The document discusses the autonomic nervous system (ANS), which controls involuntary body functions like heart rate and digestion. It describes the ANS as having two divisions - the sympathetic and parasympathetic nervous systems. The sympathetic system activates the body during stress through pathways involving the hypothalamus, amygdala and periaqueductal grey matter. The parasympathetic system calms the body during rest. The enteric nervous system is also described as the "second brain" that helps control gastrointestinal functions.

1. Central Nervous System
The Autonomic Nervous System

2. Nervous System
• coordinates the actions of the body
• transmits signals between different parts of
the body

3. Sensory input – gathering information
monitor changes occurring inside and
outside the body stimuli
Integration – process and interpret
sensory input
+/- action
Motor output
= response to integrated stimuli
activates muscles/ glands

4. Nervous System
Central Nervous System
Periferic Nervous System
SENSORY MOTOR
AUTONOMIC SOMATIC
Sympathetic NERVOUS NERVOUS
SYSTEM SYSTEM
Parasympathetic
Enteric Nervous
System

5. Autonomic Nervous System
involuntary – automatic – visceral/glands motor system
SENSORY MOTOR
AUTONOMIC
Sympathetic NERVOUS
SYSTEM
Parasympathetic
Enteric Nervous
System

6. Somatic vs. Autonomic
Effectors (Targets)
skeletal muscle smooth/cardiac muscle &
glands
Efferent pathways
1 neuron - myelinated axon 2 neuron pathway –
from ventral horn of spinal
1st- preganglionic and body
cord all the way to effector resides in brainstem/S2-S4
cord – myelinated axon;
2nd- postganglionic and body
resides in autonomic ganglion
– unmyelinated axon
SNS = short pre/long post ganglionic axon
PsNS = long pre/short post ganglionic axon

7. Somatic vs. Autonomic

8. Neurotransmitters
somatic vs. autonomic
Allpreganglionic fibers release Ach
All motor neurons release Ach postganglionic PsNS fibers release Ach
- always stimulatory postganglionic SNS fibers release
Norepinephrine
→ stimulatory or inhibitory
(based on receptor types)

9. http://health-7.com/Lippincotts%20Illustrated%20Reviews%20Pharmacology/3.%20The%20Autonomic%20Nervous%20System/8

10. Divisions of the ANS
Sympathetic NS • dual innervation
- usually stimulatory • opposing effects
=>energy consum • may work independently
• may work together - each
Parasymathetic NS one controlling one stage of
- usually inhibitory the process
=>conservation of energy

12. Sympathetic nervous system
The “fight-or-flight” system:
involves activities like: other activities are reduced
exercise, excitement, (GI/urinary)
emergency and embarrassment
↑ flow to muscle =>↓ blood flow to the organs
heart rate ↑ - breathing ↑rapid and deep
bronchioles dilate - ↑ventilation
=> delivering more oxygen to cells
the skin is cold and sweaty
the pupils dilate
liver releases more glucose into circulation
lipolysis to the level of the adipocytes

13. Sympathetic nervous system
• Cervical-thoraco-
lumbar division
• Short preggl/long
postggl

14. Adrenal medulla
• same embryological origin as
the sympathetic ganglia
• fibers from the thoracic
splanchnic nerves
pass thru the Celiac Ganglion
↓
terminate in
the medullary adrenal gland
=> secrete epi- and
norepinephrine into the Barwick et al. - Embryology of the adrenal glands and its relevance to
diagnostic imaging, Clin Rad, 2005, Vol. 60, Issue 9, pag: 953-959
blood

15. Parasympathetic nervous system
• active in non-stressful situations – keep the body energy
=> involves activities like:
salivation, lacrimation, digestion,
defecation,urination
• Activats lens accommodation - close vision
-↑ gastrointestinal tract activity
-↓ heart rate, blood pressure
-↓ respiratory rates
- constricted pupils
- warm skin

16. Parasympathetic nervous system
• Fibers emerge from
CR.NN. - III,VII,IX, X
S2-S4 spinal cord
• Long preganglionic
fibers synapse in
terminal or intramural
ganglia

