Divisions of the nervous

system

Peripheral nervous system: somatic (voluntary)Includes skin and musculo-skeletal systemInvolves a sensory neuron and a motor neuron for each reflexOutside of CNSInvolves both conscious control and reflexes

Peripheral nervous system: Autonomic (involuntary)

Portion of the PNS that controls organs unconsciouslyInnervates heart, some glands, smooth muscle walls of digestive tract, resp. system, excretory system, repro. System, blood vessels

Involves only motor neuronsComposed of two parts: sympathetic and parasympathetic nervous systemsMost organs are innervated by both

Brian break!!

SympatheticNerves originate in the thoracic-lumbar portion of the spinal cordConnects spinal cord (CNS) to the organsIt prepares the body to deal with emergency situations (flight or fight response)

Functions of sympatheticIncreased heart rate and breathing rateDecreased digestionDilation of pupilsIncreased blood flow to skeletal musclesIncreased release of glucose

ParasympatheticNerves originate in the lower spinal cord (sacral area) and brain stemVagus is important cranial nerve (regulates heat, lungs, liver, etcConnects spinal cord and organMaintains normal (relaxed) functions or organs (counteracts sympathetic system)

Functions parasympatheticPromotes digestionSlows heart rateSlows breathingStores glucoseConstricts pupils