Carilage bone and skeletal muscle VM lab Flashcards
All connective tissue consists of cells and extracellular matrix (fibers and ground substance) what is cartilage
Types of cartilage
Cells: chondrocytes become trapped within their abundant extracellular matrix secretion
It is the ECM that gives cartilage its properties of firmness and pliability
Types of cartilageL hyaline, elastic and fibrocartilage
Hyaline cartilage
- dark purple stained hyaline cartilage
- Pink staining tissue along the periphery of the cartilage matrix is called perichondrium
- Fibroblast-like, spindle-shaped cells within the perichondrium are chondrogenic cells, when cartilage is actively growing cells the chondrogenic cells gradually enlarge to become chondroblasts. Chondroblasts grow and secrete ECM. When chondroblasts become completely surrounded by ECM–> chondrocyes
2 components of the ground substances= proteoglycans and glycoproteins
chondrocytes
maintain the integrity of of the cartilage matrix by synthesizing and secreting ECM component
Prominent organelles: RER and Golgi
located in lacunae
Young chondrocytes are capable of mitosis–> cell nest (isogenous aggregates)
appositional
The process of cartilage growth at its periphery by mitotic division of chondrogenic cells and subsequent production of ECM by chondroblasts
hyaline cartilage appear homogenous (type 2 collagen fibrils)
interstitial growth
cartilage growth from within
Territorial matrix
more basophillic ECM directly surrounding the chondrocytes (as opposed to lightly basophillic chondrocytes–interterritorial matrix)
Territorial matrix is poor in collagen which stains pink, has a greater concentration of newly synthesized proteoglycans, which stains blue. because the sulfated proteoglycans are negatively charged they are basophilit
Elastic cartilage
basic structure and growth properties of elastic cartilage are nearly identical to those of hyaline cartilage
Elastic cartilage has a heterogenous appearance
Pink stringy appearance or black
Present atpinna, external auditory canal, eustachian tube, laryngeal (epigli=ottis) 3 Es ear, epiglottis, eustacian tube
more flexible than hyaline
Fibrocartilage
chondrocytes are surrounded by very little matrix, tend to be arranged in rows between coarse bundles of collagen fibers
Alternating arrangement of the collagen bundles in adjacent layers of the fibrocartilage
Unlike hyaline and elastic cartilage, fibrocartilage has no perichondrium
Type 1 collagen
Found in intervertebral discs, pubic symphysis, menisci of the knee joint. articular discs of sternoclavicular and temporomandibular joints
shock absorber resisting compression and shear forces
Articular cartilage
mostly resembles hyaline cartilage without perichondrium
Smooth surface, for low friction
Developoing cartilage
has more cells and less matrix than mature cartilage
Bone tissue classification
compact/cortical in the diaphysis of long bones and inner and outer tables of some skull bones
Spongy (trabecular and cancellous): bone found in the epiphysis and metaphysis
At microscopic level bone is woven (immature,primary) or lamellar (mature secondary)
Woven: collagen fiber bundles are parallel sheets (lamellae) mechanical strength, lamellar bone begins to appear during late fetal period. In mature bone (both compact and spongy is lamellar in structure
Lamellar bone: has oriented collagen fibers, woven is random
periosteum
consists of type 1 collagen its a fibrous connective tissue
compact bone
collagen fiber bundles organized into distinct layers/lamellae
Concentric arrangement of lamellae in compact bone is called haversian system or osteon
Interstitial lamellae occupy the gaps between the osteons
At the center of each osteon is a haversian/central canal
In living bone: blood vessels, nerves, bone forming cells (osteoblasts and osteoprogenitor cells/proteoblasts)
Lacunae
spaces between the lamellae, contains osteocytes
tiny dark lines radiating from each lacuna is canaliculi
cytoplasmic processes of osteocytes form gap juctions with processes of adjacent osteocytes, enabling diffusion of metabolites between osteocytes and blood vessels of haversion canals
Interstitial lamellae
remnants of older osteons that have been partially resorbed
Canals oriented perpendicular to haversian canal are called Volkmanns (perforating canals)
Fracture
primary callus- pinkish/red stain with cartilaginous appearance with chondrocytes in lacunae surrounded by matrix
Fibrocartilage (transitory tissue) in fracture repair then (woven primary) bone tissue forms the secondary callus,
Secondary callus remodeled and replaced with lamellar secondary bone tissue
Row of cuboidal basophilic are actively seccreting matrix and thus are important in bone deposition (Osteoblasts and osteoprogenitor cells) (basophillic due to rER for synthesis of matrix component (stained by hematoxylin)
Apposional growth
bone at the diaphysis is increased
Osteoclasts
large multinucleated cells , bone resorption, helps maintain blood calcium levels
Bone formation occurs in 2 ways
Intramembranous ossification and endochondral ossification
Endochonral ossification involves fomation of a hyaline cartilage is gradually converted to bone, (endochondral ossification in most bones of the embryo and epiphyseal plates of long bones
Zones of cartilage transformation at epiphyseal growth plate
Reserve cartilage,–> proliferation, hypertrophy, calcification, cartilage degeneration,osteogenic
nutritional and hormonal factors which influence bone calcification, growth or maintenance
Protein deficiency: decreased collagen synthesis–> inhibits bone growth and maintenance
Ca deficiency: incomplete calcification–> rickets or osteomalacia
Increased PTH: increased blood Ca by activating osteomalacia
Increased calcitonin: decreased blood Ca by inhibiting osteoclasts
