BY 471 Checkpoint Questions and Study Guide
What factors affect bone growth and bone remodeling?
Age, exercise Minerals: calcium and phosphorus Vitamins: A stimulates activity of osteoblasts, C needed for synthesis of collagen, D increases absorption of calcium from food, K and B12 needed for synthesis of bone proteins Hormones: IFGs most important during childhood, thyroid hormones stimulate osteoblasts, insulin increases synthesis of bone proteins, sex hormones increase osteoblast activity (post-puberty)
What is fibrodysplasia ossificans progressiva (FOP)?
A serious consequence of abnormal ossification -- starts in abnormal places such as muscles and soft tissue in response to minor injury
What are the opposing functions of ACL and PCL?
ACL: limits hyperextension, prevents tibia shifting anteriorly PCL: prevents posterior sliding of tibia when knee is flexed
Why is dislocation of femur so rare?
Acetabular labrum enhances the depth of the acetabulum.
How are chondrocytes different from osteocytes?
Exist as a singe cell or small cluster in a lacuna, and re not connected to each other via long cellular processes.
Difference between intramembranous and endochondral ossification?
Intramembranous ossification: simpler method, involves formation of bone within mesenchyme arranged in sheetlike layers that resemble membranes (skull bones, bones of face) Endochondral ossification: replacement of cartilage by bone
Why is bone considered a connective tissue?
It contains proteins mixed with water and forms gels.
What is trabeculae comprised of?
Lamellae, osteocytes, lacunae, and calanaliculi.
What is the one exception to sympheses?
Mandibles become synestosed.
What is calcification?
Mineral salts are deposited in framework formed by collagen fibers of extracellular matrix
How do hormones act on bone to regulate calcium homeostasis?
PTH: increases blood Ca2+ level by negative feedback system Calcitriol: promotes absorption of calcium from foods in the GI tract into the blood Calcitonin: decreases Ca2+ level in blood, speeds up Ca2+ uptake by bone, limit osteoclasts
What types of sensations are perceived at joints, and from what sources do joints receive nourishment?
Some nerves convey information, some respond to degree of movement and stretch at a joint. Arteries in vicinity send out numerous branches that penetrate the ligaments and articular capsule to deliver oxygen and nutrients.
What do IGFs do in bone growth?
Stimulate chondrocytes, promote cell division at epiphyseal plate and periosteum, and enhance synthesis of proteins needed to build new bone.
On what basis are joints classified?
Structural: presence/absence of synovial cavity, the of connective tissue that binds together - Fibrous - Cartilaginous - Synovial Classification: degree of movement they permit - Synarthrosis - Amphiarthrosis - Diarthrosis
What determines ROM?
Structure or shape of the articulating bones Strength and tension of joint ligaments Arrangement and tension of muscles Contact of soft parts Hormones Disuse
Which types of joints are uniaxial, biaxial, and triaxial?
Uniaxial: hinge, pivot Biaxial: plane, condyloid, saddle Triaxial: plane, ball-and-socket
In what ways are bursae similar to joint capsules? How do they differ?
Walls consist of an outer fibrous membrane of thin, dense connective tissue lined by a synovial membrane. Also filled with a small amount of fluid similar to synovial fluid.
How could the metaphyseal area of a bone help determine the age of a skeleton?
When adolescence comes to an end, the epiphyseal plate is closed leaving an epiphyseal line -- when bone growth in length stops completely.
What is the hierarchical organization of bone structure?
Whole bone --> osteonal microstructure --> lamellae --> extrafibrillar matrix --> fibril
What are the major events of endochondral ossification?
1. Development of cartilage model: mesenchymal cells develop into chondroblasts, which form the cartilage model 2. Growth of cartilage model: growth occurs by cell division of chondrocytes 3. Development of primary ossification center: in diaphysis, bone tissue has replaced most of cartilage 4. Development of the medullary cavity: bone breakdown by osteoclasts forms the medullary cavity 5. Development of secondary ossification centers: occur in epiphyses of the bone 6. Formation of articular cartilage and epiphyseal plate: both structures consist of hyaline cartilage
What are the major events of intramembranous ossification?
1. Development of ossification center: osteoblasts secrete organic extracellular matrix 2. Calcification: calcium and other mineral salts are deposited and extracellular matrix calcifies 3. Formation of trabeculae: ECM develops into trabeculae that fuse to form spongy bone 4. Development of the periosteum: mesenchyme at the periphery of the bone develops into the periosteum
Outline the four steps involved in repair.
1. Reactive phase: formation of fracture hematoma 2. Reparative phase: Fibrocartilaginous callus formation - fibroblasts put in collagen and chondroblasts produce fibrocartilage Bony callus formation - in areas close to healthy tissue, osteoprogenitors form osteoblasts which produce spongy bone trabiculae which joins together living and dead parts of bone fragment;fibrocartilage converted to spongy bone 3. Bone remodeling phase: reabsorbed by osteoclasts; compact bone replaces spongy bone
Steps of appositional growth.
