How do stimuli cause action potential in neurons?
Action potentials are caused when different ions cross the neuron membrane. A stimulus first causes sodium channels to open. Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron.
What triggers exocytosis of synaptic vesicle contents from an axon terminal?
Before exocytosis, neurotransmitter-filled synaptic vesicles are docked at the plasma membrane and primed: exocytosis is triggered by calcium influx.
What triggers exocytosis of synaptic vesicles?
When an action potential arrives in the nerve terminal, the membrane depolarizes and voltage-gated Ca2+ channels open. The resulting Ca2+ influx triggers exocytosis of synaptic vesicles, resulting in the release of neurotransmitter.
What are the steps in neurotransmission?
There are five major steps in the chemical synapses for transmission of signals: (1) synthesis of neurotransmitter, (2) neurotransmitter storage in synaptic vesicle (quanta), (3) release of the neurotransmitter to the synaptic space, (4) binding of the neurotransmitter to the specific receptors on postsynaptic cell …
What are the parts of an action potential?
The course of the action potential can be divided into five parts: the rising phase, the peak phase, the falling phase, the undershoot phase, and the refractory period. During the rising phase the membrane potential depolarizes (becomes more positive).
How does stimulus intensity affect neurotransmitter release?
When the stimulus intensity is increased, the number of synaptic vesicles increases. When the stimulus intensity is increased, what changes: the number of synaptic vesicles released or the amount of neurotransmitter per vesicle? There was no neurotransmitter release because it is calcium dependent.
What stimulates the release of neurotransmitters from synaptic vesicles?
The arrival of the nerve impulse at the presynaptic terminal stimulates the release of neurotransmitter into the synaptic gap. The binding of the neurotransmitter to receptors on the postsynaptic membrane stimulates the regeneration of the action potential in the postsynaptic neuron.