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Chapter 6

Anatomy and Physiology HAP101 Chapter Notes - Chapter 6: Dense Irregular Connective Tissue, Hematopoietic Stem Cell Transplantation, Epiphyseal Plate


Department
Anatomy and Physiology
Course Code
Anatomy and Physiology HAP101
Professor
judith
Chapter
6

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Chapter 6: Bones and Skeletal Tissues
early development - skeletal initially made up of cartilage and fibrous membranes
bone replaces cartilage and in adult cartilage found where flexibility needed
skeletal cartilage (Fig. 6.1)
o large portion is water
o no blood vessels or nerves
avasular
o surrounded by perichondrium dense irregular connective tissue
contains blood vessels that supply nutrients to cartilage via diffusion
o appositional growth new matrix onto surface of existing cartilage from chondroblasts in the perichondrium
o interstitial growth chrondrocytes in existing lacunae divide and secrete more matrix
o hyaline cartilage most abundant skeletal cartilage forms:
articular cartilage covers ends of most moveable joints
costal cartilage connects ribs to sternum
respiratory cartilage forms framework of larynx and reinforce respiratory passages
nasal cartilage supports external nose
o elastic cartilage similar but more flexible than hyaline cartilage
contains elastin fibers in extracellular matrix
found in pinna (external ear) and epiglottis (cover larynx when swallowing)
o fibrocartilage highly compressible and great tensile strength
parallel rows of chondrocytes and thick collagen bundles
cushion areas subject to pressure and stretch
menisci of knees, pubic symphysis, intervertebral discs
Bones
provide:
o support framework that supports body
o protection surrounds brain and spinal cord and protects vital organs of thorax
o assists in movement skeletal muscles attach to it by tendons bones act as levers to allow movement
o mineral and growth factor reservoir calcium and phosphate can be stored and removed from bone
o blood cell production = hemopoiesis occurs in red marrow of bones
o triglyceride storage fat (energy) storage in yellow marrow of bones
o hormone production osteocalcin helps regulate insulin secretion
axial skeleton (Fig. 6.1) forms long axis of body
o skull bones, vertebral column, rib cage
appendicular skeleton (Fig. 6.1) = bones of upper and lower limbs and girdles (pectoral and pelvic) that attach
them to the axial skeleton
Gross Anatomy
compact bone (Fig. 6.3)= dense outer layer of bone looks smooth and solid all bones have this
spongy bone (Fig. 6.3) - honeycomb look with bone arranged on trabeculae flat beams
o spaces between trabeculae filled with marrow
o filled with stem stemsspongy bone used for bone marrow transplant
shapes (Fig. 6.2)
o long bones (Fig. 6.4) elongated bones of limbs
diaphysis = shaft composed of thick collar of compact bone that surrounds
medullary cavity contains yellow marrow in adults
epiphyses = bony ends that are broader than diaphysis
exterior = compact bone
interior = spongy bone contains red marrow
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articular cartilage covers joint surface
o cushions opposing bone ends during movement
epiphyseal plate groth plate = dis of halie artilage etee epiphses ad diaphsis here
lengthening of bone and linear growth occurs during childhood
epiphyseal line = forms when epiphyses and diaphysis fuse in adult and linear growth ceases
periosteum = double-layered membrane surrounding external surface of bone (except on articular surface) -
dense irregular connective tissue and osteogenic cells
rich supply of blood vessel and nerves
o nutrient foramen = holes that allow blood vessels and nerves to penetrate shaft and enter marrow
cavity
endosteum = delicate connective tissue layer (reticular) covers internal bone and trabeculae
o short bones roughly cube shape
carpal and tarsal bones of wrist and foot
sesamoid bones form in a tendon and act to alter angle of pull patella, base of the thumb and great toe
o flat bones thin, flattened and usually slightly curved
sternum, scapulae, ribs and most skull bones
o irregular bones complicated shapes coxal (hip) bones and vertebrae
o short, irregular and flat bone external layer of compact bone and filled with spongy bone (and red marrow)
o bone markings (Table 6.1)
projections that bulge from outward from surface usually stresses created by muscles pulling on bone, or
where bones meet to form joints
head, trocanter, spine, tuberosity, line, crest, facet, condyle
depression and openings allow blood vessels and nerves to pass, muscles to sit
groove, fissure, foramen, notch, fossa
Microscopic Anatomy
cells (Fig. 6.5)
o osteogenic cells = mitotically active stem cells found in periosteum and edosteum
o osteoblasts = itotiall atie oe uildig ells that secrete bony matrix when they become completely
surrounded by bony matrix become:
o osteocytes = mature cells that sit in lacunae monitor and maintain matrix
respond to mechanical stimuli bone loading, deformation, weightlessness
communicate with bone remodelling cells (osteoblasts and osteoclasts)
o osteoclasts = oe-learig ells - giant multi-nucleated cells with ruffled border
located at site of bone resorption and enzymatically degrade bone
Compact (lamellar)bone (Fig. 6.6, 6.7)
o osteon = structure unit of compact bone
Haversian system = group name for osteons
elongated cylinder oriented parallel to the long axis of bone
lamellae layers of bony matrix
each layer collagen fibers in extracellular matrix run in same direction
adjacent layers collagen in different orientation from neighbour
resists twisting (torsion) forces
central (Haversian) canal in center of each osteon and contains blood vessels and nerve fibers
Volka’s perforatig caals lie at right angles to the long axis of the bone and connect the blood
vessels and nerves of the medullary cavity to the central canals (Fig. 6.7)
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