Chapter 1

Chapter 1

Chapter 16 Autonomic nervous system AP2 Chapter 16: ANS 1 Quick Review Nervous System Central Nervous System Peripheral Nervous System Sensory Division Motor Division

Somatic Nervous System AP2 Chapter 16: ANS Autonomic Nervous System 2 Focus on PNS Carries action potentials to and away from the CNS Peripheral Nervous System Sensory Division Motor Division

Carries action potentials toward the CNS for processing Carries action potentials away from the CNS toward the effector AP2 Chapter 16: ANS 3 Focus on Motor Division Motor Division Autonomic Nervous System Somatic Nervous System One neuron cell body in the anterior gray horn of the SC with its axon extending to

the effector (Monosynaptic) Carries AP for conscious control Effector = skeletal muscle Always excitatory AP2 Chapter 16: ANS 4 Focus on Motor Division Motor Division Somatic Nervous System Autonomic Nervous System Autonomic motor neurons come in pairs! 1st cell body in the CNS axon extends to the ganglion. 2nd cell body in ganglion axon extends to the effector. Carries AP for unconscious control Effectors:

Smooth muscle Cardiac muscle Glandular tissue May be excitatory or inhibitory APs 5 Somatic vs. Autonomic Division Somatic Division One neuron cell body in the anterior gray horn of the SC with its axon extending to the effector (Monosynaptic) Carries AP for conscious control Effector = skeletal muscle Always excitatory Autonomic division Autonomic motor neurons come in pairs! 1st cell body in the CNS axon extends to the ganglion.

2nd cell body in ganglion axon extends to the effector. Carries AP for unconscious control Effectors: Smooth muscle Cardiac muscle Glandular tissue 6 May be excitatory or inhibitory APs AP2 Chapter 16: ANS Focus on the Autonomic Nervous System Autonomic Nervous System

Sympathetic Nervous System Parasympathetic Nervous System Differ structurally in: 1. Location of the preganglionic cell bodies within the CNS 2. Location of the ganglia AP2 Chapter 16: ANS Enteric Nervous System Complex network of cell bodies and axons within the walls of the digestive tract.

7 II. Anatomy of the ANS A. Sympathetic Division B. Parasympathetic Division C. Enteric Nervous System D. Distribution of Autonomic Nerve Fibers AP2 Chapter 16 8 II. Anatomy of the ANS There are 3 divisions to the ANS 1. Sympathetic Nervous System 2. Parasympathetic Nervous System SNS & PNS differ structurally in location of: Preganglionic neuron cell bodies w/in CNS Autonomic Ganglia

3. Enteric Nervous System Considered part of the ANS b/c of the FX the SNS & PNS have on ENS fxn It is a complex ntwk of neuron cell bodies & axons w/in the wall of the GI-tract that influence it fxn AP2 Chapter 16 9 II. Anatomy of the ANS 1.SNS/ Thoracolumbar Division 2. PNS/Craniosacral Division AP2 Chapter 16 10 II. Anatomy of the ANS 1.SNS Location PreG cell body Gray matter btwn T1 & L2

Thoracolumbar Division Axons w/in ventral roots of T1-L2 spinal nerves Exit from CNS a) b) c) d) Spinal Nerves Sympathetic Nerves Splanchnic Nerves Innervation of the adrenal medulla Ganglia Chain Ganglia: lie in a linked chain along the length of the spinal cord Collateral Ganglia: Unpaired ganglia in the

abdominopelvic cavity anterior to spinal cord Chain ganglia along side SpCd for spinal and sympathetic nerves Collateral ganglia for Splanchnic nerves # of PostG neurons for every PreG neuron # of PostG for every PreG much divergence Relative lengths of PreGs and PostGs Short PreG Neuron Long PostG Neuron 11 II. Anatomy of the ANS 1.SNS /Thoracolumbar Division Exit from CNS a) Spinal Nerves

