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Lecture 10

NURS 364 Lecture Notes - Lecture 10: Bone Fracture, Bone Resorption, Bone Healing

Course Code
NURS 364
Deborah Van Kuiken

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Disorders of the Musculoskeletal System
Bone Cells
Major bone-forming cell
Becomes osteocytes
Cells which break down bone
Macrophage lineage
Trapped osteoblasts; maintain the bone matrix
Osteogenic cells
Undifferentiated cells that turn into osteoblasts
Active during normal growth
Activated in adult with healing of fractures/injuries
Responsible for shape and structure of the bone
Secrete collagen  bone matrix (osteoid)
Cause calcium salts and phosphorus from blood precipitate to bone matrix
Signals osteoclast activity (for remodeling of bone)
The osteoblasts also have estrogen receptors.
Estrogens can increase osteoblastic activity--- promotes building up of cells
Increasing bone matrix production
Osteoclasts—scrubbing bubbles of bone…. They break down the bone
Secrete bone-reabsorbing enzymes, which digest bone matrix.
Phagocytic! Like macrophages…
Estrogen and Calcitonin decreases osteoclast
Sparing loss of calcium from the bone
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Osteocytes maintain bones
Play a role in controlling the extracellular concentration of calcium and phosphate
Directly stimulated by calcitonin
Inhibited by PTH (Parathyroid hormone).
Bone Resorption Cycle
The human body is constantly removing old bone and replacing it with new bone. This is called
"bone turnover”
For repairing injury and bone integrity
Osteoblasts & Osteoclasts
(calcium and phosphorus)
Bone protein matrix
Your activity determines your bone structure
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Other influences on bone
Parathyroid Hormone (PTH)---- increase calcium in blood
Promotes release of calcium from bone  calcium in the blood
Calcitonin (Secreted by thyroid gland)---- increase calcum in bone
It inhibits the release of calcium from the bone  less in blood
Vitamin D
A lack of Vitamin D results in osteomalacia---- end up with soft bones because still have
matrix but don’t have the calcium to make them hard
Increases osteoblast activity/decreases osteoclast activity
Compact vs. Cancellous Bone
Compact Bone
More dense
Exterior portion of bone
Spongy /Cancellous Tissue
Interior portion of bone,
more vascular
Spongey bone heals faster because it is very
Trauma to bone
Pathologic--- someone with hyperparathyroid may get
Usually 2nd to osteoporosis, cancer, Paget’s disease
By force that wouldn’t normally produce fracture
Fatigue/stress fractures---- in athletes because building muscle and pulls on bone
Feet/knees r/t running, jumping injuries
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