Copy of Autonomic Nervous System - Dr. Ayesha Fatima - 26 September 2024.pdf

Nervous system Enables the body to react to continuous changes in its external & internal environment. Controls and integrates the various activities of the body.  Classification of Nervous system Central Nervous - Brain System(CNS) -...

Nervous system Enables the body to react to continuous changes in its external & internal environment. Controls and integrates the various activities of the body.  Classification of Nervous system Central Nervous - Brain System(CNS) - Spinal Cord Nervous System - Cranial Nerves(12pairs) Peripheral Nervous -Spinal nerves(31 pairs) System(PNS) - Ganglia Dr. Ayesha F  CRANIUM VERTEBRAL COLUMN  Brain is located in the cranial cavity protected by cranium.  Spinal cord is located in the vertebral column.  Brain and spinal cord are surrounded by protective covering called Meninges(Duramater, Arachnoid mater, and piamater)  Brain and spinal cord are surrounded by CSF fluid located in the sub arachnoid space. Dr. Ayesha F  Cells in the nervous system Two types of cells Neuro glial cells(Supporting cells, eg: Neurons (receive and oligodendrocytes, transmit signals to astrocytes, microglia, different parts of body) ependymal cells, schwann cells, satellite cells) or or Dr. Ayesha F  Peripheral Nervous System 12 cranial 31 spinal p 2 3 Peripheral nerves can be sensory, motor or mixed. PNS includes 12 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves: Spinal nerve:  31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar,5  All the 12 pairs of cranial nerves arise from the brain except sacral, 1 coccygeal nerves). the 11th cranial nerve which arises from the brain and spinal  All exit the vertebral column through intervertebral foramina. cord.  All cranial nerves exit the cranial cavity through foramina in the cranium. exit from intravertebra foramina cranial : All 12 nerves arise from except 11th arises from brain and spinal cord exi from foramina 00 O G 0 O O Dr. Ayesha F  Classification of peripheral nervous system Central Nervous System(CNS)- Brain &Spinal cord Nervous system Peripheral Nervous System(PNS)- PERIPHERAL nervous structures NERVOUS SYSTEM outside CNS SENSORY MOTOR SOMATIC VISCERAL voluntary organs VISCERAL (0R) organs SOMATIC body wall involuntary AUTONOMIC NERVOUS SYSTEM Voluntary Action On Involuntary action on smooth Skeletal Muscles muscles,glands,cardiac muscles. Skinny-fight or flight Age rests digest SYMPATHETIC PARASYMPATHETIC NERVOUS SYSTEM NERVOUS SYSTEM Fight And Flight Rest And Digest Dr. Ayesha F  Autonomic Nervous System  The part of the PNS responsible for regulating involuntary body functions, such as heartbeat, blood flow, breathing, urination,digestion and reproductive function.  An autonomic nerve pathway involves two nerve cells(neurons). Preganglionic neuron with cell body located in the brain stem or spinal cord. Postganglionic neuron, with cell body located in an autonomic ganglion. Autonomic nervous system controls - part of PNS that. involuntary actions * heartbeat * blood flow A breathing * urination * digestioneaction nervous system Autonomic contains two nerve cells 1. Preganglionic -in brain stem or Spinal cord - always myelinated - neurotransmitter is acetylcholine 2 Postganglionic. - in autonomic ganglion - non-myelinated neurotransmitter acetylcholine Schematic diagram of ANS - is or epinephrine or norepinephrine Dr. Ayesha F  CHARACTERISTICS SOMATIC NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM 1. Sensory neuron(afferent pathway) Somatic senses & special senses Mainly located in blood vessel, visceral organ. 2. Effector Skeletal muscle Smooth muscles, cardiac muscles and glands voluntary Involuntary 3. Control of motor neuron and effect Voluntary control, excitatory effect Involuntary control, excitatory or inhibitory effect 4. Motor Neuron (efferent pathway) and One motor axon from CNS to effector. First motor axon from CNS to autonomic neurotransmitter NT is Acetyl choline ganglion(preganglionic nerve) Second motor axon from autonomic ganglion to one motor effector(postganglionic nerve) NT can be acetyl choline or norepinephrine Nt : ACH 2 motors 2 NT : ACH 3 NE CNS · first motor & Preganglion · second motor postganglion Dr. Ayesha F  Subdivision of Autonomic nervous system: ANS has two sub systems: Stresse functions during stress ↑> flight sunny fight : or SYMPATHETIC NERVOUS SYSTEM: Prepares body to function under stress(exercise, excitement, emergencies) Triggers Fight or flight response Prepares the body for intense muscle activity : rest and digestive Dig M PARASYMPATHETIC NERVOUS SYSTEM Maintenance functions Triggers Rest-and-digest response Counter-balances sympathetic function opposite Both divisions operate in conjunction with one another (have antagonistic control over the viscera) to maintain a stable internal environment Dr. Ayesha F  fight or flight rest and digest Dr. Ayesha F  thorack - lumbar Sympathetic