Neuroscience: Synapses and Summation

Flashcards covering key concepts about synapses, neurotransmitter release, summation types, and their significance in neural communication.

Electrical Synapse

Direct connection between cells via gap junctions allowing ions to flow.

Chemical Synapse

Communication via neurotransmitters released into a synaptic cleft.

Speed Difference

Electrical synapses are very fast; chemical synapses are slower.

Signal Direction

Electrical signals are often bidirectional; chemical signals are one-way.

Most Common Synapse Type

Chemical synapses are more common in humans.

Control/Modulation in Synapses

Chemical synapses allow for more control and modulation.

Chemical Synapse Definition

Junction where neurons communicate using neurotransmitters.

Trigger for Neurotransmitter Release

The arrival of an action potential at the axon terminal.

Role of Calcium (Ca²⁺) in Synapses

Ca²⁺ enters terminal and triggers vesicle fusion.

After Ca²⁺ Enters Neuron

Synaptic vesicles fuse with the membrane and release neurotransmitter.

Synaptic Cleft

Small gap between neurons.

After Neurotransmitters are Released

They bind to receptors on the postsynaptic cell.

After Receptor Binding

Ion channels open leading to graded potential formation.

Removal of Neurotransmitters

They are removed by reuptake, breakdown by enzymes, or diffusion.

Excitatory Synapse

A synapse that increases the likelihood of an action potential.

EPSP

Excitatory postsynaptic potential, resulting in depolarization.

Ion Movement Causing Excitation

Sodium ions (Na⁺) entering the cell.

Effect of Depolarization on Neurons

It brings the membrane closer to threshold.

Result of Sufficient EPSPs

Threshold is reached leading to action potential generation.

Summation Definition

The process of adding multiple graded potentials together.

Importance of Summation

It determines if the neuron reaches threshold to fire an action potential.

Temporal Summation Definition

Multiple signals from the same neuron arriving rapidly over time.

Key Feature of Temporal Summation

Signals are close together in time.

Example of Temporal Summation

One neuron fires repeatedly causing EPSPs to build up.

Spatial Summation Definition

Signals from multiple neurons arriving at the same time.

Key Feature of Spatial Summation

Signals come from different locations.

Example of Spatial Summation

Several neurons firing simultaneously resulting in a combined effect.

Difference between Temporal and Spatial Summation

Temporal involves the same neuron over time, spatial involves multiple neurons at once.

Commonality in Summation Types

Both types of summation combine signals to reach threshold.