1. The autonomic nervous system

3. Comparison Of Autonomic & Somatic Nervous Systems

4. 2 Neuron Chain

6. Preganglionic Neurons
1st neuron in spinal cord: thoracic and lumbar spinal nerves
1st neuron in 4 cranial nerves in the brain stem (III, VII, IX, X) or in S2 –S4 of spinal cord
Sympathetic
Parasympatheitc

7. Postganglionic Neurons
2nd neuron in sympathetic trunk ganglion, a chain of ganglion that is found on either side lateral to spine
2nd neuron in individual ganglion closer to organ it serves
both sympathetic & parasympathetic neurons lie outside CNS
Sympathetic
Parasympathetic

9. Axons of Autonomic Nerves
Preganglionic:
in cranial or spinal n. (from CNS  ganglion)
myelinated
Postganglionic:
from ganglion  visceral effector
unmyelinated

11. ANS Neurotransmitters
based on the neurotransmitter they produce & release autonomic neurons are classified as either:
Cholinergic
release acetylcholine (ACh)
Adrenergic
release norepinephrine (NE) aka noradrenalin

12. Cholinergic Neurons & Receptors
Cholinergic neurons include:
all Sympathetic & Parasympathetic preganglionic neurons
Sympathetic postganglionic neurons that innervate most sweat glands
all Parasympathetic postganglionic neurons

13. Receptors that bind ACh called cholinergic receptors 2 types:
Nicotinic receptors
in plasma membranes & dendrites of symp. & parasymp postganglionic neurons & in NMJ
Muscarinic receptors
in plasma membrane of all effectors (smooth muscle, cardiac muscle, glands)
Muscarine: mushroom poisonmimics actions of ACh

14. ACh when activates nicotinic receptors  depolarization (excitation)
when activates muscarinic receptors  sometimes depolarization, sometimes hyperpolarization (inhibition) depending on the cell

16. NE most sympathetic postganglionic neurons are adrenergic
Adrenergic receptors bind both NE & Epinephrine (Epi)
2 types receptors:
Alpha receptors (α)
subtypes: α1, α2
Beta receptors (β)
subtypes: β1, β2, β3

17. αlpha & βeta Receptors α1 & β1 produce excitation when activated
α2 & β2 receptors cause inhibition of effector tissues
β3 found only on cells of brown adipose where activation causes thermogenesis (heat production)

18. αlpha & βeta Receptors
cells of most effectors have either α or β receptors
some visceral effectors contain both
NE stimulates α more strongly than β
Epi is potent stimulator of both

19. MAO MonoAmine Oxidase: inactivates NE in synaptic cleft
group of pharmaceuticals that are MAO inhibitors so prolong effect of NE

20. Agonists substance that binds to & activates a receptor
in the process mimicking the effect of a natural neurotransmitter or hormone
example: phenylephrine is an adrenergic α1 receptors; used in cold remedies
constricts blood vessels in nasal mucosa  reduces production of mucus

21. Antagonists
substance that blocks receptors so prevents the natural neurotransmitter or hormone from exerting its effect
example: propanolol a β1 blocker, used to treat HTN  decreases heart rate & force of contraction  lowers BP
side effects: hypoglycemia, mild bronchoconstriction, decreases frequency & severity of migraines

23. Autonomic Tone balance between sympathetic & parasympathetic activity
regulated by hypothalamus
if turns up sympathetic tone, turns down parasympathetic same time

24. Sympathetic Responses
dominate during physical or emotional stress
occur during “E situations”
Exercise
Emotions
Emergency
Excitement

25. Sympathetic Responses
Fight or Flight Response
pupils dilate
HR, force of contraction, & BP increase
airways dilate
vessels to kidneys & GI tract constrict slowing down digestion & urine production
vessels  muscles (skeletal & cardiac), liver, & adipose tissue  dilate
hepatocytes increase glycogenolysis & adipose increase lipolysis  blood glucose increases
anything nonessential slowed down

26. Sympathetic Stimulation
effects longer lasting than parasympathetic responses (NE lasts longer in synaptic cleft than ACh)
effects more widespread (more tissues activated)

28. Parasympathetic Responses
enhance “rest & digest” activities
remeber SLUDD:
Salivation
Lacrimation
Urination
Digestion
Defecation