PostGs are non-myelinated thus Gray PostGs go thru all spinal nerves & project to the skin & Skeletal Muscle b) Sympathetic Nerves Post G axons supply organs in the thoracic cavity c) Splanchnic Nerves d) Innervation of the adrenal medulla a b 12 II. Anatomy of the ANS 1.SNS /Thoracolumbar Division

Exit from CNS a) Spinal Nerves b) Sympathetic Nerves c) Splanchnic Nerves PostG extend to targets in the abdominopelvic cavity d) Innervation of the adrenal medulla c PreGs only extend thru the ganglion directly to their target cells in the adrenal medulla d 13 II. Anatomy of the ANS Location PreG cell body

2. PNS Brain stem & lateral parts of SpCd S2Craniosacral Division S4 Exit from CNS a) Cranial Nerves b) Pelvic Splanchnic Nerves Ganglia Terminal Ganglia near or on the Target Organ # of PostG neurons for every PreG neuron # of PostG for every PreG little to no divergence Terminal Ganglia Ends on the target Relative lengths of PreGs and PostGs Long PreG Neuron Short PostG Neuron

14 II. Anatomy of the ANS Enteric Nervous System Nerve plexuses w/in the wall of the digestive tract ENS contributed from 3 sources 1. Sensory neurons connecting digestive tract to the CNS 2. ANS motor neurons connecting CNS to the digestive tract 3. Enteric neurons which are confined to the enteric plexuses AP2 Chapter 16 15 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division 16 AP2 Chapter 16

II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division Sympathetic axons pass from sympathetic chain ganglia thru 3 paths: spinal, sympathetic, or splanchnic nerves to get to their target Sympathetic & Splanchnic pathways may join with autonomic nerve plexus These are complex interconnected neural ntwks formed by neurons from the SNS & PNS (sensory neurons can also contribute to the formation of these nerves There are 4 major means by wh/sympathetic axons reach organs: AP2 Chapter 16 17 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division

4 ways sympathetic axons reach organs: 1. 2. 3. 4. Spinal Nerves Head & neck nerve plexuses Thoracic Nerve Plexuses Abdominopelvic Nerve Plexus AP2 Chapter 16 18 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division 4 ways sympathetic axons reach organs: 1. Spinal Nerves

PostGs innervate same strucs as spinal nerves they follow Sweat glands of the skin Smooth muscle of bld vessels in skin & skeleton Smooth muscle of arrector pili muscles in skin 2. Head & neck nerve plexuses 3. Thoracic Nerve Plexuses 4. Abdominopelvic Nerve Plexus AP2 Chapter 16 19 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division 4 ways sympathetic axons reach organs: 1. Spinal Nerves

2. Head & neck nerve plexuses PostG extend up to the head & down to neck Sweat glands of the skin Smooth muscle of bld vessels in skin & skeleton Smooth muscle of arrector pili muscles in skin Skin of the face Iris Ciliary muscles of the eye 3. Thoracic Nerve Plexuses 4. Abdominopelvic Nerve Plexus AP2 Chapter 16

20 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division 4 ways sympathetic axons reach organs: 1. Spinal Nerves 2. Head & neck nerve plexuses 3. Thoracic Nerve Plexuses Axons supply organs of the thorax PostG axons Cardiac Plexus supplying the heart Pulmonary Plexus supplying the lungs Thoracic Plexus 4. Abdominopelvic Nerve Plexus

AP2 Chapter 16 21 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sympathetic Division 4 ways sympathetic axons reach organs: 1. 2. 3. Spinal Nerves Head & neck nerve plexuses Thoracic Nerve Plexuses 4. Abdominopelvic Nerve Plexus Axons supply AP-organs PostG from collateral ganglia innervate smooth muscle & glands in AP-cavity

Celiac Plexus: supplies diaphragm, stomach, liver, gallbladder, adrenal glands, kidneys, testis, & ovaries Superior Mesenteric Plexus: supplies pancreas, sm. Intestine, ascending & transverse colon. Inferior Mesenteric Plexus: supplies transverse colon to the rectum Superior & inferior Hypogastric Plexus: supply the descending colon to the rectum, urinary bladder, & reproductive organs 22 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 23 AP2 Chapter 16 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division

