Lecture 21 9/26/23 Flashcards
What are chondrocytes?
cells of cartilage
What are the characteristics of chondrocytes?
-live in lacunae
-secrete matrix
Why is cartilage not a source of pain?
it has no blood vessels or nerves
What is appositional cartilage growth?
-expansion of cartilage from the periphery
-continues throughout life
-from the perichondrium/outer sack
What cells are contributed by the perichondrium?
cartilage stem cells
Which type of cartilage lacks a perichondrium?
articular cartilage
Which type of cartilage has a perichondrium?
cartilage embedded within tissue
What is interstitial cartilage growth?
-expansion from within
-matrix and cell numbers increase
-cells undergoing mitosis form clusters/isogenous groups
-most important in young animals
Why are we unable to regrow articular cartilage?
interstitial cartilage growth rarely occurs in adulthood
What are the characteristics of hyaline cartilage?
-smooth matrix
-forms fetal skeleton framework
-found on articular surfaces of bone
What locations have hyaline cartilage?
-nose
-larynx
-trachea
What are the characteristics of elastic cartilage?
-has elastic fibers between chondrocytes
-elastic fibers only visible with special stains
What locations have elastic cartilage?
-pinnae
-external ear canal
What are the characteristics of fibrocartilage?
-cartilage mixed with dense collagen
-chondrocytes in rows
What locations have fibrocartilage?
-menisci
-intervertebral discs
-tendons and ligaments
What are the three cell types in bone?
-osteoblasts
-osteocytes
-osteoclasts
What are the characteristics of osteoblasts?
-produce/build bone
-polygonal cells in rows along bone surface
-secrete and mineralize osteoid
What is osteoid?
the first type of bone produced that is unmineralized
What are the characteristics of osteocytes?
-osteoblasts that become embedded
-live in lucunae
-maintain bone structure
What are the characteristics of osteoclasts?
-remove/cut bone
-multi-nucleated, giant cells
-remove bone along brush/ruffled border
What is a Howship’s lacunae?
depression in bone formed by osteoclast
What are the characteristics of the mineral portion of the matrix?
-makes up majority of bone
-formed from hydroxyapatite (calcium + phosphorus)
-gives bone rigidity
What are the characteristics of the collagen portion of the matrix?
-can only be seen using polarized light
-gives bone tensile strength
What are the two organizations of bone collagen?
-woven
-lamellar
What are the characteristics of woven bone?
-immature bone
-one step after osteoid
-formed during growth and repair
-haphazardly arranged collagen fibers
How does lamellar bone form?
from the organization of woven bone
What are the characteristics of lamellar bone?
-mature bone
-parallel collagen fibers
-osteons/cylinders of collagen
-haversian canals at center of osteon contain blood vessels and nerves
-stronger than woven bone
What are the two configurations/shapes of bone?
-compact
-cancellous
What are the characteristics of compact bone?
-solid bone with minimal marrow
-woven or lamellar
-forms cortex of adult bone
What are the characteristics of cancellous bone?
-trabeculae arranged in 3D lattice
-more bone marrow spaces
-woven or lamellar
-inside bone medullary cavity
What is the epiphysis?
-end of bone
-covered by articular cartilage
What is the physis?
growth plate made of cartilage in young animals
What is the metaphysis?
cone-shaped transition/neck between diaphysis and epiphysis
What is the diaphysis?
cylindrical shaft of bone containing the nutrient foramen
What are the characteristics of bone marrow?
-contains hematopoetic cells
-becomes increasingly fatty with age
What are the characteristics of the periosteum?
-fibrous outer bony envelope
-contains osteoprogenitor cells
-involved in repair and remodeling
What are the characteristics of the endosteum?
-inner bony envelope
-can differentiate into osteoblasts
