Peripheral Nervous System Overview and Functions

Mechanoreceptors

Respond to touch, pressure, vibration, and stretch.

Thermoreceptors

Sensitive to changes in temperature.

Photoreceptors

Respond to light energy (e.g., retina).

Chemoreceptors

Respond to chemicals (e.g., smell, taste, blood chemistry).

Nociceptors

Sensitive to pain-causing stimuli like extreme temperature or pressure.

Exteroceptors

Respond to stimuli outside the body, such as touch and temperature.

Interoceptors

Respond to stimuli from internal organs and blood vessels.

Proprioceptors

Detect stretch in muscles and inform the brain about body position.

Receptor Level

Initial interaction with stimuli via sensory receptors.

Circuit Level

Processing of the signal through ascending pathways.

Perceptual Level

Interpretation of sensory input in the cerebral cortex.

Mixed Nerve

Contains both sensory (afferent) and motor (efferent) fibers.

Ganglion

A cluster of neuron cell bodies in the PNS.

Cranial Nerves

12 pairs of nerves that emerge from the brain.

Spinal Nerves

31 pairs of mixed nerves originating from the spinal cord.

Nerve Plexus

A network of intersecting nerves. Major plexuses: cervical, brachial, lumbar, sacral.

Reflex Arc

Includes receptor, sensory neuron, integration center, motor neuron, and effector.

Somatic Reflex

Activates skeletal muscles.

Autonomic Reflex

Activates smooth or cardiac muscle or glands.

Phrenic Nerve

Major motor/sensory nerve of the diaphragm, from C3-C5.

Sciatic Nerve

Longest nerve in the body; serves most of the lower limb.