reflex arc
Automatic neural pathway
A reflex arc is the neural pathway that produces an automatic, involuntary response to a stimulus.
When you touch something hot, sensory neurons carry the signal to the spinal cord, where interneurons connect to motor neurons that trigger muscle contraction—all before the brain registers pain.
The arc bypasses conscious thought, enabling split-second protective responses like the knee-jerk reflex.
Brain's extension through vertebrae
- motor neuronNerve cell activating muscles
- interneuronNerve cell connecting others
- synapseNerve signal crossing point
- axonNeuron's signal-sending projection
dendrite · ganglion · nerve fiber · myelin sheath · gray matter · white matter · receptor · effector
What prompts a reaction
- responseAnswer to stimulus
- impulseSudden urge to act
- neural pathwaySignal route between neurons
- conductionHeat transfer through contact
transmission · integration · latency · threshold · action potential · depolarization · muscle contraction · nerve impulse
Guarding against harm
- automaticOperating without intervention
- involuntaryNot under conscious control
- unconsciousNot awake or aware
- innateExisting since birth
rapid response · homeostasis · defense mechanism · survival · coordination · proprioception · muscle tone · pain avoidance
spinal cord
Brain's extension through vertebrae
- motor neuronNerve cell activating muscles
- interneuronNerve cell connecting others
- synapseNerve signal crossing point
axon · dendrite · ganglion · nerve fiber · myelin sheath · gray matter · white matter · receptor · effector · neurotransmitter
stimulus
What prompts a reaction
- responseAnswer to stimulus
- impulseSudden urge to act
- neural pathwaySignal route between neurons
conduction · transmission · integration · latency · threshold · action potential · depolarization · muscle contraction · nerve impulse · sensory input
knee-jerk
Instinctive and unconsidered
protection
Guarding against harm
- automaticOperating without intervention
- involuntaryNot under conscious control
- unconsciousNot awake or aware
innate · rapid response · homeostasis · defense mechanism · survival · coordination · proprioception · muscle tone · pain avoidance · self-preservation