Chapter 7 Bone and Skeletal System PDF

Anatomy and Physiology, 1e Chapter 7: Bone Tissue and The Skeletal System Elizabeth Co, Ana...

Anatomy and Physiology, 1e Chapter 7: Bone Tissue and The Skeletal System Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 1  Icebreaker Bone is a solid connective tissue. The major function of bone is protection. Have you ever wondered where the strength of bone comes from? Do you know of any functions of bone other than protection? How is bone able to grow and heal after damage? In this chapter, we will investigate the anatomy and physiology of bone tissue. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 2 The Functions of the Skeletal System Section 7.1 Learning Objectives 7.1.1–7.1.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 3  Functions of the Skeletal System The skeletal system is made of bone and cartilage Functions include: Providing rigid support framework of the human body Allowing movement as muscles pull on bones Providing protection for soft internal organs Storing minerals in the bone extracellular matrix Storing energy in the form of adipose in yellow bone marrow Production of blood cells Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 4  Bone Functions (Figure 7.1) Attachment sites for muscles Protection of internal organs Storage of calcium and other minerals Production of blood cells Storage of adipose tissue Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 5  Cartilage Cartilage contributes to skeletal system Elastic cartilage is not found in the skeletal system Hyaline cartilage is found at the ends of bones where they form joints Helps bones glide past one another Loss of hyaline cartilage leads to osteoarthritis Fibrocartilage is found between vertebrae, within the knee, and the pubic symphysis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 6  Anatomy of a Typical Bone Periosteum covers the surface of the bone Outer shell of compact bone protects entire bone Spongy bone contains red bone marrow Medullary cavity contains yellow bone marrow Articular cartilage made of hyaline cartilage is found at the joints Ligaments attach bones to each other Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 7  Think, Pair, Share Activity 1 One of the functions of bone is protection. Identify some common organs that are protected by bone. Why do you think bone is used to protect these organs? Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 8  Think, Pair, Share Activity 1 Answer One of the functions of bone is protection. Identify some common organs that are protected by bone. Why do you think bone is used to protect these organs? Common organs that are protected by bone include the brain, heart, and lungs. Bone is used to protect these organs because it is a hard tissue that provides protection. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 9  Discussion Activity 1 Bones support the structure and form of the human body. Can you think of any professions where knowledge of the anatomy of physiology of bones is essential? Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 10  Discussion Activity 1 Answer Bones support the structure and form of the human body. Can you think of any professions where knowledge of the anatomy of physiology of bones is essential? Professions where knowledge of the anatomy and physiology of bones is essential include radiologist, orthopedic surgeon, and chiropractor. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 11  Bone Classification Section 7.2 Learning Objectives 7.2.1–7.2.3 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 12  Classes of Bones (Figure 7.02) Bones are classified primarily according to shape Long bones Short bones Flat bones Irregular bones Sesamoid bones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 13  Bone Classifications (Table 7.1) Bone classifications include: Long bones Short bones Flat bones Irregular bones Sesamoid bones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 14  Long Bones Bones that are longer than they are wide Function as levers Examples: Humerus Femur Ulna Tibia Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 15  Common Structures of a Long Bone (1 of 3) (Figure 7.4) Epiphysis—end of long bone Diaphysis—shaft of long bone Metaphysis—between epiphysis and diaphysis Location of epiphyseal plate/line Medullary cavity—hollow space in diaphysis Houses yellow bone marrow Articular cartilage—layer of hyaline cartilage that reduces friction in joint Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 16 Common Structures of a Long Bone (2 of 3) (Figure 7.5) Epiphyseal plate (growth plate) found in children Contains growing cartilage that allows bones to increase in length Ossifies to become epiphyseal line in adults Epiphyseal line—site of previous epiphyseal plate Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 17 Common Structures of a Long Bone (3 of 3) (Figure 7.6) Periosteum—dense irregular connective tissue lining surface Contains blood vessels, nerves, and lymphatic vessels Tendons and ligaments attach to periosteum by perforating fibers Endosteum—dense irregular connective tissue lining medullary cavity Periosteum and endosteum contain cells that allow bone growth Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 18  Periosteum (Figure 7.7) Periosteum is attachment site for tendons and ligaments Collagen fibers of tendon weave into those of periosteum to anchor muscle to bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 19  Articular Cartilage (Figure 7.8) Found at ends of long bones where joints form Made of hyaline cartilage Reduce friction and act as shock absorber Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 20  Short and Flat Bones Short bones Flat bones Cube-like in shape Usually thin, but can be curved Approximately equal length, Protect internal organs width, and thickness Examples: Provide stability and support Cranial bones (skull) Examples: Sternum Carpal bones of the wrist Ribs Tarsal bones of the ankle Scapula Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 21  Flat Bones (Figure 7.9) Composed of a layer of spongy bone between two layers of compact bone Help protect internal organs (e.g., skull, ribs) Spongy bone houses red bone marrow Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 22  Irregular and Sesamoid Bones Irregular bones Sesamoid bones Do not have an easily Small, round bones suspended characterized shape in a tendon or ligament Does not fit any other Protect tendons from classification compressive force Complex shapes Example: Examples: Patella Vertebrae Only common sesamoid bone Facial bones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 23  Sesamoid Bones (Figure 7.3) Small, round bones suspended within a tendon or ligament Develop over time due to friction Help protect tendons Typically seen in tendons of feet, hands, and knees Patella is the only common sesamoid bone in every person Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 24  Bone Markings The surface features of bones Articulating surfaces – where two bones meet Depressions—sunken portion of a bone Projections—projects above surface of bone Holes and spaces—an opening or a groove in the bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 25  The 4 Classes of Bone Markings (Table 7.2) The four general classes of bone markings include: Articulating surfaces Depressions Projections Holes and spaces Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 26  Articulating Surfaces Articulating surfaces Condyle—rounded surface Facet—flat surface Head—prominent rounded surface Trochlea—rounded articulating surface Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 27  Depressions Depressions Fossa—elongated basin Sulcus—groove Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 28  Projections Crest—ridge Spine—sharp process Epicondyle—projection off a Trochanter—rough round condyle projection Line—slight, elongated ridge Tubercle—small, rounded process Process—prominent feature Tuberosity—rough surface Ramus —long projection (branch) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 29  Holes and Spaces Canal—passage in bone Fissure—slit through bone Foramen—hole through bone Meatus—opening into canal Sinus—air-filled space in bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 30  Matching Activity 1 Match the term with 1. Condyle A. Groove its correct description. 2. Foramen B. Flat surface 3. Sulcus C. Sharp process 4. Fissure D. Slit 5. Facet E. Rounded process 6. Spine F. Hole Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 31  Matching Activity 1 Answer 1. Condyle—E 2. Foramen—F 3. Sulcus—A 4. Fissure—D 5. Facet—B 6. Spine—C Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 32  Knowledge Check Activity 1 Bones that are shaped like a cube are called: A. Long bones B. Short bones C. Sesamoid bones D. Flat bones E. Irregular bones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 33  Knowledge Check Activity 1 Answer Bones that are shaped like a cube are called: B. Short bones Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 34 The Microscopic Structure of Cartilage and Bone Section 7.3 Learning Objectives 7.3.1–7.3.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 35  Three Types of Cartilage (Figure 7.11) Hyaline, elastic, and fibrocartilage Chondroblasts – cells of cartilage that secrete matrix Chondrocytes – cells that are completely surrounded by matrix Found in lacunae Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 36  Cartilage Tissue (Figure 7.10) Semi-solid connective tissue Avascular Covered by perichondrium Dense irregular connective tissue Contains blood vessels Provides nutrients to cartilage Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 37  Bone Tissue Solid connective tissue Compact bone More dense Provides support and protection Spongy bone Provide strength to bone Spaces house red bone marrow Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 38  Cells of Bone Osteogenic cells—stem cells that replicate Develop into osteoblasts Communicate via canaliculi Osteoblasts—cells that form new bone matrix Osteocytes—mature osteoblast that are completely surrounded by matrix Located in lacunae Osteoclasts—cells that breakdown bone Aid in bone remodeling Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 39  Compact Bone (Figure 7.12) Osteon—structural unit of compact bone Made of rings of matrix called concentric lamellae Concentric lamellae surround central canal and provide support Blood vessels in central canal connected to periosteum by perforating canals Nutrients and wastes move through canaliculi Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 40  Spongy Bone (Figure 7.13) Contain osteocytes within trabeculae Trabeculae—beams of bone that form lattice-like network within spongy bone Form along stress lines to provide strength Spaces house red bone marrow where hematopoiesis occurs Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 41  Knowledge Check Activity 2 The structural unit of compact bone is the: A. Trabeculae B. Periosteum C. Osteon D. Central canal E. Concentric lamellae Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 42  Knowledge Check Activity 2 Answer The structural unit of compact bone is the: C. Osteon Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 43  Think, Pair, Share Activity 2 Compare the structure of compact and spongy bone to the trunk and branches of a tree. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 44  Think, Pair, Share Activity 2 Answer Compare the structure of compact and spongy bone to the trunk and branches of a tree. The structure of compact bone resembles the trunk of a tree. The concentric lamellae are arranged around the central canal. This is similar to the annular rings seen in the trunk of a tree. The structure of spongy bone resembles the branches of a tree. The trabeculae that form within spongy bone resemble the branching pattern. