Chapter 6 - The Skeletal System: Bone Tissue Flashcards
Support
Supports soft tissues, provides attachment points for tendons of skeletal muscles
Protection
Skeleton covers most important organs
Assistance in movement
Muscles attach to bones, contract and pull on bones to move
Mineral Homeostasis
Stores minerals, especially calcium and phosphorus.
Blood Cell Production
A connective tissue called red bone marrow produces red blood cells, white blood cells, platelets.
Red Bone Marrow
developing blood cells, adipocytes, fibroblasts, and macrophages within a network of reticular fibers.
Hemopoiesis
Red bone marrow produces red/white blood cells and platelets
Triglyceride Storage
Potential chemical energy reserve
Yellow Bone Marrow
Red turns yellow, adipose cells store fat.
Diaphysis
Shaft
Epiphysis
Proximal and distal ends
Metaphysis
Between. Has Growth plate, hyaline cartilage,
Epiphyseal Plate and Line
.Growth plate in metaphysis, replaced by bone when matured to form line
Articular Cartilage
Thin layer of hyaline cartilage covering the epiphysis at articulation. Reduces friction, absorbs shock, hard to repair
Periosteum
Tough connective tissue sheath everywhere articular cartilage isnt. Protects, heals, nourishes, attaches
Periosteum - Outer Fibrous layer
Dense and irregular
Periosteum - Inner Osteogenic layer
Cells (mostly for thickeness
Periosteum - Perforating Fibers or Sharpey’s fibers
thick bundles of collagen that extend from the periosteum into the bone extracellular matrix
Medullary Cavity
Hollow, cylindrical space within the diaphysis that contains fatty yellow bone marrow and blood vessels. Max strength min weight
Endosteum
Thin membrane, lines medullary cavity. Single layer of bone-forming cells and connective tissue.
Bone or Osseous tissue
contains an abundant extracellular matrix that surrounds widely separated cells. The extracellular matrix is about 15% water, 30% collagen fibers, and 55% crystallized mineral salts.
hydroxyapatite
Calcium phosphate + calcium hydroxide
Calcification
Mineral salts are deposited in the framework formed by the collagen fibers, crystallize and the tissue hardens.
Osteogenic Cell
Osteoprogenitor cells
1 Unspecialized bone stem cells. Found in inner periosteum, and in canals that contain blood vessels.
Osteoblast
- Bone building cells. Synthesize and secrete collagen fibers, initiate calcification.
Osteocyte
- Mature bone cells, maintain daily metabolism.
Osteoclast
Huge cells in endosteum, releases lysosomal enzymes and acids that digest protein and mineral compenets of extracellular bone matrix. Resoprtion
Resorption
Enzymes digest underlying extracellular matrix, for development, maintenance and repair.
Compact Bone Tissue
strongest form of bone tissue. protection, support.
Osteon or Haversian System
repeating structural units,
Central or Haversian Canal
what the osteons are arranged around
Concentric Lamellae
resembles growth rings of a tree, mineralized extracellular matrix surrounding a small network of blood vessels and nerves.
Lacuna
between the cocentric lamellae, are these spaces containing osteocytes.
Canaliculus
filled with extracellular fluid, out of lacuna.
Circumferential Lamellae
Around the outer and inner circumference of the shaft, develop during initial bone formation.
Spongy Bone Tissue
Does not contain osteons, interior of a short flat bones. Is light and supports/protects red bone marrow. Hips, ribs, sternum, vertebrae, and proximal ends of humerus and femur.
Trabecular
Lamellae arranged in an irregular pattern of thin columns, along lines of stress
Periosteal Arteries
Small arteries and nerves, enter diaphysis, supply periosteum and outer part of compact bone.
Nutrient Artery and Foramen
Near centre of diaphysis, and hole, branches toward each end of bone
Metaphyseal Artery
Supply ends of long bones. supply the red bone marrow and bone tissue of the metaphyses.
Epiphyseal Arteries
Supply ends of long bones. supply the red bone marrow and bone tissue of the epiphyses.
Nutrient Veins: Epiphyseal, Metaphyseal, Periosteal
Accompany the nutrient artery (or respective)and exit through the diaphysis(or respective)
Ossification
Process in which bones form, embryo/fetus or growth, or remodelling, or repair
Intramembranous Ossification
First. Bone forms within mesenchyme.
Development of the ossification centre ->Calcification -> Formation of trabeculae -> Development of the periosteum
Endochondral Ossification
Second, bone forms within hyaline cartilage. Development of the cartilage model ->Growth of the cartilage model ->Development of the primary ossification center ->Development of the medullary cavity -> Formation of articular cartilage and the epiphyseal plate
Growth in length
Interstitial growth of cartilage on the epiphyseal side of the epiphyseal plate and replacement of cartilage on the diaphyseal side of the epiphyseal plate.
Growth in thickness
Appositional growth.
Periosteal cells differentiate into osteoblasts then osteocytes.
Ridges fuse to enclose blood vessel, periosteum becomes endosteum.
Osteoblasts depost bone forming new concentric lamellae.
Osteoblasts under the periosteum deposit new circumferential lamellae increasing thickness.
Bone Remodeling
Ongoing replacement of old bone tissue by new bone tissue.
Bone resorption
Removal of minerals and collagen fibers from bone by osteoclasts. Destroys bone extcelma
Bone Deposition
Addition of minerals and collagen fibers to bone by osteoblasts. Forms bone extcelma.
Fracture, Stress Fracture
Break, stress = microscopic fissuers
Reactive phase - Fracture Hematoma
Early inflammatory phase, blotted blood form around fracture (fh) 6-8hr after injury
Fibrocartilaginous Callus
Reparative phase. Mass of repair tissue consisting of collagen fibers, and cartilage that bridges broken ends. 3 weeks.
Bony (hard) Callus
Reparative phase, fibrocartilage converted to spongy bone, in areas close to well-vascularized healthy bone tissue.
Parathyroid Hormone
Regulated calcium exchange. Increases blood calcium level.
Parathyroid detects, releases AMP, and synthesizes more PTH, which increase osteoclasts which speed up bone resorprtion.
Calcitriol
PTH stimulates formation of calcitriol (active vit D) helps elevate
Calcitonin
Parafollicular cells in the thyroid gland secrete calcitonin, decreases.
Osteoporosis
Porous bones, bone resorption replaces bone deposition, because of depletion of calcium.
Rickets and Osteomalacia
Rickets is a disease of children in which the growing bones become “soft” or rubbery and are easily deformed. Because new bone formed at the epiphyseal (growth) plates fails to ossify, bowed legs and deformities of the skull, rib cage, and pelvis are common. Osteomalacia is the adult counterpart of rickets
