MSK Mod 1B Flashcards
what are included in the cellular componene of connective tissue
fibroblasts, osteocytes, chondrocytes
the extracellular matrix is made up of 2 componenets
- non-fibours componenet
2. fibrous componenet
what is the nonfibrous component of the extracellular matrix os connective tissue
usually gel-like substance “ground substance”
-ex. proteoglycans, glycoprotein, minerals
what is the fibrous component of the extracellular matrix of connective tissue
- collagen - provides tensile strength
2. elastin - provides elastic properties
function of osteoblasts
formation of new bone
osteoblasts produces what
type 1 collagen and non mineralized bone matrix (osteoid) into immediate area surrounding osteoblast
osteoblasts facilitates
mineralization (calcification) of osteoid to complete the process
once the surround bone matrix (osteoid) is mineralized the osteoblast is now referred to as an
osteocyte
osteoblasts also produce substances that do what? (other than type 1 collagen)
regulate balance of bone formation/resorption
osteoblasts are located along
- trabecular surfaces (cancellous or spongy surface)
- inner surface of haversian’s canal
- inner surface of the periosteum (active bone formation)
osteocytes are formed from
osteoblast
the small cavity the osteocyte is located in is known as
lacunae
osteocytes make up how much of cells in mature human skeleton
90%
osteocytes blood supply
via small capillaries located and are a functionally active cell of bone
3 functions of osteocytes
- stimulate remodeling process of bone
serve as sensory mechanism for mechanical stimulus to bone - mantain homeostasis of the mineralized (calcificaation) bone
how do osteocytes stimulate remodeling process of bone
- directly signal steps in bone remodeling
2. assist by secreting enzymes to dissolve surrounding mineralized bone to prepare for bone remodeling
how do osteocytes maintain homeostasis of mineralized bone
- osteocytes synthesize molecules to assist with bone calcification
- osteocytes receive nutrients from the capillary blood supply which are needed to maintain mineral homeostasis
where are osteoclasts located
Howship’s lacunae
- depressions seen in microscopic view that represent areas of bone resorption
function of osteoclast function
resorption of bone
how do osteoclasts resorb bone
- break down bone allowing release of calcium into blood stream
- break down/resorption of inferior (poor quality) bone or surplus bone
osteoclast mechanism of bone resorption
- osteoclast secrete acid and lytic enzymes to breakdown and dissolve surrounding bone
- osteoclasts have microvilli (brush border) projecting out from cell
- elements of bone are resorbed into the osteoclast at he base of the microvilli
- the osteoclast eventually release the bony elements in the capillaries to allow the elements to be recycled into new bone at a different site
in different pathologies like metastatic bone dz and multiple myeloma - what is responsible fore the bone loss
osteoclast activity
what are collagen fibers
- how many types
- synthesized/secreted by
- arrangement
- part of the matrix component of bone
- 14 different types ID’d in body
- synthesized and secreted by osteoblasts
- fibers are arranged in fibril network allowing resistance against tensile and compressive forces
what type of collagen accounts for 90% of collgen in bone
Type 1