Human Anatomy and Physiology BIOL3306 Fall 2024 Lecture Notes PDF

Human Anatomy and Physiology BIOL3306 Fall 2024 Week 2: Bones & Bone Tissue Professor: Nour Nissan The Skeletal System The Skeletal System—Includes the bones, joints, and other supporting tissues Bones—Main organs of the system; Adults typically have............

Human Anatomy and Physiology BIOL3306 Fall 2024 Week 2: Bones & Bone Tissue Professor: Nour Nissan The Skeletal System The Skeletal System—Includes the bones, joints, and other supporting tissues Bones—Main organs of the system; Adults typically have............. bones – Each bone includes: ▪ Bone (Osseous) Tissue ▪ Dense regular collagenous tissue ▪ Dense irregular connective tissue ▪ A tissue called Bone Marrow Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Functions of the Skeletal System Functions of the Skeletal System.......................—Bones such as the skull, sternum, and ribs protect underlying organs............................................................—Bone stores minerals including calcium, phosphorus, and magnesium salts; These minerals are electrolytes, acids, and bases in the blood, and are critical for electrolyte and acid-base maintenance......................................—Red Bone Marrow in bones is the site of............................., or formation of blood cells........................—Yellow Bone Marrow in bones contains adipocytes with stored triglycerides.......................—Bones are the sites of attachment for most skeletal muscles; When muscles contract, they pull the bones which generates movement around a joint.......................—The skeleton supports the weight of the body and provides its structural framework Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Functions of the Skeletal System Figure 6.1 Functions of the skeletal system. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Structure (1 of 6) Classification of Bone by Shape Long Bones—Longer than wide; Examples include bones of the limbs; Some long bones are very small Short Bones—About as long as wide or roughly cube- shaped; Examples include the wrist and ankle bones Flat Bones—Thin and broad; Examples include most of the skull bones and bones of the pelvis Irregular Bones—Irregular shapes; Examples include the vertebrae Sesamoid Bones—Small, flat, oval-shaped bones located within tendons; An example is the kneecap Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Structure (2 of 6) Figure 6.2 Classification of bones by shape. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved  6.1 Bone Structure (3 of 6) Structure of a Long Bone Periosteum—Outer dense irregular connective tissue membrane with blood vessels and nerves Perforating Fibers—Collagen anchors that penetrate into bone matrix to attach the periosteum Diaphysis—Shaft of the bone with a....................................... lined by the Endosteum (A membrane lining the inner surface of the bony wall) and filled with marrow Epiphyses—Ends of a long bone (filled with Red Marrow) covered with Articular Cartilage, which is composed of hyaline cartilage Compact Bone—Hard, dense outer bone that resists linear compression and twisting forces Spongy (Cancellous) Bone—Inner, honeycomb- like bone framework that resists forces in many directions and provides a place for bone marrow to reside Epiphyseal Lines—Remnants of an Epiphyseal (Growth) Plate, which is a line of hyaline cartilage actively growing in children and adolescents Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Structure (4 of 6) Structure of Short, Flat, Irregular, and Sesamoid Bones Share similarities with long bones, but have fewer structures In flat bones, the spongy bone is called Diploe, and in some flat and irregular bones of the skull, there are air-filled spaces called sinuses to make the bones lighter Figure 6.4 Structure of short, flat, irregular, and sesamoid bones. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Structure (5 of 6) Blood and Nerve Supply to Bone Bones are well supplied with blood vessels and many sensory fibers – Blood supply to long bones is from the periosteum and 1 or 2 Nutrient Arteries that enter through a small hole in the diaphysis called the............................... to supply the internal structures of the long bone – Blood supply to short, flat, irregular, and sesamoid bones is provided mostly by vessels in periosteum that penetrate bone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Structure (6 of 6) Red and Yellow Marrow Yellow Bone Marrow—Consists mostly of blood vessels and adipocytes. (Can make.................,................., or during life threatening emergencies can turn to red bone marrow to produce blood cells) Red Bone Marrow—Network of reticular fibers supporting islands of hematopoietic cells (where.................. ,.......................... and......................... form) – Infants and young children have mostly red bone marrow because of their rapid growth rate, which begins to change to yellow marrow at about age 5-7 – Adults have mostly yellow marrow with red marrow found mostly in flat bones such as the hip bone, sternum, skull, vertebrae, ribs, shoulder blades and ends of long bones. