The document discusses the enteric nervous system (ENS), describing its intrinsic and extrinsic nerve supplies that regulate gastrointestinal (GI) functions, including movements and secretions. It details the roles of the myenteric (Auerbach's) and submucosal (Meissner's) plexuses, as well as the influence of the parasympathetic and sympathetic nervous systems on gut motility and blood flow. Overall, the ENS is depicted as a complex network referred to as the 'second brain' due to its extensive neural connections and regulatory control over digestive processes.

1. ENTERIC NERVOUS
SYSTEM
GIT PHYSIOLOGY

2. GIT NERVE SUPPLY
•GIT has 2 types of nerve supply-
• Intrinsic nerve supply (ENTERIC NERVOUS
SYSTEM)
• Extrinsic nerve supply

3. EXTRINSIC
•PARASYMPATHETIC NERVOUS
SYSTEM
•SYMPATHETIC NERVOUS SYSTEM

4. INTRINSIC
•MYENTERIC/AUERBACH’S PLEXUS
•SUBMUCOSAL/MESISSNER’S
PLEXUS

7. ABOUT INTRINSIC NERVOUS SYSTEM• GIT has a nervous system called enteric nervous system.
• Number of neurons = 100 million
• ENS controls= GIT movements , Secretions
• Second brain which is influenced by CNS
• The receptors in the GIT are stretch and chemoreceptors.
• ENS is controlled by extrinsic nerves.

8. MYENTERIC
NERVOUS
SYSTEM
Also called Auerbach’s
plexus.
Present between longitudinal
and circular muscles.
Ascending and descending
neurons
Mainly motor

9. •Increases tone of gut wall
•Rhythmic contraction
•Increases velocity of conduction of excitatory
waves
1)Intensity
2)Rate

11. LOCAL REFLEX
(BEHIND BOLUS AND IN FRONT OF BOLUS)
•Ascending neurons Ach, SP
(CONTRACTION)
•Descending NO, VIP (RELAXATION)

12. MEISSNER’S
PLEXUS
Lies. between submucosa and inner
circular muscle layer.
Sensory
Exocrine and endocrine secretions
Blood flow regulation

13. •Regulation of secretory functions of GIT.
•Cause constriction of blood vessels of GIT
•Help in local absorption
•Local contraction of submucosal layer

15. EXTRINSIC
• Both plexuses are connected by extrinsic nervous system.
PARASYMPATHETIC
SYMPATHETIC

16. PARASYMPATHETIC
•Releases Ach
•Increases motility and tone
•Relaxes the sphincters
•Increases the secretions from stomach

17. Anatomical
features
VAGUS- Dorsal nucleus
of 10th nerve
myenteric and
Meissner’s plexus
SACRAL- hypogastric
segments 2,3,4.
Nerve erigentes

18. SYMPATHETIC
•Brakes of GIT
•Releases epinephrine
•Fight or flight
•Decrease motility and tone

19. • Inhibits secretions from stomach
• Decreases blood flow
• Decreases peristalsis
• Decreases absorption

20. Viscera of abdomen proper
T6-T12
Superior + coeliac mesenteryAnatomical
features
Pelvic viscera
L1-L2
Hypogastric ganglion

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