Bone structure and function Flashcards
Long and short bones are formed by ______
Flat bones are formed by ______
endochondral ossification
intramembranous ossification
_____ pass into the diaphysis and supply the inner 2/3 of the diaphyseal cortex
nutrient arteries
Arteries in the ____ supply the outer 1/3 of the diaphysis
periosteal membrane
Why do bones like the femur or humerus heal more quickly than bones like the tibia or talus
bones surrounded by highly vascular soft tissue (rather than skin or cartilage) have a better blood supply and can heal more quickly
Describe trabecular or cancellous bone
found primarily in the metaphyseal region of long bones
porous and filled with marrow
designed to maximize strength and minimize weight
Describe cortical bone
compact, non-porous bone arranged in osteons
_____ are bone forming cells
osteoblasts
_____ are osteoblasts that are surrounded by bone matrix
osteocytes
What is the lineage of osteoblasts and osteocytes?
marrow stromal cells/ pluripotent marrow cells- mesenchymal lineage
_____ are responsible for bone breakdown
osteoclasts
What is the lineage of osteoclasts?
hematopoietic- related to monocytes and macrophages
Ostoclasts produce _________+
tartrate resistant acid phosphatase
Osteoblasts produce _____ collagen, _____, as well as alkaline phosphatase
type 1 collagen
ostocalcin
The major degradation- formation signaling in bone originates form the ______
osteoblasts
What is the role of RANK ligand?
activate osteoclast activity
What is the role of osteoprotegrin
competitive inhibitor of RANK ligand, decreases osteoclast formation
Differentiate the effects of continuous vs intermittent exposure to PTH
Continuous: signals bone degradation via osteoblast signaling
intermittent: causes bone formation
How do bisphosphonates work to treat osteoporosis
Interfere with osteoclasts directly, may disrupt ruffled border or cause apoptosis
Bone’s greatest strength is in ____ and it is weaker in ____ and weakest in ____
compression
tension
shear
Torsion causes ____ fractures
spiral
Describe the formation of butterfly fractures
bending with an axial load
tension side develops a transverse fracture
compression side has shear failure
the butterfly fragment is on the compression side
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.
lytic
prostate cancer- blastic bone lesions
Cortical bone has maximum strength and stiffness for _____ loads.
Trabecular bone is important for compliance around ____
axial
joints
