Chapter 5a: Bone and Cartilage Flashcards
Name all three types of mineralized tissues and where they come from
- Enamel comes from ameloblasts
- Dentin comes from odontoblasts
- Osteocytes are living cells in bones
What kinds of cells a) make cartilage/bone, b) remove cartilage/bone?
o A)chondroblasts make cartilage and osteoblasts make bone
o B) chondroclasts remove cartilage and osteoclasts remove bone
What are the functions of bone/cartilage?
o Movement and support
o Protection of vital organs(skull, ribcage)
o Production of blood cells(marrow: produces red and white blood cells/stem cells)
o Calcium and phosphorus metabolism
Cartilage
Connective tissue primarily associated with the skeleton; Can make substantial parts of the skeleton in some groups
Collagen matrix
glycosaminoglycans and proteoglycans
Name the 3 types of cartilage
Hyaline, Elastic, and Fibrous
Hylaine cartilage
On the ends of ribs and on the trachea; Joint surfaces; Skeleton of cartilaginous fishes, parts of bony fish skeletons
Elastic cartilage
matrix + elastic fibers
External ear, auditory tubes, epiglottis, larynx
Fibrous cartilage
matrix + collagen fibers
Intervertebral disks of the spine; At the insertions of ligaments and tendons; Dense collagen fiber
Bone
a composite tissue
Has inorganic hydroxyapatite; Comrpession
Has organic collagen; Tension(pulls on part of skeleton, thinks it is elastic fiber)
Understand the difference between a) non-lamellar bone and b) lamellar bone
Lamellar bone: Orderly, regular arrangement of collagen fibers within the matrix
Can be spongy or compact bone in appearance
Nonlamellar (woven) bone: Immature bone with a disorderly, irregular arrangement of collagen within the matrix; Is not stress oriented
Can be spongy bone in appearance
Understand the difference between spongy bone and compact bone
Spongy bone: Lighter and less dense than compact bone; Consists of plates (trabeculae) and bars of bone adjacent to small, irregular cavities that contain red bone marrow
Typically at the end of bone
Compact bone: dense, made of haversian systems
What are the 3 kinds of forces that create mechanical stress?
compression, shear, and tension
What is bone hypertrophy and atrophy?
Atrophy: loss of bone due to lack of activity
Hypertrophy: gain of bone due to activity
What kind of stress does the organic component of bone tissue resist?
Organic Component (Collagen): The organic part of bone, primarily made up of collagen fibers, resists tensile stress. This means it helps bones withstand stretching and twisting forces.
What kind of stress does the inorganic component of bone tissue resist?
(Hydroxyapatite Crystals): The inorganic part, mainly hydroxyapatite, resists compressive stress. This means it helps bones handle heavy loads and pressure.
What is the trajectorial theory and how does it influence bone structure?
A beam projecting from a wall tends to bend under its own weight, placing internal stresses on the material from which it is made – lines called stress trajectories ; Compressive forces concentrated along the bottom of the beam, tensile forces along the top
Both forces are greatest at the surface of the beam
How it is seen in bones:
Latticework of bone, with material concentrated at the surface ; A cross section through the proximal end of a femur reveals the lattice of bone spicules within the head that become concentrated and compacted along the wall within the shaft of the femur
What does Wolff’s Law describe?
Remodeling of bone occurs in proportion to the mechanical demands placed upon it
Physiological response that both thickens and straightens it; New bone forms along the concave surface ; Bone remodels - shape is restored; The walls are now thicker to withstand the new, increased load
in compact bone, describe structure of osteon
o Cylinders surrounding blood vessels
o Haversian system
o Cylinder structure incases osteocytes
Describe how Intramembraneous Ossification works
Bone forms directly from mesenchyme without a cartilage precursor
Mesencymal cells(connective tissue cells) lay down collaen, turn into osteoblast; Osteoid tissue: Unmineralized, oranic part of bone
Sheet of tissue with large supply of blood vessels; Osteoblast formed from tissue and blood vessels will begin ossification; Osteocyte forms and bone matrix(mineralized stuff) forms
Spongy bone forms first and eventually spongy bone and compact bone will form
Describe how endochondral Ossification works
Bone develops from a cartilage precursor (an anlage)
Chondrocytes growing cartilage die and matrix calcifies
Osteoblsats will cover the shaft of the cartilage in a thin layer of bone
Blood vessels penetrate cartilage and form primary ossification center
Bone of the saft thickens and epiphysis cartilage areas are replaced by shafts of bone
Blood vessels enter epiphyses and osteoblasts to form secondary ossification centers
Describe Diarthrosis
o Diarthrosis - moveable
o An articular capsule made up of the fibrous cpasule and synovial membrane has fluid inside of it to allow movement
What are synarthroses?
o Little to no movement
o Sutures example: start as series of bones, develop sutures(fused together later on, will allow brain to grow first)
o Example: Symphysis pubis
