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An in-depth exploration of the structures of the nervous system, focusing on somatic, autonomic, and enteric systems. It covers the functions of the brain, spinal cord, ganglia, and pathways for sensory and motor functions. Additionally, it discusses neurotransmitters, their release, and interaction with receptors, as well as the therapeutic importance of CNS acting drugs. Topics include anesthesia, pain relief, epileptic seizure prevention, anxiety reduction, and depression treatment.
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Structures of the Nervous System
Perception and processing of sensory stimula(somatic/auton omic). Execution of voluntary motor responses(somatic). Regulation of homeostatic mechanisms (autonomic) Nerves (PNS) Fibers of sensory and motor neurons (somati c/auton omic) Digestive tract (ENS)
The enteric nervous system (ENS), located in the digestive tract, is responsible for autonomous functions and can operate independently of the brain and spinal cord.
Initiation of reflexes from ventral horn (somatic) and lateral horn (autonomic) gray matter Pathways for sensory and motor functions between periphery and brain (somatic/autono mic) Ganglia (PNS) Reception of sensory stimuli by dorsal root and cranial ganglia (somatic/ autonomic) Relay of visceral motor responses
CNS acting drugs have a major therapeutic & clinical importa Drugs can produce diverse pharmacological psychological effects such as:
Treatment of Depression TTT. of Alzheimer's disease & Parkinsonism CNS Drugs : Sedatives, Tranquilizers, Hypn Anesthetics, Anticonvulsants , Analgesics, Psychot agents, Behavioral modifing drugs Prof rehal 10/
Medulla oblongata contain 5 vital Cs.[ Vagal, Vasom Respiratory, Cough, Vomiting(chemoreceptor trigger (CTZ Il- Spinal cord A cylindrical mass of nerves extends from the end of M.O. to the lower lumbar vertebrae Impulses flow from and to brain through descending & ascending tracts of spinal cord. Contain sex centers (Erection & ejaculation)
Pharmacology of Synaptic transmission How brain cells communicate? Neurotransmitter (NT): A chemical released by a terminal nerve; has an excitatory or inhibitory effect on another neuron. Calcium entry transmitter release Prof t•khal Mfi 10/31/
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Noradrenaline (NA) & Dopamine(DA)
Blocking central Hl- receptors have Sedative, Antiemetic effe Drugs acting on CNS
Pharmacological Effects 1- Smooth muscle relaxant (Spasmolytic) Aminophylline 2- Cardiac stimulant:t force of contraction (+ve inotropic) Heart rate (+ve chronotropic) increase BL. Pressure Coronary Vasodilatation & vagal stim.—+ decres BL. pressur Both effects lead to slight rise in BL. Pressure Caffeine is contraindicated in hypertensive patients. 3- Secondary diuretic: Increase renal BI. Flow due to cardiac stimulant effect. Renal vasodilatation -+ increase glomerular filtration. Inhibit release ADH -+ decrease water reabsorption. Decrease Na tubular reabsorption. 4- GIT: caffeine increase gastric secretions improve digestion.
e Antagonize cortex depression & awake animal from anesthesia. Caffeine combined with Aspirin or Paracetamol for treatment of Headache
Aminophylline used for bronchial asthma For ttt billiary, renal & intestinal colic (spasmolytic). Differences Caffeine Theophylline Theobromine Plant origin Coffee^ Tea^ Coca Cerebral stimulant powerful^ Moderate^ Weak Cardiac stimulant (^) Weak Powerful Moderate
Diuretic Weak^ Powerful^ Moderate Smooth ms. Relaxant (^) Weak Powerful Moderate Amphetamine (Benzedrine): Powerful CNS stimulant; t mental & muscular activities. Non catecholamine, stimulate & receptors by inhibit MAO enz. Increase basal metabolic rate for treatment of obesity. Therapeutic uses: Illegally as a motor activator for race horse (doping). For ttt. of CNS depression in barbiturate & narcotic poisoning. Prof téhal Mfi 10/31/ Medullary stimulants 22 Direct medullary Reflex medullary stimulants stimulants Picrotoxine Nikethamide Camphor Ammonia Cardiazol (^) Sol. Bemegride Doxapram
e Drug cannot induce only one pharmacologic effect & Many drugs cannot be categorized by only one pharmacologic effect, i.e., as tranquilizers, sedatives, or analgesics. Phenothiazines provide good muscle relaxation —Y used in conjunction with anesthetics (e.g., Ketamine) Ph. are antiemetic from block of dopamine Rs. in the CTZ within the medulla. Phenothiazines have little or No analgesic activity. Used to treat psychiatric problems in people & animals Tranquilizers : 1- Phenothiazine derivatives Tranquilizer relieve anxiety & mental tension in man. In animals, quieting & calming effect and reduce fear Phenothiazines in vet. Med. science 1950.as tranquilizers, & as antipsychotic drugs. The effect of Phenothiazine on CNS is called Neuroleptic. Acepromazine maleate — Chlorpromazine hydrochloride Promazine hydrochloride. MOA: I-Phenothiazine inhibit central dopamenergic receptors (D2) which produce sedation & tranquilization. 2-Peripherally, Ph. block Nor epinephrine at alpha adrenergic Rs.
Other pharmacological effects of tranquilizers: 1 - Anti- emetic 2 — Antihistaminic. 3- Hypotensive 4- Antispasmodic. 5- Sympatholytic. Examples of tranquilizer: Phenothiazines , & azaperone. Alpha—2-adrenerqic Aqonists: [Xylazine Detomidine Medetomidine ,& Romifidinel Produce profound sedation by activation of 8-2-adrenergic Rs. located in brainstem. Hypnotics produce normal sleep & deep sleep ( narcosis) or general anesthesia at L. D. Chloral Barbiturates hydrate Sedative hypnotics Benzodiazepine Diazepam Zolazepam Prof 35 10/31/
