MSK Histology Flashcards
how can skeletal muscles be described
striated
unbranched
multinucleate
what do muscle fibres look like
long cylanders
nuclei are at the periphery of the fibre just under the cell membrane
what is the cell membrane called in muscle cells
sarcolemma
what is skeletal muscle made up of
fascicles - individuals bundles of muscle fibres
what is the name of the connective tissue that surrounds to whole muscle
epimysium
what is the connective tissue around a single fascicle called
perimysium
what is the connective tissue around a single muscle fibre called
endomysium
what is inside a muscle fascicle
muscle fibres
whats inside a muscle fibre
myofibrils
what are myofibrils made up of
sarcomeres placed end to end
by definition where does the sarcomere stretch between
Z lines
what causes striation in skeletal muscle
result of the arrangement of the sarcomeres held in registry with one another across the fibre giving the illusion of transversal stripes
what is the neuromuscular junction
the synapse where the axon on the motor neurone terminates
describe type 1 muscle fibres
slow contracting depend on oxidative metabolism abundant mitochondria and myoglobin resistant to fatigue and produce less force 'red fibres'
describe type 2a muscle fibres
intermediate between 1 and 2b
relatively fast contracting
reasonably resistant to disease
relatively uncommon
describe type 2b muscle fibres
fast contracting fibres that depend on anaerobic metabolism
very few mitochondria and less myoglobin than type 1 fibres
fatigue relatively easily
produce greater force
‘white meat’
describe cartilage
semi-rigid and deformable
permeable
avascular
cells nourished by diffusion through ECM
describe bone
rigid
non-permeable
cells nourished by blood vessels that pervade the tissue
what are chondrocytes
cells found in cartilage
called chondroblasts when immature
what are the components of the ECM
75% water
25% organic material
type 2 collagen
proteoglycan aggregates
what is hyaline cartilage
most common form of cartilage
blue-white in colour
what is elastic cartilage
light yellow in colour
addition of elastic fibres make it flexible
what is fibrocartilage
hybrid between tendon and hyaline cartilage
bands of densely packed type 1 collagen interwoven with rows of chondrocytes
surrounded by ECM
appears white
where is hyaline cartilage found
articular surfaces tracheal rings costal cartilage epiphyseal growth plates precursor in fetus to many bones
what are the functions of bone
support levers for moment protection of internal organs calcium store haemopoiesis (blood cell production)
what is cauliflower ear
when vasculature around the cartilage is damaged so it cant get nourished from diffusion
where is involved in blood production after early 20s
axial skeleton and limb girdle
what is marrow not producing blood
yellow marrow
producing fat
what makes up bone
collagen
bioapatitie (a form of calcium phosphatte- mineral)
water
non-collagen proteins
what is cortical bone
the outer shell of dense bone which makes up the shaft
what is cancellous/trabecular bone
occupies the ends of bone
fine meshwork of bone which looks like an aero bar
what bone never remodels
otic capsule
what makes up cortical bone
groups of lamellar bone
blood vessels within canal in the middle
canals run both ways through the bone
what are osteons
groups of lamellar bodies
product of later bone remodelling
why do osteons have a lamellar structure
lots of different layers overlapping with collagen fibres in different directions to make it stronger
what is a key difference between trabecular and compact bone
presence of spaces in trabecular bone
what are canaliculi
tiny channels which allow communication between osteocytes
what is the cement line
marks the boundary of an osteon
only found in osteons that are formed from remodelling
why does trabecular bone lack Haversian canals
because the struts are thin, the osteocytes can survive from contact with the marrow spaces
what are osteoprogenitor cells
located on bone surfaces
pool of reserve osteoblasts
what are osteoblasts
bone forming cells found on the surface of developing bone
what are osteocytes
bone cell trapped within bone matrix
what are osteoclasts
large multibucleated cells found on the surface of the bone responsible for bone reabsorption work together to dissolve the bone fuse to form giant cell
what happens to bone during remodelling
osteoclasts drill out bone to form a tunnel
blood vessels grow into tunnel bringing osteoblasts
osteoblasts start laying down new lamellar bone
process continues until only the Haversian canal remains
what do osteoblasts secrete
osteoid
a progenitor material which in the extracellular space will become hard as it attracts calcium phosphate crystals
what are osteoclasts derived from
macrophages
where can you add bone to
a surface
how is early bone lade down in utero
quickly
as woven bone
collagen fibres run in all orientations
when is woven bone put down
when there is a break
then undergoes subsequent remodelling
