Chapter 6 – Part a bones and Skeletal Tissue 1 Skeletal Cartilages

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Chapter 6 – Part A

Bones and Skeletal Tissue

6.1 Skeletal Cartilages

  • The human skeleton initially consists of just ______________, which is replaced by bone, except in areas requiring flexibility

Basic Structure, Types, and Locations

  • Skeletal cartilage: is highly resilient, molded cartilage tissue that consists primarily of water

  • Contains no blood vessels or nerves

  • Cartilage is made up of chondrocytes, cells encased in small cavities (lacunae) within jelly-like extracellular matrix

  • Three types of cartilage:

  • Hyaline cartilage

  • Provides ____________, _________________, and resilience

  • ______________________; contains collagen fibers only

  • Articular (joints), costal (ribs), respiratory (larynx), nasal cartilage (nose tip)

  • Elastic cartilage

  • Fibrocartilage

  • Thick _____________________ fibers – has great tensile strength

  • _______________ of knee; _________________ discs

6.2 Functions of Bones

  • There are seven important functions of bones:

  1. Support

  • For _________ and soft organs

  1. Protection

  • Protect ________, __________________, and __________ organs

  1. Movement

  • _____________ for muscle action

  1. Storage

    • _______________ and growth factor storage

    • Calcium and phosphorus, and growth factors reservoir

    • _________________ storage

    • Fat, used for an energy source, is stored in bone cavities

  1. Blood cell formation

  • ____________________ occurs in red marrow cavities of certain bones

6.3 Classification of Bones

  • _______________ skeleton

  • Long axis of body

  • Skull, vertebral column, rib cage

  • _______________ skeleton

  • Bones of upper and lower limbs

  • Girdles attaching limbs to axial skeleton

  • Bones are also classified according to one of four shapes:

  1. ____________ bones

  • Longer than they are wide

  • Limb bones

  1. ____________ bones

  • Cube-shaped bones (in wrist and ankle)

  • ______________ bones form within tendons (example: patella)

  • Vary in size and number in different individuals

  1. ____________ bones

  • Thin, flat, slightly curved

  • Sternum, scapulae, ribs, most skull bones

  1. ____________ bones

  • Complicated shapes

  • Vertebrae and hip bones

6.4 Bone Structure

  • Bones are organs because they contain different types of tissues

  • Bone (______________) tissue predominates, but a bone also has nervous tissue, cartilage, fibrous connective tissue, muscle cells, and epithelial cells in its blood vessels

Gross Anatomy

  • _________________ and __________________ bone

  • Compact bone: dense outer layer on every bone that appears smooth and solid

  • Spongy bone: made up of a honeycomb of small, needle-like or flat pieces of bone called ________________ – lattice or scafolding

  • Open spaces between trabeculae are filled with red or yellow bone marrow

  • Structure of short, irregular, and flat bones

  • Consist of thin plates of spongy bone (diploe) covered by compact bone

  • Compact bone ______________________________________

  • Bone marrow is scattered throughout spongy bone

Gross Anatomy (cont.)

  • Structure of typical long bone

  • All long bones have a shaft (diaphysis), bone ends (epiphyses), and membranes

  • _________________: tubular shaft that forms long axis of bone

  • Consists of compact bone surrounding central medullary cavity; filled with yellow marrow
  • _________________: ends of long bones that consist of compact bone externally and spongy bone internally

  • Articular cartilage (Hyaline) covers articular (___________) surfaces
  • Between diaphysis and epiphysis is epiphyseal __________

  • Remnant of childhood epiphyseal ________ where ______________ occurs

  • Membranes: two types (periosteum and endosteum)

  • ___________________: white, double-layered membrane that covers external surfaces except joints
  • Contains many nerve fibers and blood vessels that continue on to the shaft through nutrient ___________________ openings
  • ________________ points for tendons and ligaments

  • ____________________

  • Hematopoietic tissue in bones

  • _______________ is found within trabecular cavities of spongy bone such as sternum

  • In adults, red marrow is located in heads of femur and humerus, but most active areas of hematopoiesis are flat bone diploë and some irregular bones (such as the hip bone)

