structure of skeletal muscle Flashcards
muscles
act in antagonitistic pairs against an incompressible skeleton to create movement.
can be autonomic as part of a reflex response or controlled through conscious thought.
h zone
i band
h zone- myosin
i band- action
sliding filament theory
when an action potential reaches a muscle, it stimulates a response.
protein tropomysin which covers binding site of myosin head of action is uncovered
ADP which is bound to myosin head binds to the binding site on the actin forming a cross bridge
the angle formed by the cross bridge creates tension, so the actin filament is pulled and slides along the myosin
adp is released
ATP attached to the myosin head changes it shape slightly so it dettaches from the actin
within the sarcoplasm, the enzyme ATPase hydrolyses ATP to release enough energy to return the myosin to its original position
this process occurs contiualy while the calcium ions remain high and the muscles continue to remain stimulated by the nervous system.
myofibrls, actin and myosin
muscles contain millions of myofibrils
myofibrils contain 2 proteins- actin and myosin
myofibrls are fused cells which share nuclei and cytoplasm
have many mitochondria
ATP
active muscles require a high ATP concentration
when the rate of aerobic respiration is not great enough to provide enough ATP, anaerobic respiration occurs
the chemical, phosphocreatine, stored in muscles assists this by providing phosphate to regenerate ATP from ADP.
i band
a band
z line
m line
a band- total width of myosin
h zone- myosin by itself
i band- actin by itself
m line- middle point of myosin
z line- length of one sarcomere
slow twitch muscles
rich blood supply
many mitochondria
large myoglobin store
found in calf muscles
contract slower
can respire aerobically for longer due to rich blood supply and large myoglobin store
for endurance work e.g. marathons
fast twitch muscle fibres
thicker
more myosin filaments
larger glycogen store
store of phosphocreatine to make ATP from ADP
high concentration of enzymes involved in anaerobic respiration
contract faster to provide short burst of powerful contraction
adapted for intense exercise e.g. sprinting or weight lifting.
neuromusclar junction
synpase between a motor neurone and msucle
similar to a synaptic junction
neuromusclar junctions vs cholinergic synapse
only excitatory vs excitatory or inhibitory
synapse between motor neurone and muscle vs synaphase between two neurones/can be relay, motor or sensory
end for action potential vs action potential generated in next neurone
undirectional as receptors for neurotransmitter only on post SM
acetylcholine binds to receptors on muscle fibre membrane vs acetylcholine binds to receptors on post SM of neurone.
i band
a band
z line
m line
z line- between sarcomere
m line- midle of sarcomere
no overlap between actin and myosin
contains myosin
i band- contains actin
a band- contains myosin
sarcolemma
sarcoplasm
sacromere
t tububles
myofibrils
membrane of muscle cell
cytoplasm of muscle cell
unit of muscle cell
memberane of sarcolemma
forming a cavity
contain actin and myosin
skeletal/voluntary muscle
many mitochondria
many cylindrical cells- muscle fibres
contain myofibrils which contain myofilaments e.g. actin and myosin
relaxed muscle
actin myosin binding site covered by tropomysin protein
no cross bridge formed
