Download Ch 16- Autonomic NS

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