Exit from cranial & pelvic splanchnic nerves Branches supply organs directly or join nerve plexuses to be distributed to organs 4 major means by wh/parasympathetic axons reach their organs: AP2 Chapter 16 24 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 4 ways parasympathetic axons reach organs: 1. 2. 3. 4. Cranial nerves supplying the head & neck Vegus nerve & thoracic nerve plexus

Abdominal Nerve Plexus Pelvic splanchnic nerves & pelvic nerve plexuses AP2 Chapter 16 25 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 4 ways parasympathetic axons reach organs: 1. Cranial nerves supplying the head & neck 3 pairs of cranial nerves end at terminal ganglia where PostG axons supply near by strucs: exs/ Oculomotor nerve thru ciliary ganglion ciliary muscles & iris Pterygopalatine ganglion lacrimal gland, mucosal glands of nasal cavity & palate

2. Vegus nerve & thoracic nerve plexus 3. Abdominal Nerve Plexus 4. Pelvic splanchnic nerves & pelvic nerve plexuses AP2 Chapter 16 26 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 4 ways parasympathetic axons reach organs: 1. Cranial nerves supplying the head & neck 2. Vegus nerve & thoracic nerve plexus The vegus nerve parasympathetic distribution goes to the thorax & abdomen PreGs go thru vegus nerve to thorax to contribute to:

Cardiac Plexus heart Pulmonary Plexus Lungs Vegus continues down esophagus & braches to form esophageal plexus 3. Abdominal Nerve Plexus 4. Pelvic splanchnic nerves & pelvic nerve plexuses AP2 Chapter 16 27 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 4 ways parasympathetic axons reach organs: 1. Cranial nerves supplying the head & neck 2. Vegus nerve & thoracic nerve plexus 3. Abdominal Nerve Plexus Terminal ganglia in stomach wall contribute to celiac &

superior plexus PreG supply terminal ganglia in walls of: Gallbladder, biliary ducts, pancreas, Sm. Intestine, ascending colon, & transverse colon 4. Pelvic splanchnic nerves & pelvic nerve plexuses AP2 Chapter 16 28 II. Anatomy of the ANS Distribution of autonomic nerve fibers Parasympathetic Division 4 ways parasympathetic axons reach organs: 1. 2. 3. 4. Cranial nerves supplying the head & neck

Vegus nerve & thoracic nerve plexus Abdominal Nerve Plexus Pelvic splanchnic nerves & pelvic nerve plexuses PreGs of S2-S4 region pass to ventral rami of spinal nerves & enter pelvic splanchnic nerves which supply Terminal ganglia in transverse colon to rectum Contribute to hypogastric plexus Supplies: lower colon, rectum, urinary bladder, organs of the reproductive system in the pelvis AP2 Chapter 16 29 II. Anatomy of the ANS Distribution of autonomic nerve fibers Sensory neurons in autonomic nerve plexuses Not strictly part of the ANS but axons run along ANS axons w/in the ANS & plexuses

These are also part of the reflex arches regulating organ activity They transmit pain & pressure sensations from organs to the CNS Cells Bodies Found in dorsal root ganglia Found in some sensory ganglia of certain cranial nerves AP2 Chapter 16 30 III. Physiology of the ANS A. Neurons and their NTs 1. Cholinergic Neurons 2. Adrenergic Neurons B. Receptors 1. Cholinergic receptors 2. Adrenergic Receptors AP2 Chapter 16

31 Neuron- a cell inside of the nervous system that reacts to neurotransmitters and transmits electrical signals Neurotransmitter- chemical signals released by a neuron that causes a cell carrying the correct target receptor to respond Receptor- transmembrane protein that will react to the matching ligand. AP2- ANS Neurons & Receptors 32 Neurons of the Autonomic Nervous System 2 Major types Cholinergic Neuron- neurons that release acetylcholine as their neurotransmitter