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 45 Formation and Growth of Bone and Cartilage Section 7.4 Learning Objectives 7.4.1–7.4.2 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 46  Formation of Bone Ossification—the process of forming bone A cartilage or membranous model is required New bone tissue is built on the model Intramembranous ossification—connective tissue membrane is used to make bone Endochondral ossification—hyaline cartilage is used to make bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 47 Intramembranous Ossification (Figure 7.14) Forms flat bones of cranium and face Mesenchymal cells group together and differentiate into osteoblasts forming ossification center Osteoblasts begin to secret osteoid Trabeculae and periosteum form Compact bone surrounds trabecular bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 48  Endochondral Ossification (Figure 7.15) Forms most long bones Cells in cartilage differentiate into osteoblasts Minerals are deposited on collagen fibers in cartilage starting at diaphysis Perichondrium becomes periosteum Blood vessels penetrate periosteum forming primary ossification center Mineralization increases Cartilage remains at epiphyseal plate to allow bone to grow in length Epiphyses ossify after birth at secondary ossification centers Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 49  Ossification of Embryonic and Fetal Skeletons (Figure 7.16) Embryonic and fetal skeletons form by combination of intramembranous and endochondral ossification Long bones are formed via endochondral ossification Flat bones are formed via intramembranous ossification Mineralization increases during development Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 50  Breakout Group Activity 1 Review the steps of intramembranous and endochondral ossification by having each group member diagram a step in the process. After the group diagrams each step, present those steps to the class as a group. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 51  Breakout Group Activity 1 Answer The diagram for intramembranous The diagram for endochondral ossification ossification should resemble Figure 7.14. should resemble Figure 7.15. The steps are: The steps are: Forms most long bones Forms flat bones of cranium and face Cells in cartilage differentiate into Mesenchymal cells group together and osteoblasts differentiate into osteoblasts forming Minerals are deposited on collagen fibers ossification center starting at diaphysis Osteoblasts begin to secret osteoid Perichondrium becomes periosteum Trabeculae and periosteum form Blood vessels penetrate periosteum forming primary ossification center Compact bone surrounds trabecular bone mineralization increases Cartilage remains at epiphyseal plate to allow bone to grow in length Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 52  Think, Pair, Share Activity 3 Ossification of a connective tissue model is required to make bone. Why is the development of new blood vessels necessary for the ossification of bone regardless of the model used? Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 53  Think, Pair, Share Activity 3 Answer Ossification of a connective tissue model is required to make bone. Why is the development of new blood vessels necessary for the ossification of bone regardless of the model used? The development of new blood vessels is required because the cartilage and membranous models are poorly vascularized. The deficient number of vessels in the cartilage and membranes is not enough to supply the nutrients needed for bone development so additional blood vessels are required. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 54  Growth, Repair, and Remodeling Section 7.5 Learning Objectives 7.5.1–7.5.2 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 55  Cartilage Growth Interstitial cartilage growth—cartilage grows longer Due to mitotic replication of chondrocytes Allows bone to increase in length Appositional cartilage growth—cartilage grows wider Occurs as cells in perichondrium become chondroblasts and secrete matrix Allows bone to increase in width Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 56  Interstitial Cartilage Growth (Figure 7.17) Chondrocytes divide by mitosis which allows cartilage to grow in length Initially share same lacuna Chondrocytes move apart as they secrete matrix Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 57 Appositional Cartilage Growth (Figure 7.18) Allows cartilage to increase in width Cell in perichondrium differentiate into chondroblasts Chondroblasts secrete matrix allowing increase in width Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 58  How Bones Grow in Length (Figure 7.19) Epiphyseal plate grows The increase in size increases the distance between the epiphysis and diaphysis Cartilage on the diaphysis side of the plate is replaced with bone Bone is longer as a result Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 59  Anatomy of Epiphyseal Plate Epiphyseal plates exhibit four zones of activity Reserve zone – anchors epiphyseal plate to epiphysis Proliferative zone – chondrocytes that recently underwent mitosis Zone of mature cartilage – older, more mature chondrocytes Zone of calcified matrix – dead chondrocytes surrounded by bone matrix Anchors epiphyseal plate to diaphysis Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 60  How Bones Grow in Diameter (Figure 7.20) Occurs by appositional growth Osteoblasts in periosteum form new matrix on surface of bone Osteoclasts break down older bone that lines medullary cavity Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 61  Bone Remodeling The changes bones go through on a daily basis Bone is constantly broken down and new bone is formed Aids homeostasis by making minerals available Caused by injury, exercise, and other activities Bone remodels to increase strength along line of resistance Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 62  Blood Calcium Regulation (Figure 7.21) Bones store calcium and other minerals Hormones influence bone: Calcitonin causes bones to take up calcium Lowers blood calcium levels Parathyroid hormone causes bones to release calcium Increases blood calcium levels Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 63  Hormones that Influence