Specialized CT Flashcards
Cartilage is ____ (avascular/vascular).
avascular; also contains nutrients & waste pass in and out of cells through matrix
Function of Cartilage
support soft tissues; guide the development of long bones
Types of Cartilage
hyaline, elastic, and fibrocartilage
Location of Hyaline
articular ends of long bones in adults, walls of respiratory system, ventral ends of ribs, *temporary skeleton for the fetus until replaced with bone
Contents of Hyaline Cartilage Matrix (name the specific GAGs and glycoprotein)
homogenous, amorphous ground substance of proteoglycan aggregates (chondroitin/ keratan sulfate/hyaluronic acid) and chondronectin (glycoprotein) embedded Type II collagen
Territorial (capsular) Matrix
area adjacent to chondrocytes; low in collagen, but high [glycosaminoglycans]
Staining of Territorial Matrix
stains more intensely with PAS than interterritorial matrix due to sulfate groups on proteoglycans; basophilic and metachromatic
Perichondrium
Layer of dense irregular connective tissue surrounding hyaline cartilage EXCEPT at articular surfaces
Layers of Periochondrium
Outer fibrous- Type I collagen, fibroblasts, blood vessels. Inner fibrous- chondrogenic cells
Function of Periochondrium
provides blood supply to avascular cartilage
Chondrocytes
mature cartilage cells embedded in lacunae of matrix
Chondrocytes develop from ___ cells into ____ (produce matrix).
chondrogenic; chondroblasts; once cells are totally surrounded by matrix = chondrocytes
Isogenous Groups of Chondrocytes
groups of 2-8 cells that stay in same lacunae once they divide
Description of Elastic Cartilage
perichondrium similar to hyaline; matrix contains elastic fibers giving it a yellowish color; less prone to degeneration than hyaline
Location of Elastic Cartilage
where flexible support is required (e.g., external ear, Eustachian tube, epiglottis, larynx)
Fibrocartilage (does/does not) have perichondrium.
no perichondrium
Contents of Fibrocartilage
alternating rows of fibroblast-derived chondrocytes & thick bundles of Type I collagen; chondrocytes may align along lines of stress
Location of Fibrocartilage
where support & tensile strength are needed in conjunction with hyaline, other fibrous tissues, or both (e.g., IV disks, articular disks, pubic symphysis, tendon and ligament insertions, knee joint menisci)… don’t confuse with dense irregular CT!
Contents of Bone
calcified extracellular matrix w/ osteocytes embedded in matrix
Functions of Bone
body wall protection, supports soft structures, provides Ca2+ reserve (99% of body’s calcium); dynamic to deal with biomechanical forces
Contents of Bone Matrix
primarily hydroxyapatite crystals; inorganic (calcified) portion- calcium, phosphate, bicarbonate, citrate, magnesium, potassium, sodium; minerals are 50% of dry weight; organic portion- 95 % Type I collagen, chondroitin sulfate and keratan sulfate
Bone Types
Primary (immature, woven)- first bones in fetal development & bone repair, lower mineral content than secondary Secondary (mature, lamellar)
Types of Secondary Bone
Compact- dense, outer portion. Spongy- meshwork of trabeculae in interior
Organization of Compact Bone
outer circumferential lamellae underneath periosteum–> circles of haversian canal systems (osteons) connected to each other by Volkmann’s canals–> inner circumferential lamella adjacent to marrow cavity in center
Bone Periosteum
layer of noncalcified CT covering bone on external surfaces, EXCEPT at synovial articulations. outer layer is fibrous dense collagenous; inner layer is cellular (osteogenic) layer
Sharpey’s Fibers
Type I collagen; attaches periosteum to bone
Endosteum
Thin specialized CT; lines marrow cavities; source of osteoprogenitor cells & osteoblasts for bone growth and repair
Canaliculi
fluid filled microchannels in bone that allow osteocytes to communicate
Haversian Canals
contain blood vessels to conduct blood flow in bone
Osteoprogenitor cells
inner layer of periosteum & endosteal cells that line marrow cavity; flattened/spindle shaped; can differentiate into osteoblasts
Osteoblasts
secrete collagen, ground substance, osteoid (unmineralized bone)- regulates mineralization of bone; cuboidal/polygonal in shape- found as single layer in regions where bone is being formed
Osteocytes
maintain bone matrix- to a limited extent can both synthesize & resorb matrix; reside in lacuna; communicate via processes that extend through canaliculi & gap junctions
Osteoclasts
multinucleated; acidophilic; macrophage lineage (phagocytic); resorb bone/release lysosomes into extracellular space
Howship’s Lacuna
depression in bone created by osteoclast; cell seals off area, acidifies and secretes acid hydrolases to resorb bone
Osteoporosis
decrease in bone mass; primarily in old age because of diminished secretion of growth hormone; in immobile patients because lack of physical stress on bone; in postmenopausal women because of diminished estrogen secretion
Osteomalacia
due to calcium deficiency in adults, deficient calcification of newly formed bone & decalcification of calcified bone; maybe severe in pregnancy- requirements of fetus may cause calcium losses from mother
Rickets
Osteomalacia for kids! Primarily due to Vitamin D deficiency (as we have now seen a zillion times), but calcium deficiency can be contributing factor; usually accompanied by deformation of bone spicules in epiphyseal plate = slower bone growth and bone deformation
Acromegaly
excess pituitary growth hormone in adults; thick bones in the extremities and in parts of the facial skeleton
Paget’s Disease
bone remodeling not functioning properly; bone is abnormally shaped, enlarged, not as dense, prone to breaks
___ are embedded in cartilage extracellular matrix.
Chondrocytes
Location of fibrocartilage
between dense connective tissue and hyaline
Bone periosteum distributes ___ to bone.
blood vessels