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.1 Bone Marrow Transplantation Leukemia, sickle-cell anemia, and aplastic anemic patients have improperly functioning hematopoietic cells and may benefit from Bone Marrow Transplantation A needle is inserted into the pelvic bone of a matching donor, called a Bone Marrow Harvest, and up to 2 quarts of red marrow is withdrawn Recipient’s marrow is destroyed with chemotherapy and/or radiation and donor marrow is given intravenously so that cells can travel to the recipient’s marrow cavities If successful, new blood cells will be produced in 2–4 weeks, but infection and transplant rejection are possible Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 The Extracellular Matrix of Bone (1 of 3) The Extracellular Matrix of Bone (Bone Matrix) Inorganic Matrix—About 65% of bones total weight Consists mostly of calcium salts and phosphorus as part of a large mineral called..................................... [Ca10 (PO4 )6 (OH)2 ] which gives bone its hardness and ability to resist compression and bending Bicarbonate (HCO3  ), potassium, magnesium, and sodium salts are also in the inorganic matrix Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 The Extracellular Matrix of Bone (2 of 3) The Extracellular Matrix of Bone (continued) Organic Matrix (Osteiod)—About 35% of bones total weight – Consists of protein fibers (mostly collagen), proteoglycans, glycosaminoglycans, glycoproteins, and bone-specific proteins such as Osteocalcin – Collagen helps bone resist torsion (twisting) and tensile (pulling or stretching) forces that would cause breaks in bones, and aligns with hydroxyapatite crystals to enhance bone hardness Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 The Extracellular Matrix of Bone (3 of 3) Figure 6.5 The importance of bone matrices. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 Bone Cells Bone is dynamic tissue Figure 6.6 Types of bone cells. because new bone is continually being formed as older bone is broken down Osteoblasts build bone and matures into; Osteocytes which maintain bone Osteoclasts break down bone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 Osteopetrosis Osteopetrosis or “Marble Bone Disease” occurs when defective osteoclasts do not properly degrade bone Bone mass increases, but the bone is weak and brittle and appears stonelike (petra = “rock”) Infantile Osteopetrosis—Predominantly inherited, more severe form; Skull openings fail to enlarge trapping nerves resulting in blindness and deafness; Medullary cavities in all bones fail to enlarge, decreases red bone marrow which can prove fatal; Drugs are used to stimulate osteoclasts and bone marrow Adult Osteopetrosis— Inherited; Symptoms include bone pain, recurrent fractures, nerve trapping, and joint pain Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 Histology of Bone (1 of 3) Histology of Bone Compact Bone—Hard, dense, outer shell that is able to resist a great amount of stress that would typically strain or deform an object – Units are called.................... or Haversion Systems Spongy Bone—Resists forces from many directions and forms a protective framework for the bone marrow although not weight bearing – Organized into branching “ribs” of bone called....................... ▪ Trabeculae—Covered with endosteum; Contain concentric lamellae, houses osteocytes; Access blood supply from blood vessels in bone marrow Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 Histology of Bone (2 of 3) Compact Bone Osteon Structure – Lamellae (Concentric Lamellae) —Rings of very thin layers of bone; Osteons contain 4 to 20 lamellae; Collagen fibers of adjacent lamellae run in opposite directions which resists twisting and bending forces – Central (Haversian) Canal—Contains blood vessels and nerves; Lined by endosteum – Lacunae—Small cavities between lamellae filled with E C F; About 20,000–30,000 osteocytes and lacunae are found in each cubic millimeter of bone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.2 Histology of Bone (3 of 3) Figure 6.9 Structure of compact bone. