Gulf Medical University Nervous System Physiology PDF

Good morning Nervous System Physiology (neurophysiology) Autonomic Nervous system (ANS) Prof. Dr. Faten Mahmoud A. Diab April 4, 2024 Professor of Medical physiology Egypt www.gmu.ac.ae COLLEGE OF MEDICINE introduction: Regulation of Different Body Functions, either: Rapid Nervous system Slow Endocr...

Good morning Nervous System Physiology (neurophysiology) Autonomic Nervous system (ANS) Prof. Dr. Faten Mahmoud A. Diab April 4, 2024 Professor of Medical physiology Egypt www.gmu.ac.ae COLLEGE OF MEDICINE introduction: Regulation of Different Body Functions, either: Rapid Nervous system Slow Endocrine system Functional Organization of the Nervous System Motor portion of the NS Integrative centers (CNS) Sensory portion of the NS  To detect & transmit different sensations to CNS:  To control voluntary movements by descending motor tracts by (somatic NS)  To control involuntary functions by the autonomic NS (sympathetic & parasympathetic NS)  General senses  Special senses.  Perceive & interpret the meaning of different sensations by the sensory cortex.  Generate orders to control both voluntary & involuntary functions of the body.  Higher brain functions (sleep & memory & learning & emotions ……) 4/4/2024 4 Functional Organization of The Nervous System Integrative centers (CNS) Motor portion of the NS Sensory portion of the NS 4/4/2024 5 Anatomical Organization of The Nervous System 4/4/2024 6 Organization of The Nervous System Central Nervous System (CNS) Autonomic Nervous System (ANS) Sympathetic Peripheral Nervous System (PNS) Somatic Nervous System (SNS) Parasympathetic Learning Objectives  Introduction to the neurophysiology.  Define the autonomic nervous system (ANS) and explain how it differs from the somatic nervous system.1  Describe the structures and functions of the sympathetic and parasympathetic divisions of the ANS.2  Define autonomic ganglia, Peripheral nervous system Efferent neurons carry signals out from the CNS to skeletal muscles to mediate voluntary movements. Efferent neurons carry signals out from the CNS to smooth m. & cardiac m, glandular cells to control its involuntary function. Somatic nervous system Autonomic nervous system 9 Comparison between somatic & autonomic NS Comparison between somatic & autonomic NS Somatic nervous system 1. It is voluntary 2. Supply skeletal m. 3. Arise from the anterior horn cell of the spinal cord. 4. One type only 5. No ganglia 6. One efferent neuron. 7. It is always excitatory (operator system) 8. Neurotransmitter: only acetylcholine 9. The skeletal m receptors are nicotinic Receptors. Autonomic nervous system 1. It is involuntary 2. Supply smooth, cardiac, glands... 3. Two types (sympathetic & parasympathetic) systems. 4. Arise from lateral horn cell of the spinal cord. 5. There is autonomic ganglia 6. Two efferent neurons (preganglionic & postganglionic). 7. It is excitatory or inhibitory (regulatory system) 8. Neurotransmitter: acetylcholine in all ganglia & and in the effectors: either acetylcholine or catecholamines. 9. The receptors are muscarinic receptors or adrenergic receptors Comparison between sympathetic & parasympathetic NS (ACh, acetylcholine; NE, norepinephrine; Epi, epinephrine; N-AChR, nicotinic acetylcholine receptor; M-AChR, muscarinic acetylcholine receptor) Adrenal medulla 4/4/2024 12 Autonomic Nervous System 1. 2. 3. 4. 5. Arise from lateral horn cell of the spinal cord. There is autonomic ganglia (lateral, collateral & terminal ganglia). Two efferent neurons: (preganglionic & postganglionic). It is excitatory or inhibitory (regulatory). Neurotransmitters (NT):  in all autonomic ganglia: acetyl choline  in the effectors: acetylcholine (in parasympathetic NS) OR catecholamines (in sympathetic NS). 6. 4/4/2024 Two divisions (sympathetic & parasympathetic) systems. 