Peripheral Nervous System Lecture PDF

NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM OVERVIEW OF THE NERVOUS SYSTEM Basic functions include:  The nervous system transmits signals between the brain and the rest of the body, including internal organs. In this way, the nervous system's activity controls the abi...

NERVOUS SYSTEM PERIPHERAL NERVOUS SYSTEM OVERVIEW OF THE NERVOUS SYSTEM Basic functions include:  The nervous system transmits signals between the brain and the rest of the body, including internal organs. In this way, the nervous system's activity controls the ability to move, breathe, see, think, and more.  Recognizing changes in internal and external environments  Processing and integrating the environmental changes that are perceived  Reacting to the environmental changes by producing an action or response  PHYSIOLOGY OF THE NERVOUS SYSTEM Two Divisions 1. Central Nervous System 2. Peripheral Nervous System OVERVIEW OF THE NERVOUS SYSTEM  Two major subdivisions  Central nervous system (CNS)  Consists of:  Brain  Spinal cord  Peripheral nervous system (PNS)  Consists of:  Cranial nerves (12 pairs)  Spinal nerves (31 pairs) THE CENTRAL NERVOUS SYSTEM  The central nervous system (CNS) includes the cerebrum, cerebellum, brainstem and spinal cord  The CNS relays and processes signals received from the peripheral nervous system; the processing results in responses that are formulated and relayed back to the periphery. THE CENTRAL NERVOUS SYSTEM  The CNS is responsible for important functions such as perception—including sensory, auditory, and visual processing—wakefulness, language, and consciousness  FUNCTIONS OF THE PERIPHERAL NERVOUS SYSTEM  Recognize changes in the internal and external environment  Relies on receptors that respond to different sensory modalities  React to environmental changes by producing an action or response  Relies on somatic and autonomic motor neurons to carry out action or response OVERVIEW OF THE NERVOUS SYSTEM  Peripheral nervous system  Consists of:  Nerves that carry messages to the CNS (sensory) about environment  Nerves that carry messages from the CNS (motor) to carry out responses  Somatic component – voluntary  Autonomic component - involuntary  NEURONS OF THE PERIPHERAL NERVOUS SYSTEM  Sensory Neurons  Specialized receptors and nerves that recognize changes in the environment  Touch  Pain  Heat  Body position  Light  Sound  Composition of body fluids  NEURONS OF THE PERIPHERAL NERVOUS SYSTEM  Motor  Respond to changes by contracting muscles or secreting chemicals  Somatic nervous system  Voluntary control over skeletal muscles  Autonomic nervous system (ANS)  Involuntary control over vital functions of the cardiovascular, digestive, respiratory, and genitourinary systems 13-12  NERVOUS SYSTEM REVIEW  CNS-brain and spinal cord communication with each other  PNS -Messages between CNS and rest of the body  SNS -everything that is VOLUNTARY  ex: messages going to skeletal muscle to move your arm  Sympathetic division - fight or flight (automatic response)  Targets ADRENERGIC receptors - alpha and beta  Parasympathetic -rest and digest -aids in digestion  Targets CHOLINERGIC receptors  THE AUTONOMIC NERVOUS SYSTEM Sympathetic Division Parasympathetic Division PARASYMPATHETIC NERVOUS SYSTEM  Seven regulatory functions  Slowing the heart rate  Increasing gastric secretions  Emptying the bladder  Emptying the bowel  Focusing the eye for near vision  Constricting the pupil  Contracting bronchial smooth muscle RECEPTORS OF THE PERIPHERAL NERVOUS SYSTEM Adrenergic Cholinergic receptors receptors Mediated by epinephrine and Mediated by norepinephrine acetylcholine Two basic categori es of receptor s  ACETYLCHOLINE  A major neurotransmitter in the Cholinergic System  In normal neuromuscular function, Acetylcholine is released from nerve endings and binds to receptors on cell membranes of muscle cells to cause muscle contractions  What receptor subtypes are found in the Cholinergic system?  TERMS  Agonist Drugs (Cholinergic Agonist)  Agonist drugs mimic the effects of neurotransmitters naturally found in the human brain  Antagonist Drugs (Anticholinergic drugs)  In contrast to agonist drugs which bind to the neurotransmitters in the brain, antagonist drugs do the opposite: they block the brain’s neurotransmitters FUNCTIONS OF CHOLINERGIC (PSNS) RECEPTOR SUBTYPES  Functions of cholinergic receptor subtypes  Activation of nicotinic receptors  Activation of muscarinic receptors  MUSCARINIC RECEPTORS  Location of Muscarinic Receptors  Heart  Blood vessels  Bladder  Pulmonary system  Gastrointestinal tract  Eyes  Smooth muscles  Exocrine Glands  NICOTINIC RECEPTORS  Receptors are present in skeletal muscle contraction- Main Function in body  NICOTINIC RECEPTOR BLOCKERS (ANTAGONISTS)  What could be the purpose of these?  