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 short- term into long-term Damage to Hippocampus = no consolidation Can be linked to amygdala (emotions)

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 Sleep

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