13 4/4/2024 14 Comparison between sympathetic & parasympathetic NS Parasympathetic NS 1. Origin of the 1st order n. Craniosacral outflow 2. Ganglia: are mostly terminal (near effector organs) 3. Long preganglionic fiber 4. Short postganglionic fiber 5. An anabolic system Dominates in quiet relaxed situations 6. Localized discharge. 7. Rest-Digest state 15 Comparison between sympathetic & parasympathetic NS Sympathetic NS 1. Origin of the 1st order n: thoracolumbar outflow 2. Ganglia: lateral (near the spinal cord) & collateral (in the middle) 3. Short preganglionic fiber 4. Long postganglionic fiber 5. A catabolic system Dominates in emergency situations 6. Mass discharge 7. Fight or flight response. 16 Comparison between sympathetic & parasympathetic NS Parasympathetic NS 1. Origin of the 1st order n. Craniosacral outflow 2. Ganglia: are mostly terminal (near effector organs) 3. Long preganglionic fiber 4. Short postganglionic fiber 5. An anabolic system Dominates in quiet relaxed situations 6. Localized discharge. 7. Rest-Digest state Sympathetic NS 1. Origin of the 1st order n: thoracolumbar outflow 2. Ganglia: lateral (near the spinal cord) & collateral (in the middle) 3. Short preganglionic fiber 4. Long postganglionic fiber 5. A catabolic system Dominates in emergency situations 6. Mass discharge 7. Fight or flight response. 17 Sympathetic NS 4/4/2024 Parasympathetic NS 18 Autonomic Ganglia  It is a collection of nerve cells outside the CNS & and contains the nerve cells of the postganglionic neurons of the ANS.  Lateral: (paravertebral or the sympathetic chain): near the spinal cord.  Collateral: around the origin of big vessels in the abdomen, e.g., coeliac, superior mesenteric & inferior mesenteric ganglia  Terminal: very near or even inside the effector organ.  Relay stations: for preganglionic and origin for postganglionic fibers.  Distributing centers:  Site of action of drugs used to modify autonomic functions. 4/4/2024 19 Autonomic Ganglia Lateral ganglia Sympathetic NS Collateral ganglia Parasympathetic NS Terminal ganglia 20 Adrenal medulla Structure function of the adrenal medulla:  It is the inner part of adrenal gland  It has nervous origin.  It is a big modified sympathetic ganglia. It secretes: Its secretion is stimulated by acetylcholine released from preganglionic sympathetic fibers innervating it. Adrenal medulla releases a mixture of:  80% epinephrine (E) and  20% norepinephrine (NE) a small amounts of  dopamine, ATP, and neuropeptides. 4/4/2024 21 Adrenal medulla Functions of the adrenal medulla:  It reinforces the function of sympathetic nervous system in facing different stresses. 1. (E) and (NE) are released by the adrenal medulla by its stimulation directly during generalized sympathetic activation. How? 2. So, the different body organs are actually stimulated in two ways: directly by the sympathetic nerves and indirectly by the adrenal medullary hormones (longer duration of action). The two means of stimulation support each other. 3. Thus, the dual mechanism of sympathetic stimulation provides a safety factor, with one mechanism substituting for the other if it is missing. 4. Their effects are prolonged, lasting 2 to 4 minutes after the stimulation is over, because they are removed from the blood slowly. 4/4/2024 22 Q1 True or false ?? 1. Acetylcholine is the neurotransmitter in all autonomic ganglia. (True or false?) 2. Parasympathetic NS originates from the thoracolumbar outflow. (True or false?) 3. The adrenal medulla can be considered as a big parasympathetic ganglia. (True or false?) 4/4/2024 23 Learning Resources  https://exchange.scholarrx.com/brick/autonomic-nervous-system  Textbook: Hall, J. and Hall, M. Guyton and Hall textbook of medical physiology, Fourteenth Edition, Elsevier 2021. ISBN: 978-0-323-59712-8. International Edition ISBN: 978-0-323-67280-1. Chapters 61, Page no. 763775.  PowerPoint presentation in the Moodle.  https://youtu.be/D96mSg2_h0c April 4, 2024 www.gmu.ac.ae COLLEGE OF MEDICINE Thank you 4/4/2024 25