Carilage bone and skeletal muscle VM lab

Question 1

All connective tissue consists of cells and extracellular matrix (fibers and ground substance) what is cartilage

Types of cartilage

Answer 1

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

Question 2

Hyaline cartilage

Answer 2

• 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

Question 3

chondrocytes

Answer 3

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)

Question 4

appositional

Answer 4

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)

Question 5

interstitial growth

Answer 5

cartilage growth from within

Question 6

Territorial matrix

Answer 6

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

Question 7

Elastic cartilage

Answer 7

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

Question 8

Fibrocartilage

Answer 8

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

Question 9

Articular cartilage

Answer 9

mostly resembles hyaline cartilage without perichondrium

Smooth surface, for low friction

Question 10

Developoing cartilage

Answer 10

has more cells and less matrix than mature cartilage

Question 11

Bone tissue classification

Answer 11

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

Question 12

periosteum

Answer 12

consists of type 1 collagen its a fibrous connective tissue

Question 13

compact bone

Answer 13

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)

Question 14

Lacunae

Answer 14

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

Question 15

Interstitial lamellae

Answer 15

remnants of older osteons that have been partially resorbed

Canals oriented perpendicular to haversian canal are called Volkmanns (perforating canals)

Question 16

Fracture

Answer 16

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)

Question 17

Apposional growth

Answer 17

bone at the diaphysis is increased

Question 18

Osteoclasts

Answer 18

large multinucleated cells , bone resorption, helps maintain blood calcium levels

Question 19

Bone formation occurs in 2 ways

Answer 19

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

Question 20

Zones of cartilage transformation at epiphyseal growth plate

Answer 20

Reserve cartilage,–> proliferation, hypertrophy, calcification, cartilage degeneration,osteogenic

Question 21

nutritional and hormonal factors which influence bone calcification, growth or maintenance

Answer 21

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