Histology Lecture 4 - Bone and Cartilage

Name the two types of cartilage cells

Chondroblasts and Chondrocytes

What type of bones does cartilage line?

Articulating Bone

Why does cartilage usually not heal well?

Cartilage does not get good blood supply and is not metabolically active

What are Chondroblasts?

Precursor cartilage cells that differentiate into chondrocytes

What are chondrocytes?

Mature cartilage cells that lie in little artificial lacunae

Name the 3 components of Cartilage

Cartilage cells, extracellular matrix, and perichondrium

What are the two components of the extracellular matrix?

Fibers and GAG's/Proteoglycans

What is the name of the dense connective tissue that is composed of fibroblasts and type I collagen fibers?

Perichondrium

What surfaces does the Perichondrium cover?

The surfaces of elastic cartilage and all non-articular hyaline cartilage

What main example of hyaline cartilage is the perichondrium not present?

The Epiphyseal plate

Name the 3 types of cartilage

Hyaline cartilage
Elastic cartilage
Fibrocartilage

What type of collagen is in hyaline cartilage?

Type II

What type of collagen is in elastic cartilage?

Type II w/ elastic fibers

What type of collagen is in fibrocartilage?

Type I (with a little type II)

Where can hyaline cartilage be found?

Supporting respiratory airways, lining bone surfaces in articulating joints, and in the epiphyseal plate.

Where can elastic cartilage be found?

epiglottis and external ear

Where can fibrocartilage be found?

intervertebral discs, pubic symphysis, attachments of tendons and ligaments

What are the two methods of cartilage formation?

Interstitial growth and Appositional growth

What is the type of growth from within cartilage where chondrocytes divide and secrete matrix?

Interstitial growth

What is the type of growth from along the outside of cartilage where chondroblasts secrete matrix and differentiate into chondrocytes?

Appositional growth

What are two functions of bone?

Support/protection of soft tissues and attachment of muscles for movement

What is the name of the substance within bones where blood cells are produced?

Hematopoietic bone marrow

Broadly, what is bone made of?

Cells and extracellular matrix

What is it called when two or more cartilaginous cells are sitting together?

An Isogenous group

Name the 3 types of cells in bones

Osteoblasts
Osteoclasts
Osteocytes

What do osteoblasts produce?

bone matrix

What is the organic part of the bone matrix produced by osteoblasts called?

Osteoid

What do Osteoblasts turn into when they become fixed in the dense bone matrix?

Osteocytes

Where are osteoblasts found?

Along the edges of bone

Where are osteocytes located?

within lacunae surrounded by matrix

What do osteocytes do?

maintain the bone matrix

Where are osteoclasts located?

in little bone surface indentations called Howship's lacunae

What do osteoclasts do?

Chew up and resorb bone

What two hormones control how/when bone is resorbed?

Parathyroid hormone (stimulates bone resorption) and calcitonin (inhibits bone resorption)

What is the extracellular matrix of bone made out of

Organic: Type 1 collagen and ground substance
Inorganic: minerals (calcium & phosphate)

Name the four types of bones

Compact bone, spongy bone, primary bone, and secondary bone

What type of bone is Located on the outer surfaces of bones, and is a dense, solid structure

Compact bone

What type of bone is Located on the inside of bones in an open, loose structure

Spongy bone

What type of bone is the first bone tissue formed during growth or repair?

Primary bone

What type of bone contains an irregular arrangement of collagen fibers?

Primary bone

What type of bone contains osteons with parallel arrangement of collagen fibers?

Secondary bone

What is the name of the membrane that lines the outer surface of compact bone?

Periosteum

What are the two layers of the periosteum?

outer dense connective tissue layer and inner osteogenic layer

What is the name of the fibers that tightly attach the periosteum to the bone matrix?

Sharpey's fibers

What is the name of the membrane that lines the inner surface of compact bone?

Endosteum

What other two surfaces does endosteum line?

Traberculae of spongy bone, and the Haversian canals

How is bone formed in flat bones?

Intramembranous ossification

How is bone formed in long bones?

Endochondrial ossification

What is the end of a long bone called?

epiphysis

What is the shaft of a long bone called?

diaphysis

list the 5 zones of the epiphyseal plate

Zone of resting cartilage
Zone of proliferating cartilage
Zone of hypertrophic cartilage
Zone of calcified cartilage
Zone of ossification