Module 5 Flashcards
MSK Metabolic Disorders (Bones types, cells, function, growth and disorders)
What is a flat bones shape and purpose?
Thin and curved; protects internal organs form compressive forces (Example: Sternum)
What is a long bones shape and function?
cylinder-shaped bone that is longer than it is wide; functions as a lever (Ex. Femur)
What is an irregular bones shape and function?
bone of complex shape; protects internal organs form compressive forces
Ex: vertebrae
What is a sesamoid bones shape and purpose?
small, round bone embedded in a tendon; protects the tendon from compressive forces
Ex: patella
What is a short bones shape and purpose?
cube-shaped bone that is approximately equal in length, width, and thickness; provides limited motion
Ex: cuneiform
Diaphysis of long bones
tubular shaft that runs between the proximal and distal ends of a long bone
Epiphysis
wide section at each end of a long bone; filled with spongy bone and red marrow
Epiphyseal plate (growth plate)
sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length
Periosteum
fibrous membrane covering the outer surface of bone and continuous with ligaments
Spongy (cancellous) bone
trabeculated osseous tissue that supports shifts in weight distribution
Trabeculae
sections of the lattice-like matrix in spongy bone
Compact (cortical) bone
dense osseous tissue that can withstand compressive forces
Endosteum
delicate membranous lining of a bone’s medullary cavity
Medullary cavity
hollow region of the diaphysis; filled with yellow marrow
Lacunae
spaces in a bone that house an osteocyte
Osteon (harversian system)
basic structural unit of compact bone; made of concentric layers of calcified matrix
Articular cartilage
thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber
Where is an osteogenic cell (stem cell) located and what is its purpose?
undifferentiated and develop into osteoblasts; located in endosteum, cellular layer of periosteum
What is an osteoblasts purpose and where is it located?
forms/deposit bone matrix; located in endosteum, cellular layer of periosteum, growing portions of bone
Blasts Build
What is an osteocytes purpose and where is it located?
maintains bone tissue; entrapped in matrix
What is an osteocytes purpose and where is it located?
develop from different cell lineage and act to reabsorb bone; located in endosteum, cellular layer of periosteum, at sites of old, injured, or unneeded bone
Clasts Chew
What is intramembranous ossification?
compact and spongy bone develops directly from sheets of mesenchymal cells (flat bones of the face, most of the cranial bones, and the clavicles)
What is endochondral ossification?
bone develops by replacing hyaline cartilage
Is endochondral ossification or intramembranous ossification longer?
Endochondral
Reserve zone
region closest to the epiphyseal end of the plate and contains small chondrocytes within the matrix
What are the four layers of bone growth?
- Reserve zone
- Proliferation zone
- Zone of maturation and hypertrophy
- Zone of calcified matrix
Proliferation zone
contains stacks of slightly larger chondrocytes
Zone of maturation and hypertrophy
older and larger
Zone of calcified matrix
zone closest to the diaphysis, are dead because the matrix around them has calcified, restricting nutrient diffusion
Transverse fracture
occurs straight across the long axis of a bone
Oblique
occurs at an angle that is not 90 degrees
Spiral fracture
bone segments are pulled apart as a result of a twisting motion
Open (compound) fracture
a fracture in which at least one end of the broken bone tears through the skin; carries a high risk of infection
Impacted fracture
one fragment is driven into the other, usually as a result of compression
Comminuted fracture
several breaks result in many small pieces between two large segments
Greenstick fracture
a partial fracture in which only one side of the bone is broken, often occurs in the young
Closed (simple) fracture
a fracture in which the skin remains intact
What are the 6 phases of bone remodeling/healing process?
- Quiescent phase
- Activation phase
- Reabsorption phase
- Reversal phase
- Formation phase
- Mineralization phase
What is happening during the quiescent phase of bone remodeling?
Bone is at rest
What is happening at the activation phase of bone remodeling?
retraction of bone lining cells (mature osteoblasts) and digestion of endosteal membrane by collagenase. Recruitment and activation of osteoclasts to initiate bone resorption
What is happening at the resorption phase of bone remodeling?
osteoclasts begin to dissolve mineral material and decompose osteoid matrix. Approx 2-4 weeks during each remodeling cycle
What is happening at the reversal phase of bone remodeling?
bone resorption transition to bone formation. Mononuclear cells (monocytes, osteocytes, preosteoblasts) recruited to begin new bone formation
What is happening during the formation phase of bone remodeling?
osteoblasts release and synthesize new osteoid matrix
What is happening at the mineralization phase of bone remodeling?
new matrix is mineralized with calcium and phosphorous. Quiescent phase begin again.
How do genetic factors impact bone remodeling?
60-80% of bone mass is genetically determined.
How do mechanical factors impact bone remodeling?
Load, stress, PA
How does vascularization impact bone remodeling?
Supplies blood, oxygen and nutrients
How do nutritional factors impact bone remodeling?
Calcium, caffeine, alcohol, excess salt
How do Thyroid hormones affect bone remodeling?
stimulate bone resorption and formation e.g. bone loss in hyperthyroidism
Parathyroid hormone
controls homeostasis of calcium. PTH stimulate bone resorption by RANKL. Intermittent doses of PTH would stimulate bone formation
Calcitonin effects on bone remodeling
inhibitor of bone resorption by reducing number and activity of osteoclasts
Calcitriol effects on bone remodeling
intestinal absorption of calcium and phosphate, favors bone mineralization
Androgens effects on bone remodeling
anabolic effect on bone by stimulation of osteoblasts
Estrogens effects on bone remodeling
favor bone formation by increasing number and function of osteoblasts and reduce resorption