MUSCARINIC AGONISTS  Principal structures affected by muscarinic activation  Heart: bradycardia  Exocrine glands: increase sweating, salivation, bronchial secretions, and secretion of gastric acid  Smooth muscles  Contraction in lung (constriction)  GI tract (increased tone/motility)  Bladder (contraction of detrusor)  Vascular (relaxation, vasodilation, hypotension) MUSCARINIC RECEPTORS AGONIST USES?  Dry mouth (Xerostomia)  Urinary retention  Digestion aid  PARASYMPATHETIC NERVOUS SYSTEM DRUGS  Drugs that stimulate the PSNS are called:  –Cholinergics  Drugs that inhibit the PSNS are called:  –Anticholinergics  TIPS FOR UNDERSTANDING THE CHOLINERGIC DRUGS  Know the receptors that the drug affects.  Know the normal responses to activation of those receptors.  Know whether the drug in question increases or decreases receptor activation.  DRUG: BETHANECHOL (DUVOID) CHOLINERGIC AGONIST  Mechanism Of Action: to interact with muscarinic receptors to cause actions typical of parasympathetic stimulation  Primary Use: increase Contraindicated in urination (Urinary patients with Retention)  Digestive tract  Side Effects: salivation, hypermobility disorders sweating, abdominal  Active ulcers cramping, nausea, vomiting  Broncho-constrictive and hypotension disorders  Physical bladder obstructions USE OF CHOLINERGIC AGONISTS AGENTS ACROSS THE LIFESPAN  Children may be more susceptible to adverse affects associated with the cholinergic agonists  Adults should be cautioned about the many adverse affects that can be anticipated when using cholinergic agonists  PULLING IT TOGETHER 1. James is 10 years old with a history of spina bifida. He has been performing self- catheterizations for the last 2 years. During his last clinic visit, he was started on Bethanechol for neurogenic bladder. a. How does Bethanechol treat neurogenic bladder?  NURSING INTERVENTIONS CHOLINERGIC DRUGS Assessment Patient Education  Assessment Take medication on  Health History empty stomach  Vital Signs Avoid standing or sitting  down quickly Allergies  Do not drive until effects Reason of drugs are known  Urinary retention Contraindications patterns  Monitor for side effects  Monitor Liver Enzymes  Monitor intake and output  Monitor vital signs Clinical Application  CLINICAL APPLICATION TO ANTI-CHOLINERGICS  Peptic Ulcers  Cardiac Rhythm Abnormalities  Pre-anesthesia  Asthma ANTI-CHOLINERGIC AGENTS  Action  Used to block the effects of acetylcholine  Block effects of the PNS  Side Effects  Increase in heart rate  Decrease in GI activity  Decrease in urinary bladder tone and function  Pupil dilation  Inhibit sweating, dry eyes and mouth  CNS stimulation ANTI-CHOLINERGIC AGENTS EFFECTS Hot as a hare: increased body temperature Blind as a bat: mydriasis (dilated pupils) Dry as a bone: dry mouth, dry eyes, decreased sweat Red as a beet: red face ANTI-CHOLINERGIC AGENTS Assessment and Education Assess for contraindications or cautions (e.g., history of allergy to drug and GI obstruction) to avoid adverse effects. Assess neurological status (e.g., orientation, affect, reflexes) to evaluate any CNS effects. Assess abdomen (e.g., bowel sounds, bowel and bladder patterns, urinary output) to evaluate for gastrointestinal and urinary adverse effects. Ensure proper administration of the drug to ensure effective use and decrease the risk of adverse effects. Monitor patient response (e.g vital signs and urine output) for changes that may indicate need to intervention Provide comfort measures (e.g., sugarless lozenges, lighting control, small and frequent meals) to help patient cope with drug effects.  DRUG: ATROPINE (ATROPEN) ANTI-CHOLINERGIC Drug DRUG Interactions  Mechanism Of Action: Blocks the Antihistamine parasympathetic actions of Acetylcholine and s induces the fight or flight Tricyclic response Antidepressa  Primary Use: Antidote to nts cholinergic toxicity, suppress secretions during surgical procedures, increase heart rate for Contraindicated in patients and dilation patients with during eye examinations  Glaucoma  Side Effects: Dry mouth,  Heart disease  Urinary retention and constipation, urinary retention, and tachycardia prostate problems  Tachy Cardia 13-37  DRUG: SCOPOLAMINE (BUSCOPAN) ANTI-CHOLINERGIC DRUG  Drug: Scopolamine (Buscopan)  Use: For the treatment of excessive salivation, bradycardia and motion sickness.  Action: Scopolamine is a muscarinic antagonist and acts by blocking the muscarinic receptors and is thus classified as an anticholinergic. Side Effects: Dry mouth, constipation, urinary retention, and tachycardia