Bones and cartilage

What are some functions of cartilage

Smooth articular surfacd at bony ends, shock absorber, structural support and new bone formation

What are the 2 types of lamellar bone

Spongy and compact bone

What cells secrete osteoid

osteoblasts

What can be found in the matrix?

Proteoglycans, sulphated glycosaminoglycans—keratin sulphate, chondrotin sulphate. Hyaluronic acid

Describe the process of mineralization of osteoid

1. After osteoblasts produce new matrix, they secrete glycoproteins (osteocalcin) invites calcium and phosphate ions and osteocalcin binds to them 2. Alkaline phosphatase raises calcium and phosphate ions concentrations 3. Osteoblasts secrete vesicles to create space to deposit mineral ions 4. Final product is hydroxyapatite salts

Describe endochondral ossification

1. From hyaline cartilage, mitosis occurs and cartilage calsifies. 2. Periosteal bone collar forms around diaphysis. 3. Blood vessels are invited to vasularize the developing bone and primary ossification center forms in diaphysis where osteoblasts start multiplying 4. Secondary ossification centers from in epiphyses 5. Bone replaces cartilage, except the articular cartilage and epiphyseal plates. Ends are now covered by articular cartilage while diaphysis covered by periosteum. 6. Epiphyseal plates ossify and form epiphyseal lines.

Stages of fracture healing

1. Hematoma (mass of clotted blood) forms 2. This process invites stem cells from periosteum to form cartilage cells, forming callus. 3. The endochondrial bone form process occurs, forming a bony callus (spongy bone). 4. Bone remodeling occurs where spongy is removed by hard callus, forming compact bone.

Describe intramembranous ossification

1. Ossification centers appear in the fibrous connective tissue membrane. Selected mesenchymal cells cluster and differentiate into osteoblasts, forming an ossification center. 2. Osteoid is secreted within the fibrous membrane and calsifies. Trapped osteoblasts become osteocytes. 3. Accumulating osteoid is laid down between embryonic blood vessels in a random manner, forming network of trabeculae of woven bone. Vascularized mesenchyme condenses on the external face of woven bone and becomes the periosteum. 4. Trabeculae just deep to the periosteum thicken and replaced by mature lamellar bone, forming compact bone plates. Spongy bone persists internally and it's vascular tissue becomes red marrow.

Where can you find hyaline cartilage

Articular ends of bones, costal cartilage, trachea, epiphyseal growth plate

What are the exceptions to which hyaline cartilage does not have perichondrium

Articular ends of joints, epiphyseal plate, nasal and costal cartilage

Why is cartilage repair poor

Avascular, immobility of chondrocytes, limited ability of adult chondrocytes to divide

How does cartilage receive its nourishment

Avascular, so it needs diffusion through the water in ground substance

Osteoporosis

Bone mineral density decreases, more prone to fractures (esp old ppl and postmenopausal women)

What are the inorganic components of bone

Calcium phosphate, hydroxyapatite crystals

Harvesian canals are also known as...their function

Central canal, for artery, nerve and vein to reach the bones and lined by stem cells

Where is elastic cartilage found

Ear, epiglottis

What is howship's lacuna

Empty space created after acid phosphatase dissolved matrix after being released through ruffled border

What is the inner layer that lines the bone called

Endosteum

What is appositional growth

Growth in diameter within the periosteum

What is interstitial growth in bones

Growth in length in epiphyseal plate as chondrocytes undergo mitosis

What is canaliculi

Hairlike canals that connect lacunae to each other, helps in communication between osteocytes

Another name for osteon

Haversian system

What is Goldman's canal

Horizontal blood vessels across osteons

What is woven bone

Immature mechanically weak bone, irregularly arranged collagen fibres

Chondrocytes are present in empty spaces called

Lacunae

Where are osteocytes found

Lacunae in osteoid

Types of bones formed by endochondral osteogenesis

Long, irregular and short bones

What are the functions of bones

Mechanical support, locomotion, protection, metabolic reservoir of mineral salts

What is the area between epiphysis and shaft (diaphysis) called

Metaphysis

Type of bones formed by intramembranous ossification

Mostly flat bones like clavicle, scapula, cranial bones

Does fibrocartilage have perichondrium

No

When you wear out cartilage in knees what happens

Osteoarthritis

What are bone destructing cells and their properties

Osteoclasts, multi-nucleated, contains lots of lysosomal enzymes

What is another name for bone matrix and what does it contain

Osteoid. collagen, glycosaminoglycans, inorganic mineral salts, the 3 cells, proteoglycans, matricelluar glycoproteins (osteonectin and osteocalcin)

What is periosteum made up of

Outer fibrous layer and inner cellular layers with cells that can convert into bone producing cells

What is the outer layer that covers the bone called

Periosteum

Why does bone have very good regeneration capacity

Periosteum and endosteum. Very good blood supply

What is the role of perichondrium

Surround hyaline cartilage, outer layer give support and protection, inner layer is chondrogenic

What is the most important chemical for demineralising bone in osteoclasts

Tartrate-resistant acid phosphatase

Define bone remodeling

The continual deposition of new bone tissue and the removal (resorption) of old bone tissue occurs throughout life at both periosteal and endosteal surfaces

What type of collagen fibres in bones

Type 1

Type of collagen between fibrocartilage

Type 1 and type 2 to some extent

Chondrocytes secrete the matrix and which type of collagen

Type 2

Do you have perichondrium in elastic cartilage

Yes! It's ground substance only has proteoglycans

What cells form cartilage

chondroblasts

Function of sharpey's fibres

connect periosteum to bone and attach tendon to bone

Where is fibrocartilage found

intervertebral discs, articular discs of acromial end of sternoclavicular joint, glenoid labrum, symphysis pubis

Why does bone have excellent repair ability

it contains osteoprogenitor cells in the periosteum,endosteumand marrow and it is highly vascularised

Another name for spongy bone

trabecular bone