Sistema Nervioso Autónomo

• The autonomic nervous system controls involuntary physiological processes

Introduction

• The autonomic nervous system coordinates the activity of smooth muscle in visceral organs, cardiac muscle, and glands
• This includes arterial pressure, digestive motility, temperature and sweating

Organización

• The sympathetic nervous system's main function is the body's response to stress
• The parasympathetic nervous system's main function is body's vegetative response
• The regulation of bodily functions is produced by the interaction of both systems

Organización: Componentes Centrales

• The hypothalamus is a central component
• The tronco-encefalo is a central component
• The medulla spinal is a central component

Hipotálamo

• Preoptic nuclei function in the secretion of the gonadotropin releasing hormone
• Anterior nuclei functions in thermoregulation
• Posterior nuclei functions in thermoregulation
• Ventromedial nuclei function as a satiety center that inhibits food intake
• Dorsomedial nuclei function in feeding
• Suprachiasmatic nuclei function in circadian rhythm
• Supraoptic nuclei function to release antidiuretic hormone(ADH) and ocytocin
• Paraventricular nuclei function in the secretion of ADH and ocytocin: secretion of hormone that liberate corticotropin and hormone that liberate thyrotropin
• Curved nuclei secretes hormone that liberates growth hormone

Organización: Componentes periféricos

• Preganglionic neurons exit the medulla
• The sympathetic and parasympathetic ganglia function as postganglionic neurons
• Motor axons reach effector organs and tissues
• The neurotransmitter is Acetylcholine (ACh)

Neurotransmisores

• Acetylcholine (ACh) is widely distributed in the nervous system
• Acetylcholine (ACh) is implicated in circuit of memory and the reward system
• Acetylcholine (ACh) is involved in the peripheral nervous system and the autonomic nervous system
• The inhibition of acetylcholinesterase leads to constant activation of muscles, glands, and nervous system
• Agonists for Acetylcholine (ACh) are nicotine and muscarine
• Antagonists for Acetylcholine (ACh) are botulinum and atropine/scopolamine
• Noradrenaline synthesis begins from dopamine
• Noradrenaline can be liberated from the suprarenal gland, SNC, and SNP
• Noradrenaline mediates stress
• Noradrenaline increments cardiac frequency
• Noradrenaline facilitates liberation of glucose
• Noradrenaline increases blood flow to skeletal muscle
• Noradrenaline increases the oxygen supply the brain
• Adrenaline is produced by the suprarenal glands
• Adrenaline increases the cardiac frequency
• Adrenaline increases the arterial pressure via vasoconstriction
• Adrenaline causes bronchodilation

Organización: Sistema Nervioso Simpático

• The Sympathetic Nervous System releases Noradrenaline, excluding suderiparous glads which release Acetylcholine
• The stimulus causes the suprarenal to produce adrenaline which stems from the sympathetic nervous system
• The sympathetic nervous system's postganglionic NTs: neuropéptido Y, ATP, sustancia P
• The parasympathetic nervous system's Acetylcholine acts on the muscarinic receptors

Receptores

• Couple to cellular membrane and transduce signals in effector cells
• ACh receptors can be classified into nicotinic and muscarinic
• Receptors for Noradrenaline and Adrenaline are categorized by response to different drugs
• Alpha-Adrenergic receptors: α1, α2
• Beta-Adrenergic receptors: β1, β2
• The response of a tissue or organ to sympathetic stimulation depends on the type of receptor stimulated

Sist Nervioso Simpático

• Eye: Mydriasis
• Glands: Decrease secretions
• Lungs: Bronchodilation
• Heart: Increase frequency and contractility
• Liver: Increase glucose liberation
• Intestine: Decrease contractility, increase sphincter constriction
• Bladder: Relaxes bladder
• Genitalia: Ejaculation

Sist Nervioso Parasimpático

• Eye: Miosis
• Glandular: Increases secretion
• Lung: Bronchoconstriction
• Heart: Reduce cardiac rhythm
• Intestine: Increased motility
• Rectum: Dilates the rectum
• Contraes: Contracts bladder

Parasimpatico

• Sinoatrial Node: Decrease cardiac frequency
• Myocardium: Decrease atrial contractility, low effect on ventricules
• AV Node: Decrease velocity conduction
• Smooth Muscle (vascular): Vasodilation of genitals and the tractus digestorius
• Gastrointestinal Smooth Muscle: Increased motility, relaxes sphincter
• Gastric Parietal Cells: Acid secretion
• Pancreas: Exocrine secretion
• Pulmonary Smooth Muscle and Bronchial Muscle: Contraction
• Reproductive System (masculine): Erection
• Reproductive System (feminine): Vascular Contestion
• Pupila: Mydriasis

Simpatico

• Sinoatrial Node: Increased cardiac frequency
• Myocardium: Increased contractility
• AV Node: Increased velocity conduction
• Most smooth muscle is subject to constriction
• Vasodilation in Vascular smooth muscle
• Gastrointestinal Smooth Muscle: Reduced motility and constricted sphincters
• Bronchial & Pulmonary Smooth Muscle: Dilation
• Suderiparous glands secrete in general, with specific palm secretion
• Reproductive System (masculine): Ejaculation
• Reproductive System (feminine): Smooth Muscle Contriction during orgasm
• Pupila: Mydriasis

Divisións do Sist Nervioso Autónomo:

• Parasympathetic originates from the brainstem (cranial nerves III, VII, IX, X) and sacral spinal cord (S2-S4)
• Sympathetic originates from the thoracolumbar regions of the spinal cord (T1-L2)
• Parasympathetic ganglia are located near or within effector organs
• Sympathetic ganglia are located in paravertebral or prevertebral regions
• Both systems use Acetylcholine to bind to nicotinic receptors on preganglionic neurons
• Parasympathetic release Acetylcholine for postganglionic neurons using muscarinic receptors
• Sympathetic release Noradrenaline for postganglionic neurons, which binds to adrenergic (alpha and beta) receptors