Histology Flashcards
what three key words describe skeletal muscle cells
striated, unbranched, multinucleated
where are the nuclei in muscle cells found
at the periphery of the fibre, just under cell membrane (sarcolemma)
how long are muscle cells
as long as the muscle
what are muscle cells grouped into
fascicles
what is the epimysium
the connective tissue that surrounds the whole muscle
what is the perimysium
the connective tissue around a single fascicle
what is the endomysium
the connective tissue around a single muscle fibre
what are sarcomeres
the functional unit- unit of contraction of the muscle cell (smallest contractile element)
list what makes up a muscle cell
muscle fibre= lots of myofibrils= lots of sacromeres
what makes up band A
myosin (dark, thick)
what makes up the I band
actin (light)
what creates the striations in muscle cells
regular patterns of alternating dark and light bands (z discs aligned)
what is the motor unit
one motor neurone and all of the muscle fibres that it innervates
what happens to the axon of the muscle fibre as it nears its termination
branches to synapse with more neuromuscular junctions
describe type I muscle fibres
relatively slow contracting, depend on oxidatitive metabolism, have abundant metabolism and are resistant to fatigue. produce relatively less force- red fibres
describe type IIa muscle fibres
relatively fast contracting, reasonably resistant to fatigue, relatively uncommon
describe type IIB fibres
fast contracting, depend on anaerobic metabolism, few mitochondrian, less myoglobin, fatigue easily, produce greater force- white fibres
does cartilage have a blood supply
no is avascular- blood diffuses into it through matrix
is bone permeable
no
what are chondrocytes
the cell found in cartilage
what are chondroblasts
immature cartilage cells
what is a lacuna
space in the extracellular matrix in which chondrocytes live
what do chondrocytes do
seceret and maintain the extracellular matrix around them
what organic material makes up hyaline (extra cellular matrix) cartilage
type II collagen and proteoglycan aggregates
what is the most common type of cartilage
hyaline
describe hyaline cartilage
blue/white in colour and translucent
describe elastic cartilage
light yellow, elastic fibres make it quite flexible
describe fibrocartilage
hybrid between tendon and hyaline cartilage
has bands of densely packed type one collagen interleaved with rows of chondrocytes surrounded by small amounts of cartilagenous 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 (5)
support levels protection of internal organs calcium store haemopoiesis (blood cell production)
what makes up bone
23% collagen
65% bioapatitie (form of calcium phosphate, mostly hydroxyaptite)
10% water
2% non collagen proteins
what type of bone makes up the diaphysis (shaft)
cortical bone
what type of bone makes up the epiphyses (ends of the bone)
cancellous or trabecular bone
does bone remodel
yes constantly throughout life
what is a haversian canal
blood vessel inside each lamellae circle (osteon)
what is the main different between compact and trabecular bone
presence of spaces (marrow cavities) adjacent to trabecular bone
what are osteocytes
bone forming cells found on the surface of developing bone
what are cement lines
line visible around osteons, formed during remodelling
describe the morphology of trabecular bone
has osteocytes and is lamellar in nature but generally lacks haversian canals
what are osteoprogenitor cells
cells located on bone surfaces (e.g. under periosteum) that serve as pool of reserve osteoblasts
what is an osteocyte
a bone cell trapped within the bone matrix
what is an osteoclast
large multinucleated cells found on the surface of bone and are responsible for bone resorption
describe the ‘cutting cone’ of bone remodelling
when a number of osteoclasts congregate and ‘drill’ into bone forming a tunnel. a blood vessel will grow into the tunnel bringing with it osteoblasts which line the tunnel and begin laying down new lamellar bone. this continues until only space of a haversian canal remains
what us a basic multicellular unit
collection of osteoclast and osteoblasts involved in bone remodelling
what do osteoblasts do
secret collagen, glycosaminoglycans (GAGs), proteoglycans and other organic components of matrix= osteoid which becomes mineralised over time
what are osteoclasts derived from
macrophage lineage
what do osteoclasts form if they fuse
giant cells
where matrix secrete that will become be added on to
only to surface of existing bone
what is woven bone
disorganised bone that is layed down in response to a fracture
