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Ch 16- Autonomic NS Autonomic Nervous System • Operates without conscious instruction, controlled by hypothalamus • Controls visceral effectors (smooth muscles, glands, cardiac muscle) • Coordinates system functions • 2 divisions: usually have opposing effects • May work independently or together Organization • CNS > PNS > smooth muscle, glands, heart (effector) • 2 motor neurons • 1. preganglionic axon- in brain or S.C. • 2. postganglionic axon- outside the CNS, extends to the organ itself • Visceral/sensory information triggers visceral reflexes • Ex: Cold weather > ANS causes contraction of arrector pili muscles 1. Sympathetic is the "Fight or Flight" Branch • Physical or emotional stress • Favors storage of energy • E situations (exercise, emergency, excitement, embarrassment) • Increases: cardiac output and pulmonary ventilation, routes blood to the muscles, raises blood glucose, sweat glands, mental alertness • Decreases digestion, kidney filtration and other functions not needed during emergencies 2. Parasympathetic is the "Rest and Digest" Branch • Normal maintenance of the body • Increases: SUDD (salivation, urination, defecation, digestion) • Decreases :heart rate, diameter of airways, & diameter of pupils Effects Dual Innervation • Most organs are innervated by both divisions and have opposing effects • Autonomic tone= balance • Ex: • Heart receives dual innervation • Parasympathetic releases ACh = decrease HR • Sympathetic division release NE = increase HR • Balance between two = autonomic tone No Dual Innervation • Ex: Blood vessels controlled by sympathetic division • Sympathetic division release NE = increase partial contraction of BVs = autonomic tone • Decrease in NE = dilation of BVs Visceral Reflexes • Provide automatic motor responses that can be modified, facilitated or inhibited by higher centers, such as hypothalamus • All are polysynaptic, can be long or short • Long reflexes coordinate activities of entire organs, involves CNS • Short reflexes bypass CNS and control activity in one small part of organ • Examples of Visceral Reflexes Table 16-4 Memory • Fact-specific bits of information (color of a stop sign) • Skill- learned motor behavior (walking) • Short-term- recalled immediately (name, phone number) • Long-term- memory consolidation=turning shortterm into long-term • Damage to Hippocampus = no consolidation • Can be linked to amygdala (emotions) Sleep • Needed for protein synthesis in neurons • Alternation of cycles throughout: • Deep- entire body relaxed, minimum cerebral activity, (HR, BP, & respiration decline) • REM (rapid eye movement)dreaming, BP & respiration change Reticular Activating System • network found within reticular formation in brain stem • Interacts with cerebral cortex via nuclei in thalamus • Stimulus = RAS active = cortex active = arousal from sleep + maintaining consciousness • Neural fatigue/decrease in response to stimuli = RAS inactive = cortex inactive = decrease in alertness + lethargy • Stimulation can end sleep • Needs breaks-can become immune to sensory information