the Skeletal System (Table 7.3) Growth hormone (GH) – promotes bone growth T3 and T4 – promotes bone growth Estrogen and testosterone – increase osteoblast activity Calcitriol – increases absorption of calcium and phosphate from intestine PTH – increases osteoclast activity Calcitonin – increases osteoblast and decreases osteoclast activity Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 64  Bone Repair (Figure 7.22) Fracture—break of a bone Steps in bone repair: 1. Hematoma prevents blood loss 2. Cartilage callus forms new bone template 3. Callus is replaced by bone 4. Compact bone is built around the outer surface of bone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 65  Assisting Bone Repair (Figure 7.23) Reduction = aligning of bones for optimal healing Should be done as soon as possible Cylinders and screws can be added surgically for stabilization Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 66  Types of Fractures Fractures classified based on complexity, location, and other features Closed Open Transverse Spiral Comminuted Impacted Greenstick Oblique Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 67 Common Types of Fractures (Table 7.4) Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 68  Think, Pair, Share Activity 4 Think of reasons why the bones of an astronaut who has been in space for a year might look different than the bones of person that has been on Earth during the same time. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 69  Think, Pair, Share Activity 4 Answer Think of reasons why the bones of an astronaut who has been in space for a year might look different than the bones of person that has been on Earth during the same time. The bones of an astronaut would be thinner and less dense than those of a person living on Earth. This is because a person in space does not experience the force of gravity and less stress is placed on the bones. Without the stress of gravity, bone mass decreases because there is less stress on the bone. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 70  Discussion Activity 2 Can you identify reasons for a physician to splint a bone when it’s fractured? Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 71  Discussion Activity 2 Answer Can you identify reasons for a physician to splint a bone when it’s fractured? A physician would splint a fractured bone to allow the ends of the fracture to maintain proper alignment during healing and repair. This decreases the risk of deformity as the bone heals. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 72 Bones and Homeostasis Section 7.6 Learning Objectives 7.6.1–7.6.4 Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 73  Nutrition and Bone Tissue Calcium is stored in the extracellular matrix of bone Hypocalcemia – low blood levels of calcium Hypercalcemia – high blood levels of calcium Parathyroid hormone (PTH) – stimulates osteoclasts The breakdown of bone increases blood calcium Calcitonin (CT) – inhibits osteoclasts Increased formation of bone decreases blood calcium Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 74  Calcium Homeostasis Bones store calcium Calcitonin and parathyroid hormones aid in calcium homeostasis Calcium is absorbed by small intestine Requires vitamin D for absorption Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 75  Dietary Calcium (Figure 7.24) Good sources of dietary calcium include: Cheese Milk Nuts Leafy greens Fish Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 76  Importance of Vitamin D (Figure 7.25) Vitamin D is synthesized by the body Not found in many foods Can be added to foods like milk and cereal for supplementation Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 77  Vitamin D Synthesis (Figure 7.26) Human body can produce vitamin D Requires exposure to sunlight/UV radiation Activated by kidneys Active forms = calcitriol and calcidiol Travels through blood to small intestine Facilitates calcium absorption by small intestine Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 78  Exercise and Bone Tissue (Figure 7.27) Exercise and physical stress strengthen bones Increased exercise leads to thicker, denser bones Lack of exercise leads to weaker, lighter bones Increases risk of fracture Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 79  Osteoporosis Characterized by a decrease in bone mass with age Rate of bone resorption exceeds rate of bone formation Osteoclasts more active than osteoblasts Rapidly declining levels of estradiol in females increases risk Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 80  Discussion Activity 3 Describe possible reasons for a patient to have decreased bone density. What lifestyle changes can the patient start that can lead to increased bone density? Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 81  Discussion Activity 3 Answer Describe possible reasons for a patient to have decreased bone density. What lifestyle changes can the patient start that can lead to increased bone density? A patient may experience decreased bone density for reasons such as poor diet, long-term smoking, or lack of exercise. Lifestyle changes that can increase bone density would include a proper diet with the nutrients necessary for bone growth, weight-bearing exercise, and smoking cessation. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 82  Knowledge Check Activity 3 What hormone will increase the activity of osteoclasts? A. Parathyroid hormone B. Growth hormone C. Calcitriol D. Calcitonin Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 83  Knowledge Check Activity 3 Answer What hormone will increase the activity of osteoclasts? A. Parathyroid hormone Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 84  Summary At the end of this chapter, you should be able to: List the classes of bones and examples of each class. Describe the anatomy of compact and spongy bones. Discuss bone growth and formation. Describe the process of fracture repair. Elizabeth Co, Anatomy and Physiology, 1st Edition. © 2023 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. 85