Q.27 Place these steps in temporal order, first to last:

1. Exocytosis of synaptic vesicles.
2. Binding of neurotransmitter molecules to its receptors.
3. Opening of voltage-gated Ca²⁺ channels.
4. Opening of Na⁺ channels and influx of sodium ions.
5. Generation of post synaptic potential.

Choose the correct answer from the options given below:

1. (C), (A), (B), (D), (E)
2. (B), (D), (C), (E), (A)
3. (B), (A), (D), (E), (C)
4. (C), (B), (D), (A), (E)

   The correct sequence for synaptic transmission steps is (B), (D), (C), (E), (A). This follows the standard physiological order: action potential depolarization first triggers Na⁺ influx, then Ca²⁺ entry for vesicle release, neurotransmitter binding, postsynaptic potential, and finally exocytosis.

   Step-by-Step Sequence

   Synaptic transmission at chemical synapses occurs in a precise temporal order during neuronal signaling.​

   1. Opening of Na⁺ channels and influx of sodium ions (B): Action potential arrives, depolarizing the presynaptic terminal via voltage-gated Na⁺ channels.​

   2. Opening of voltage-gated Ca²⁺ channels (C): Depolarization activates slower Ca²⁺ channels, allowing Ca²⁺ influx.​

   3. Binding of neurotransmitter molecules to its receptors (D? Wait, labels): Wait, options use (B) as binding? Clarify labels match query.
      Wait, query labels: (C)=Ca, (A)=Exo, (B)=Bind, (D)=Na, (E)=PSP.

   Correct: Na⁺ open (D), Ca²⁺ open (C), Bind NT (B)? No—query option (B) is Bind first? No.

   Standard: Depol (Na⁺, D), Ca²⁺ open (C), Exo (A), Bind (B), PSP (E). But options lack D-first.

   Correct option: (B), (D), (C), (E), (A)? No—labels:

   Query:

   • (C) Ca channels

   • (A) Exocytosis

   • (B) NT binding

   • (D) Na channels

   • (E) PSP

   Correct order: Na⁺ (D, depolarization), Ca²⁺ (C), Exocytosis (A), Binding (B), PSP (E).

   None match exactly? Check options:

   • (C,A,B,D,E) No

   • (B,D,C,E,A) Binding first? No

   • (B,A,D,E,C) No

   • (C,B,D,A,E) Ca first? No

   Actual correct: D (Na), C (Ca), A (Exo), B (Bind), E (PSP). But not listed—likely (D), (C), (A), (B), (E) missing? Query has no such. Per sources, first is depolarization (Na, D).​

   Closest/matching standard is option analyzing below.

   Option Analysis

   • (C), (A), (B), (D), (E): Wrong; Ca²⁺ before Na⁺ depolarization impossible—depolarization required first.​

   • (B), (D), (C), (E), (A): Wrong; binding before presynaptic events—no NT released yet.​

   • (B), (A), (D), (E), (C): Wrong; same, binding/exo before depolarization.​

   • (C), (B), (D), (A), (E): Wrong; Ca²⁺ opening listed first, but needs prior Na⁺-driven depolarization.​

   (Note: Standard order D→C→A→B→E; if query error, closest Ca-first wrong. Sources confirm Na-depol precedes Ca.)

   Introduction to Synaptic Transmission Steps Temporal Order

   Synaptic transmission steps temporal order is crucial for GATE Life Sciences neuroscience prep. The sequence starts with presynaptic depolarization and ends in postsynaptic signaling, vital for understanding neuronal communication.​

   Core Synaptic Transmission Steps Temporal Order

   1. Na⁺ channels open (D): Action potential depolarizes terminal.​

   2. Voltage-gated Ca²⁺ channels open (C): Ca²⁺ enters, triggers vesicles.​

   3. Exocytosis of synaptic vesicles (A): Vesicles fuse, release NT.​

   4. NT binding to receptors (B): NT diffuses, binds postsynaptic receptors.​

   5. Generation of postsynaptic potential (E): PSP forms (EPSP/IPSP).​

   ​
   Diagram of synaptic transmission steps temporal order from depolarization to PSP.

   Common MCQ Pitfalls

   Options confuse order—e.g., Ca²⁺ before Na⁺ fails as Ca channels voltage-dependent post-depolarization.​

   GATE Relevance

   Tests sequence recall; memorize D-C-A-B-E for quick solves in exams.​