1. Lecture 12: Chapter 16 Neural Integration II: The Autonomic Nervous System and Higher Order Functions. Pages:
Lecturer: Dr. Barjis
Room P313 /P307
Phone: (718)

2. Learning Objectives
Compare the organization of the autonomic nervous system with the somatic nervous system.
Describe the structures and functions of the sympathetic and parasympathetic divisions of the ANS.
Describe the mechanisms of neurotransmitter release in the sympathetic and parasympathetic divisions.
Describe the effects of sympathetic and parasympathetic neurotransmitters on target organs and tissues.

3. Learning Objectives
Describe the hierarchy of interacting levels of control in the ANS
Explain how memories are created, stored and recalled.
Summarize the effects of aging on the nervous system.

4. Autonomic Nervous System (ANS)
An Overview of the ANS
Autonomic Nervous System (ANS)
Routin homeostatic adjustments in physiological systems are made by ANS
Coordinates cardiovascular, respiratory, digestive, urinary and reproductive functions
In ANS there is always a synapse between CNS and the effector organs
2nd order neurons of the autonomic nervous system are located in autonomic ganglia

5. An Overview of the ANS
Preganglionic neurons in the CNS send axons to synapse on ganglionic neurons in autonomic ganglia outside the CNS
Preganglionic neuron’s body lies in the CNS
Postganglionic axons of ANS are usually unmyelinated
CNS (brain and Spinal Cord)
Preganglionic
Ganglion
Postganglionic

6. Divisions of the ANS ANS contain two primary subdivisions:
Sympathetic division (thoracolumbar, “fight or flight”) – prepare body for stress and activity
Thoracic and lumbar segments
Parasympathetic division (craniosacral, “rest and repose”) – Maintains homeostasis at rest
Preganglionic fibers leaving the brain and sacral segments
Often the two divisions have opposing effects e.g. one would excite and the other will inhibit.
Sometime they may also work together or independently.

7. Sympathetic division anatomy
Preganglionic neurons are located in the latheral gray horns between segments T1 and L2 of spinal cord
Ganglionic neurons in ganglia near vertebral column
Specialized second order neurons of the sympathetic NS that release neurotransmitter into blood are located in adrenal glands

8. The Organization of the Sympathetic Division of the ANS

9. Sympathetic ganglia
Sympathetic chain ganglia (paravertebral ganglia) – preganglionic fibers of the sympathetic NS that carry motor impulses to the body wall or thoracic cavity synapses in chain ganglia
Collateral ganglia (prevertebral ganglia) – group of second order neurons that innervate organs in the abdominopelvic region

10. Sympathetic Pathways

11. Sympathetic Pathways

12. Sympathetic Pathways

13. The Distribution of Sympathetic Innervation
Animation: The sympathetic division (see tutorial)

14. Postganglionic fibers
Rejoin spinal nerves and reach their destination by way of the dorsal and ventral rami
Those targeting structures in the thoracic cavity form sympathetic nerves
Go directly to their destination

15. Abdominopelvic viscera
Sympathetic innervation via preganglionic fibers that synapse within collateral ganglia
Splanchic nerves – carry fibers that synapse in collatheral ganglia

16. Abdominopelvic viscera
Celiac ganglion
Innervates stomach, liver, gall bladder, pancreas, spleen
Superior mesenteric ganglion
Innervates small intestine and initial portion of large intestine
Inferior mesenteric ganglion
Innervates kidney, urinary bladder, sex organs, and final portion of large intestine

17. Sympathetic activation
Sympathetic activation is controlled by sypathetic centers in the hypothalamus.
In crises, the entire sympathetic division responds
Sympathetic activation
Affects include increased alertness, energy and euphoria, increased cardiovascular and respiratory activities, elevation in muscle tone, mobilization of energy resources

18. Neurotransmitters and sympathetic function
Stimulation of sympathetic division has two distinct results
Release of ACh or NE at specific locations
Secretion of E and NE into general circulation
Most postganglionic fibers are adrenergic, a few are cholinergic or nitroxidergic

19. Sympathetic Variosities

20. Parasympathetic division
Preganglionic neurons in the brainstem and sacral segments of spinal cord
Ganglionic neurons in peripheral ganglia located within or near target organs

21. The Organization of the Parasympathetic Division of the ANS

22. Organization and anatomy of the parasympathetic division
Preganglionic fibers of parasympathetic neurons can be found in cranial nerves III, VI, IX, X
Sacral neurons form the pelvic nerves
Almost 75% of all parasympathetic outflow travels along the vagus nerve (cranial nerve X)

23. The Distribution of Parasympathetic Innervation

24. Parasympathetic activation
Effects produced by the parasympathetic division
relaxation
food processing
energy absorption

25. Neurotransmitters and parasympathetic functions
All parasympathetic fibers release ACh
Short-lived response as ACH is broken down by AChE and tissue cholinesterase

26. Sympathetic and parasympathetic divisions
Widespread influence on visceral and somatic structures
Parasympathetic
Innervates only visceral structures serviced by cranial nerves or lying within the abdominopelvic cavity
Effects produced by the parasympathetic branch include increased secretion by digestive glands
Dual innervation = organs that receive input from both systems

27. Anatomy of dual innervation
Sympathetic and parasympathetic systems intermingle to form autonomic plexuses
Cardiac plexus – sympathetic and parasympathetic fibers bound for the heart and kungs pass through the cardiac plexus
Pulmonary plexus
Esophageal plexus
Celiac plexus
Inferior mesenteric plexus
Hypogastric plexus

28. The Autonomic Plexuses

29. Comparison of the two divisions
Important physiological and functional differences exist

30. Summary: The Anatomical Differences between the Sympathetic and Parasympathetic Divisions

31. A Comparison of Somatic and Autonomic Function

32. Higher levels of autonomic control
Activity in the ANS is controlled by centers in the brainstem that deal with visceral functioning

33. Levels of Autonomic Control
Example of higher-level of autonomic function would be increased heart rate when you see a person that you dislike.

34. Higher order functions
Are performed by the cerebral cortex and involve complex interactions
Involve conscious and unconscious information processing
Are subject to modification and adjustment over time

35. Memory Short term or long term
Memory consolidation is moving from short term to long term
Hippocampus is essential for memory consolidation
Mechanisms involved in memory formation and storage are:
Increased release of neurotransmitter
Formation of additional synaptic connection
Formation of memory engrams (single circuit that correspond to single memory)
Amnesia is the loss of memory due to disease or trauma

36. Memory
Memory that can be voluntarily retrieved and verbally expressed are called declarative memories
Conversion of a short term memory to a long term memory is called memory consolidation

37. Memory Storage

38. Consciousness
Deep sleep, the body relaxes and cerebral cortex activity is low
The reticular activating system (RAS) is important to arousal and maintenance of consciousness
RAS is located in the mesencephalon

39. The Reticular Activating System

40. Age-related changes Reduction in brain size and weight
Reduction in the number of neurons
Decrease in blood flow to the brain
Changes in synaptic organization of the brain
Intracellular and extracellular changes in CNS neurons

41. You should now be familiar with:
The organization of the autonomic nervous system.
The structures and functions of the sympathetic and parasympathetic divisions of the ANS.
The mechanisms of neurotransmitter release in the sympathetic and parasympathetic divisions.
The effects of sympathetic and parasympathetic neurotransmitters on target organs and tissues.
The hierarchy of interacting levels of control in the ANS.
How memories are created, stored and recalled.
The effects of aging on the nervous system.