Synaptic transmission I The Synapse I How Neurons Communicate

Summary

This video dives into the fascinating process of synaptic transmission, where neurons communicate using electrical and chemical signals. It explains how messages can be excitatory, increasing the likelihood of a neuron firing, or inhibitory, decreasing that chance. The script covers the key structures of neurons, such as dendrites, soma, and axons, and walks through the action potential process, including the opening of sodium and calcium channels, the release of neurotransmitters via exocytosis, and how signals are transmitted to the next neuron. The video also highlights the recycling process of neurotransmitters and the importance of repolarization for the neuron to reset.

Takeaways

• 😀 Neurons communicate through chemical messages and electrical signals, unlike human communication, which relies on spoken words.
• 😀 There are two types of synaptic messages: excitatory (increases the likelihood of the next neuron firing) and inhibitory (decreases that likelihood).
• 😀 The neuron has key parts: dendrites (receive messages), soma (cell body), and axon (sends signals to other neurons).
• 😀 The tiny space between two neurons is called the synapse, where communication occurs between the pre-synaptic and post-synaptic neurons.
• 😀 Neurons are negatively charged on the inside and positively charged on the outside, maintaining a resting membrane potential of -70mV.
• 😀 An action potential is a charge that travels down the neuron when stimulated and reaches the threshold potential of -55mV.
• 😀 Voltage-gated sodium channels open when the neuron reaches the threshold, allowing sodium to enter, depolarizing the neuron to +40mV.
• 😀 Depolarization is a wave-like process that moves down the neuron, causing the next set of sodium channels to open and continue the process.
• 😀 Once the depolarization wave reaches the axon terminal, calcium channels open, allowing calcium ions to enter, triggering neurotransmitter release.
• 😀 Neurotransmitters are stored in synaptic vesicles and released into the synaptic cleft via exocytosis to transmit signals to the next neuron.
• 😀 Some neurotransmitters bind to receptors on the post-synaptic neuron, opening ion channels and potentially triggering another action potential.
• 😀 The process of reuptake allows neurotransmitters to be absorbed back into the pre-synaptic neuron for recycling and reuse.

Q & A

What is the primary method through which neurons communicate?

Neurons communicate through chemical messages and electrical signals, specifically via synaptic transmission.

What are the two types of messages neurons can send to each other?

Neurons can send excitatory messages, which increase the likelihood of the next cell firing, and inhibitory messages, which decrease the likelihood of the next cell firing.

What are the main parts of a neuron involved in synaptic transmission?

The main parts of a neuron involved in synaptic transmission are the dendrites, soma (cell body), axon, and axon terminal (synaptic bulb).

What is the term for the tiny space between two neurons?

The tiny space between two neurons is called the synaptic cleft.

What is the resting potential of a neuron, and why is it important?

The resting potential of a neuron is -70 millivolts (mV), meaning the inside of the neuron is more negatively charged compared to the outside. This resting state is essential for the neuron to respond to stimuli and generate action potentials.

What triggers an action potential in a neuron?

An action potential is triggered when a neuron receives sufficient stimulation, causing its membrane potential to reach a threshold of -55 mV, known as the threshold potential.

What happens when the action potential reaches the threshold potential of -55 mV?

When the threshold potential of -55 mV is reached, voltage-gated sodium channels open, allowing sodium ions to enter the cell and depolarize the neuron, making it more positive.

What role does calcium play in synaptic transmission?

Calcium ions enter the neuron after the action potential reaches the threshold, triggering the release of neurotransmitters from synaptic vesicles into the synaptic cleft.

What is exocytosis in the context of synaptic transmission?

Exocytosis is the process through which neurotransmitters are released from synaptic vesicles into the synaptic cleft. This occurs when calcium ions bind to proteins in the vesicles, causing them to fuse with the membrane and release their contents.

What happens to neurotransmitters after they are released into the synaptic cleft?

After being released into the synaptic cleft, neurotransmitters bind to receptors on the post-synaptic neuron, which can initiate an action potential in that neuron. Some neurotransmitters are also recycled through reuptake, where they are reabsorbed by the presynaptic neuron for future use.

How does the neuron return to its resting state after depolarization?

After depolarization, potassium ions exit the neuron, causing the cell to repolarize. The neuron then returns to its resting membrane potential, with negative charge inside and positive charge outside.