Muscle Flashcards
3 types of muscle
skeletal, cardiac, smooth
skeletal is the only one that is?
voluntary one
cell membrane is the
sarcolemma
skeletal muscle
attached to bones by tendons
flexor
brings bones togeher- biceps
extensor
moves bones away- triceps
when do skeletal muscles contract
only when response from a motor neuron
epi, peri, ende -mysium
epi- around the whole thing
peri- binding fascicles (bundles) together
endo-covers individual muscle fibres
t-tubules
are formed from inward extensions of the sarcolemma
- allow electrical signals to go deeper into the cell
triad
formed from a triplet ( one T-tubual and 2 terminal cristae) of tubules made of the sarcoplasmic reticulum which surrounds the T-tubule
I band
only thin filaments
H zone
only thick filaments
A band
both thick and thin
myosin
thick filament
actin
thin filament
- globular protein that forms wo strands that twist together
troponin
holds tropomyosin molecules in place
tropomyosin
protein that blocks the active sites on the actin molecule
titin
provides elasticity and stabilizes myosin
nebulin
helps to align the actin
muscle fibres contain lots of?
mitochondria and several nuclei
what are myofilaments?
the microfilaments- thick and thin in myofibrils
segment of myofibril between 2 successive Z lines?
sacromere
conratile unit of muscle fibres?
sacromere
each myofibril consist of many contractile units called
sacromeres
Z line
anchor for myofibriles
- thiner striation than the A band
A band
wide dark stripe
what band gives muscles their striation look?
A band
4 things muscle fibres contain?
sarcolemma
t-tubules
sarcoplasm ( which has myofibrils, mito, SR)
multiple nuclei
6 types off myofibriles
actin, troponin, tropomyosin (thin)
myosin (thick)
titin and nebulin
sarcolemma
muscle cell plasm
SR stores?
Ca2+
4 types of protein that make up the myofilament?
myosin, actin, tropomyosin and troponin
______ filaments DO NOT attach to z lines
thick (myosin)
- just in the centre A band area
Actin
globular protein that forms two fibrous strands that twist around each other to form bulk of the thin filaments
tropomyosin
protein that blocks the active sites (for myosin to bind to actin) on the actin molecules
troponin
protein that holds tropomyosin molecules in place
titin and nebulan are____ proteins
regulatory
nebulin helps to ?
align actin
titan provides?
elasticity and stabilizes myosin
motor neurons connect to sarcolemma at _____
motor endplate
this is a neuromuscular junction
neuromuscular junction
is a synapse where neurotransmitter molecules transmit signals
motor neuron releases at the motor endplate
acetylcholine (ACH) which binds with receptors on the muscle fibre and depolarizes the cytoplasmic membrane of the muscle fibre
what happens when the fibre is stimulated by ACH
net entry of Na2+ into the muscle through ACH channel receptors ( they open to let Na inside) which creates an
electrical impulse which travels from the sarcolemma and down t-tubules where the voltage change triggers the opening of voltage gated Ca2+ channels—-> which allows Ca2+ to diffuse out of the SR and this is what causes contraction –. Ca2+ interacts with troponin, allowing actin-myosin binding
RyR
ryanodine receptor channel- it is in the ER membrane, when the action potenical travels down the t-tubuleit alters the conformation of DHP receptor which then opens RyR channel and Ca2+ can flow out of SR
DHP-
calcium channel that is in t-tubules and when triggered by an action poetical will open up RyR to allow Ca2+ to flow out of the SR
ca2+ binds to __________, which allows _________ to shift and expose the actin site
ca binds to troponin
allowing tropomyosin to shift and expose the active site for mason heads to bind to actin
the binding of myosin heads triggers?
the hydrolysis of ATP into ADP and P