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Regulation of the Visceral Function by the Nervous System

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Section 5 Regulation of the Visceral Function by the Nervous System I Autonomic Nervous System 1. Basic of the Anatomy ANS We subdivide the ANS into the ... – PowerPoint PPT presentation

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Title: Regulation of the Visceral Function by the Nervous System


1
Section 5 Regulation of the Visceral Function by
the Nervous System
2
I Autonomic Nervous System1. 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
  • Autonomic
  • 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
11
Acetylcholine
  • Nicotinic 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
  • 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
  • Youre 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
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
Hypothalamus Functions
  • 6). Circadian
  • 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
Atria
Heart
SA node
AV node
Ventricles
35

36

Blood vessels
37
Lungs and salivary glands
38
Gastrointestinal tract and liver
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