Lecture 13 Flashcards
(29 cards)
explain compact bone matrix and its function
- densely packed matrix
- serves as covering of all bones and main component of shafts of long and short bones
what is compact bone characterized by
its tensile and compression strength and hardness
describe spongy bone
porous arrangement of trabecular, creates spaces between bone columns filled with marrow
where is spongy bone found
in ends of long bones and fills most other differently shaped bones
how are trabeculae oriented in spongy bone
to resist tension or stresses placed on each particular bone
what do osteoblasts do
- bone forming cells that are plentiful in infants
- in adults these are recruited from layer of cells lining bone for repair
what do osteocytes do
cells responsible for maintenance of bone
-they are seniors for tensions applied to bone and for essential nutrients and growth factors influencing bone structure and function
what do osteoclasts do
- responsible for resorbing or removing bone
- these originate in circulating blood and are activated by factors released from osteocytes
what comprises the majority of bone mass
extracellular matrix
how do you describe organic component of extracellular matrix
meshwork of lattice of protein
what is the function of collagen in organic component fo ECM
provides tensile strength to bone
why is the lattice structure important in the organic layer
required for deposition of minerals
what composes to inorganic component of the ECM
calcium salts or calcium phosphates
what does the inorganic layer provide for bone
compression strength
describe compact bone
densely packed cylindrical structures called osteons
describe trabecular bone
free standing columns of bone with spaces between them
what occurs after osteoblasts proliferate
they start depositing ECM around themselves
what occurs after osteoblasts are surrounded by ECM
they reduce their mitotic activity and convert to osteocytes
where do osteocytes live
in small fluid areas called lacuna
how do osteocytes connect with other osteocytes
they extend long projections through cacnaliculi and connect with those from adjacent osteocytes via gap junctions
what are the functions of bone
- provide structure
- leverage for movement
- house for blood formation tissues
- serves as bank for minerals
what must bone be able to do
remodel ECM and strengthen reshape or reconfigure its composition
what are the steps in bone remodeling
- osteoclasts are activates and recruited to the site of repair
- by releasing concentrated acid, osteoclasts cause the underlying matrix to be dissolved and removed
- osteoblasts from the surrounding bone lining layer of cells move in to begin the process of bone deposition
what regulated the remodeling process
hormone, diet, age, physical stresses and changes in ionic concentration in ECM or blood
