muscles and histo features Flashcards
functional unit of muscle
myofiber/myocyte
types of myofiber
smooth
striated (skeletal, cardiac)
skeletal muscle features
voluntary, striated somatic
smooth muscle features
involuntary, nonstriated, visceral
multiple muscle fibers are a
fascicle
multiple fascicles are
single muscle
what holds the fascicles together
collagenous CT
what CT surrounds a muscle fiber
endomysium
what CT surrounds fascicle
perimysium
what CT surrounds whole muscle
epimysium
each muscle fiber cell/myocyte is comprised of
myofibril
myofibril contains
myofilaments
what do myofilaments do
generate contractile force
what is a sarcomere
areas along a myofibril where contractile proteins overlap
what are the contractile proteins/myofilaments
actin (thin)
myosin (thick)
muscles contracting is what:
contraction of sarcomeres
I band
light, only actin
H band
myosin only
A band
dark, actin and myosin
bands are
myofilaments , either light areas or dark (overlap)
discs or lines are
regions where they are anchored in a myofibril
Z line
actin anchor
M line
myosin anchor
sarcomere is what line to what
Z line to Z line
as a sarcomere shortens, what happens to the bands
I band shrinks
A band remains constant
during contraction, what happens to myofilaments
myofilaments dont shorten, just pull Z lines closer by sliding actin over myosin
where does smooth muscle reside
walls of tubular organs, ciliary muscles of eye, glands, hair follicles
smooth muscle contraction is specialized for
continuous contraction at low force
smooth muscle histologically looks:
elongated, spindle shaped cells with no striations and single central nucleus
surrounding network of collagen
fusiform shape
do smooth muscle fibers have CT wrapping
no
what is smooth muscle fiber and fasciculi surrounded by
network of collagenous tissue
what is the functional contractile unit of smooth muscles
fascicles
what is the functional contractile unit of skeletal muscle
myocyte / muscle fiber
how are myofilaments arranged in smooth muscle
criss cross pattern throughout cell and inserts on dense bodies
during contraction of smooth muscle, what happens to the cell shape
elongated slender resting state into globular conformation
how do smooth muscle cells coordinate contraction with adjacent muscle fibers
gap junction
histological appearance of skeletal muscle
large, elongated multinucleated cells
multiple peripherally situated nuclei
arranged in fascicles
cross striations
cardiac muscle histological appearance
elongated branching cells joined by intercalated discs
usually single central nucleus
branching interconnected cells
cross striations dur to myofibrils