The Peripheral Nervous System and Afferent Division

These flashcards cover key vocabulary and concepts from the lecture on the Peripheral Nervous System and its afferent division, focusing on receptor types, sensory pathways, and pain perception.

Peripheral Nervous System (PNS)

The part of the nervous system that connects the Central Nervous System (CNS) to the body regions, containing nerve fibers that carry information.

Afferent Division

The division of the PNS that sends sensory information from the external and internal environment to the CNS.

Visceral Afferent Pathways

Pathways that convey subconscious information from internal organs to the CNS.

Sensory Afferent

Sensory information that is conveyed to the level of conscious awareness.

Receptors

Structures at the peripheral endings of afferent neurons that detect stimuli and carry information toward the CNS.

Photoreceptor

A type of receptor that responds to visible wavelengths of light.

Mechanoreceptor

A receptor that is sensitive to mechanical energy.

Thermoreceptor

A receptor that is sensitive to heat and cold.

Osmoreceptor

A receptor that detects changes in the concentration of solutes in body fluids.

Chemoreceptor

A receptor that is sensitive to specific chemicals, such as the concentration of oxygen in the blood.

Nociceptor

A pain receptor that is sensitive to tissue damage.

Exteroceptors

Receptors that detect stimuli from outside the body.

Interoceptors

Receptors that detect stimuli from inside the body.

Proprioceptors

Receptors that provide information about the position of the body.

Graded Receptor Potential

A change in membrane permeability that alters the potential of the receptor in response to a stimulus.

Tonic Receptors

Receptors that adapt slowly or do not adapt to sustained stimulation.

Phasic Receptors

Receptors that adapt rapidly to stimuli.

Afferent Pathways

Pathways that carry sensory information from receptors to the CNS.

First-order Sensory Neuron

The neuron that sends a signal from the receptor to the spinal cord.

Second-order Neuron

The neuron that receives input from the first-order neuron and sends it to the brain.

Third-order Neuron

The neuron that relays signals from the thalamus to the cerebral cortex.

Acuity

The discriminative ability to perceive a sensory stimulus clearly.

Lateral Inhibition

A mechanism by which the center of a stimulus inhibits less excited areas around the point of stimulation.

Nociceptors and Pain Perception

Pain receptors that produce the sensation of pain in response to damaging stimuli.

A-delta Fibers

Fast-afferent pain fibers that transmit pain signals quickly at rates of 30 meters per second.

C Fibers

Slow-afferent pain fibers that transmit pain signals at 12 meters per second.

Analgesic System

The brain’s built-in system that can reduce the perception of pain.