Peripheral Nervous System - Chapter 13 Lecture Notes

These flashcards cover key concepts of the peripheral nervous system, including motor endings, reflex arcs, and neuromuscular junctions.

Motor Endings

PNS elements that activate effectors by releasing neurotransmitters.

Neuromuscular Junction

The site where innervation of skeletal muscle occurs.

Acetylcholine (ACh)

A neurotransmitter released when a nerve impulse reaches the axon terminal.

End Plate Potential

A local change in membrane potential triggered by the movement of Na+ and K+ across the muscle cell membrane.

Autonomic Motor Endings

Simpler elements that form synapses en passant with visceral effectors.

Precommand Level

The highest level of motor control, which includes the cerebellum and basal nuclei.

Reflex Arc

The neural path involved in reflex actions, consisting of receptors, sensory neurons, an integration center, motor neurons, and effectors.

Somatic Reflexes

Reflexes that activate skeletal muscles.

Tendon Reflex

A polysynaptic reflex that helps prevent damage due to excessive tension.

Stretch Reflex

A monosynaptic reflex that helps maintain muscle tone and posture.

Reciprocal inhibition

A mechanism where afferent fibers synapse with interneurons that inhibit motor neurons of antagonistic muscles.

Plantar Reflex

A superficial reflex that tests the integrity of the spinal cord from L4 to S2.

Babinski's Sign

An abnormal response in the plantar reflex where the hallux dorsiflexes and smaller toes fan laterally.

Developmental Aspects of PNS

The process through which spinal and cranial nerves grow and innervate developing muscles.

Extrafusal Muscle Fibers

Contractile muscle fibers that are innervated by alpha efferent fibers.

Intrafusal Muscle Fibers

Modified muscle fibers found in muscle spindles that are involved in proprioception.

Gamma Efferent Fibers

Fibers that innervate the contractile ends of intrafusal muscle fibers.

Muscle Tone

The continuous and passive partial contraction of the muscles.