1. Anatomy and Physiology Autonomic Nervous System
Marieb’s Human
Anatomy and Physiology
Marieb w Hoehn
Chapter 14
Autonomic Nervous System
Lecture 21

2. Autonomic (Visceral) Nervous System
CNS
PNS

3. Autonomic Nervous System
functions without conscious effort
controls visceral (squishy!) activities
regulates smooth muscle, cardiac muscle, and glands
Two Main Divisions
sympathetic – prepares body for fight or flight situations
parasympathetic – prepares body for rest and digest activities
Third Division – Enteric Nervous System (ENS)
Enteric – related to the intestines

4. Somatic vs. Autonomic Nervous Systems
Dual
Figure from: Marieb, Human Anatomy & Physiology, Pearson, 2013

5. Autonomic Nerve Fibers
Figure from: Hole’s Human A&P, 12th edition, 2010
*ANS = a motor division of the PNS

6. Overview of Sympathetic NS
From:
From:

7. Sympathetic Division of ANS*
Paravertebral ganglion
Effectors in head and thoracic cavity
Effectors in muscles and body wall * *
(T5 – T12)
1- Preganglionic fibers that synapse within the ganglion
2 – Preganglionic fibers that extend up or down within the sympathetic trunk
3 – Preganglionic fibers that synapse in collateral ganglia
NOTE: Arrangement of nerves creates DIVERGENCE
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

8. Sympathetic Division of the ANS
SYMPATHETIC (Thoracolumbar outflow)
Fight or Flight
“E” situations Emergency Embarrassment Excitement Exercise
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

9. Sympathetic Division - Divergence
NOTE: Arrangement of nerves creates DIVERGENCE
There are between 15 and 20 postganglionic fibers for every preganglionic neuron in the sympathetic nervous system.
Sympathy spreads…

10. Parasympathetic (Craniosacral outflow) “REST AND DIGEST”
Salivation Lacrimation Urination Digestion Defecation
3 decreases - Heart rate - Airway diameter - Pupil size (constrict)
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

11. Autonomic Plexuses Sympathetic collateral (prevertebral) ganglia
(Solar plexus)
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004
Autonomic plexuses contain sympathetic and parasympathetic postganglionic fibers

12. Autonomic Neurotransmitters
= always excitatory in ganglia
You should know which neurotransmitters are released, and the locations where they are released

13. Sympathetic Myoneural Junctions
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004
NE is either:
reabsorbed and reused or broken down by monoamine oxidase (MAO) in varicosities
or broken down by catechol-O-methyltransferase (COMT) in surrounding tissues

14. Actions of Autonomic Neurotransmitters
depend on receptor
Cholinergic receptors
bind acetylcholine
nicotinic
excitatory
muscarinic
excitatory or inhibitory
Adrenergic receptors
bind norepinephrine
alpha (Types 1 and 2)
different responses on various effectors
beta (Types 1 and 2)

15. Actions of Cholinergic Receptors
Nicotinic receptors  always excitatory
Muscarinic  Excitatory or inhibitory
Remember: the RECEPTOR determines the effect of a neurotransmitter
Always excitatory
(Sweat glands, blood vessels to skeletal muscles, brain)

16. Control of Autonomic Activity
Sympathetic and Parasympathetic
Sympathetic
Parasympathetic
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

17. Review of Autonomic Nervous System
Branch of ANS
PARASYMPATHETIC
SYMPATHETIC
General
Function
* “rest and digest”
* (SLUDD); Salivation, lacrimation, urination, digestion, defecation * 3 decreses; ↓ heart rate, ↓ pupil size, ↓ airway diameter
* “fight or flight” * E situations: Emergency, exercise, embarassment, excitement
Origin of Preganglionic fiber
cranial region of brain or sacral region of spinal cord
(craniosacral outflow)
thoracic or lumbar region of spinal cord (thoracolumbar outflow)
Divergence for widespread activation of body
Location of Ganglia
within or near effector organ
alongside or in front of spinal cord (paravertebral ganglia; collateral ganglia)
NTx secreted by postganglionic
fiber
acetylcholine
Norepinephrine (some acetylcholine; sweat glands, smooth muscle on blood vessels, brain)
Good summary chart to know

18. Review The autonomic nervous system (ANS)
Controls visceral activities involuntarily
Sympathetic (thoracolumbar) = fight or flight
Parasympathetic (craniosacral) = rest and digest
Efferent fibers synapse in ganglia outside CNS
NTx of the ANS
Acetylcholine (cholinergic) – pre- and postganglionic parasympathetic and preganglionic sympathetic
Adrenergic (norepinephrine) – postganglionic sympathetic ONLY