5.2 - Lab - Bone

Question 1

Osteoblast

Answer 1

• bone forming cell
• interconnected by gap junctions
• cuboidal appearance
• above apcial aspect of osteoblast is pale staining area = osteoid (unmineralized bone)

Question 2

osteoclast

Answer 2

• derived from fusion of mononuclear hematopoietic cells (give rise to monocyte - travels to bone in blood and becomes osteoclast; also makes alpha synoviocyte and macrophage)
• responsible for breakdown of bone
• large multinucleated cells
• has resorption bay = howship’s lacunae
• is highly polarized

Question 3

what is the osteoid and where is it located

Answer 3

= unmineralized bone

- located directly above the apical aspect of osteoblast cells

Question 4

What are the 3 specialized regions of an osteoclast cell

Answer 4

1) Ruffled Border = deep infoldings of plasma membrane - increase SA for more H+ pumps –> pump H+ ions into howship’s lacunae
2) Clear Zone = seals off howship’s lacunae, contains actin filaments + extracellular adhesion molecules (tight seal)
3) Basolateral region = fxns in exocytosis of digested materials - transcytosis (exocytosed material is released on opposite side that it comes in) - sometimes to blood capillaries