Test 1: Bone Flashcards
What is the function of compact bone?
Spongy bone?
(12)
Compact bone: “Carry the load”.
Spongy bone: “Distribute the load”.
What is lamellar bone and what kind of bone is it found?
12
Found in both compact and spongy bone.
Parallel alignment of collagen in sheets.
Preferred condition b/c this organization results in strength.
What is woven bone and where is it found?
12
Fetal form of bone and also seen during wound repair.
Collagen is layed down in a very irregular pattern.
It is a temporary condition which will later be remodeled into lamellar bone.
What is articular cartilage?
13
Hyaline cartilage remaining from endochondral ossification.
No perichondrium present.
What are the zones/levels of articular cartilage?
13
Superficial zone: Flattened chondrocytes adjacent to synovial fluid; Collagen bundles oriented parallel to articular surface create smooth surface.
Intermediate zone: Round, evenly distributed chondrocytes; Disorganized collagen bundles permit deformation; Fluid moves in and out in response to load and also allows for metabolic exchange for chondrocytes.
Deep zone: Clustered chondrocytes near the epiphyseal bone; responsible for interstitial growth to maintain articular cartilage.
What is the transition line between deep zone and calcified zone called?
(13)
Tidemark.
Is articular cartilage subject to calcification?
13
Yes.
Causes range from trauma, immobility, to normal aging.
Begins with small calcium salt deposits which increase in size. It interferes with adequate diffusion to/from chondrocytes. When the chondrocytes die the cartilage matrix is slowly resorbed with eventual erosion to the subchondral bone.
What is the stratum fibrosum?
13
Outer portion of capsule comprised of dense irregular CT.
Transitions to fibrocartilage at insertion point on bones.
Poorly vascularized, but richly innervated with proprioceptive nerve endings.
What is the stratum synovium?
13
Inner lining layer of capsule. Has 2 layers (Intima and subsynovial layer).
Intima consists of 1-3 layers of specialized fibroblasts know as synoviocytes. Responsible for producing and recycling synovial fluid and removing debris.
Subsynovial layer is the highly vascular supporting CT layer for the intima.
What is the thin fluid film that coats articular surfaces and the stratum synovium?
(13)
Synovial fluid.
Lubricates internal joint surfaces to reduce friction.
Provides a medium for metabolic transport to/from articular cartilage chondrocytes.
What are the 4 bone cell types?
14
Osteogenic cells, osteoblasts, osteocytes, osteoclasts.
What are osteogenic cells, where are they located, and what do they do?
(14)
Undifferentiated cell derived from embryonic mesenchyme.
Found lining the endosteum, periosteum, Haversian canals, and volkmann’s canals (places where you can add or take away bone).
Participates in wound repair and remodeling by providing cells for those processes.
What are osteoblasts, where are they found, and what do they do?
(14)
Derived as a result of osteogenic cell mitosis.
Line the endosteum, periosteum, Haversian canals, and volkmann’s canals. Appear as a cuboidal or polygonal cell lining these surfaces.
They secrete the organic, unmineralized matrix of bone (osteoid).
What are osteocytes, where are they found, and what do they do?
(15)
Terminal stage of bone cell maturation.
Located in a lacunae surrounded by matrix it secreted previously as an osteoblast. (Land-locked). Remains intact with other osteocytes via canaliculi.
Relatively inactive that no longer secretes matrix appreciably. (Still has the ability to secrete and resorb matrix to a small extent).
What are osteoclasts, where are they found, and what do they do?
(15)
Derived from monocytes (circulating with blood cells).
Found on resorptive surfaces know as howship’s lacuna. Very large, multinucleated cell.
Secrete lysosomal enzymes extracellularly to resorb surplus or inferior bone matrix. It’s an essential component of bone growth and repair.
