9. The regulation of muscle work and muscle nerve connection: the motor unit Flashcards
Muscle-nerve connection: where does The transmission of neural action potential to the muscle
takes place in the area of the myoneural junction.
Muscle-nerve connection: explain the transmission at the neutral action potential
the acetyl choline release induced by the action potential at the nerve terminals. This chemical sign binds to the nicotinic receptors of the muscle membrane and results in the opening of ligand activated cationic channels.
Muscle-nerve connection: what happens when you open the channels cationic channels
The opening of these cationic channels produces a local current which is gradually decreasing conducted to the fast, voltage gated sodium channel situated next to the myoneural junction.
What happens at the Presynaptic area
Action potential from axon
o Neural action potential induces calcium entry to the synaptic ending
o Acetylcholine vesicle release
what happens at the Synaptic cleft
Filled with acetylcholine
what happens at the post synaptic area
- Acetylcholine binds to its specific receptors on the myolemma
- Ligand gated ion channel is opening: a local end plate potential (EPP) is developing
- EPP activates neighboring voltage gated sodium channels, which result in a formation and propagation of action potentials.
Motor Unit: Large motor unit: nerve
Large diameter, very fast conduction,
difficult stimulation
Motor Unit: Large motor unit: muscle
Muscle: Large fiber number, large diameter, large
force, anaerobic metabolism, speed is fast, easily
fatigues, fiber length is very long.
Motor Unit: Small motor unit: nerve
Nerve: Small diameter, fast conduction, easy stimulation
Motor Unit: Small motor unit: muscle
Muscle: Few fiber number, intermediate diameter, small force, oxidative metabolism, speed is slow, does not fatigue, fibre length is short.
