Histology Flashcards
skeletal muscle cells are striated/nonstriated, branched/unbranched
striated and unbranched
skeletal muscle cells are multinucleated- what does this form
syncytium
define syncytium
cell containing multiple nuclei
where in a skeletal muscle cell are the nuclei found?
periphery of the fibre, just under the cell membrane
what is the cell membrane in a muscle cell called?
sarcolemma
muscle fibres are grouped into bundles- what are these bundles called?
fascicles
the connective tissue surrounding the entire muscle is called what?
the epimysium
the connective tissue surrounding a single fascicle is called what?
the perimysium
the connective tissue surrounding a single muscle fibre is called what?
endomysium
each muscle fibre contains many myofibrils which are made up of what?
sarcomeres placed end-to-end
what other structures are contained within muscle?
blood vessels connective tissue nerves lymphatics
by definition where do sarcomeres begin/end?
Z lines
when does the axon of a motor neurone branch?
as it nears its termination
what is the name given to the special synapse at the end of each branch of a motor neurons axon?
neuromuscular junction
the fibres in a motor unit are bunched/scattered?
scattered
list some features of cartilage
semi-rigid and deformable permeable avascular
what are the cells found in cartilage called?
chondrocytes
what is the name given to immature chondrocytes?
chondroblasts
where exactly are chondrocytes found?
space within the extracellular matrix termed a lacuna
what is the function of chondrocytes?
secrete and maintin the extracellular matrix around them
what are the three types of cartilage?
hyaline
elastic
fibrocartilage
what is the most common type of cartilage?
hyaline
describe the appearance of hyaline cartilage
blue-white in colour
translucent
describe the appearance of elastic cartilage
light yellow in colour
quite flexible (addition of elastic fibres)
describe fibrocatilage
appears white
hybrid between tendon and hyaline cartilage
bands of densely packed type I collagen with rows of chondrocytes
what are the components of the ECM in hyaline cartllage?
75% water
25% organic material- type II collagen and proteoglycan
what is the difference between type I and type II collagen
type I
- thicker (75nm)
- aggregates into linear bundles
type II
- finer (15-45nm)
- forsm 3D meshwork
list some of the sites hyaline cartilage can be found in?
articular surfaces
tracheal rings
costal cartilage
epiphyseal growth plates
precursor in fetus to many bones
list the functions of bone
support
levers for movement
protection
calcium store
haemopoesis
what is the compostiion of bone?
65% bioapatite(calcium phosphate)
23% collagen
10% water
2% non collagen protiens
name the two types of bone visible to the naked eye?
cortical bone (outer shell)
cancellous/trabeciullar bone (epiphyses)
what process does bone undergo throughout life?
remodelling
what is the main difference between cortical and trabecular bone?
the presence of spaces- marrow cavities
define lamellar
made up of layers
what is the name given to the circular layers foudn in compact bone?
circumferential lamellae
what is an osteon?
unit of lamellar bone layed down in circles
what is the name given to the canal in the centre of an osteon?
haversion canal e.g. blood vessel
what is the name given to the canal type that runs across the bone?
Volkmanns canal
how does trabecullar bone differ from comapct bone?
both are lamellar however trabecullar doesnt have blood vessels
what is the name of the livign cells within bone?
osteocytes
name the following
A- osteocytes in lucunae
B- haversion canal
C- volkmanns canal
D- osteons
what are cement lines?
the lines often visible surroundign the osteon
- not seen in oroginal developmetn onyl in those that have formed durign remodelling
which bone cells are loacted on the surface and serve as a pool of reserve osteoblasts?
osteoprogenitor cells
what are osteoblasts
cells found on surface of developing bone- they have plentiful RER and prominent mitochondria
which bone cells are trapped within the bone matrix?
osteocytes
what are osteoclasts
large multinucleated cells found on the surface of bone
which bone cells are bone forming
osteoblasts
which boen cells are responsible for bone resorption?
osteoclasts
desctibe the process of remodelling in bone
- osteoclasts congreagte and ‘drill’ down into the bone formign a tunnel
- a blood vessel will grow into the tunnel
- osteoblasts line the tunnel laying down lamellar bone
- process contnues until only the space known as haversian canal is left
what do osteoblasts secrete?
collagen
glycoaminoglycans (GAGs)
proteoglycans
what is teh collective term fo rthe secretions of an osteoblast?
osteoid- this becomes mineralised over time
the mineral of bone is made up principally of what?
calcium phosphate crystals (particularly hydroxyapatite)
osteoblasts will fuse to form what?
a single giant cell
why can the matrix that will become bone only be added at the surface?
becasue bone is a solid matrix
in developing bone how are the collagen fibres arranged? what is the name given to this pattern of bone?
arranged in random, haphazard fashion- this is called woven bone
