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Glycineand GABA(gamma aminobutyric acid) are the major inhibitory neuropeptides in the CNS. II. Vertebrate nervous system (we may not have time to cover all of this in lecture) Definitions: CNS = brain and spinal cord nerve = group of neuronal processes (axons and/or dendrites) nucleus = cluster of neuron cell bodies within the CNS ganglion = cluster of neuron cell bodies outside the brain and spinal cord cholinergic = release acetylcholine adrenergic = release norepinephrine A. Peripheral nervous system (PNS)48.15 The basic role of the PNS is to collect sensory information from the periphery and dispense motor info to it. The PNS consists of 2 functional systems; the sensorysystem that brings info to CNS (afferent), and the motorsystem that conveys signals out (efferent).

Sensory

Sympathetic Parasympathetic

PNS

Autonomic Somatic

Motor

The PNS consists of a set of nerves that originatein specific regions of the brain (cranial) or spinal cord (spinal and innervate specific regions. Most of these nerves contain both sensory and motor neurons. (Certain cranial nerves are only sensory, e.g. the optic nerve). 1. Sensory The sensory component of the PNS conveys information from sensors that detect stimuli from the external environment or changes in internal organs. The cell bodies of the sensory neurons are outside the spinal cord. 2. Motor a. Somatic The somaticcomponent of motor neurons carry signals to skeletal muscles in response to external stimuli. In general, these are subject to conscious control, but many signals result from reflexes. The cell bodies are