1. Section 5
Regulation of the Visceral Function by the Nervous System

2. I Autonomic Nervous System 1. Basic of the Anatomy

3. ANS
We subdivide the ANS into the parasympathetic, sympathetic, and enteric divisions.
The enteric system is essentially an independent nervous system responsible for regulation of digestive functions.
The ANS coordinates cardiovascular, respiratory, digestive, excretory and reproductive systems.

4. Somatic and Autonomic Nervous System

5. Somatic and Autonomic Nervous System
Smooth and cardiac muscle and glands
Unconscious regulation
Target tissues stimulated or inhibited
Two synapses
Acetycholine by preganglionic neurons and ACh or norepinephrine by postganglionic neurons
Somatic
Skeletal muscle
Conscious and unconscious movement
Skeletal muscle contracts
One synapse
Acetylcholine

6. Sympathetic Division
Preganglionic cell bodies in lateral horns of spinal cord T1-L2

7. Parasympathetic Division
Preganglionic cell bodies in nuclei of brainstem or lateral parts of spinal cord gray matter from S2-S4
Preganglionic axons from brain pass to ganglia through cranial nerves
Preganglionic axons from sacral region pass through pelvic nerves to ganglia
Preganglionic axons pass to terminal ganglia within wall of or near organ innervated

8. Parasympathetic and sympathetic nerve distribution

9. 2. Neurotransmitters and Neuroreceptors
Acetylcholine and Norepinephrine
All preganglionic neurons are cholinergic
Parasympathetic post ganglionic neurons are cholinergic
Sympathetic post ganglionic neurons are adrenergic except
Sympathetics innervating sweat glands, blood vessels in skeletal muscle, and piloerection muscles are cholinergic

10. Neurotransmitters SOMATIC NERVOUS SYSTEM Striated ACh muscle
Heart
Sm. mus.
Glands
ACh NE
AUTONOMIC NERVOUS SYSTEM
Sympathetic
ACh
E, NE
Ad. M.
 
ACh
Sweat
glands
Heart
Sm. mus.
Glands
ACh
Parasympathetic

11. Acetylcholine Nicotinic receptors Muscarinic receptors
Nm (muscular-type or N2): skeletal muscle
Nn (neuron-type, or N1): autonomic ganglia, CNS
Muscarinic receptors
Postganglionic parasympathetic and a few sympathetic sites, CNS (also autonomic gang.)
Receptor subtypes: M1-5

12. Catecholamines Norepinephrine Epinephrine Dopamine
Postganglionic sympathetic, CNS, adrenal medulla
Receptors: a1, a2, b1
Epinephrine
Adrenal medulla, CNS
Receptors: a1, a2, b1 , b2
Dopamine
Autonomic ganglia, CNS
Receptors: D(1-5), a1, b1

13. Location of ANS Receptors

14. 3 Function of the Sympathetic and Parasympathetic Nerve

15. SNS Sympathetic nervous system prototypically “fight” or “flight”.
Associated with increased
energy expenditure,
cardiopulmonary adjustments for intense activity,
blood flow adjustments for maximum energy expenditure.

16. SNS - Fight & Flight Reaction
You’re walking alone at night and all the sudden you hear an unfamiliar noise near by… In a matter of seconds,
your heart rate increases dramatically,
blood vessels in your skeletal muscles dilate,
blood vessels in the visceral muscles constrict,
digestion is ceased,
your liver ramps up glucose release,
your pupils dilate,
salivary production decreases,
sweat increases.

17. Parasympathetic Nervous System
If that noise turns out to be the result of wind, then the body is returned to “pre-noise” state.
This is the job of the parasympathetic nervous system.

18. Autonomic Nervous System
Parasympathicus
Wind down, relaxation, digestion
Dominated by Acetylcholine
Sympathicus
Fight & Flight Reaction
Dominated by Noradrenaline (Adrenaline)
Fear, exercise, rage

19. Interactions of the ANS
Most visceral organs are innervated by both types of nerves.
Most blood vessels are innervated only by sympathetic nerves.
PS activity dominates the heart and GI tract.
Activation of the sympathetic division causes wide spread, long-lasting mobilization of the fight-or-flight response.
PS effects are highly localized and short lived.

20.  bladder and rectum reflex (micturition and defecation)
II. Central Regulation of Visceral Function
1. Spinal cord
 bladder and rectum reflex (micturition and defecation)
 the baroreceptor reflex,
 sweating of the skin

21. 2. Medulla oblongata
 Vital (respiratory and cardiovascular) center:
 Other autonomic reflexes: Swallow, cough, sneeze, gag, and vomit.

22.  3. Hypothalamus
Tu :19.17

23. Hypothalamic Functions
1). Body temperature:
heat loss center in anterior HT (preoptic area)
stimulates sweating and peripheral vasodilation,
lesions cause hyperthermia;
heat gain center in posterior HT
stimulates cutaneous vasoconstriction, piloerection, shivering;
lesions cause poikilothermy
(the difference between poikilothermal or cold-blooded animal and homoiothermal or warm-blooded animal)

24. Hypothalamic Functions
2). Food intake:
ventromedial and paraventricular nuclei are satiety centers,
lesion causes obesity;
lateral HT (feeding center) stimulates food and water intake

25. Hypothalamus Functions
3) Water balance
ADH (vasopressin)
Osmotic pressure in hypothalamus – Thirst - Drink

26. 4) Sleep/wake cycle:
suprachiasmatic nuc is biological clock;
preoptic nuc can initiate sleep;
lat HT can change cortical arousal;
post HT lesion can cause coma or impaired arousal

27. Hypothalamus Functions
5). Emotions and behavior:
ventromedial lesions can cause viciousness/rage
Posterior HT stimulates sympathetic functions
Anterior HT stimulates parasympathetic functions
Mamillary nuclei: recent memory

28. 6). Circadian: Hypothalamus Functions
Almost all land animals coordinate their behavior according to circadian rhythms, the daily cycles of lightness and darkness that result from the spin of the earth.
Most if not all living organisms have rhythmic fluctuation in bodily function that are about 24 hs in length. (sleep-wake, and body temperature cycles).
Suprachiasmatic muclei (SCN)

29. Circadian rhythms of physiological functions.

30. Hypothalamus Functions
7) Regulation of the Endocrine Function

31. 4 Influence of Brain on Autonomic Functions

32. III Function of Sympathetic and Parasympathetic nerve on the target organs

33. Physiology (Table 5-1)
Cornea
Iris
Lens
Eye
Ciliary muscle

34. Heart
Atria
SA node
AV node
Ventricles

36. Blood vessels

37. Lungs and salivary glands

38. Gastrointestinal tract and liver