The Peripheral Nervous System (PNS)

Flashcards covering key concepts from the 'Peripheral Nervous System' lecture, including sensory receptor types, nervous system divisions, and nerve structure.

The Peripheral Nervous System (PNS) consists of all neural structures outside the __ and spinal cord.

brain

When a stimulus is detected by a sensory receptor, it creates a __, also known as a graded potential.

receptor potential

The awareness of a stimulus is called __.

sensation

__ are sensory receptors that respond to touch, pressure, vibration, stretch, and itch.

Mechanoreceptors

Sensory receptors that respond to light energy are called __.

photoreceptors

__ are sensory receptors that respond to pain-causing stimuli.

Nociceptors

__ are receptors that respond to stimuli arising outside the body, such as touch and temperature in the skin.

Exteroceptors

__ are receptors located in internal viscera and blood vessels, sensitive to chemical changes, tissue stretch, and temperature.

Interoceptors

__ are receptors that respond to stretch in skeletal muscles, tendons, joints, ligaments, informing the brain of one's movements and position in space.

Proprioceptors

Modified dendritic endings of sensory neurons for general senses can be either nonencapsulated (free) or __.

encapsulated

__ (Meissner's corpuscles) are encapsulated receptors in hairless skin responsible for light pressure and discriminative touch.

Tactile corpuscles

Deep pressure and high-frequency vibration are detected by __ (Pacinian corpuscles).

Lamellar corpuscles

Muscle spindles detect __.

muscle stretch and length

Sensory impulses are relayed toward the central nervous system via __ neurons.

afferent

At the receptor level, __ occurs when a stimulus is changed to a graded potential.

transduction

__ sensory neurons conduct impulses from the receptor level to spinal reflexes or second-order neurons in the CNS.

First-order

Third-order sensory neurons conduct impulses from the thalamus to the __.

somatosensory cortex

The ability to detect a stimulus, which requires summation of impulses, is known as __.

perceptual detection

Identifying the site or pattern of a stimulus is called __ and is studied by the two-point discrimination test.

spatial discrimination

Visceral pain is often felt as vague aching, gnawing, or burning, and can be activated by tissue stretching, ischemia, chemicals, and __.

muscle spasms

In the PNS, a nerve is a bundle of myelinated and unmyelinated peripheral axons enclosed by __ tissue.

connective

The loose connective tissue that encloses axons and their myelin sheaths within a nerve is called the __.

endoneurium

The fibrous sheath around an entire nerve is the __.

epineurium

Mixed nerves contain both sensory and __ fibers.

motor

__ nerves transmit impulses only away from the CNS.

Motor (efferent)

Mature neurons are amitotic, but if the cell body of a damaged nerve is intact, a peripheral axon may __.

regenerate