Question

Name the neurotransmitter that allows the transmission of impulses across the synapse.

Hint:

Acetylcholine is crucial for various functions such as muscle movement, heart rate regulation, and memory. Its action is rapidly terminated by acetylcholinesterase to prevent overstimulation.

Answer 1

Step 1: Identify the neurotransmitter.
The neurotransmitter that allows the transmission of impulses across the synapse is {acetylcholine}. Acetylcholine is a chemical messenger that plays a vital role in transmitting nerve impulses in both the central nervous system (CNS) and peripheral nervous system (PNS). It is primarily involved in the transmission of signals between neurons and muscles, especially at the neuromuscular junction, where it activates muscle contraction.
Step 2: Role of acetylcholine in synaptic transmission.
At the synapse, acetylcholine is released from the presynaptic neuron in response to an action potential. It then travels across the synaptic cleft and binds to specific receptors (called cholinergic receptors) on the postsynaptic neuron or effector cell (e.g., muscle). This binding opens ion channels in the postsynaptic membrane, allowing the influx of sodium ions, which initiates a response, such as the generation of an action potential in the postsynaptic cell or muscle contraction.
Step 3: Types of acetylcholine receptors.
Acetylcholine acts on two types of receptors: 1. Nicotinic receptors: Found at the neuromuscular junction and in the autonomic ganglia. These receptors are ion channels that, when activated by acetylcholine, lead to depolarization of the postsynaptic membrane and the initiation of an action potential. 2. Muscarinic receptors: Found in the heart, smooth muscles, and various glands. These receptors are G-protein-coupled receptors that mediate slower, longer-lasting effects such as the regulation of heart rate and smooth muscle contraction.
Step 4: Degradation of acetylcholine.
Once acetylcholine has transmitted its signal, it must be broken down to prevent continuous stimulation of the postsynaptic cell. This is done by the enzyme {acetylcholinesterase}, which breaks acetylcholine into acetic acid and choline. The choline is then reabsorbed by the presynaptic neuron to be used for the synthesis of more acetylcholine.