Ch. 6 - Bone Tissue Flashcards
First 3 Functions of the skeletal system.
- Provide support by acting as a structural framework and a point of attachment for tendons and ligaments.
- Protect the internal organs (brain, heart, etc.)
- Assist body movements (in conjunction with muscles)
Last 3 functions of the skeletal system,
- Store and release salts of calcium and phosphorus.
- Store triglycerides in adipose cells of yellow marrow
- Participate in blood cell production (hematopoiesis)
two major tissues of skeletal system
bone (osseous tissue) and cartilage.
What is bone?
Bone is a highly vascularized C.T. with a hard, mineralized extracellular matrix. It is found in the body in two different arrangements: compact bone and spongy bone
Compact bone
Function- provides protection and support.
Structure- It forms the external layer of all bones.
Spongy bone
Function- is lightweight and provides tissue support.
Structure- It forms most of the interior of bones.
Cartilage?
is a poorly vascularized C.T. with a matrix composed of collagen, proteoglycans (chondroitin sulfate) and various fibers.
Fiber types
hyaline cartilage
different from fibrocartilage or elastic cartilage.
Articular cartilage?
Structure: thin layer of hyaline cartilage covering the epiphysis of long bones. Found where the bone forms an articulation, or joint (where one bone moves against another bone).
Function: Reduces friction and
Absorbs shock
Periosteum
The periosteum is only found on areas where there is no articular cartilage.
Structure: tough sheath of dense, irregular connective tissue on the outside of the bone.
Periosteum- outer fiber layer
- Provides protection and nourishment
- Attachment point for tendons and ligaments
Periosteum- inner osteogenic layer: osteoblasts
growth and fracture repair.
Medullary Cavity
space within the diaphysis of long bones. contains fatty yellow bone marrow in adults.
Endosteum
Membrane that lines the medullary cavity.
-The endosteum is composed of osteoclasts, osteoblasts, and connective tissue.
Perichondrium
dense irregular connective tissue membrane that surrounds cartilage.
Chondroblasts/chondrocytes are
cells that build/maintain cartilage.
Many major bones are formed from cartilage.
Osteoprogenitor cells:
bone stem cells that differentiate into specialized bone cells
osteoblasts
bone building cells:
- Synthesize and secrete collagen fibers and other organic components
- Initiate calcification
Osteocytes
mature osteoblasts
-maintain tissue
Osteoclasts:
large bone crushing cells:
- White blood cells that migrate from bone marrow to become “fixed ” in bone tissue
- Remodel bones and cause them to release calcium
Tissues of skeletal system- epithelium
(endothelium) form the capillary walls
Tissues of skeletal system- nerves
(the periosteum is especially tender)
Tissues of skeletal system- red marrow
hematopoiesis
Tissues of skeletal system- yellow marrow
fat storage
Chemical constituents of bone
Bone is 15% water, 30% collagen fibers, 55% mineral salts (hydroxyapatite crystals).
Organic constituents of bone
Collagen fibers provide flexibility and tensile strength.
Inorganic hydroxyapatite crystals (mineral salts)
- Calcium Phosphate (Ca3PO4)2
- Calcium Carbonate (CaCO3 – marble)
- Other trace elements: magnesium, fluoride, sulfate
Bone structure- long bone- diaphysis
the shaft/ body of a long bone
Bone structure- long bone- epiphyses
the distal and proximal ends of a long bone, at the joints
Bone structure- long bone- metaphyses
areas where the epiphyses and diaphysis join
Adolescent bone structure
In adolescents, through the end of active growth, the epiphysis of the long bones contains hyaline cartilage and forms an “epiphyseal growth plate”.
-The growth plate is always actively dividing and causing the bone to elongate from each end.
Adult bone structure
In adults, the epiphyseal cartilage is no longer present and elongation of bones has stopped.
The epiphyseal growth plate becomes an “epiphyseal line”,
as growing cartilage is replaced by calcified bone.
The epiphyseal line is visible externally and on X-rays.
Osteons?
AKA: Haversian systems
- structural unit of compact bone
- formed from concentric lamellae –> rings of calcified matrix
Interstitial lamellae
between osteons are left over fragments of older osteons.
Outer circumferential lamellae
encircle the bone beneath the periosteum.
Inner circumferential lamellae
encircle the medullary cavity.
Lacunae
small spaces between the lamellae which house osteocytes.
Canaliculi
small channels filled with extracellular fluid connecting the lacunae.
central canal
contain blood and lymphatic vessels
-found in the center of osteon
Perforating (Volkmann’s) canals
allow transit of vessels to the periosteum and medullary cavity