1. Autonomic Nervous System
Ch 9
The
Autonomic Nervous System

2. SLOs Review the organization of the ANS
Describe how neural regulation of smooth and cardiac muscles differs from that of skeletal muscles
Describe the structure and innervation pathways of the two branches of the ANS
Explain the relationship between the sympathetic NS and the adrenal medulla.
Identify the NTs of the sympathetic and parasympathetic divisions, and the hormones released by the adrenal medulla
Describe the effects of adrenergic stimulation on different organs, and identify the types of adrenergic receptors involved
Describe the effects of cholinergic stimulation on different organs, and identify the types of cholinergic receptors involved
Give examples and explain the prinicple of agonists and antagonists of the ANS
Explain how  blockers and atropine affect the ANS
Explain and give examples for dual innervation

4. 9.1 Neural Control of Involuntary Effectors Visceral Effector Organs
ANS regulates organs not under voluntary control
ES (Ch 11)
Smooth muscles (Ch 12)
Heart and circulatory system (Chs 13 & 14)
Target organs not completely dependent on ANS innervation. Will not atrophy if nerve cut (unlike skeletal muscle)
Cardiac muscle contracts independent of nerve stimulation. ANS speeds up or slows down intrinsic contractions.
ANS stimulates or inhibits depending on ___________ present in organ
receptors

5. Somatic vs. Autonomic System

6. Neurotransmitters
Somatic motor neurons release only _____________which is always excitatory.
Autonomic neurons release _____________ and _____________. Response may be excitatory or inhibitory depending on __________

7. Anatomical Differences between somatic NS and ANS
Somatic motor neurons have cell bodies in _____________ of the spinal cord. One neuron travels from spinal cord to effector.
ANS has two sets of neurons in the PNS.

8. Autonomic pathway: 2 Efferent Neurons in Series
Preganglionic neuron cell body in CNS Synapsis in autonomic ganglion outside CNS  divergence Postganglionic neurons target cells?
Compare to Fig 9-1

9. _______________ Division of the ANS
9.2
_______________ Division of the ANS
= Thoracolumbar
division (T1 to L2)
Preganglionic neurons from thoracolumbar region of spinal cord
Paravertebral ganglia (Sympathetic chain of ganglia)
Prevertebral (or collateral) ganglia
Long postganglionic axons secrete NE onto adrenergic receptors
Compare to Fig 9-5

10. _______________ Division of the ANS
= Craniosacral Division
Long preganglionic axons from brain & S2- S4
Terminal or intramural ganglia
Postganglio nic neurons secrete Ach onto cholinergic muscarinic receptors
Compare to Fig 9-5

11. 9.3 Functions of the ANS
Responsible for homeostasis of BP, HR, Resp., H2O balance, Temp. . .
Mostly dual innervation; antagonistic
Tonic activity (unlike somatic NS)
Sympathetic: fight-or-flight through release of _______
Parasympathetic: rest and digest
Sympathetic Functions
The sympathetic division activates the body for “fight or flight” through the release of norepinephrine from postganglionic neurons and the secretion of epinephrine from the adrenal medulla.
Prepares the body for intense physical activity in emergencies by increasing heart rate and blood glucose levels and by diverting blood to skeletal muscles
Tonically regulates heart, blood vessels, and other organs

12. Adernergic and Cholinergic Synaptic Transmission
Acetylcholine (ACh) → cholinergic (nicotinic or muscarinic) neurons and receptors
Secreted from
preganglionic neurons of both divisions
Postganglionic neurons of para-symp. division
Norepinephrine (NE) → adrenergic ( and ) neurons and receptors
Postganglionic neurons of sympathetic division

13. NTs of Autonomic NS
Fig 9-7

14. Catecholamine Family of Molecules
Tyrosin derivatives
Adrenergic
synapses
Fig 9-8

15. Adrenal Medulla
More similar to a) anterior b) posterior pituitary ??? Modified ___________ Adrenal gland subdivided into medulla and __________

16. Neuroeffector Junction of ANS
= Synapse between postganglionic cell and target organ
Most are different from model synapse  Axon has varicosities containing NT
NT synthesized in axon
Compare to Fig 9.9

17. Varicosities of Sympathetic and Parasympathetic Division Release different NTs
Fig 9.9
Form “synapses en passant” - in passing.
Dual Innervation: Sympathetic and parasympathetic neurons innervate same tissue, releasng different NTs
Dual innervation

18. Responses to Adrenergic Stimulation
E in the blood or NE from sympathetic nerves
Response depends on receptors
α1 and α2
β1 and β2
All use G-proteins & 2nd messenger systems
Stimulation:
heart,
dilatory muscles of iris,
vasoconstriction of many blood vessels
Inhibition:
bronchodilation