1. Ridges in periosteum create groove for periosteal blood vessel 2. Periosteal ridges fuse, forming an endosteum-lined tunnel 3. Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming a new osteon 4. Bone grows outward as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessels
What is the composition of the extracellular matrix of bone tissue?
10-20% Water 30% collagen fibers 55-60% crystalized mineral salts. Most abundant mineral salt is calcium phosphate, which combines with calcium hydroxide to form crystals of hydroxyapatite.
Explain how bone growth in thickness differs from bone growth in length.
Appositional growth: tissue growth occurs only at surface by proliferation of cells and deposition of ECM Interstitial growth: cells inside tissue divide, deposit new ECM, and increase tissue mass
What doesn't the synovial membrane cover?
Articular cartilage.
What are the functions of the articular cartilage, synovial fluid, and articular discs?
Articular cartilage: a layer of hyaline cartilage covering the bones at a synovial joint Synovial fluid: hyaluronic acid secreted by synovial cells; forms thin layer over surfaces in articulate capsule; reduces friction through lubrication, absorbs shock, supplies oxygen and mineral, removes CO2 Articular discs: pads of fibrocartilage that lie between articular surfaces of bones and attach to fibrous capsule; shock absorption, fit bony surfaces, adaptable surface for combined movements, weight distribution
Define remodeling and describe the role of osteoblasts and osteoclasts in the process.
Bone remodeling: ongoing replacement of old bone tissue by new bone tissue Bone resorption: removal of mineral and collagen fibers from bone by osteoclasts Bone deposition: addition of minerals and collagen fibers to bone by osteoblasts Bone resorption followed by bone deposition.
What is a bone scan and how is it used clinically?
Bone scan: standard test for bone density screening Used to screen for bone disease, decalcified bone, fracture, infections, diseases
How are compact and spongy bone tissues different in microscopic appearance, location, and function?
Compact bone: few spaces; strongest form of bone tissue; provides protection and support and resists the stresses; beneath periosteum, makes up bulk of dipahysis Spongy bone: lacks osteons; lightweight; provides tissue support; forms interior bone tissue of short, flat, sesamoid bones and end of long bones
Which bones contain Red Bone Marrow?
Developing bones of the fetus and some adult bones, such as the hip bones, ribs, sternum, vertebrae, skull, and ends of humerus and femur.
Diagram the parts of a long bone, and list the functions of each part.
Diaphysis: shaft Epiphysis: proximal/distal ends of bone Metaphysis: between the diaphysis and epiphyses, contains growth plate Epiphyseal plate: a layer of hyaline cartilage that allows the diaphysis of the bone to grow in length Articular cartilage: thin layer of hyaline cartilage covering the epiphyses where articulation occurs Periosteum: tough connective sheath associated with blood supply; attachment point for ligaments and tendons; attached to underlying bone with perforating fibers Medullary cavity: hollow space that contains bone marrow Endosteum: thin membrane lines medullar cavity; contains single layer of bone forming cells and little connective tissue
How are osteoblasts formed?
Differentiate from osteoprogenitor cells when stimulated by bone morphogenetic proteins (BMPs)
What are the major categories of movements that occur at synovial joints?
Gliding Angular: flexion, extension, lateral flexion, hyperextension, abduction, adduction, circumduction Rotation Special movements: elevation, depression, protraction, retraction, inversion, eversion, dorsiflexion, plantar flexion, supination, pronation, opposition
What does it mean if someone is double-jointed?
Greater flexibility in articular capsules and ligaments; less structurally stable and more easily dislocated
What factors contribute to the hardness and tensile strength of bone?
Hardness: mineral salts (hydroxyapatic crystals) Tensile strength: collagen fibers and other organic molecules
What are the different cartilage types and their characteristics?
Hyaline cartilage: majority of cartilage found in body (articular cartilage, cartilage template for bones, trachea, nasal cartilage) Fibrocartilage: rich in thick bundles of collagen fibers; provides strong tensile strength; not covered with perichondrium (symphysis pubis, IV disc, menisci) Elastic cartilage: rich in elastic fibers (external ear, epiglottis)
How is a bone marrow needle biopsy performed?
Needle is inserted into the middle of the bone to withdraw a sample of red bone marrow to examine it for conditions.
What distinguishes the TMJ from other joints of the skull?
Only freely movable joint between skull bones.
Define each of the common fractures.
Open (compound): broken ends of bone protrude through skin Comminuted: bone is splintered, crushed, broken into pieces at site of impact and smaller bone fragments lie between two main fragments Greenstick: partial fracture in which one side is broken and other side bends (only in children since bones aren't fully ossified) Impacted: one end of bone is forcefully driven into interior of other Pott: fracture of distal end of fibula with serious injury of distal tibia articulation
What are the components that comprise the compact bone tissue?
