Autonomic Nervous System PDF

+ BTM Interactive Tutorials-3 Autonomic Nervous System By :Dr. Shaheen + Questions & Answers session Recap from previous lectures + Objectives ◼ The organization and functions of the Autonomic Nervous System ◼ Synthesis of autonomic ne...

+ BTM Interactive Tutorials-3 Autonomic Nervous System By :Dr. Shaheen + Questions & Answers session Recap from previous lectures + Objectives ◼ The organization and functions of the Autonomic Nervous System ◼ Synthesis of autonomic neurotransmitters ◼ Receptor types in the Autonomic Nervous System and their distribution.. + Organization of ANS + Organization of ANS + Functions of ANS ◼ The autonomic nervous system is a component of the peripheral nervous system that regulates involuntary physiologic processes including Mechanism for the fight-or-flight response Regulating blood pressure Regulating heart rate Secretion of bodily fluids such as saliva, sweat, and urine Breathing Regulating body temperature Pupillary responses Regulating metabolism + Organization of ANS.. It contains three anatomically distinct divisions: ◼Sympathetic ◼Parasympathetic ◼ Enteric. Neurotransmitters -------ANS.. + Parasympathetic system.  SITES OF RELEASE OF ACETYLCHOLINE Acetylcholine is the chemical transmitter at: 1) All preganglionic nerve endings whether sympathetic or paras-ympathetic. 2) Preganglionic sympathetic nerve fibers to suprarenal medulla. 3) All postganglionic parasympathetic nerve ending. 4) Some sympathetic post ganglionic nerve endings like those supplying skeletal muscle blood vessels and sweat glands. 5) Somatic motor nerve ending to skeletal muscle (motor end plate). 6) Some synapses at CNS (brain and spinal cord).  choline acetyltransferase Acetylcholinesterase (AChE) Classification of cholinergic receptors  1- Muscarinic receptors They are present on the effector organs at all postganglionic Site: cholinergic nerve terminals (all postganglionic parasympathetic nerve endings and postganglionic sympathetic nerve endings to skeletal muscle blood vessels and sweat glands). M1 in the brain and autonomic ganglia. M2 in the heart Subtypes: M3 in the smooth muscles and secretory glands. M4 in the pancreas & CNS. M5 CNS under investigation. Stimulated by muscarine alkaloid. Blocked by atropine. Mechanism G-protein coupled receptor. +  2- Nicotinic receptors Site: Present in autonomic ganglia (either sympathetic or parasympathetic), suprarenal medulla and motor end plate. ❑ Neuronal Nicotinic Receptors (Nn) ▪ at autonomic ganglia. Subtypes: ▪ at supra renal medulla. ❑ Muscle Nicotinic Receptors (Nm) ▪ at motor end plate. Stimulated Nicotine (small dose), by Blocked by Nm blocker= d-tubocurarine Nn blocker= Hexamethonium Mechanism Ligand-gated ion channel + + Sympathetic system.  SITES OF RELEASE AND ACTION OF CATECHOLAMINES 1) All postganglionic sympathetic fibers except those supplying skin, skeletal muscle blood vessels and sweat glands. 2) Some synapses in CNS. 3) Suprarenal medulla: adrenaline (80%) and noradrenaline (20%) are released from chromaffin cells of suprarenal medulla.  ADRENERGIC TRANSMISSION Noradrenaline is the chemical transmitter of sympathetic nervous system. Noradrenaline is a member of catecholamines. Three catecholamines 1. Noradrenaline 2. Adrenaline 3. Dopamine. STEPS OF SYNTHESIS OF CATECHOLAMINES  ADRENERGIC RECEPTORS Defn: Adrenergic receptors are receptors which respond to specifically to neurotransmitter Noradrenaline & Adrenaline. Major types of Adrenergic receptors: 2 types  adrenergic receptors (mostly excitatory) : α1 & α2 Recently 1 & 2 : further subdivided into: 1 (A, B, D) & 2 (A, B, C).  adrenergic receptors (mostly inhibitory) :β1, β2, β3, β4, β5 β3 receptors: are located in the adipose tissues. β4 & β5 receptors: under research. + the ethical aspects + +