19. Clinical Application:  Blockers
 - Receptors
Clinically more important even though not as abundant as  receptors
1 E = NE  Excitation heart
2 not innervated! E > NE!  usually inhibitory: smooth muscle relaxation of some blood vessels and bronchioles
Antagonist
“ -blockers” = ______________(e.g.: Propranolol and atenolol)
Atenolol used for high BP medicine
Toprol-XL, metoprolol succinate, is a beta1-selective (cardioselective) adrenoceptor blocking agent, for oral administration, available as extended release tablets.
Clinical Application:  Blockers

20. Drugs that mimic adrenergic responses
Agonists: Promote the process stimulated by the NT
Antagonists: Block the NT action
Agonists and antagonists are used for many medical applications
Sympathomimetic drugs (also known as adrenergic drugs and adrenergic amines) are stimulant compounds which mimic the effects of agonists of the sympathetic nervous system such as the catecholamines (epinephrine (adrenaline), norepinephrine (noradrenaline), dopamine, etc.) These drugs can act through several mechanisms, such as directly activating postsynaptic receptors, blocking breakdown and reuptake of certain neurotransmitters, or stimulating production and release of catecholamines.
A parasympathomimetic drug, sometimes called a cholinomimetic drug, is a substance that stimulates the parasympathetic nervous system (PSNS).[1] These chemicals are also called cholinergic drugs because acetylcholine (ACh) is the neurotransmitter used by the PSNS. Chemicals in this family can act either directly by stimulating the nicotinic or muscarinic receptors (thus mimicking acetylcholine), or indirectly by inhibiting cholinesterase, promoting acetylcholine release, or other mechanisms.[2]
Some chemical weapons such as sarin or VX, non-lethal riot control agents such as tear gas, and insecticides such as diazinon fall into this category.
A parasympatholytic agent is a substance or activity that reduces the activity of the parasympathetic nervous system.[1] (The parasympathetic nervous system is often colloquially described as the "Feed and Breed" or "Rest and Digest" portion of the autonomic nervous system. The parasympathetic nervous system becomes strongly engaged during or after a meal and during times when the body is at rest.)
The term parasympatholytic typically refers to the effect of a drug, although some poisons act to block the parasympathetic nervous system as well. Most drugs with parasympatholytic properties are anticholinergics.
"Parasympatholytic" and sympathomimetic agents have similar but not identical effects. For example, both cause mydriasis, but parasympatholytics reduce accommodation (cycloplegia), whereas sympathomimetics do not.
A sympatholytic (or sympathoplegic) drug is a medication which inhibits the postganglionic functioning of the sympathetic nervous system (SNS).[1] They are indicated for various functions, for example they may be used as antihypertensives. They are also used to treat anxiety, such as Generalized Anxiety Disorder, Panic Disorder and PTSD.

21. One more time: Review of Location of NTs of ANS
Compare to Fig 9-7

22. Responses to Cholinergic Stimulation
ACh released from preganglionic neurons of the sympathetic and parasympathetic division is stimulatory.
ACh from postganglionic neurons of the parasympathetic division can be stimulatory or inhibitory, depending on _________.
2 major subtypes of receptors:
In general, sympathetic and parasympathetic effects are opposite  hence: Dual innerervation

23. Nicotinic cholinergic receptors
Review from Ch 7
Outcome of opening monovalent Na+ / K+ channels?
Curare inactivates this receptor  = ____________ (see Table 11-3)
Nicotine = agonist
When acetylcholine opens nonspecific cation channels on the neuromusclar junction, more Na+ enters the cell than K+ leaves. The ECF and ICF concentrations of Na+ and K+ are shown in the table below. Explain what causes net entry of Na+.
ECF
ICF
Na+
150 mM
50 mM K+
The concentration gradients of the two ions are equal and opposite. However, the interior of the cell is negative relative to the outside, therefore favoring Na+ entry over K+ efflux.

24. Muscarinic cholinergic receptors
Review Ch 7
Muscarine = _________
G-protein coupled mechanisms
Amanita muscaria
Clinical Aplication: Atropine
Muscarin is agonist
Atropin is antagoist
Atropin is __________ for these receptors

25. Comparison of Nicotinic & Muscarinic ACh Receptors
Fig 9.11
Be able to explain what happens in each of the above situations

26. Cholinergic Receptors & Responses to ACh

27. Summary of Autonomic Functions

28. Organs with Dual Innervation
Most visceral organs
Mostly dual innervation is antagonistic. E.g.:
Heart rate – sym increases, para decreases
Digestive functions – sym decreases, para increases
Pupil diameter – sym dilates, para constricts

29. Clinical Investigation: Sophia was nervous about her upcoming exam....
The End
Clinical Investigation: Sophia was nervous about her upcoming exam....