MUSCLE PHYSIOLOGY

Detailed explanation-1: -When an action potential reaches the axon terminal it depolarizes the membrane and opens voltage-gated Na+ channels. Na+ ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated Ca2+ channels to open.

Detailed explanation-2: -Presynaptic terminal depolarization and ACH release. With the arrival of the action potential to the nerve terminal, voltage gated calcium channels (VGCCs) open allowing calcium to enter the presynaptic terminal.

Detailed explanation-3: -In neurons, calcium channels open in response to the binding of neurotransmitters to cell surface receptors that are permeable to calcium, such as NMDA and AMPA receptors.

Detailed explanation-4: -Presynaptic Ca2+ entry occurs through voltage-gated Ca2+ (CaV) channels which are activated by membrane depolarization. Depolarization accompanies neuronal firing and elevation of Ca2+ triggers neurotransmitter release from synaptic vesicles.

Detailed explanation-5: -When calcium ions enter the synaptic terminal, neurotransmitter molecules are quickly removed from the synaptic cleft. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. they cause an action potential in the sending neuron.