Acetylcholine Adrenergic Neuron- neurons that release norepinephrine as their neurotransmitter AP2- ANS Neurons & Receptors Norepinephrine 33 Receptors of the Autonomic Nervous System 2 Major types Adrenergic receptors *Respond to Norepi* 2 subtypes GPCRs a or b types

Ligand-gated receptors GPCRs Nicotinic Muscarinic Cell Membrane Cholinergic receptors *Respond to Ach* Cell Membrane Cell Membrane - Ligand

- Ligand + Ligand - Ligand + Ligand + Ligand 34 Receptors of the Autonomic Nervous System 2 Major types Cholinergic receptors *Respond to Ach* Adrenergic receptors *Respond to Norepi* 2 subtypes GPCRs

a or b types Ligand-gated receptors GPCRs Nicotinic Muscarinic Binding = excitatory FX Na+ chs open Prodn of an AP Binding may be excitatory or inhibitory Target tissue dependent Activation can result from the ANS or endocrine system Binding may be

excitatory or inhibitory Target tissue dependent 35 Sympathetic Nervous System (Fight or Flight) Post ganglionic cell Post ganglionic cell Preganglionic cell Preganglionic cell Parasympathetic Nervous System (Rest and Digest) Effector AP2- ANS Neurons & Receptors 36

Parasympathetic Nervous System (Rest and Digest) Sympathetic Nervous System (Fight or Flight) Cholinergic Neuronneurons that release acetylcholine as their neurotransmitter Adrenergic Neuronneurons that release norepinephrine as their neurotransmitter Effector AP2- ANS Neurons & Receptors 37 Parasympathetic Nervous System (Rest and Digest)

Sympathetic Nervous System (Fight or Flight) Cholinergic receptors *Respond to Ach* Effector Cholinergic receptors *Respond to Ach* AP2- ANS Neurons & Receptors Adrenergic receptors *Respond to Norepi* 38 Parasympathetic nervous system (Rest and digest) Parasympathetic Nervous System (Rest and Digest)

Preganglionic Cholinergic Neuron- neurons receive a signal and thus release acetylcholine as their neurotransmitter Acetylcholine release Effector AP2- ANS Neurons & Receptors 39 Parasympathetic nervous system (Rest and digest) ACh binding to acetylcholine receptors signals the postsynaptic neuron to release its NT ACh.

Effector Acetylcholine release AP2- ANS Neurons & Receptors 40 Parasympathetic nervous system (Rest and digest) ACh binding to acetylcholine receptors on the effector (The heart). The parasympathetic dividion produces a parasympathetic response (Rest and digest) The heart rate slows down. Effector AP2- ANS Neurons & Receptors 41

Acetylcholine release Effector AP2- ANS Neurons & Receptors Sympathetic nervous system (Fight or Flight) Preganglionic Cholinergic Neuron- neurons receive a signal and thus release acetylcholine as their neurotransmitter 42 Norepinephrine release Effector

AP2- ANS Neurons & Receptors Sympathetic nervous system (Fight or Flight) ACh binding to acetylcholine receptors signals the postsynaptic neuron to release its NT Norepinephrine 43 Sympathetic nervous system (Fight or Flight) Norepinephrine binds to the adrenergic receptor on the effecter (heart). The sympathetic division produces a sympathetic response (fight or flight) The heart rate speeds up!

Effector AP2- ANS Neurons & Receptors 44 IV. Regulation of the ANS A. Autonomic Reflexes B. Enteric NS involved with autonomic reflexes & local reflexes that regulate GI-tract activity AP2 Chapter 16 45 IV. Regulation of the ANS Much occurs via autonomic reflexes Input from the cerebrum, hypothalamus, & other areas of the brain allow conscious thought & actions, emotions, & other CNS activities to influence ANS.

