Autonomic Nervous System

Autonomic Nervous System

1. Parasympathic

   • No Mass Activation
     • Effectors Stimulated Separately
   • Rest & Digest
     • Effects On The Body
       • Decrease Heart Rate
       • Increase Digestion
       • Vision
         • Pupil Constriction
         • Lens Thicken, Round-up
   • CNS -> Effectors = 2 Neurons
     • Presynaptic Neuron
       • Always Release: ACh
         • Cholenergic Stimulation
           • Cholenergic Receptors
             • Muscarinic Receptors
               • K+, Ca2+, ACh
               • G-Protein & 2nd Messenger
                 • receptor separate from ion channel = indirect
                 • other ex: dopamine & norepinehrine receptors
                 • alpha or (beta & gamma) subunit dissociates to open or close channel = indirect
               • Stimulated By: ACh From Postganglionic Neuron
               • excitatory (EPSP) - closed
                 • K+ stays in cell increasing membrane potential -> EPSP
               • CNS
               • smooth & cardiac muscle
               • glands innervated by autonomic motor neaurons
               • inhibitory (IPSP) - open
                 • K+ leaves cell lowering membrane potential -> IPSP
           • Inhibitory
             • some autonomic motor neurons
               • decrease HR
           • Stimulatory
             • Nicotinic Receptors
               • Ligand Gated Ion Channels
                 • Na+, K+, ACh
                 • receptor protein = ion channel = direct
               • Cholenergic Receptors (ACh)
               • Stimulated By: ACh From Preganglion Neuron
               • Always Excitatory (EPSP)
                 • some parts of CNS
                 • some autonomic motor neurons/ganglia (cardiac, smooth muscles, glands)
                 • all somatic neurons
                   • skeletal muscles
             • Stimulate Autonomic Ganglia
             • Smooth Muscle Contraction
             • Secretion Release From Glands
           • Release: ACh
     • Postsynaptic Neuron
       • Release NT: ACh
         • Some Neurons
         • Most Neurons

2. Sympathetic

   • Mass activation
     • Due To Divergence & Convergence
       • Divergence
         • 1 Preganglionic Neuron -> Several Postganglionic Neuron
       • Convergence
         • Several Preganglionic Neuron -> 1 Postganglionic Neuron
   • CNS -> Effectors = 2 Neurons
     • Presynaptic Neuron
       • Always Release: ACh
         • Innervates Adrenal Medulla
           • Release: Epinephrine & Norepinephrine
             • Bloodstream
     • Postsynaptic Neuron
       • Some Release: ACh
         • Sweat Glands
         • Skeletal Muscle Blood Vessels
         • Muscarinic receptors
       • Most Release: Norepinephrine
         • Adrenergic Stimulation
           • Stimulatory
             • Increase Heart Rate
             • Pupil Dilation
             • Vasoconstriction
           • Inhibitory
             • Bronchoilation
             • Vasodilation
           • Adrenergic Receptors
             • Alpha
               • Sensitive: Norepinephrine
               • G-Proteins & 2nd Messenger
                 • Ca2+ 2nd messenger
             • Beta
               • Sensitive: blood epinephrine
               • G-Proteins & 2nd Messenger
                 • cAMP 2nd Messenger
       • Some release other NT
         • ATP
           • excitatory co-transmitter
         • Vasoactive intestinal peptide (VIP)
           • vasodilator in smooth muscle blood vessels
         • Nitric oxide (NO)
           • smooth muscle relaxation
   • Fight Or Flight
     • Increase HR & Blood Glucose
     • Diverts Blood To Skeletal Muscles
     • Bronchodilation
     • Vision
       • Pupil Dilation
       • Lens Flattens
     • decrease digestive functions

3. Involuntary

   • Smooth, Cardiac Muscles & Glands
     • Visceral Organs & Blood Vessels