Which of the following signaling molecules are used by simple nerve reflexes?

(a) Proteases

(b) Nitric oxides

(c) G proteins

(d) Neurotransmitters

The correct answer is (d) Neurotransmitters.

Simple nerve reflexes, like the knee-jerk reflex, rely on the rapid communication between nerve cells (neurons) at specialized junctions called synapses.This communication is carried out by chemical messengers known as neurotransmitters.

The Role of Neurotransmitters

When a nerve impulse reaches the end of a neuron, it triggers the release of neurotransmitters into the synaptic cleft (the small gap between neurons).These molecules then travel across the gap and bind to specific receptors on the next neuron or target cell (like a muscle cell), transmitting the signal and causing a response.

Common neurotransmitters include:

• Acetylcholine: Often used at the neuromuscular junction to trigger muscle contraction.
• GABA (Gamma-Aminobutyric acid): A major inhibitory neurotransmitter in the central nervous system.

G proteins, on the other hand, are part of the intracellular signaling cascade that occurs after a neurotransmitter has bound to its receptor. They don't travel between cells.