Lecture 4 Flashcards
myofilaments
actin and myosin are two filaments which have a structure referred to as cross-bridges. This structure forms the smallest unit of skeletal muscle, the sarcomere
components of skeletal muscle
the sarcolemma is a membrane which has within its structure the sarcoplasm which contains myofilaments and sarcoplasmic reticulum
__________ is created when a signal is sent from the CNS to the muscle intended to move.
movement
innervation is referred to as:
the nerve which sends signals to a specific muscle.
How does the action potential travel during communication between axon and muscle in the neuromuscular synapse (junction)
The action potential travels down the axon and arrives at the neuromuscular junction and muscle contraction occurs due to obligatory nature of neuromuscular synapses
How is the neuromuscular synapse (junction) different from other synapse?
some can be non-obligatory
Neuromuscular Synapse
- neurotransmitter: acetylcholine (ACh)
- always excitatory
- obligatory
- no multiple innervation
- AChesterase quickly destroysACh in the synaptic cleft
MEPP’s
Moter End Plate Potential
Where to MEPP’s occur?
MEPP’s spontaneously occur on the postsynaptic muscle membrane
Functional meaning of MEPP’s?
Functional meaning unclear
presynaptic nerves and MEPP’s
A presynaptic nerve action potential always reaches the depolarization threshold and induces a msucle action potneital
Direct Effects of the Muscle Action Potential
Muscle action potential travels along the sarcolemma enters T-tubules, and leads to a release of Ca++ ions from the sarcoplasmic reticulum.
Sliding Filament Theory
Sliding Filament Theory
Ca++ ions remove tropomyosin and free a site for myosin to bind to troponin (this process uses the energy from ATP). A ratchet motion occurs, moving the filaments with respect to each other.
A ________ of a muscle in response to a single stimulus
typical twitch
Under neurological stimulation. Muscle ONLY _______.
contracts.
It does not extend or flex.