  • Yellow marrow can convert to red, if person becomes anemic

  • Bone markings

  • Sites of muscle, ligament, and tendon __________________ on external surfaces

  • Areas involved in joint formation or ______________ for blood vessels and nerves

  • Three types of markings:

  • ______________: outward bulge of bone

  • May be due to increased __________ from muscle pull or is a modification for joints
  • ______________: bowl- or groove-like cut-out that can serve as passageways for vessels and nerves, or plays a role in joints

  • ______________: hole or canal in bone that serves as passageways for blood vessels and nerves

Microscopic Anatomy of Bone

  • Cells of bone tissue

  • Five major cell types, each of which is a specialized form of the same basic cell type

  1. Osteogenic cells

  2. Osteoblasts

  3. Osteocytes

  4. Bone-lining cells

  5. Osteoclasts

  1. Osteogenic cells

  • Mitotically active ________________ in periosteum and endosteum

  • When stimulated, they differentiate into osteoblasts or bone-lining cells

  1. Osteoblasts

  • Bone-forming cells that _______________________ bone matrix called osteoid

  • Osteoid is made up of collagen and calcium-binding proteins

  • Collagen makes up _____% of bone protein

  • Osteoblasts are actively _____________

  1. Osteocytes

  • _______________ bone cells in lacunae that no longer divide

  • Maintain bone matrix and act as __________________ sensors

  • Respond to ______________________ stimuli such as increased force on bone or weightlessness

  • ___________________ information to osteoblasts and osteoclasts (cells that destroy bone) so bone ________________ can occur

  1. Bone-lining cells

  1. Osteoclasts

  • Derived from same hematopoietic stem cells that become _____________________

  • Giant, multinucleate cells function in bone ________________ (breakdown of bone)

  • Also helps seal off area from surrounding matrix

  • Compact bone

  • Also called lamellar bone

  • Consists of:

  • ____________

  • An osteon is the structural unit of compact bone

  • Consists of an elongated cylinder that runs parallel to long axis of bone

  • Acts as tiny weight-bearing pillars

  • An osteon cylinder consists of several rings of bone matrix called lamellae

  • Lamellae contain collagen fibers that run in different directions in adjacent rings

  • Withstands stress and resist twisting

  • Bone salts are found between collagen fibers

Microscopic Anatomy of Bone (cont.)

  • Canals and canaliculi

  • ________________ (Haversian) canal runs through core of osteon

  • Contains blood vessels and nerve fibers

  • ________________ (Volkmann’s) canals: canals lined with endosteum that occur at right angles to central canal

  • Connect ________________________ of periosteum, medullary cavity, and central canal

  • _________________: small cavities that contain osteocytes

  • _________________: hairlike canals that connect lacunae to each other and to central canal

  • Allow _____________________ between all osteocytes of osteon and permit nutrients and wastes to be _____________ from one cell to another

  • Interstitial and circumferential lamellae

  • Interstitial lamellae

  • Some fill gaps between forming osteons; others are remnants of osteons cut by bone remodeling

  • Circumferential lamellae

  • Help long bone to resist twisting

  • Spongy bone

  • Appears poorly organized but is actually organized along lines of stress to help bone ____________________

  • Trabeculae, like cables on a suspension bridge, confer _____________ to bone

  • No osteons are present

  • Capillaries in endosteum supply ________________

Chemical Composition of Bone

  • Bone is made up of both ________________ and __________________ components

  • Organic components

  • Includes osteogenic cells, osteoblasts, osteocytes, bone-lining cells, osteoclasts, and osteoid

  • Osteoid, which makes up ___________________, is secreted by osteoblasts
  • Consists of ground substance and collagen fibers, which contribute to high tensile strength and flexibility of bone
    • Inorganic components

    • Hydroxyapatites (mineral salts)

    • Makeup ____% of bone by mass

    • Consist mainly of tiny ____________________ crystals in and around collagen fibers

    • Responsible for _______________ and resistance to compression

    • Bone is half as strong as steel in resisting ________________ and as strong as steel in resisting _______________

    • Lasts long after death because of _______________ composition

    • Can reveal information about ______________ people

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