Bone structure and function

Question 1

Long and short bones are formed by ______

Flat bones are formed by ______

Answer 1

endochondral ossification

intramembranous ossification

Question 2

_____ pass into the diaphysis and supply the inner 2/3 of the diaphyseal cortex

Answer 2

nutrient arteries

Question 3

Arteries in the ____ supply the outer 1/3 of the diaphysis

Answer 3

periosteal membrane

Question 4

Why do bones like the femur or humerus heal more quickly than bones like the tibia or talus

Answer 4

bones surrounded by highly vascular soft tissue (rather than skin or cartilage) have a better blood supply and can heal more quickly

Question 5

Describe trabecular or cancellous bone

Answer 5

found primarily in the metaphyseal region of long bones
porous and filled with marrow
designed to maximize strength and minimize weight

Question 6

Describe cortical bone

Answer 6

compact, non-porous bone arranged in osteons

Question 7

_____ are bone forming cells

Answer 7

osteoblasts

Question 8

_____ are osteoblasts that are surrounded by bone matrix

Answer 8

osteocytes

Question 9

What is the lineage of osteoblasts and osteocytes?

Answer 9

marrow stromal cells/ pluripotent marrow cells- mesenchymal lineage

Question 10

_____ are responsible for bone breakdown

Answer 10

osteoclasts

Question 11

What is the lineage of osteoclasts?

Answer 11

hematopoietic- related to monocytes and macrophages

Question 12

Ostoclasts produce _________+

Answer 12

tartrate resistant acid phosphatase

Question 13

Osteoblasts produce _____ collagen, _____, as well as alkaline phosphatase

Answer 13

type 1 collagen

ostocalcin

Question 14

The major degradation- formation signaling in bone originates form the ______

Answer 14

osteoblasts

Question 15

What is the role of RANK ligand?

Answer 15

activate osteoclast activity

Question 16

What is the role of osteoprotegrin

Answer 16

competitive inhibitor of RANK ligand, decreases osteoclast formation

Question 17

Differentiate the effects of continuous vs intermittent exposure to PTH

Answer 17

Continuous: signals bone degradation via osteoblast signaling
intermittent: causes bone formation

Question 18

How do bisphosphonates work to treat osteoporosis

Answer 18

Interfere with osteoclasts directly, may disrupt ruffled border or cause apoptosis

Question 19

Bone’s greatest strength is in ____ and it is weaker in ____ and weakest in ____

Answer 19

compression
tension
shear

Question 20

Torsion causes ____ fractures

Answer 20

spiral

Question 21

Describe the formation of butterfly fractures

Answer 21

bending with an axial load
tension side develops a transverse fracture
compression side has shear failure
the butterfly fragment is on the compression side

Question 22

In most cancers, there is greater expression of RANK-L compared to OPG leading to ______ bone lesions.
In ________ there is greater expression of OPG leading to _____ lesions.

Answer 22

lytic

prostate cancer- blastic bone lesions

Question 23

Cortical bone has maximum strength and stiffness for _____ loads.
Trabecular bone is important for compliance around ____

Answer 23

axial

joints