Chapter 33 Regulation of the Visceral Function by the Nervous System

I Autonomic Nervous System 1. Basic of the Anatomy

Autonomic Nervous System Including parasympathetic, sympathetic, and enteric divisions. Coordinates cardiovascular, respiratory, digestive, excretory and reproductive systems. The enteric system is essentially an independent nervous system responsible for regulation of digestive functions.

Somatic and Autonomic Nervous System

Somatic Skeletal muscle Conscious and unconscious movement Skeletal muscle contracts One synapse Acetylcholine 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

Preganglionic cell bodies in lateral horns of spinal cord T1-L2 Sympathetic Division 侧副神经节

Parasympathetic Division Preganglionic cell bodies in nuclei of brainstem or lateral parts of spinal cord （ 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 ganglia within wall of or near organ innervated

Parasympathetic and sympathetic nerve distribution

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

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

Acetylcholine Nicotinic receptors – Nm (muscular-type or N 2 ): skeletal muscle – Nn (neuron-type, or N 1 ): autonomic ganglia, CNS Muscarinic receptors – Postganglionic parasympathetic and a few sympathetic sites, CNS – Receptor subtypes: M 1-5

Catecholamines Norepinephrine – Postganglionic sympathetic, CNS, adrenal medulla – Receptors:  1,  2,  1 Epinephrine – Adrenal medulla, CNS – Receptors:  1,  2,  1,  2 Dopamine – Autonomic ganglia, CNS – Receptors: D (1-5),  1,  1

Location of ANS Receptors

3 Function of the Sympathetic and Parasympathetic Nerve

Properties of the ANS Tonic discharge Double innervation – Most blood vessels are innervated only by sympathetic nerves. – Parasympathetic activity dominates the heart and GI tract. Dependent on the states of the target organ Different physiological significance – Sympathetic nerve: fight and flight reaction – Parasympathetic nerve: Wind down, relaxation, digestion

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.

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.

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

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

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

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

Tu : Hypothalamus

Hypothalamic Functions Food Intake Water Balance Sleep/wake cycle Emotions and behavior Circadian Endocrine Functions Body Temperature Autonomic Nervous System

Food Intake Ventromedial and Paraventricular Nuclei are satiety centers – Lesion causes obesity – Through disrupting satiety input to the periventricular nucleus Lateral HT is feeding center – Stimulation cause food and water intake – Lesion causes starvation behavior – Through damage the medial forebrain bundle, leading to neglect syndrome – no motivation to eat

Water Balance Thirst center in the hypothalamus (supraotic nucleus) is stimulated by: – Cellular dehydration – Decreased salivary production – Increased blood osmotic pressure – Decreased blood volume Thirst center response – Release vasopressin – Cause sensation of thirst

Sleep/Wake Cycle  suprachiasmatic nuc is biological clock  preoptic nuc can initiate sleep  lateral hypothalamus can change cortical arousal  post hypothalamus lesion can cause coma or impaired arousal

Emotions and Behavior  Ventromedial lesions can cause viciousness/rage  Posterior HT stimulates sympathetic functions  Anterior HT stimulates parasympathetic functions  Mamillary nuclei recent memory

 Almost all land animals coordinate their behavior according to circadian rhythms  Suprachiasmatic Nuclei (SCN) Circadian

Circadian Rhythms of Physiological Functions

Endocrine Function Regulation of Adenohypophysis Secretion of Hormones (Vasopressin and Oxytocin)

Functions of the Hypothalamus Food intake Water balance Sleep/wake cycle Emotions and behavior Circadian Endocrine Function Body temperature Autonomic Nervous System

4 Influence of Brain on Autonomic Functions

III Function of Sympathetic and Parasympathetic nerve on the target organs

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

SA node Atria AV node Ventricles Heart

Blood vessels

Lungs and salivary glands

Gastrointestinal tract and liver