Cartilage And Intramembranous Bone Formation

Front 1

Compostion of cartilage

Back 1

Extracellular Matrix (glycosaminoglycosides and Type II collagen fibers) and Chondrocytes

Front 2

Types of cartilage

Back 2

Hyaline: model for bones, articular cartilage, respiratory support

Elastic: Auricle of the ear, walls of auditory canal, epiglottis

Fibrocartilage: Intervertebral discs, tendon attachment to bone, junctions between flat bones of the pelvis.

Front 3

Chondroblasts/chondrocytes do what

Back 3

Make and secrete matrix of the cartilage. F

Front 4

Lacunae

Back 4

Where the chondrocytes and chondroblasts sit

Front 5

How do chondrocytes get nutrients or remove waste products

Back 5

Diffusion, The tissue is 60-80 water buy weight.

Front 6

Perichondrium

Back 6

Flattened fibroblast-like cells, precursors to chondroblasts, highly vascularized

Front 7

Cartilage proteoglycan

Back 7

Core protein + GAGs, the GAGs are negatively charged so they repel each other. This gives the structural integrity, porosity for nutrient movement and resists compression. (Bottle brush structure)

Front 8

High water content is important for:

Back 8

Nutrient movement, and biomechanics (compensate for different pressures, allow for weight bearing properties). Internal remodeling process is vital to continued ability to respond to changes in mechanical pressure.

Front 9

Cartilage growth: Interstitial growth

Back 9

The cells in the middle of the cartilage divide and secrete matrix. During the early stages of matrix development the matrix is not hard, and the daughter cells move away from one another. Later on they stay close together when it hardens and form a cell nest (isotonic group)

Front 10

Cartilage growth: appositional growth

Back 10

The cells in the perichondrium divide and then differentiate into chondroblasts which secrete matrix. Eventually they are surrounded by matrix and are referred to as chondrocytes. This occurs at the edge through proliferation of the flattened perichondrial cells, their conversion to chondroblasts and their secretion of matrix.

Front 11

What type of cartilage does not have a perichondrium

Back 11

Fibrocartilage. It has everything that hyaline has + Type 1 Fibers.

Front 12

Cartilage Repair

Back 12

Very strong but limited ability to heal well. This is due to avascularity and limited chondrocyte movement and proliferation.

The process can also be complicated by ossification. When bone replaces cartilage, this is obviously not ideal.

Front 13

Osteoblasts

Back 13

Build bone. Come from osteoprogenitor cells. When they secrete their matrix they are osteocytes.

Front 14

Osteoclasts

Back 14

Crush bone. Come from hematopoietic stem cells in bone marrow.

Front 15

Bone spicules

Back 15

An early formed portion of bone.

Front 16

How do osteocytes connect with one another

Back 16

Canaliculi. (Enhance information, get nutrients). These connected cells sense mechanical forces and signal osteoblast and osteoclasts to remodel the bone.

Front 17

Periosteum and endosteum

Back 17

Periosteum covers the outside of all bone, expect in the joint. Endosteum covers the inner surface of the bone.

Front 18

Osteoclasts MOA

Back 18

MOA: secrete H+ which decalcifies bone, release lysosomal enzymes that degrade the collagen and proteoglycan components of osteoid.

Front 19

Zones of Osteoclast cytoplasm

Back 19

Ruffled border: site of resorption

Clear Zone: attachment region

Basolateral Zone: location of exocytosis of the degraded bone mineral.

Front 20

Bone formation (Intramembranous vs Endochondral)

Back 20

Intramembranous: no cartilage precursor. Mainly the flat bones of the skull.

Endochondral: cartilage precursor. Bones of the axial skeleton and appendages.

Front 21

Intramembranous bone formation

Back 21

Step 1: the osteoblasts begin secreting Type 1 collagen and other bone matrix components. This is called osteoid.

Step 2: the organic matrix is mineralized. The osteoblasts at the edge secrete additional osteoid which will eventually become mineralized.

Front 22

Woven bone

Back 22

What is initially laid down during primary deposition. The bone is converted to secondary bone through resorption and re-depostion.

Primary/woven bone is only found in the initial stages of bone formation, during remodeling, and recovery from injury.