Synaptic Transmission Flashcards
What is synaptic transmission?
Synaptic transmission is the process by which a nerve impulse (action potential) is transmitted across a synapse from one neuron to another, or to an effector cell.
What are the key structures involved in synaptic transmission?
The key structures include the presynaptic neuron (axon terminal), synaptic vesicles containing neurotransmitters, synaptic cleft (gap), and the postsynaptic membrane.
How does an action potential arrive at the presynaptic terminal?
An action potential travels along the axon of the presynaptic neuron and arrives at the axon terminal, triggering neurotransmitter release.
What role do calcium ions (Ca²⁺) play in synaptic transmission?
When the action potential reaches the presynaptic terminal, calcium ions (Ca²⁺) enter through voltage-gated channels, triggering the release of neurotransmitters.
How are neurotransmitters released from the presynaptic neuron?
Neurotransmitters are released by exocytosis, where synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft.
What is the role of neurotransmitters in synaptic transmission?
Neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane, triggering a response in the postsynaptic neuron or target cell.
What is the function of receptor proteins on the postsynaptic membrane?
Receptor proteins on the postsynaptic membrane bind with neurotransmitters, causing either depolarization (excitatory) or hyperpolarization (inhibitory) of the postsynaptic membrane.
What is the difference between excitatory and inhibitory neurotransmitters?
Excitatory neurotransmitters cause depolarization of the postsynaptic membrane (increasing the likelihood of an action potential), while inhibitory neurotransmitters cause hyperpolarization (decreasing the likelihood of an action potential).
What is an excitatory postsynaptic potential (EPSP)?
An EPSP is a small depolarization of the postsynaptic membrane caused by the binding of excitatory neurotransmitters, making the postsynaptic neuron more likely to fire.
What is an inhibitory postsynaptic potential (IPSP)?
An IPSP is a small hyperpolarization of the postsynaptic membrane caused by the binding of inhibitory neurotransmitters, making the postsynaptic neuron less likely to fire.
How does acetylcholine function at synapses?
Acetylcholine is released from the presynaptic terminal, binds to receptors on the postsynaptic membrane, and is broken down by acetylcholinesterase to terminate its action.
What is the role of acetylcholinesterase in synaptic transmission?
Acetylcholinesterase breaks down acetylcholine in the synaptic cleft, preventing continuous stimulation of the postsynaptic cell.
How is neurotransmitter action terminated?
Neurotransmitter action is terminated by enzymatic breakdown (e.g., acetylcholinesterase) or by reuptake of the neurotransmitter back into the presynaptic neuron.
What is the role of synaptic vesicles in synaptic transmission?
Synaptic vesicles store neurotransmitters and release them into the synaptic cleft upon arrival of an action potential.
How do neurotransmitters affect the postsynaptic membrane?
Neurotransmitters bind to specific receptors on the postsynaptic membrane, which can cause depolarization (EPSP) or hyperpolarization (IPSP) of the membrane.
What is the significance of synaptic plasticity?
Synaptic plasticity is the ability of synapses to strengthen or weaken over time, which is important for learning, memory, and adaptation.
How do drugs affect synaptic transmission?
Drugs can alter synaptic transmission by mimicking neurotransmitters, blocking receptors, inhibiting neurotransmitter breakdown, or affecting neurotransmitter release
