Autonomic Sensory nerves flash card

Autonomic Sensory nerves
– Main input of the ANS
– In visceral organs and blood vessles conveys information to intergrating centers
Intergrating centers
– in the CNS
interoceptors
-sensory receptors located in blood vessels, visceral organs, muscles and nervous system that monitor conditions of the internal environment- can be chemoreceptors or mechanoreceptors, respond to stimuli arising within the body;
– found in the internal visceral organs and include stretch receptors (in hollow organs), chemoreceptors and others
Autonomic Motor Neurons
– Propogate from the CNS to effector tissues
– regulate visceral activities by either increasing (exciting) or decreasing (inhibiting) ongoing activities in their effector tissues (cardiac muscle, smooth muscle, and glands).
– Changes in the diameter of the pupils, dilation and constriction of blood vessels, and adjustment of the rate and force of the heartbeat are examples of autonomic motor responses.
– Unlike skeletal muscle, tissues innervated by the ANS often function to some extent even if their nerve supply is damaged.
i.e. The heart continues to beat when it is removed for transplantation into another person
Enternic Division
– Independent network of nerves and ganglia within the wall of the gastrointestinal tract
Somatic Nervous System
-Consists of spinal and cranial nerves connected to skeletal muscles and skin receptors. These enable us to feel changes we can control
-Includes both sensory and motor neurons
– Convey input from somatic and special senses
-Sensory Input motor output
Autonomic Nervous System
-Consists of cranal nerves connected to non-skeletal muscles and glands. These nerves control functions that
contol breathing heartbeat and organ functions: things we cannot control
-Main input comes from autonomic sensory neurons
– Regulate visceral activities
-Sensory Input comes from visceral
– Sympathetic
– Parasympathetic
Anatomy of Autonomic motor pathway
Each ANS pathway has two motor neurons starting in the CNS and ending at an effector organ
Preganglionic neuron
-an autonomic motor neuron that extends from the CNS to an autonomic ganglion
-preganglionic neuron cell body lies in the CNS and its myelinated axon exits as part of a cranial or spinal nerve
Autonomic ganglia
– cluster of migrated nueral crest cells ( body and dendrites)
– Divided into 3 general groups : two are sympathetic ganglia one is parasympathetic ganglia
– are essentially a junction between autonomic nerves
originating from the central nervous system and autonomic nerves innervating their target organs in the periphery.
postganglionic nuerons
– second nueron in the pathway
– preganglion neuron synapses with a postganglionic neuron within the autonomic ganglion
-an autonomic motor neuron that extends from an autonomic ganglion to a visceral effector
– lies completely outside the CNS in the PNS
Motor neuron pathways information
– in the somatic nervous system and autonomic nervous system
-Note that autonomic motor neurons release either acetylcholine or nonepinephrine
-Somatic motor neurons release acetlycholine
Acetylocholine
-in the autonomic nervous system, all preganglionic fibers release the neurotransmitte
Norepinephrine
-In the autonimic nervous system, most sympathetic postganglionic fibers release the neurotransmitter:
Two divisions of ANS
– Sympathetic and Parasympathetic
– Most organs have dual innervation
– Nerve impulses from one division may stimulate and organ to increase its activity (excite)
– Nerve impulses form another division may decrease the activity (inhibit) the same organ
Development of autonomic Motor pathways
– nueral plate – formed the third week of gestation with a thickening of ectoderm
Nueral Groove- during the process of nerolation the plate forls inward and forms logitudinal groove
– Nueral Folds – the raised edge of the neural plate
– Nueral Tube – As development continues the neural folds increase in height and meet to form a tube (bcomes CNS)
– Nueral crest – becomes PNS, mass of cells from the edge of the fold migrate between the neural tube and skin ectoderm
Shared Anatomical components of an Autonomic Motor pathways
– as a result of there development both sympathetic and parasympathetic divisions share certian features while other aspects of there anatomy are unique.
Shared Anatomic components of the Autonomic Motor Pathway
– Motor neurons and autonomic ganglia
Shared Anatomic components of the Autonomic Motor Pathway
– in the thorax abdomen and pelvis, axons of preganglionic neurons of both sympathetic and parasympathetic divisions from the AUTONOMIC PLEXUS, many of which lie in major arteries.