Osteons thats consist of osteonic canal, concnetric lamella, lacunae, canaliculi, interstitial lamellae, interosteonic canals, circumferential lamellae, and perforating fibers..
List the four type of cells in bone tissue and their function
Osteoprogenitor cells: develops into an osteoblast; stem cell, high rate of proliferation Osteoblasts: builds bone; synthesize and secrete collagen fibers and organic compounds needed to build extracellular matrix of bone tissue (initiate calcification); metabolically active cells with high rate of protein synthesis; key role in hormonal regulation of bone resorption Osteocytes: mature bone cells, main cells in bone tissue and maintain daily metabolism; exchange of nutrients and wastes in blood; no cell division Osteoclasts: huge cells derived from fusion of monocytes; ruffled borer faces bone surface; breaks down bone matrix for resorption; concentrated in endosteum
Explain the location and roles of the nutrient arteries, nutrient foramina, epiphyseal arteries, and periosteal arteries.
Periosteal arteries: enter the diaphysis through Volkmann's canals and supply periosteum and outer part of compact bone Nutrient artery: near center of diaphysis; divides into proximal and distal branches Nutrient foramen: hole in compact bone that nutrient artery passes through (nutrient veins exit via same canal) Metaphyseal arteries: enter the metaphyses and supply the red bone marrow and bone tissue of metaphyses Epiphyseal arteries: enter epiphyses and supply red bone marrow and bone tissue of epiphyses
Describe the types of synovial joints.
Plane: articulated surfaces flat or slightly curved; back and forth, side to side, rotation (intercarpal, intertarsal, sternocotal, vertebrocostal) Hinge: convex surface fits into concave surface; flexion, extension (knee modified, elbow, ankle, interphalangeal) Pivot: rounded or pointed surface fits into ring formed by bone and ligament; rotation (atlanto-axial and radioulnar) Condyloid: oval-shaped projection fits into oval-shaped depression; flexion-extension, abduction-adduction (radiocarpal and metacarpophalangeal) Saddle: saddle shaped; flexion-extension, abduction-adduction (trapezium/metacarpal of thumb Ball-and-socket: ball-like surface fits into cuplike depression; flexion-extension, abduction-adduction, rotation (shoulder and hip)
How does the structure of synovial joints classify them as diarthroses?
Possess synovial cavity, a space between articulating bones, which allows considerable movement at a joint.
What are the functions of the skeletal system?
Provides support Protects internal organs Assists body movements Mineral homeostasis - stores and releases salts of calcium and phosphorus Participates in blood cell production Triglyceride storage - stores triglycerides in adipose cells of yelllow marrow
Describe one situation in which these sensory neurons of periosteum are important.
Reason for intense pain felt when periosteum is injured or stretched.
How does red bone marrow and yellow bone marrow differ in composition and function?
Red bone marrow consists of developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers. Yellow bone marrow consists mainly of adipose cells, which store triglercides -- a potential chemical energy reserve.
Describe the role of bones in blood cell production.
Red bone marrow, a connective tissue, produces: red blood cells, white blood cells, and platelets through the process of homopoiesis.
How do osteoclasts breakdown ECM?
Release acid, acid phosphatase, and other hydrolytic enzymes in the pit, dissolving the mineral and breaking down organic matrix (mainly collagen). Degradation products release to extracellular fluid by transcytosis.
How does the skeletal system function in support, protection, movement, and storage of minerals?
Support: supports soft tissues and attachment points for tendons Protection: protects internal organs Movement: assists in movement,along with skeletal muscles Storage of minerals: stores and releases several minerals - especially calcium and phosphorus - contributing to strength of bone
Which fibrous joints are synarthroses? Which are amphiarthroses?
Synarthroses: suture (adult), Amphiarthroses: suture (infant/children), syndesmosis, gomphosis
Which cartilaginous joints are synarthroses? Which are amphiarthroses?
Synarthroses: synchondrosis, epiphyseal cartilage Amphiarthroses: symphyses
How do strength and tension of ligaments determine range of motion?
Tense ligaments restrict ROM and direct movement of articulating bones with respect to one another
Which part of the bone contains sensory neurons that are important?
The periosteum
Describe zones of the epiphyseal growth plate and their functions and the significance of the epiphyseal line.
Zone of resting cartilage: small scattered chondrocytes, mot much role in growth Zone of proliferating cartilage: chondrocytes arranged in stacks, divide and secrete ECM, replace those in diaphyseal side of plate Zone of hypertrophic cartilage: large, maturing chondrocytes in columns Zone of calcified cartilage: mostly dead chondrocytes (b/c ECM is calcified), osteoblasts lay down ECM while osteoclasts dissolve calcified cartilage