Nervous System: Neurons, Synapses, and Reflexes

Flashcards cover neuron types, synapse definition, nerve-impulse sequence, neuromuscular junction, limitations of impulse conduction, and reflex actions.

What role do interneurons (relay neurons) play in the nervous system?

They connect sensory neurons to motor neurons, forming links within the brain and spinal cord.

Where are interneurons primarily located?

In the brain and spinal cord.

What is a synapse?

A small gap between two adjacent neurons across which a nerve impulse passes in one direction.

How does a nerve impulse compare to electric current in a wire?

It is an electrical signal that travels along a neuron similar to how electric current flows through a wire.

What detects stimuli from the environment in the first step of a nerve‐impulse pathway?

Receptors (sense organs).

Which part of a sensory neuron first generates the electrical impulse?

The dendritic tip, after a chemical reaction occurs there.

In what order does an impulse travel within a sensory neuron?

From dendrite → cell body (cyton) → along the axon to its terminal end.

What happens at the end of a neuron's axon to transmit the signal onward?

Neurotransmitters are released, cross the synapse, and initiate an impulse in the next neuron.

What is the neuromuscular junction?

The point where a motor neuron's axon terminal meets a muscle fiber, allowing the neuron to transmit impulses to the muscle.

Give one limitation of electrical impulse transmission through neurons.

Only cells directly connected by nervous tissue can receive the signal.

Give a second limitation of electrical impulse transmission.

A neuron must reset its membrane mechanism before it can transmit a new impulse, creating a brief delay.

Define reflex action.

An automatic, rapid response to a stimulus without conscious thought (e.g., coughing when dust enters the nose).

Why are most reflex actions routed through the spinal cord rather than the brain?

Routing through the spinal cord speeds up the response because signals do not have to travel to the brain for processing.

What is the neural pathway called that links detection of a stimulus to an immediate response in a reflex?

Reflex arc.

Which structures act as effectors at the end of a nerve‐impulse pathway?

Muscles or glands that carry out the response.