Neural Synapses and Neurotransmitter Transmission in the Nervous System

What are the two types of synapses?

Electrical and Chemical.

What are the two main types of cells involved in synapses?

Presynaptic cell and Postsynaptic cell.

What is the synaptic cleft?

The space between the presynaptic and postsynaptic cells.

What initiates the release of neurotransmitters in a chemical synapse?

An action potential (AP) in the presynaptic cell.

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

They diffuse across the cleft and bind to specific receptors on the postsynaptic cell.

What are the two types of postsynaptic potentials?

Excitatory Postsynaptic Potential (EPSP) and Inhibitory Postsynaptic Potential (IPSP).

What is the effect of EPSP on the postsynaptic cell?

It causes depolarization, moving the membrane potential closer to the threshold for an action potential.

What is the effect of IPSP on the postsynaptic cell?

It causes hyperpolarization, moving the membrane potential further from the threshold for an action potential.

What is the role of calcium ions (Ca2+) in neurotransmitter release?

Ca2+ diffuses into the presynaptic cell and causes synaptic vesicles to fuse with the presynaptic membrane, releasing neurotransmitters.

What are graded potentials?

Changes in membrane potential that are not all-or-none and can vary in size.

Where do postsynaptic potentials typically occur?

At the dendrites or soma of the neuron.

What is temporal summation?

The additive effect of multiple EPSPs or IPSPs occurring at the same location over time.

What is spatial summation?

The additive effect of multiple EPSPs or IPSPs occurring at different locations simultaneously.

What is the function of ligand-gated channels?

They open in response to the binding of neurotransmitters, allowing ions to flow across the membrane.

What are ionotropic receptors?

Receptors that are channels themselves and allow ions to pass directly through upon neurotransmitter binding.

What are metabotropic receptors?

Receptors that communicate with channels indirectly through second messenger systems, such as G-proteins.

What happens if the axon hillock reaches the threshold potential?

An action potential (AP) is generated and propagated along the axon.

Why can't dendrites or soma generate action potentials?

They have few voltage-gated channels and primarily generate graded potentials.

What is the role of acetylcholinesterase in neurotransmission?

It degrades acetylcholine in the synaptic cleft to prevent prolonged activation of the postsynaptic cell.

What neurotransmitter is important in the peripheral nervous system (PNS)?

Acetylcholine.

What are examples of inhibitory neurotransmitters in the CNS?

GABA and Glycine.

What are examples of excitatory neurotransmitters in the CNS?

Serotonin and Glutamate.

What are neuropeptides?

Small peptides that can have long-lasting effects and often coexist with other neurotransmitters.

What is the primary neurotransmitter type that each presynaptic cell has?

Each presynaptic cell has only one main neurotransmitter, making it either excitatory or inhibitory.