Question

describe the role of osteoblast and osteoclast in your own word Describe layers pf epidermis in your own word

Answer 1

OSTEOBLASTS:

Derived from mesenchymal stem cells

Found in compact and spongy bone of all bones

They are responsible for bone formation- they secrete bone matrix and play a major role in the calcification of matrix .

They secrete the following things which contribute to the formation of osteoid,the softer organic part of bone matrix

–type 1 collagen fibres

–proteoglycans

–IGF - 1

–alkaline phosphate

–osteocalcin.

OSTEOCLASTS :

They are derived from macrophages.

Only known cell that can reabsorb mature bone.

Their purpose is to degrade dead or dying chondrocytes in juveniles as well as degrade mature,mineralized bone in juveniles as well as adults .

They work by introducing HCl into ossified matrix,lowering the pH to 4.5,effectively dissolving the bone.

LAYERS OF EPIDERMIS:

–From superficial to deep-

Startum corneum

Stratum lucidum(only on soles and palms)

Startum granulosum

Stratum spinosum

Stratum basale

1. Startum corneum- is a closely packed layers of dead cells and protects from friction and abrasion.

2. Stratum lucidum - only found in thick skin. Also closely packed layers of dead cells and protects from friction and abrasion

3. Stratum granulosum- small cells,close together,when dehydrated create little spikes. They provide water proofing and water impermeable layer.

4. Stratum spinosum- very close contact,they bind things together and form strong binding layer.

5. Stratum basale -single layer, produces new cells(keratinocytes), protects from UV rays, makes melanin(melanocytes)