MSK Flashcards
How many bones in adults
206
How many bones in infant
300
What are the 5 functions of skeleton
Shape and support
Movement
Protect vital organs
Hematopoietsis
Mineral hemeostais and storage (ca & ph)
Is bone a living organism
Yes
What is the structural elements of bone tissue?
Bone cells
Fibres (collagen)
Gelatinous material
Minerals (calcium)
What’s the function of bone cells
To grow, repair, synthesize new tissue and reabsorb old bone tissue
Fiber (collagen) function
To give bone it tensile strength
Gelatinous material of bone cell’s function
Medium between bone and blood
Bone Minerals (calcium) function
Provide rigidity
What are the 3 types of bone cells?
Osteoblasts
Osteoclasts
Osteocytes
Osteoblast
Immature cells that form new bone
Derived from mesenchymal cells
Form osteoids which mineralized to form new bone
Produce hormones (prostaglandins) ALP and other matrix protein
Bone shaped according to its function
What is osteoid
Protein mixture which mineralized to form new bone
What’s function is osteoclast
Function in bone reabsorption and remodeling
Xitcs
Large multinucleatedcwll ( ruffled borders)
Loosen from surface, become inactive and rest
Osteocytes function
Transform osteoblast to mature bone cells
Most abundant bone cells
Cell has dendrites, extend into canaliculi and secrete substances
Help to maintain bone by signaling osteoblast and osteoclasts to form and reabsorb bone
What’s the composition of bone matrix
Composition: 35% organic 65% inorganic 5% water
Organic component of bone
Collagen fiber ( provide bone strength)
Synthesized and secreted by osteoblasts
Inorganic component of bone is what?
Calcium
Phosphate minerals
Proteins
Carbohydrates- protein complexes
Proteoglycans
What’s the function of proteoglycans
Strengthen bone, form network fibrils
Help calcium deposit and calcify in bone
What’s the process of bone remodelling
- Activated osteoclasts scoop out bone and reabsorb it
- Osteoblasts lay down a new section of bones
- Osteocytes are spread throughout bone matrix
Transmit signal, recruit or inhibit osteoblast and osteoclast this influencing bone remodelling
What are the 3 phases of bone remodelling
Phase 1. Activation: a stimuli (ie physical stressor increased PTH secretion) activate osteoclast cell death (apoptosis)
Phase 2. Rrabsorption: osteoclast gradually digest bone minerals and leave behind a reabsorption cavity
Phase 3 formation : the layer down of new bone by osteoblasts line the walls of the reabsorption cavity
Successive layers (lamellae) in compact bone are then laid down until reabsorption cavity is reduced to a narrow Haversian canal
Process of bone remodelling takes how many months?
Reabsorption and new bone laid down to replace it takes 3-4 months
What regulates bone remodelling, bone integrity and bone mass
RANKL, RANK, OPG signalling pathway
What is the role of RANKL
It binds to RANK to activate osteoclasts and process of bone reabsorption
What is RANKL
It’s a transmembrane protein that is produced by osteoblasts,
It binds to its signaling receptor RANK on osteoclasts surface which activates osteoclasts and the process of bone resorption
What is Osteoprotgerin (OPG)
It’s a cytokine produced by osteoblast and act as a decoy receptor - inhibiting the binding of RANKL/RANK
Which protects the skeleton from increased bone resorption
What caused degenerative bone diseased?
Imbalance in the RANKL, RANK, OPG signalling pathway
What is the cause of osteoporosis and RA?
Imbalance between bone resorption and bone formation
In osteoporosis what do you find?
Bone formation is less than bone resorption
Bone formation < bone resorption
Which of the following best describe the xtics and function of osteoblasts
A. Synthesize the bone matrix and maintain skeleton
B. Found on bone surface and release enzymes which dissolve bone and connective tissues
C. Single nucleus cell derived from mature osteoclast and influence osteocyte activity
D. Found in the bone matrix and regulate bone mass and mineral homeostasis
Correct answer B
A. is describing osteoclasts
C incorrec
D describes osteocytes
The outer shell of all bones and shafts of long bones (femur) comprises of what % of skeleton
80%
What are the major structural elements of bone?
Bone cell- the grow, repair, synthesize, new tissue, and resorb old bones
Fiber (collagen) give bone it’s tensile strength
Gelatinous materials- medium between bone and blood vessels
Minerals - (calcium) provide regidity
What are the different types of bones
Compact bone
Spongy bone
Outer shell off all bones and shaft of long bones (femur) comprises of what percentage of skeleton
85%
What is the basic structural unit of compact bones
Osteon or Haversian system
Haversian canal is surrounded by what?
Rings of matrix (Lamellae)
Lacunae is located where
Between the matrix ring osteocytes
What is canaliculi?
Canaliculi are small channels that radiate from the lacunae to Haversian canal. It provide a passage through the hard matrix
What’s role of Haversian canal
Carries blood, lymphatic vessel and nerve branches