Nervous System Thorax and Columbar Also called THORACOLUMBAR system Cell bodies of preganglionic neurons are in lateral horn of gray matter of spinal cord from T1-L2 (L3) Cell bodies of postganglionic neurons occur in two locations: Paravertebral and prevertebral ganglia. Paravertebral ganglia: either side of the vertebral column form sympathetic trunks(chains) Prevertebral ganglia: located in plexus that surround the origins of main branches of abdominal aorta. Postganglionic Preganglionic fibers are short and myelinated. paraventral preventeral plexus column-located in Post-ganglionic fibers are long and non-myelinated. - - side of vertebral form sympathetic trunks Dr. Ayesha F  cells outside CNs ganglion : ganglia of sympathetic nervous system Dr. Ayesha F  Sympathetic Nervous System(continued) Course of preganglionic fibres: they take one of the three courses 1. Remain at same level: Synapse with postganglionic neuron of paravertebral ganglia. synapseat same level 2. Ascend or descend within sympathetic ascend trunk, synapse with a paravertebral Splanchnic nerve postganglionic neuron, form 3. No synapse: pass through Pass , splanchic nerve, paravertebral ganglion without synapse at prevertebral No remain synpase synapse,form splanchnic nerve. synapse in prevertebral ganglion Postganglionic axons follow arteries to reach the Abdomino pelvic organs descend Dr. Ayesha F  Adrenal gland is an exception included in sympathetic system but has an exception Preganglionic sympathetic fibres do not synapse in prevertebral ganglia and terminate directly in the cells of adrenal medulla. These cells acts as modified postganglionic neurons and release the NT(epinephrine/nor epinephrine) directly into the blood vessels. widespread sympathetic response.(adrenaline “surge” in emergency) Dr. Ayesha F  Sympathetic nervous system(Continue) Via spinal nerves and periarterial plexuses,post synaptic sympathetic fibres reach almost all parts of the body including sweat glands,arector pili muscle and viscera except avascular tissue like nails and cartilage. Examples of sympathetic effect:  when nervous, you sweat;  when afraid, hair stands on end;  when excited blood pressure rises (vasoconstriction): these are sympathetic only  dry mouth,  Dilated pupils,  increased heart & respiratory rates to increase O2 to skeletal muscles,  liver to release glucose Dr. Ayesha F  PARASYMPATHETIC NERVOUS SYSTEM CRANIUM-SACRUM Also called CRANIOSACRAL system Location of preganglionic neurons: Cranial site: cranial nerve nuclei of brainstem, exit CNS within CN III(occulolotor n.),CN VII(Facial n.),CN IX (glossopharyngeal n.) and CN X(Vagus n.) Sacral site: gray matter of spinal cord from (S2-S4) exit through anterior roots of spinal nerves and form pelvic splanchnic nerves. Dr. Ayesha F  Parasympathetic System (continued) Location of postganglionic neurons: Cranial site: 4 parasympathetic ganglia (Ciliary ganglion, Pterygopalatine ganglion, Submandibular ganglion and Otic ganglion) Other parts of body: individually in (or)on the wall of target organ. Preganglionic fibres are long and myelinated. Post ganglionic fibres are short and non myelinated. Dr. Ayesha F  Parasympathetic System distribution and function localized Para: distribution Symp : Localized distribution. Cranial outflow 3 III {Oculomotor} - pupils constrict 7 VII {Facial} - tears, nasal mucus, saliva 9 IX {Glossopharyngeal} – parotid salivary gland 10 X (Vagus) – visceral organs of thorax & abdomen: Stimulates digestive glands Increases motility of smooth muscle of digestive tract Decreases heart rate Causes bronchial constriction Sacral outflow (S2-4): form pelvic splanchnic nerves Supply 2nd half of large intestine Contracts the bladder,relaxes sphincter urination Supply all the pelvic (genitourinary) organscauses erection  AUTONOMIC PLEXUSES A network of sympathetic and parasympathetic axons. Cardiac plexus- heart. Cardiac plexus Pulmonary plexus- the bronchial tree. Celiac plexus- largest. Supplies the stomach, spleen, pancreas, liver, gallbladder, and adrenal medullae. Superior mesenteric plexus- small intestine and proximal colon. Inferior mesenteric plexus- distal colon and rectum. Hypogastric plexus- urinary bladder and genital organs. Renal plexus- kidneys and ureters. Dr. Ayesha F  Amygdala: main limbic Central control of the Autonomic NS region for emotions structure hypothalamus : main -Stimulates sympathetic activity, especially previously learned fear-related behavior -Can be voluntary when decide to recall frightful experience - cerebral cortex acts through amygdala -Some people can regulate some autonomic activities by gaining extraordinary control over their emotions Hypothalamus: main integration center Reticular formation: most direct influence over autonomic function 25  only one axon ; releasing acetylcholine rest und digest Dr. Ayesha F Structural differences between Sympathetic and Parasympathetic Systems Dr. Ayesha F Dr. Ayesha F