Component 3 Human Musculoskeletal anatomy

Option B

What type of tissue is cartilage?

Connective tissue

Cartilage features

Hard, but flexible

Compressible

Elastic

How is cartilage built?

All cartilage built by Chondrocytes - these build a matrix around them

Chondrocytes

Cells responsible for cartilage formation

Found in lacunae

Lacunae

Pockets that they (Chondrocytes) live in within the matrix

Matrix

Made of Chondrin (forms the matrix of cartilage)

Made of proteins (collagen) and glycoproteins

Collagen

A fibrous protein that provides structural support and strength to tissues.

Collagen molecules assemble into fibrils (small strands), which then organise into larger fibres.

True or False

The relative abundance of collagen and glycoproteins varies depending on the type of cartilage.

True

What are the 3 types of cartilage?

Hyaline cartilage

Yellow elastic cartilage

White fibrous cartilage

Hyaline cartilage

It has a high proportion of collagen fibres for added strength

Weakest type of cartilage

Location of Hyaline cartilage

Found in the most different places

Location - as support rings in the trachea and bronchi and as articular cartilage on the bone ends.

Articular cartilage is made of Hyaline cartilage

Hyaline cartilage extra information

Blood vessels do not penetrate cartilage, nutrients and oxygen slowly diffuse through it, leading to slow healing.

Long bones are laid down and grow as cartilage and gradually turn to bone (ossify).

Yellow elastic cartilage

Contains yellow elastic fibres containing elastin - matrix is flexible but retains it’s shape

Can see fibres in matrix

Location of Yellow elastic cartilage

Located in the external ear and end of nose

White fibrous cartilage

The cartilage that has the greatest tensile strength

With added parallel bundles of collagen fibres within Chondrin matrix

Located in discs between the vertebrae

Ossification

Involves the conversion of other types of connective tissue turning into bone

Why does cartilage take a long time to heal?

Because it doesn’t have blood vessels running through it so the oxygen and nutrients have to slowly diffuse through.

Cartilage to bones

Most bone is first deposited as hyaline cartilage

It turns bone (ossifies) during growth

A small plate of cartilage is left near the tips of bone shafts until after puberty

Cartilage is maintained at the bone ends as articular cartilage

Compact bone

Compact bone is in a tube at the edge of the bone shaft. Bars of spongy bone support the heads

Compact bone matrix components

30% organic - mainly collagen, which resists tensile forces and fracture

70% inorganic - Hydroxyapatite, which resists compressive forces

Organic

Has carbon to hydrogen covalent bonds

Hydroxyapatite

Collective name for calcium salts, most abundant in bones is calcium phosphate

Collagen structure

Amino acid → Collagen molecule → Collagen fibre

How are bones so strong?

The combination of the two (high tensile strength and resistance to compressive forces) make bones so strong

Tension is resisted by…

Collagen

Compression is resisted by…

Hydroxyapatite

The properties of tension and compression combine to resist other forces like…

Bending and torsion

What is bone formation called?

Ossification

Bone cells

Osteocytes - cells that build and destroy bones

Osteoblasts

Secrete layers of bone matrix around the cartilage

Osteoclasts

Break down the cartilage/matrix and bone

Why do osteoclasts break down cartilage?

So it can be replaced by bone