– Autonomic Plexus also contains autonomic ganglia which is a group of cell bodies for the postgagnlionic neurons in the plexuses
Major Plexus in the thorax
Cardiac Plexus – supplies to the heart
Pulmonary – supplies to the bronchial tree
Major Autonomic Plexus in the abdomen and pelvis
Celiac of Solar – largest plexus surrounds the celiac and superior mesenteric arteries. distributed to the liver gallbladder stomach spleen kindney, superarnal medullae, gonads
Superior Mesenteric – supplies small and large intestines
Inferior Mesenteric – supplies the large intestine
Hypogastric – supplies the pelvic viscera
Renal – supplies the renal arteries with the kidney and ureters
Sympathetic Vs. Parasympathetic Preganglionic Neurons
– cell bodies of sympathetic preganglionic neurons are located in the later horns of the gray matter in the 12 thoracic segments and the first two lumbar segments of the spinal cord – thats why its also known as thoracolumbar division
– white and gray communication
Symathetic Vs. Parasympathetic Preganglionic Neurons
– cell bodies of parasympathetic preganglionic neurons are located in the nuclei of 4 crinal nerves in the brain stem (lll,VII,lX,X) and in the lateral gray horns of the second through forth sacral segments – why its also known as the craniosacral division
Axons of the Sympathetic Preganglionic Neurons
– preganglionic axons extend from white ramus communicans into the sympathetic trunk ganglion, they give off several axon collaterals ( branches) – terminate synapses in several way
1) some synapse in the first ganglion at the level of entry
2) pass up/down trunk to form the sympathetic chain ( fibers where ganglia are strung)
3) pass through sympathetic trunk without terminating it , beyond the trunk they form splanchinic nerves which extend to and terminate in the outlyning preventrebral ganglia.
Sympathetic Ganglia and Postganglionic Neurons
– Sympathetic Trunk Ganglia lie on each side of the spinal cord, extend from the base of the skill to the coccyx
– Postganglionic neurons arise form sympathetic trunk ganglia and do one of the following
1) return via gray communicating rami to anterior ramus of spinal nerve
2) exit into nerve branches that supply the heart
3) exit trunk in nerves that enter the plexuses that follow blood vessels in that region
Sympathetic Ganglia and Postganglionic Neurons part 2
– The cervical portion of each trunk ganglion is located in the neck and is subdivided into superior middle and inferior ganglia
– Superior – serve the head and heart
– Middle/Inferior – innervate the heart and blood vessels of the neck and shoulder
Sympathetic Prevertebral Ganglia
-Nerves that lead the second group of sympathetic ganglia
– lies in front of the spine
– 4 major preventrebral ganglia – celiac, superior mesentreric, inferior mesenteric, aorticorenal
4 major Preventrebral Ganglia
Celiac ganglion – is on either side of the celiac artery just inferior to the diaphram
Superior mesenteric ganglion – near the begining of the superior mesenteric artery in the upper abdomen
Inferior mesenteric- near the begininng of the inferior mesenteric in the middle of the abdomen
Aorticorenal – near the renal artery as it branches from the aorta
Structure of the Parasympathetic Division
– Cell bodies of parasympathetic preganglioonic neurons are found in the nuclei in the brain stem and in the lateral horns of the 2-4th sacral segments of the spinal cord
– Their axons emerge as part of a cranial nerve or as part of the anterior root of a spinal nerve
Parasympathetic Ganglia and Postganglionic Neurons
– Parasympathetic ganglia are the sights of synapse between parasympathetic preganglionic neurons and contain the postganglionic neuron cell body in the terminal ganglia
terminal ganglia
contain cell bodies of parasympathetic and postsympathetic neurons; ganglia located at the end of an autonomic motor pathway close to or actually within the wall of a visceral organ.
