Large quantities of positive potassium ions diffuse out of the SA node.

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#Id: 5468

#Unit 7. System Physiology – Animal

Principle of one-way conduction at chemical synapses 

always transmit the signals in one direction i.e., from the neuron that secretes the neurotransmitter called the presynaptic neuron, to the neuron on which the transmitter acts, called the postsynaptic neuron

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#Unit 7. System Physiology – Animal

Once an impulse reaches the presynaptic terminals, a response can be obtained in the postsynaptic neuron after a Synaptic delay.

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#Id: 5470

#Unit 7. System Physiology – Animal

Synaptic delay is due to the time it takes for the synaptic mediator to be released and to act on the receptors on the membrane of the postsynaptic cell. 

The minimum time for synaptic delay is 0.5 ms

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#Id: 5471

#Unit 7. System Physiology – Animal

Three states of a neuron

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#Id: 5472

#Unit 7. System Physiology – Animal

Excitatory postsynaptic potential (EPSP) is produced by depolarization of the postsynaptic cell membrane immediately under the presynaptic ending

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#Id: 5473

#Unit 7. System Physiology – Animal

Excitatory postsynaptic potential (EPSP)

During this potential, excitatory transmitter opens Na+ or Ca2+ channels in the postsynaptic membrane, producing an inward current & the excitability of the neuron to other stimuli is increased