Biology, Eighth Edition (Raven)

Chapter 35: Vertebrates

Bone Growth in Width

Why is bone growth different from the growth of many other organs? Although bone may appear to be rigid and lifeless it is actually living tissue that is capable of growth. Unlike soft tissues, bone cannot simply grow by adding additional cells and removing cells that are no longer necessary. The calcium laid down in bone gives the skeleton the strength and rigidity needed to protect and support the body. The rigidity means that expansion requires addition of cells on the outside and, when necessary, the removal of calcium and other material on the inside.

View the animation below, then complete the quiz to test your knowledge of the concept.


1.	Bone producing cells are...

		A)	lamellae.
		B)	osteons.
		C)	osteoblasts.
		D)	periosteum.
		E)	endosteum.

2.	The concentric rings of bone produced are...

		A)	lamellae.
		B)	osteons.
		C)	osteoblasts.
		D)	periosteum.
		E)	endosteum.

3.	The combination of all of the concentric rings of bone built around a single blood vessel is called a(n)...

		A)	lamella.
		B)	osteon.
		C)	osteoblast.
		D)	periosteum.
		E)	endosteum.

4.	Bone building cells beneath the endosteum lay down bone to form ridges around a blood vessel.

		A)	True
		B)	False

5.	Once a tunnel of bone is formed around a blood vessel, the bone building cells of the periosteum lay down bone in concentric circles that fill in the tunnel.

		A)	True
		B)	False