Skeletal Muscle and Nerve Tissue Histology Flashcards
How many nerves innervate a muscle fiber?
1
a single nerve can innervate more than one muscle, but only 1 nerve per muscle
What type of muscle never fatigues?
cardiac
What do smooth muscle cells look like?
NOT striated
uninucleated
What do cardiac muscle cells look like?
striated
uninucleated
branched cells
separated by intercalated disks
What is in a triad?
T tubule + 2 terminal cisternae (one on either side)
What are a-motor nerve fibers?
efferent
receive signal from Ia fibers and cause extrafusal fibers to contract
What is in the soma/body of a neuron
all the organelles
What is the synapse?
space btw axon and tissue; transfers electrical impulse from neuron to target tissue
What is a muscle made of?
What is it surrounded by?
group of fascicles
surrounded by epimysium
What is the I band
space on either side of the Z disk where there is no myosin
what are type I muscle fibers?
slow twitch, less powerful
many mitochondria = slow fatigability
aerobic respiration
abundant myoglobin
What is the A band
distance from end of one myosin head to the head of opposite myosin = overlap of actin and myosin
H band is within a band
What is a myofiber/muscle fiber made up of?
what surrounds a myofiber?
myofibrils = chains of sarcomeres
covered by endomysium
What is the z-disk
separates sarcomeres; attachment site for actin and titin
What is myosin made up of?
2 heavy chains
2 light chains
Held in place on z-disk by Titin
What is a dendrite?
part of neuron that receives signals
What is a sarcomere?
contractile unit of muscle made of actin and myosin
What is the axon?
part of neuron that sends out signal to synapse
what does tropomyosin do?
wraps between actin strands
troponin sits on top of tropomyosin
What is the axon hillock?
connection btw soma and axon
summates electrical signals received by all dendrites
What makes an entire muscle shorten during contraction?
All myofibrils contract at the same time
actin and myosin DO NOT change in length - overlap each other
What are bipolar neurons?
single dendrite (w/ multiple extensions) one axon
what are intrafusal muscle fibers?
fibers that sense length and rate of change of muscle
What is a nerve?
What surrounds it?
group of fascicles
surrounded by epineurium
What are type Ia sensory nerve fibers?
afferent
innervate intrafusal fibers to sense change in length and send signal back to spinal cord of overstretching
What is an actin filament made of?
f-actin monomers
What is the sarcoplasmic reticulum?
tubular system acting like smooth ER
What type of muscle is not striated?
smooth muscle
What is nebulin?
ruler for determining length of actin filament
What are type IIB muscle fibers?
fast twitch, powerful contraction few mitochondria few myoglobin rapidly fatigue anaerobic respiration
What are extrafusal muscle fibers?
regular skeletal M, contract muscle
What is the M-line?
attachment site for myosin on sarcomere
What are transverse T tubules
branches are sarcolemma penetrating muscle cells to convey electrical signal
What is a schwann cell
myelinate axons in PNS
wrap around one part of ONE axon
What is the H band?
space on either side of M line where there is no actin, but there is myosin
shortens during contraction
What are terminal cisternae?
flattened sac of SR on either side of transverse T tubule
What are g-motor nerve fibers
efferent
receive signal from type Ia fibers and cause intrafusal muscle fibers to contract
What covers an axon?
endoneurium
on top of myelin if axon is myelinated
What are on the heavy chains of myosin?
globular heads w/ actin binding site and ATPase domains
What is the sarclemma?
membrane around each muscle cell
What are multipolar neurons?
multiple dendrites
one axon
What is the nissle substance?
abundant rER w/in cytoplasm of the soma
What are pseudounipolar neurons?
one cell process w/ single axon branch and single dendrite branch
arise from neural crest = sensory
What is a fascicle?
What is it covered by?
group of axons
covered by perineurium
What causes troponin to move so myosin can bind actin?
calcium released from SR –> binds troponin –> conformational change –> actin binding sites accessible to myosin
what type of motor neurons innervate skeletal muscle?
a-motor neurons from anterior horn of spinal cord
What does troponin do?
sits on tropomyosin strands and covers myosin binding sites on actin filament
What type of muscle is multinucleated?
skeletal muscle
What is a fasicle?
What is it surrounded by?
group of myofibers
covered by perimysium
What do skeletal muscle cells look like?
striated
multinucleated
large cells
What are end feet?
connect T tubules w/ SR to allow Ca release
What are type IIA muscle fibers?
fast/intermediate, powerful many mitochondria many myoglobin intermediate fatigability aerobic, but less O2 than type I
What is the sarcoplasm?
cytoplasm of muscle cell
What is an oligodendrocyte?
myelinate axons in CNS
Wrap around a part of MANY axons
