Synaptic Transmission

Definition

Synaptic transmission is the process by which an electrical or chemical signal is transmitted from one neuron to another across the synaptic cleft, the small gap between the axon terminal of the presynaptic neuron and the dendrite or cell body of the postsynaptic neuron. This process is essential for the communication and coordination of the nervous system.

5 Must Know Facts For Your Next Test

1. Synaptic transmission can be either electrical or chemical, depending on the type of synapse.
2. In chemical synaptic transmission, the arrival of an action potential at the presynaptic terminal triggers the release of neurotransmitters into the synaptic cleft.
3. The released neurotransmitters bind to specific receptors on the postsynaptic membrane, causing either an excitatory or inhibitory response.
4. The strength and duration of the postsynaptic response depend on the type and concentration of neurotransmitters, as well as the number and sensitivity of receptors.
5. Synaptic transmission is modulated by various factors, including the rate of neurotransmitter release, reuptake, and degradation, as well as the activity of presynaptic and postsynaptic receptors.

Review Questions

• Describe the process of chemical synaptic transmission and how it differs from electrical synaptic transmission.
  • In chemical synaptic transmission, the arrival of an action potential at the presynaptic terminal triggers the release of neurotransmitters into the synaptic cleft. These neurotransmitters then bind to specific receptors on the postsynaptic membrane, causing either an excitatory or inhibitory response. This process differs from electrical synaptic transmission, where the signal is directly transmitted through gap junctions between the presynaptic and postsynaptic neurons, without the involvement of neurotransmitters.
• Explain how the strength and duration of the postsynaptic response are influenced by the characteristics of the neurotransmitters and receptors involved in synaptic transmission.
  • The strength and duration of the postsynaptic response depend on the type and concentration of neurotransmitters released, as well as the number and sensitivity of the receptors on the postsynaptic membrane. For example, the binding of excitatory neurotransmitters, such as glutamate, to their receptors will result in a stronger and longer-lasting postsynaptic response compared to the binding of inhibitory neurotransmitters, such as GABA. Additionally, the presence of more receptors or receptors with higher sensitivity will amplify the postsynaptic response, while the reuptake and degradation of neurotransmitters will limit the duration of the response.
• Analyze how the modulation of synaptic transmission, through factors such as neurotransmitter release, reuptake, and receptor activity, can influence the overall function and coordination of the nervous system.
  • The modulation of synaptic transmission is crucial for the proper functioning and coordination of the nervous system. By regulating the release, reuptake, and degradation of neurotransmitters, as well as the activity of presynaptic and postsynaptic receptors, the nervous system can fine-tune the strength and duration of synaptic responses. This allows for the precise control of neuronal excitability, the integration of multiple inputs, and the selective amplification or suppression of specific signals. Disruptions in these modulatory mechanisms can lead to various neurological and psychiatric disorders, highlighting the importance of synaptic transmission in the central processing and central control of the nervous system.

Related terms

Neurotransmitter: Chemicals released by the presynaptic neuron that bind to receptors on the postsynaptic neuron, triggering a response.

Synaptic Vesicle: Small membrane-bound organelles in the axon terminal that store and release neurotransmitters during synaptic transmission.

Synaptic Cleft: The small gap between the presynaptic and postsynaptic neurons where neurotransmitters are released and diffuse across.