The regulation provided by the ANS is reqd to maintain homeostasis AP2 Chapter 16 46 IV. Regulation of the ANS Autonomic Reflexes Involves Sensory receptors Sensory neurons Interneurons Motor Neurons Effector Cells 2 imp. autonomic reflex centers:

Brainstem Spinal Cord Overall Control of the ANS: Hypothalamus Monitors & controls body temp Cxns w/ cerebrum (fxns in limbic system) thus the hypothalamus uses thoughts & emotions to prod ANS responses. There is overlap Posterior Hypothalamus: stimulation Sympathetic Response Anterior Hypothalamus: stimulation Parasympathetic Response 47 IV. Regulation of the ANS Enteric NS involved w/Autonomic & local reflexes that regulate activity of the GI-tract Autonomic Reflexes Help to control the GI-tract b/ c sensory neruons of the enteric plexus supply CNS w/

info about intestinal contents & ANS neurons to the enteric plexus affect the responses of the smooth muscle & glands w/in the GI-tract Ex: sensory neurons detect stretch & send info CNS wh/ sends signalsto smooth muscle of GI-tract to contract Local Reflexes Neurons of the ENS can also act independently A local reflex doesnt involve the CNS but it still produced an involuntary, unconscious, stereotypic response to a stimulus Ex: Sensory neurons not connected to CNS detect stretch action potential thru enteric plexus motor neurons cause muscle contraction or

48 relaxation V. Fxnal Generalizations about the ANS A. Stimulatory vs. Inhibitory FX B. Duel Innervation C. Opposite FX D. Cooperative FX E. General vs. Localized FX F. Fxns at rest vs. Activity AP2 Chapter 16 49 V. Fxnal Generalizations about the ANS on effector organs but most have exceptions A. Stimulatory vs. Inhibitory FX Both the SNS & PNS have both FX. Ex/ SNS will increase the heart rate but decrease contraction of the stomach

B. Duel Innervation Most effectors are innervated by both types of neurons Although most are not regulated equally by both (one side is more dominate) Ex: GI-tract PNS is more extensive than SNS BUT it isnt universal: Sweat glands & blood vessels are almost exclusively SNS AP2 Chapter 16 50 V. Fxnal Generalizations about the ANS on effector organs but most have exceptions C. Opposite FX D. Cooperative FX

In the situation of duel innervation the FX of the SNS are opposite of the PNS This means the ANS can increase or decrease the activity of a structure But it isnt always clear cut 1 division of the ANS can coordinate the activities of diff strucs Ex: PNS: salivary glands prod lrg vol of thin watery saliva SNS: Salivary glands prod sm. Vol of viscous saliva Both divisions can also wk. together to coordinate activity of diff strucs Ex: PNS can stimulate the

pancreas to secrete digestive enzs into sm. intest. & also stimulate contractions of the sm.intest to mix food w/enzs AP2 Chapter 16 Ex: In males: PNS initiates an erection SNS stimulates the release of secretions from glands & helps initiate ejaculation 51 V. Fxnal Generalizations about the ANS on effector organs but most have exceptions E. General vs. Localized FX: SNS has more general FX than PNS SNS: b/c activation often causes secretion of both epi & norepi from adrenal medulla These go throughout the bld stream & stimulate effectors throughout the body

Also prod longer FX than postsynaptic stimulation SNS diverges more than PNS SNS PreG synapse w/multiple PostG PNS PreG synapse w/only 2 PostG THUS stmulation of SNS PreG can result in greater stimulation of the effector SNS also often activates many diff kinds of effectors simultaneously but it can isolate 52 V. Fxnal Generalizations about the ANS on effector organs but most have exceptions F. Fxns at rest vs. Activity SNS PNS Fight or Flight Response Fxns under conditions of physical activity or stress Decreases activity of organs not essential for maintenance of

physical activity & shunts bld & nutrients to structures that are active during exercise Rest & Digest Response Fxns under resting conditions Regulates digestion by increasing the secretions of glands, promoting the mixing of fd w/ digestive enzs & bile, and moving material thru digestive tract Defecation & urination also controlled Increased activity of the PNS lower: heart rate, BP, constricts air passages, thus decreasing air mvmt 53

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