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What are the components of the skeletal system?
bones of skeleton, cartilage, ligaments, other CT
two types of bone
compact bone and spongy bone
what type of bone is dense or cortical bone?
compact
what type of bone takes of 80% of bone mass?
compact bone
what type of bone is known as cancellous or trabecular?
spongy bone
what type of bone is located internal to compact bone, appears porous, and is 20% of bone mass?
spongy bone
what structure is semirigid connective tissue that is more flexible than bone?
cartilage
two types of cartilage
hyaline and fibrocartilage
what type of cartilage attaches ribs to sternum, covers ends of some bones, is found within growth plates, and is a model for bone formation?
hyaline cartilage
what type of cartilage withstands compression and is located in intervertebral discs, public symphysis, and menisci of knee?
fibrocartilage
What connects muscle to bone?
tendons
what connects bone to bone?
ligaments
what are the four basic functions of bones?
-support and protection
-levers for movement
-hematopoiesis
-storage of mineral and energy reserves
what is known as blood cell production and occurs in red bone marrow CT?
hematopoiesis
what minerals are stored in bones?
calcium and phosphate
this type of bone is greater in length than width
long bones
example of long bone
femur, humerus
this type of bone has a length that is nearly equal to width
short bones
example of short bone
carpals and tarsals
this type of bone has flat, thin surfaces that may be slightly curved
flat bones
example of flat bones
cranial bones
this type of bone is elaborate and sometimes has a complex shape
irregular bones
example of irregular bones
vertebrae
What region of the bone is elongated, with a usual cylindrical shaft
diaphysis
What region of the bone provides leverage and weight support?
diaphysis
What regions of the bone has compact bone with thin spicules of spongy bone extending inward?
diaphysis
what is the diaphysis?
the shaft of a long bone
What region of the bone is a hollow, cylindrical space within the diaphysis?
medullary (marrow) cavity
What region of the bone contains red bone marrow in children and yellow bone marrow in adults?
medullary (marrow) cavity
What is the knobby region at each end of long bone?
epiphysis
What epiphysis is the end of the bone closest to body trunk?
proximal epiphysis
What epiphysis is the end farthest from trunk?
distal epiphysis
What is the epiphysis composed of?
Outer thin layer of compact bone and inner region of spongy bone.
What type of cartilage covers the joint surface?
articular cartilage
What type of cartilage is a thin layer of hyaline cartilage?
articular cartilage
What type of cartilage reduces friction?
articular cartilage
What type of cartilage absorbs shock in moveable joints?
articular cartilage
Metaphysis
Region where bone widens and transfers weight between the diaphysis and epiphysis.
Epiphyseal plate
growth plate
what is the epiphyseal plate composed of?
hyaline cartilage
what does the epiphyseal line become in adults?
epiphyseal line
periostem
tough sheath covering outer surface of bone
role of periosteum
serves an an attachment point for tendons and ligaments, anchors blood vessels and nerves to bone surface, and protects bone from surrounding structures
What structure anchors the periosteum to the bone?
perforating fibers
What is the inner cellular layer of the periosteum composed of?
osteoprogenitor cells, osteoblasts, osteoclasts
What are the three "layers" of the periosteum?
fibrous layer, cellular layer, perforating fibers
Endosteum
covers all internal surfaces of bone within medullary cavity
what do flat bones, irregular bones, and short bones lack?
medullary cavity
Diploƫ
spongy bone in flat bone of skull
nutrient foramen
small opening or hole in bone, artery entrance and vein exit here.
Red bone marrow (myeloid tissue)
forms red blood cells
Where is red bone marrow found in children?
spongy bone and medullary cavity of long bones
Where is red bone marrow found in adults?
skull, vertebrae, ribs, sternum, ossa coxae, proximal epiphyses of humerus and femur
What is yellow bone marrow?
fatty substance; product of red bone marrow degeneration as children mature.
When would yellow bone marrow convert back to red bone marrow?
severe anemia
four types of cells found in bone connective tissue
osteoprogenitor, osteoblast, osteoclast, osteocyte
What are osteoprogenitor cells?
Mesenchymal stem cells that divide to produce osteoblasts
Where are osteoprogenitor cells located?
periosteum and endosteum
osteoblasts
bone forming cells
What do osteoblasts secrete?
osteoid
osteoid
initial semisolid organic form of bone matrix that later calcifies
what do osteoblasts differentiate into?
osteocytes
osteocytes
mature bone cells derived from osteoblasts
what do osteoblasts do?
detect stress on bone; trigger new bone formation
osteoclasts
large, multinuclear, phagocytic cells that resorb or break down bone matrix
Resorption lacuna
a depression or pit in the bone surface that contains osteoclasts
what type of border do osteoclasts have?
ruffled border
organic components of the bone matrix
Osteoid produced by osteoblasts, contains
Collagen protein
Semisolid ground substance of proteoglycans and glycoproteins
Gives bone tensile strength by resisting stretching
Contributes to bone flexibility
What do the organic components of the bone matrix do?
gives bone tensile strength by resisting stretching and contributes to bone flexibility
inorganic components of bone
salt crystals, calcium phosphate
What do the inorganic components of bone interact with?
calcium hydroxide
what do the inorganic components and calcium hydroxide form?
crystals called hydroxyapatite
What do the hydroxyapatite crystals do?
harden matrix and account for rigidity of bones
Calcification
deposition of hydroxyapatite crystals
How does bone formation start?
secretion of osteoid
What does the bone formation process require?
vitamin D, vitamin C, calcium and phosphate
osteitis deformans
results from disruption between osteoclast and osteoblast function
osteons (bulls-eye target)
basic functional and structural unit of mature compact bone
central (Haversian) canal
-Cylindrical channel at center of osteon and parallel to it.
-Blood vessels and nerves extend through channel
Concentric lamellae
Rings of bone CT that surround the central canal. Composed of collagen fibers.
osteocytes (car)
mature bone cells
where are osteocytes found?
lacunae
Canaliculi
tiny, interconnecting channels within bone CT that extend from each lacuna, travel through lamellae and connect to lacunae and central canal.
canaliculi role
allow exchange of nutrients, minerals, gases, and wastes between blood vessels and osteocytes.
Perforating (Volkmann's) canals
perpendicular to central canals and connect to central canals within different osteons
external circumferential lamellae
rings of bone run immediately internal to periosteum
internal circumferential lamellae
rings of bone run next to the endosteum
Interstitial lamellae
components of compact bone between osteons or partially resorbed osteons
Trabeculae (spongy bone)
Open lattice of narrow rods and plates of bones (crisscrossing fibers)
What fills the spaces of trabeculae?
bone marrow
Parallel lamellae
Bone matrix with osteocytes between lamellae. Canaliculi radiate from lacunae.
Is hyaline cartilage vascular or avascular?
avascular
structure of hyaline cartilage
-cells scattered through matrix of protein fibers
-embedded in a gel-like ground substance
-resilient and flexible
-high percentage of water
-highly compressible and a good shock absorber
Chondroblasts
produce cartilage matrix
Chondrocytes
-Chondroblasts encased within the matrix
Occupy small spaces, lacunae
-Maintain the matrix
Perichondrium
covers cartilage and helps maintain its shape
interstitial growth
growth in length
where does interstitial growth occur?
internal regions of cartilage (epiphyseal plate)
appositional growth
growth in width
where does appositional growth occur?
cartilage's outside edge
Note
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