Integration is the :

Options

A. self-propagation of ion flow along a neuron
B. trigger that releases neurotransmitters
C. summation of signals acting at all synapses on a neuron
D. collection of all information about several stimuli

Explanation

**Step-by-Step Solution:**

1. **Understanding Integration in the Nervous System:**
- Integration refers to the process by which the nervous system processes and interprets sensory information. It involves combining various signals received from sensory neurons to produce a coherent response.

2. **Functions of the Nervous System:**
- The nervous system has three overlapping functions: sensory input, integration, and motor output.
- **Sensory Input:** Detection of stimuli by sensory receptors.
- **Integration:** Processing of sensory information to determine the appropriate response.
- **Motor Output:** Execution of a response through effectors (muscles or glands).

3. **Role of the Central Nervous System (CNS):**
- The CNS (comprising the brain and spinal cord) plays a crucial role in integration. It receives signals from sensory neurons, processes this information, and sends commands to motor neurons.

4. **Identifying the Correct Definition of Integration:**
- Among the options provided, the correct definition of integration is: "summation of signals acting at all synapses on a neuron." This means that integration involves the combination of all incoming signals to generate an appropriate response.

5. **Eliminating Incorrect Options:**
- The other options can be ruled out:
- "Self-propagation of ion flow along a neuron" refers to action potentials and does not encompass the concept of integration.
- "Trigger that releases neurotransmitters" is part of synaptic transmission but does not define integration.
- "Collection of all information about several stimuli" lacks the aspect of generating an output or response, which is essential for integration.

6. **Conclusion:**
- Therefore, the correct answer to the question "Integration is the:" is the summation of signals acting at all synapses on a neuron.

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