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.3 Osteoporosis and Healthy Bone Tissue (1 of 2) Osteoporosis—Bone disease caused by inadequate inorganic matrix in the EC M Makes bone brittle and increases the risk of fractures, which also heal more slowly Note the differences in healthy versus osteoporotic bone (right) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.3 Osteoporosis and Healthy Bone Tissue (2 of 2) Causes of Osteoporosis—Dietary factors, such as calcium ion and vitamin D deficiency; Female sex; Advanced age; Lack of exercise; Hormonal factors, such as lack of protective estrogen in postmenopausal women; Genetic factors; Diseases of the skin, digestive and urinary systems Preventative Measures and Treatments—Ensure adequate intake of calcium and vitamin D; Engage in weight-bearing exercises; Replace estrogen, if appropriate; Use drugs that inhibit osteoclasts or stimulate osteoblasts Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved  6.4 Bone Growth in Length (1 of 5) Longitudinal Growth—Lengthening of long bones when chondrocytes divide at the Epiphyseal Plate The Epiphyseal Plate has 5 Different Zones of Cells: 1) Zone of Reserve Cartilage—Cells are not directly involved in bone growth, but can divide if needed 2) Zone of Proliferation—Chondrocytes are...............................................;........................................................ 3) Zone of Hypertrophy and Maturation—Contains................................. 4) Zone of Calcification—Contains..............................., matrix becomes calcified; Far from blood supply 5) Zone of Ossification—Contains calcified chondrocytes and osteoblasts to build bone Zones 2–5 are actively involved in longitudinal growth, and as cells divide, the cells “above” them progressively become part of the next zones Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved  6.4 Bone Growth in Length (2 of 5) Figure 6.13 Structure of the epiphyseal plate. Bone growth Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.4 Bone Growth in Length (3 of 5) Steps of Longitudinal Growth 1) Chondrocytes divide in the zone of proliferation 2) Chondrocytes that reach the next zone enlarge and mature Lacunae surrounding the chondrocytes are larger here 3) Chondrocytes die and their matrix calcifies 4) Calcified cartilage is replaced with bone In the zone of ossification, osteoblasts invade the calcified cartilage and lay down bone; Osteoclasts resorb the calcified cartilage/bone which is replaced by bone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.4 Bone Growth in Length (4 of 5) Figure 6.14 Growth at the epiphyseal plate. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.4 Bone Growth in Length (5 of 5) Longitudinal growth continues at the epiphyseal plate as long as mitosis is happening in the zone of proliferation At about 12–15 years of age, the rate of mitosis slows, but ossification in steps 3 and 4 continues which causes the epiphyseal plate to shrink until the zone of proliferation is overtaken by the zones of calcification and ossification When the zone of proliferation completely ossifies (between ages 13 up to 21), the plate is said to be “closed” and leaves a remnant called the....................................... Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.4 Bone Growth in Width Appositional Growth—Growth of all bones in width; May continue after bone growth in length ceases Osteoblasts between the periosteum and the bone surface lay down new bone Begins with the formation of new circumferential lamellae; As new lamellae are added, the deeper circumferential lamellae are removed or incorporated into osteons Primarily thickens the compact bone of the diaphysis; Osteoclasts in the medullary cavity digest the inner circumferential lamellae so as bones increase in width, their medullary cavities enlarge as well Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.4 Gigantism and Acromegaly Gigantism—Excess growth hormone is secreted in childhood before the closure of the epiphyseal plates Excessive longitudinal and appositional growth occurs Acromegaly—Excess growth hormone is secreted after closure of the epiphyseal plates Results in enlarged bones of the skull, face, hands and feet, and soft tissues such as the tongue Can cause heart and kidney malfunction and diabetes mellitus Both gigantism and acromegaly are generally treated by removing a tumor that secretes growth hormone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Remodeling (1 of 5) Bone Remodeling—The continual process of bone formation, by Bone Deposition, and bone loss, by Bone Resorption Occurs for many reasons: – Maintenance of calcium ion homeostasis – Bone repair – Replacement of primary bone with secondary bone – Replacement of older, brittle bone, with newer bone – Bone adaptation to tension and stresses Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Remodeling (2 of 5) Bone Remodeling (continued) In healthy adult bone, bone formation and bone loss occur simultaneously by osteoblasts and osteoclasts, respectively In children, bone formation outweighs bone loss Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Remodeling (3 of 5) Bone Remodeling in Response to Tension and Stress The heavier the load a bone carries, the more bone tissue is deposited in that bone – Tension—Stretching force; Stimulates bone............... – Pressure—Application of a continuous downward force; Stimulates bone.................. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Remodeling (4 of 5) Other Factors Influencing Bone Remodeling Hormones – Testosterone strongly promotes bone deposition, while estrogen depresses osteoclast activity Age – Hormone levels decline with advancing age, such as growth hormone, which causes a reduction in protein synthesis, and estrogen, which reduces the protective effects of the hormone on bone remodeling Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Remodeling (5 of 5) Other Factors Influencing Bone Remodeling (continued) Nutrient Intake – Calcium Ion Intake—Required for bone deposition – Vitamin D Intake—Promotes calcium ion absorption in the intestines and prevents calcium loss in the urine; Inadequate amounts in children causes Rickets, which results in bone deformities, fractures, and muscle weakness – Vitamin K Intake—Required for osteocalcin to bind to calcium ions; Promotes proliferation of osteoblasts, increases their lifespan, and causes them to deposit more matrix; Inhibits osteoclast division and activity Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Calcium Ion Intake and Fracture Risk National Academy of Sciences—Recommends a very high amount— 1,000 mg/day for adults ages 19–50 and 1,200 mg/day for adults over age 50 However, long-term studies have shown that high calcium ion intakes do not result in lower fracture rates in the U.S., and that lower calcium ion intakes in some other countries does not correlate with high fracture rates Also, high calcium ion intakes have been linked to prostate cancer in men Most data suggest that 700 mg/day with adequate vitamin D and K intakes are appropriate for most people Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Repair (1 of 5) Bone Repair: Steps of Fracture Healing 1) A hematoma fills the gap between the bone fragments Hematoma—Ruptured blood vessels that bleed into the injured site. 2) Fibroblasts and chrondroblasts infiltrate the hematoma, and a............................ forms Fibroblasts form dense irregular connective tissue and chondroblasts secrete hyaline cartilage; These 2 components produce the soft callus Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Repair (2 of 5) Figure 6.17 The process of fracture repair. 1 A hematoma fills the gap between the bone fragments. 2 Fibroblasts and chondroblasts infiltrate the hematoma, and a soft callus forms. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Repair (3 of 5) Bone Repair: Steps of Fracture Healing (continued) 3) Osteoblasts build a................................ Over several weeks, osteoblasts from the periosteum lay down a collar of primary bone called a bone callus 4) The bone callus is remodeled and primary bone is replaced with secondary bone Over several months, the primary bone is resorbed and replaced with secondary bone; The bone callus often remains visible following full healing of the injury Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Repair (4 of 5) Figure 6.17 The process of fracture repair. 3 Osteoblasts build a bone callus. 4 The bone callus is remodeled and primary bone is replaced with secondary bone. Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 6.5 Bone Repair (5 of 5) Classes of Fractures Simple (Closed) Fractures—Skin and surrounding tissue remain intact Compound (Open) Fractures—Damage around the fracture Treatment of Fractures—Stabilization of the fracture, followed by immobilization for about 6 weeks Closed Reduction—Bone ends are brought into contact Open Reduction—Fracture is surgically fixated with plates, wires, and/or screws Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved