MSKS Histology Lecture 1_Skeletal System Flashcards
Define woven and lamillar bone
• Woven (immature) — during bone tissue formation, the cells and bone matrix are arranged
randomly, without any obvious pattern.
• Lamellar (mature) — during bone tissue formation, the cells and bone matrix are arranged
into well-organized layers, known as lamellae
What is the main cell type at the perifery of the perichondrium
chondroblast
describe the function of Parathyroid hormone (PTH) and Calcitonin
• Parathyroid hormone (PTH) — released by parathyroid gland; raises low blood Ca2⁺ by stimulating osteoclast activity indirectly (via RANKL produced by osteoblasts) and osteocytes (directly); both cells resorb surrounding bone matrix and release Ca2⁺ into the blood stream.
• Calcitonin — released by thyroid gland; lowers elevated blood Ca2⁺ by opposing PTH in bone to
decrease osteoclast activity
What is the main cell type in the perichondrium?
It is typically a fibroblast
What are the 6 steps of Endochondral ossification
see attached
Describe Osteoporosis and osteopetrosis
- Osteoporosis — bone resorption exceeds bone formation and leads to a reduced bone mineral density (BMD), not due to a calcium deficiency.
- Osteopetrosis (“marble bones”) — bone resorption is defective and leads to thickening of cortical bone and obliteration of the marrow cavity
Deffine Appositional growth
growth occurs at the periphery of the cartilage or deep layer of perichondrium, if present
Define Endochondral ossification
hyaline cartilage precursors forms within the mesenchyme initially, which is later replaces by bone deposition and ossification; occurs in nearly all long bones, short bones, and ribs.
Define:
- Diaphysis
- Metaphyses
- Epiphyseal line
- Epiphyses
• Diaphysis — shaft
• Metaphyses — widening ends of shaft
• Epiphyseal line — remnant of growth plate
• Epiphyses — proximal and distal ends,
articular surface covered by articular cartilage
(see attached)
What is a chondroma and condrosarcoma
Cartilage cell tumors — chondroma (benign) vs. chondrosarcoma (malignant)
Why is it difficult for adults to repair cartilage?
avascularity, low metabolic rate, immobility of chondrocytes, and limited proliferation of mature chondrocytes
Describe Osteoarthritis and Rheumatoid arthritis
- Osteoarthritis — gradual loss or changed physical properties of the articular cartilage due to physical or pathological damage or old age.
- Rheumatoid arthritis — autoimmune disorder that causes chronic inflammation of the synovial membrane due to the release collagenases and other hydrolytic enzymes by macrophages into the synovial fluid, which degrades the articular cartilage.
Define
- Pituitary dwarfism
- Gigantism
- Acromegaly
how is growth hormon related to each of these conditions?
- Pituitary dwarfism — lack of GH during growth period leads to short bones
- Gigantism — excess GH during growth period leads to long bones
- Acromegaly — excess GH after epiphyseal plates have closed leads to wide bones through Appositional Bone Growth
What causes Osteogenesis imperfecta (“brittle bone disease”)
deficit in type I collagen fiber, either in the amount or the production of defective fibers (genetic mutation)
What cell type is a the cartilage proper, often within a lacunae?
chondrocyte
Define Intramembranous ossification
bone deposition and ossification occurs directly within the mesenchymal tissue; occurs in most flat bones of the skull and face, scapula, and clavicle
Where is elastic Cartilage typically found?
the ears and the epiglotsis
What are the three layers of Periosteum?
- Fibrous layer — outer layer of dense (irregular) CT
- Cellular layer — contains osteoprogenitor cells and is well-defined in bones that are actively growing
- Perforating (Sharpey) fibers — penetration of the periosteum into underlying bone tissue, most dense at attachment sites of tendon and ligaments
What is the main difference between hyaline cartilage and elastic cartilage?
the presence of elastic fibers. (see attached)
What are the three types of “bone cells”
Osteoblasts, Osteocytes, Osteoclasts
Deffine Interstitial growth
chondrocyte proliferation within cartilage gives rise to isogenous groups
Hyaline Cartilage is often bound on either side by what?
perichondrium (see attached)
What are the 4 steps in cartilage growth?
see attached
What are the protein fibers in the Cartilage ECM? What produces them?
• Type II collagen (produced by chondrocytes) is most prevalent, among all three cartilage types • Elastic fibers (produced by chondrocytes) is prevalent within elastic cartilage • Type I collagen (produced by fibroblasts and some chondrocytes) is present only within fibrocartilage
Define the calcium deficency for children and adults
Calcium deficiency — insufficient calcium in diet or failure to produce vitamin D
• Rickets — bone growth is impeded and developing bones and epiphyseal plates become deformed
• Osteomalacia — in adults, it leads to deficient calcification of newly formed bone matrix
and partial decalcification of already calcified bone matrix
How are chondrocytes typically arranged in fibrocartilage?
axially (see attached)
Define compact and cancellous bone
• Compact — bone tissue is highly packed with no medullary spaces; typically found in the
cortical region of bone (underlying the periosteum)
• Cancellous — bone tissue is arranged in thin spicules, or trabeculae, which form an
anastomosing meshwork with spaces between the trabeculae that are lined by endosteum
and filled with bone marrow; typically found within the medullary space of the bone
What are two important sub groups of hyaline cartilage?
Articular cartilage, Epiphyseal
(growth) plate
What are the 5 steps of Intramembranous ossification
see attacehd
Where is fibrocartilage typically found?
It is typically in symphisis joints and in between vertebral disks