17. Enteric Nervous
System
•a
complex, independent
nervous system
lines the gastrointestinal tract
“second brain”
“the brain of the gut”
► motility
controls essential functions► secretion
► blood flow

18. ENS
Furness JB (2006) The Enteric Nervous System. Blackwell, Oxford, pp 274

19. Connections CNS - ENS
ANS: Sympathetic & Parasympathetic

20. The neural connections between the
ENS and CNS, and neural
connections between
gastrointestinal organs
The digestive system contains full reflex circuits of the
ENS (motor neurons and interneurons in blue, sensory
neurons in purple). Pathways from the gastrointestinal
tract project outwards, via intestinofugal neurons
(red), to the CNS (neurons in yellow), sympathetic
ganglia, gallbladder and pancreas. Neurons in
sympathetic prevertebral ganglia (green) receive both
CNS and ENS inputs. Sensory information goes both
to the ENS, via intrinsic primary afferent (sensory)
neurons (purple) and to the CNS via extrinsic primary
afferent neurons (also purple) that follow spinal and
vagal afferent routes. Pathways from the CNS reach
the ENS and gastrointestinal effector tissues through
vagal, sympathetic and pelvic pathways.
Abbreviations: CNS, central nervous system;
ENS, enteric nervous system.
Furness, JB – The enteric nervous system and neurogastroenterology, Nat Rev Gastroenterol. Hepatol,
doi: 10.1038/nrgastro. 2012.32

21. Visceral afferents and referred pain
Maps of Referred Pain
Grant’s Atlas 12 2009

22. Referred pain
• visceral pain afferents
travel the same path as
somatic pain afferents
• sometimes - pain stimuli
from viscera is interpreted
as somatic pain origin by
the brain
Eg - heart attack (T1-T5
supply chest & medial
aspect of left arm)

23. CNS processing and modulation
of visceral sensation
Pain sensation →
sensory discriminatory
components
Pain affect →
combination of
emotional and
cognitive appraisals
related to the pain
experience
PAG, periaqueductal gray; PB, parabrachial nucleus of the dorsolateral pons; AMYG,
amygdala; HT, hypothalamus; Vmpo, MDvc & VPL, thalamic nuclei (ventromedial part of
the posterior nuclear complex, ventrocaudal part of the medial dorsal nucleus and
ventroposterior lateral nucleus respectively); ACC, anterior cingulate cortex; PCC, posterior
cingulate cortex; PF, prefrontal cortex; SMA, supplementary motor area; S1 & S2, primary
& secondary somatosensory cortices; M1, primary motor cortex; PPC, posterior parietal
complex.
Van Oudenhove L, Demittenaere K., Tack J, Aziz Q – Central nervous system involvement in functional
gastrointestinal disorders, 2004, Best Pract & Research Cl Gastroentero, Vol 18, pag 663-680

24. Levels of ANS Control
• hypothalamus = the main
integration center of ANS
activity
• subconscious cerebral
input - via limbic system -
influences hypothalamic
function
• other controls come from:
- the cerebral cortex
- the reticular formation
- the spinal cord

25. Hypothalamic
Control
• centers of the hypothalamus control:
– heart activity and blood pressure
– body temperature
– water balance
– endocrine activity http://www.upright-health.com/pituitary-gland.html
– emotional stages (rage, pleasure)
– biological drives (hunger, thirst, sex)
– reactions to fear and the “fight-or-flight” system.

26. Superior nervous structures involve
in control of ANS: PAG

27. Superior nervous structures involve
in control of ANS: Amygdala
Hamann S – Affective neuroscience – Amygadala’s role in Experiencing
Fear, 2011, Current Biol, Vol 21, R75-R77

28. EMS (Emotional Motor System) – amygdala
- hypothalamus
- periaquaductal grey
Integrates: - autonomic
- neuroendocrine
- pain modulatory
responses
EMS = neurobiological
basis of stress sensitivity
http://brainmind.com/BrainLecture5.html