thyroid gland, calcitonin helps regulate calcium levels in the blood by inhibiting osteoclast activity, reducing bone resorption, and promoting calcium deposition into bone. 5) Estrogen and Testosterone: Sex hormones play a significant role in bone health. Estrogen helps maintain bone density in females by inhibiting osteoclast activity, whereas testosterone stimulates bone growth and density in males. Both hormones play roles in bone remodeling. 6) Vitamin D: While not a hormone, vitamin D is essential for bone health. It promotes calcium absorption in the intestines, which is necessary for proper mineralization of bone tissue. 6

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