1.3.2 Bone, Cartilage, and Joint Histology Flashcards
Osteoblasts synthesize RANK-L which?
Stimulates osteoclastogenesis
What is the cellular action of bisphosphonates?
Encourage osteoclastic apoptosis
What is osteopetrosis?
Absence of secondary marrow cavity
What are some of the general aspects of osteogenesis?
What are two types of arthritis?
What are the two mechanisms for calcification?
Matrix vesicles and mineralization in adult bone
What are the covered parts?
What is the role of osteoblasts?
Osteoblasts synthesize type I collagen and the bone matrix and then synthesize alkaline phosphatase which increases the local Ca2/PO4- ratio resulting in calcification. When the osteoblasts become trapped in the calcified matrix they are called osteocytes.
Deposition of lime salts, in the form of hydroxyapatite crystals prevents?
Diffusion of metabolites
Interstitial growth
Both of which occur in cartilage
What are the three phases of charcot joints?
What are the characteristics of endochondral ossification?
Mesenchymal cells differentiate into chondrocytes and form a hyaline cartilage model of the long bone.
In the center of the diaphysis:
–Cartilage cells enlarge (hypertrophy)
–Chondrocytes synthesize alkaline phosphatase
–The matrix becomes calcified and does not permit diffusion.
–A vascular/osteogenic bud forms.
–Ossification occurs as bone is deposited on cores of calcified cartilage.
Primary ossification center establishes itself across the width of the shaft and extends toward the epiphyses.
Zones of endochondral ossification:
–Reserve/quiescent zone
–Multiplication/proliferative zone
–Hypertrophic zone
–Calcification/Vascular Invasion
–Zone of cartilage removal and bone deposition
Describe the growth of cartilage and what are the two types of growth?
Centers of chondrification consist of mesenchymal cell aggregates which differentiate into chondrocytes
Interstitial growth - growth from within, isogenous groups formed by mitosis
Appositional growth - Growth from the perichondrium
Describe the ARF cycle
Hyaline cartilage consists of?
Type II collagen and proteoglycans
What is this an image of?
Hyaline cartilage
What are osteoclasts?
Osteoclasts contain ruffled borders and are responsible for the enzymatic dissolution of the bone.
What is the process of bone growth in width/ diameter?
Growth in width occurs by depostion of new membrane bone (intramembranous ossification) beneth the periosteum.
An osteoprogenitor cell is?
Pluripotential stem cell (from the sclerotome in case of the vertebrae) capable of differentiating into osteoblasts. They are found in the periosteum and endosteum as bone lining cells in non-growing regions.
Describe the vascular supply to a joint?
Articular arteries and veins provide an abundant supply of blood to the joints. Diffusion plays an important part in the movement of nutrients from the perichondrium to the cartilage. Th absence of a continuous basal lamina facilitates diffusion.
What is the role of parathyroid hormone?
Causes bone release of Ca2+. Leads to increased osteoclast activity
Understand this chart
What are the characteristics of bone development?
What are the type of cells that the arrow is pointing at?
Osteoclasts
Explain endochondral ossification again
What is this an image of?
Woven bone
The joint (articular) cavity is filled with?
Synovial fluid, containing very few lymphocytes, macrophages, monocytes and neutrophils. The fluid is a plasma dialysate. The fluid also contains hyaluronan and lubricin.
Osteoblasts synthesize osteopontin which?
Allows for formation of sealing zones
What are Charcot Joints?
What are joints?
What is this an image of?
A groove becoming a tunnel in bone
Formation of Haversian systems and Volkmann’s canals and internal remodeling of long bones
Filling in of tunnels with lamellae of bone to form osteons
What is this an image of?
Diathrosis
Osteoblasts synthesize osteocalcin which?
Is required for mineralization
What are some of the characteristics of bone?
Intermittent PTH exposure leads to?
Osteoblast proliferation and increased bone mass
What is the role of the V-type ATPase on the osteoclast?
The V-type H+ ATPase is an ATP-driven enzyme that transforms the energy of ATP hydrolysis to electrochemical potential differences of protons across diverse biological membranes via the primary active transport of H+. It is essential for the production of an acidic environment in the Howship’s lacuna.
Describe the innervation of a joint.
What are the characteristics of intramembranous ossification?
What are the types of cells in the synovial membrane?
Marcrophages - involved in phagocytosis and antigen presentation
Fibroblasts - synthesize hyaluronan and lubrican
What is the effect of continuous PTH exposure on bone?
Continuous PTH exposure results in RANKL upregulation and concomitant OPG suppression (OPG serves as a decoy receptor for RANKL and prevents its interaction with osteoclast RANK). The stimulated RANKL-RANK interaction leads to osteoclast proliferation and increased bone turnover. Calcitonin receptors are found on the osteoclasts, but calcitonin is not a strong antagonist to PTH.
PTH binding to osteoblast also increases M-CSF. This will increase monocyte activity which will lead to more osteoclast progenitor cells.
