Question | Answer |
job of tropomyosin | covers actin's binding site |
has a myosin binding site | actin |
have heads (crossbridges) | myosin |
holds tropomyosin in place | troponin |
covers binding site of actin | tropomyosin |
excitation-contraction coupling | receiving and propagating a stimulus to contraction |
the contraction cycle | when stimulated, crossbridges attach to myosin binding site on actin |
job of crossbridges | act like tiny ratchets to propel thin filaments toward center of sarcomere |
location of sarcomere | Z line to Z line of myofibril |
NMJ | area f contact between neuron and sarcolemma |
synapse | where nerve cell communicates with other cell through release of Ach |
synaptic gap | space between synaptic terminal and sarcolemma |
synaptic end bulbs | expanded ends of neuron that fit into motor end plate |
motor end plate | area on sarcolemma where acetylcholine receptors are found |
Acetylcholine (Ach) | neurotransmitter (chemical messenger) released at the NMJ |
When Ach binds to receptors at motor end plate, muscle becomes | more permeable to sodium |
ATP | the main energy currency in living cells; usd to transfer the chemical energy needed for metabolic reactions |
where does the energy for muscular activity come from? | ATP |
ATP is needed for what in muscle metabolism? | energy for conractions, to detach cross bridges, to pump calcium ions back into the SR |
in order for muscle contractions to continue, ___ needs to be regenerated | ATP |
where is ATP made? | mitochondria |
the SR stores this | Calcium |
at rest, active sites of actin are covered by | tropomyosin |
the ___contains vesicles filled w/ Ach | synaptic end bulb |
contains receptors for Ach | motor end plate |
at rest, tropomyosin held in place by | troponin |
synaptic cleft | space between end bulb and motor end plate; where Ach is released for diffusion |
motor unit | single neuron and all the muscle fibers it controls |
isotonic | muscle changes in length as tension rises |
isometric | does not change lengthen as tension rises |