1. PERIPHERAL NERVOUS SYSTEM ϋ Link between neurons of CNS and rest of body ϋ All sensory information and motor commands ϋ Axons bundled together and wrapped in Connective Tissue= Peripheral Nerves ϋ Contains cell bodies (ganglia) and axons Do you remember the names of the accessory neuroglia cells of the PNS? Hint: See page 99

2. Divisions of PNS “Afferent Division” Sensory Receives info from: 1) Somatic Receptors Monitor environment 2) Visceral Receptors Monitor internal conditions “Efferent Division” Motor Divided into: 1) Somatic NS Sends signals to skeletal muscles 2) Autonomic NS Sends signals to smooth & cardiac muscles, glands, adipose tissue

3. Autonomic NS (“Efferent”) Divided into: 1) Sympathetic NS “Fight or Flight” responses Stimulates metabolism, ↑ alertness, prepares body for emergencies 2) Parasympathetic NS “Rest & Digest”responses Conserves energy & promotes sedentary activities (i.e. digestion)

4. Reflexes A) Simple Reflexes: “monosynaptic” Sensory neuron synapses directly to motor neuron Almost immediate response i.e.: Knee Jerk reflex B) Complex Reflexes: “polysynaptic” Sensory neuron communicates with motor neuron via interneuron Slight delay between stimulus & response i.e.: Withdrawl reflex

5. Cranial Nerves Attach to base of brain & lead to muscles & sense organs in head & neck 12 pairs in 3 categories: A) Sensory: detect stimuli only I, II, VIII B) Motor: stimulate muscle contraction & provide info about body position & orientation III, IV, VI, XI, XII C) Mixed: Sensory & motor functions are unrelated (i.e. sense taste but control facial expression) V, VII, IX, X

6. Aging of the Nervous System As we age (30+), certain anatomical changes occur: 1) ↓ brain size & weight (especially cerebral cortex) 2) ↓ # neurons (do not regenerate) 3) ↓ blood flow to brain as fatty deposits accumulate in blood vessels 4) Changes in synaptic organization (# dendrite branches, synapses lost, neurotransmitter production ↓) 5) Cellular changes (accumulation of deposits with cells) These changes may affect our ability to form new memories and affect our senses and reactions