microscopic osteology and myology Flashcards
Functions of skeletal sys (6)
support
mineral storage
hemopoiesis
protection
body movement -levers
fat and stem cells
What are the specialised cells of mature bone (4)
osteocytes -maintain bone
osteoblasts -bone making
osteoprogenitor -stem
osteoclasts -bone breakdown
where are osteoblasts on bone usually
outer and inner surface
where are osteoclasts on bone usually
outer and inner surface
where are epiphysis and what do they contain
end of bones and contains red bone marrow
diaphysis where and what contain
shaft of bone and contains yellow bone marrow
metaphyses
connects epiphysis and diaphysis
what are the two protective layers on bone
periosteum and endosteum
describe the periosteum structure and location
comprised of an outer fibrous layer and inner osteogenic layer. located on outer surface of bone
describe the endosteum
located on the inner surface of bone, it is an incomplete layer of osteoblasts, osteoprogenitors and osteoclasts
what are the roles of periosteum (5)
isolate bone
protect bone from surrounding
attachment for nerve and blood vessels
participate in bone growth and repair
attaches bone to connective tissue
what is another term for osteogensesis
ossification
before 6 weeks of development, bone is _______
cartilage
what is intra membranous ossification?
bone forms from inside mesenchyme(stem) or fibrous connective tissues.
ex. roof of skull
what is endochondral ossification.
bone from hyaline cartilage. usually involves a bone growing in length
describe the 7 stages of endochondral ossification
stage 1
chondrocytes disintegrate a cavity inside the diaphysis of hyaline cartilage
stage 2
periosteum formed first and vascularity is developed (hyaline cartilage lack vascularity)
stage 3
diaphysis development starts from the inside out starting with spongy bone in the primary ossification centre.
stage 4
diaphysis completed to metaphysis
stage 5
secondary ossification centres form in epiphysis
stage 6
Bone grows in length when chondrocytes on the epiphyseal side continue to to divide and grow in size. The osteoblasts on the diaphysial side chase the chondrocytes and replace them with bone.
stage 7
Bone is complete with articular cartilage being remnants of the cartilage and a epiphyseal line being created.
How does bone grow in width
like a tree outwards. If it must go around a blood vessel it can form ridges and surround the vessel
What are the 4 properties of muscle tissue
excitability, contractility, extensibility, elasticity
what is the order of skeletal muscle organisation
muscle, fascicle, fibre, myofibril, sarcomere
what is skeletal muscle surrounded by
epimysium
what are fascicles surrounded by
perimysium
what are muscle fibres surrounded by
endomysium
What is the A band of a sarcomere
full length of myosin thick filament
what is the M line of a sarcomere
perpendicular myosin
what is the H band of a sarcomere
myosin only
what is the I band of a sarcomere
Actin thin filament only
what happens to the H and I bands when a muscle shortens?
they shorten
what happens to the H and I bands when a muscle relaxes
they lengthen
What is the thin filament composed of
g actin, troponin, tropomyosin around a nebulin fibre
what is the site of neural control for muscle fibres
motor end plate
what is a motor unit comprised of
motor neuron and the fibres it innervates
