Introduction to ans
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The document provides an overview of the autonomic nervous system (ANS), including its distribution and differences between the sympathetic and parasympathetic nervous systems. It discusses neurohumoral transmission in the ANS and the main neurotransmitters for each division. The sympathetic nervous system uses norepinephrine and epinephrine as neurotransmitters, while the parasympathetic nervous system uses acetylcholine. It also briefly describes the synthesis of acetylcholine and catecholamines.
Introduction to ans
- 1. INTRODUCTION TO AUTONOMIC NERVOUS SYSTEM DR NASER ASHRAF TADVI
- 2. OBJECTIVES • Describe distribution of ANS • Enlist differences between ANS and PNS • Describe Neurohumoral transmission • Enlist main neurotransmitter for Sympathetic and Parasympathetic NS • Enlist receptors for Sympathetic and Parasympathetic nervous system • Briefly describe the synthesis of Acetyl choline and Catecholamines
- 3. Introduction to ANS • Peripheral nervous system is divided into – Somatic nervous system (SNS) – Autonomic nervous system (ANS)
- 4. Differences between Somatic and autonomic nervous system Somatic Autonomic 1 Organ supplied Skeletal Muscles All other organs 2 Distal most synapse Within CNS Outside CNS (in ganglia) 3 Nerve fibers Myelinated Preganglionic Myelinated Post Ganglionic Non myelinated 4 Peripheral plexus formation Absent Present 5 Primary efferent transmitter Acetylcholine(Ach) Ach, Noradrenaline 6 Effect of nerve section on organ supplied Paralysis & atrophy Activity maintained, no atrophy
- 6. Distribution of parasympathetic nervous system
- 7. Distribution of Sympathetic nervous system
- 8. ANS FIBRES Afferents Efferent Sympathetic nervous system Para sympathetic nervous system •Origin: thoraco lumbar (lateral horns) outflow C8 to L2/L3 •Ganglia – paravertebral (22 pairs) •Prevertebral (coeliac, superior & inferior mesentric & aortorenal) •Adrenal medulla •Terminal (u. bladder, rectum) •Cranio sacral •Midbrain – 3rd •Medulla – 7,9,10 Sacral – 2,3,4, (nervi erigentis) • terminal near/with in innervated tissue.
- 9. • Symp n. system • Neurotansmitter • PSNS • Neurotansmitter Nonadrenaline/ ADR Acetyl choline •Function: prepare body for fight Acetyl choline Acetyl choline •Tissue building reaction
- 11. Differences between sympathetic & parasympathetic Features Sympathetic Parasympathetic 1 Origin From CNS Thoracolumbar segments of spinal cord (T1-T12, L1-L3) Craniosacral regions (Cranial nerves 3, 7,9,10 & sacral segments of spinal cord S 2,3,4) 2 Preganglionic fiber Short Myelinated Long Myelinated 3 Ganglia Located away from the organs of innervation Located very close to organs of innervation 4 Post ganglionic Fiber Long non myelinated Short non myelinated 5 Response to stimulation Diffused or generalized Localized reaction 6 Neurotransmitter Preganglionic Post Ganglionic Acetylcholine Noradrenaline Acetylcholine Acetylcholine 7 Important function Tackling stress and Emergency Assimilation of food and conservation of energy
- 14. Co-transmission Examples of co-transmitters • Purines : ATP, Adenosine • VIP, NPY • Substance P, enkephalins • Somatostatin • Nitric oxide
- 15. Synthesis of catechol amines
- 16. Synthesis of acetyl choline
- 17. Cholinergic receptors Nicotinic Muscarinic NM (Skeletal muscle) NN (Ganglia) M1 •CNS •GASTRIC SECRETION M2 Heart M3 Smooth muscle & Gland secretion
- 19. Important terminology • Sympathomimetic (Adrenergic) • Sympatholytic (Antiadrenergic) • Parasympathomimetic (Cholinergic) • Parasympatholytic (Anticholinergic)
- 20. Summary • Distribution • Neurohumoral transmission • Main neurotransmitters • Main receptors
- 21. Which of the following is correct regarding the autonomic nervous system (ANS)? A. Afferent neurons carry signals from the CNS to the effector organs. B. The neurotransmitter at the parasympathetic ganglion is norepinephrine (NE). C. The neurotransmitter at the sympathetic ganglion is acetylcholine (ACh). D. Sympathetic neurons release ACh in the effector organs. E. Parasympathetic neurons release NE in the effector organs.
- 22. Which of the following is correct regarding somatic motor neurons? A. The neurotransmitter at the somatic motor neuron ganglion is acetylcholine. B. The neurotransmitter at the somatic motor neuron ganglion is norepinephrine. C. Somatic motor neurons innervate smooth muscles. D. Somatic motor neurons do not have ganglia. E. Responses in the somatic motor neurons are generally slower than in the autonomic nervous system.
- 23. Which of the following physiological changes could happen when a person is attacked by a dog? A. Increase in heart rate. B. Increase in lacrimation (tears). C. Constriction of the pupil (miosis). D. Increase in gastric motility.
- 24. A. Reduction in heart rate. B. Constriction of the pupil (miosis). C. Increase in gastric motility. D. Dry mouth (xerostomia). E. Contraction of detrusor muscle in the bladder. Which of the following changes could theoretically happen in a person when the parasympathetic system is inhibited using a pharmacological agent?
- 25. Which of the following is correct regarding neurotransmitters and neurotransmission? A. Neurotransmitters are released from the presynaptic nerve terminals. B. Neurotransmitter release is triggered by the arrival of action potentials in the postsynaptic cell. C. Intracellular calcium levels drop in the neuron before the neurotransmitter is released. D. Serotonin and dopamine are the primary neurotransmitters in the ANS.
- 26. All of the following statements regarding central control of autonomic functions are correct except A. Baroreceptors are pressure sensors located at various cardiovascular sites. B. The parasympathetic system is activated by the CNS in response to a sudden drop in blood pressure. C. The parasympathetic system is activated by the CNS in response to a sudden increase in blood pressure. D. The sympathetic system is activated by the CNS in response to a sudden drop in blood pressure.
Editor's Notes
- #5: ANS: Interference with nerve supply does not completely abolish functions of organs supplied by ANS Structures receiving ANS supply possess an inherent activity & nervous influences either ↑ or ↓ initial function Somatic nervous system Interference with nerve supply cause paralysis of skeletal muscles supplied by somatic (motor) nerves. Structures receiving SNS supply do not possess inherent activity.
- #12: Except sympathetic nerve supplying adrenal medulla
- #13: The entire process of transmission of impulse from one neuron to another through the participation of a chemical substance or transmitter is known as neurohumoral transmission Co-transmission: the main transmitters of ANS are ACH and NA . A large number of other substances co-exist with the main neurotransmitters and act as neuromodulators (enhance or inhibit release of transmitters). They comprise of amines such as dopamine, serotonin peptides such as VIP , EDRF, or nitric oxide, enkephalins, somatostatin, vasopressin, calcitonin gene related peptide neuropeptide Y
- #15: On stimulation most peripheral and central neurons shown to release more than one active substance
- #19: Alpha 1 gq Alpha 2 gi Beta = gs
- #22: c
- #23: d
- #24: A
- #25: d
- #26: A
- #27: c