Terminal Ganglia in the head have specific names ( ciliary & pterygopalatine )
ciliary ganglia – in the orbit behind the eye that receives preganglionic innervation through the oculomotor nerve and gives rise to the postganglionic fibers that innverate the ciliary and sphincter muscles of the pupil
pterygopalatine ganglia – lateral to the sphenopalatine forearm ,send postganglionic axons to the nasal mucosa, palate, pharynx and lacrimal glands
Terminal Ganglia in the head have specific names (submandibular & otic)
submandibular ganglia- found near ducts of submandibular salivary glands, receive preganglionic axons from facial nerves and send postganglionic axons to the submandibular and sublingual salivary gland
otic ganglia- situated just inferior to each foramen ovale, receive preganglionic axons from the glossopharyngeal nerves and send postganlgionic axons to the parotid salivary glands
Structures of the Enteric Division
– the gastrointestinal tract forms an extensive areaof contact with the environment
– Consists of a specialized network of nerves and ganglia with the wall of the GI tract, pancreas, gallbladder
-forms an intergrated neuronal network that contains millions of neurons ( same # as in the spinal cord)
– capable of continued function without input from the CNS
-Most nerve fibers that innervate the digestive organs arise from two plexuses within the enteric system * Myenteric plexus *Submucosal plexus
Structures of the Enteric Division : Myenteric plexus & submucosal plexus
* (Largest )positioned between the smooth muscle layers from the upper esophagus to the anus communicated extensively with submucosal plexus
* within the gut wall (between the circular muscle layers and the muscularis mucosae) from the stomach to the anus.
ANS Neurotransmitters and Receptors
– classified by the neurotransmitter they produce and release
– receptors for the neurotransmitters are integral membrane proteins in the plasma membrane of the postsynaptic neuron or effector cell
* type of receptor determines whether the effect will be to excite or inhibit.
Cholinergic Neurons and Receptors
-In the ANS the cholinergic neurons release acteylocholine (ACh)
– includes all sympathetic and parasympathetic preganglionic nuerons
– sympathetic postganglionic neurons that innervate most sweat glands
– All parasympathetic post ganglionic neurons
Two types of Cholinergic receptors : Nicotinic receptor & Muscarinic receptor
-located on both sympathetic and parasympathetic postganglionic neurons . Activation by ACh always causes depolirizations ( excitation)
– found in plasma membrane of all effectors innervated by parasympathetic postganglionic axons(gland, smooth and cardiac muscle cells) activation by ACh can either excite or inhibit depending on which cell bears the muscarinic receptor
Adrenergic Neurons and Receptors
– in the ANS release noreepinephrine (NE) aka nonadrenalin
– Most sympathetic postganglionic neurons are adrenergic
– Like ACh NE is synthesized and sotred in synaptic vesicles and released by exocytosis
:Alpha receptors beta receptors
– bind NE and epinephrine
– -two main types of adrenergic receptors
– found on visceral effectors innervated by most sympathetic postganglionic axons
*a1 & b1= produce excitations
*a2 & b2 = causes inhibition of effector tissues
Adrenergic Receptors
– NE lingers in the synapse longer than ACh
* activity is terminated when either
1) the reuptake of the NE by the axon
2) NE is inactivated by the enzymes COMT or MAD
Functions of the ANS
– Most body organs are innervated by both divisions of the ANS
* typically work in poosition to one anaother
* balance is regulated by hypothalamus
– Role of the hypothalmus
* increase sympathetic activity at the same time it decreases parasympathetic activity and vs
Functions of the ANS : Two divisions affect body organs differently
– b/c of the time of neurotransmitter released by their postganglionic neuron and the type of receptors the cell of there effector organs
– Structures innervated only by the sympathetic division include :
*sweat glands, arrector pill muscles, kidneys, spleen, most blood vessels and the suprarenal medullae
Sympathetic Responses : Fight or Flight Response
– activation of the sympathetic division and release hormones
* dilate pupils *increased heart rate, force of heart contraction and blood pressure
*dilate airways- allowing faster movement of air into and out of the lungs
* dilation and constriction of blood vessels
* activate liver cells to perform glycogenolysis (breakdown of glycogen to glucose) and adipose tissue to perform lipolysis ( breakdown of triglycerides to fatty acids ) -> release of glucose by the liver increase blood level glucose
* processes that are not essential for meeting the stressful situation are inhibited `
Clinical Connection
– Drugs and natural products can selectively activate or block cholinergic/adrenergic receptors by mimicking a natural NT or hormone
* AGONIST- substance that binds to and activates a receptor –> phenylephrine alpha agonist (A1>A2) constricts blood vessels in the nasal mucosa – reduce production of mucus.
*ANTAGONIST – substance that binds to and blocks a receptor —>
– atropine – blocks muscarinic ACh receptors, dialates the pupils, reduces the glandular secretion, and relaxes smooth muscle in the GI tract
– propranol – non selective beta blocker for hypertension, reduces heart rate.
Parasympathetic Responses : Rest and Digest
– SLUDD – salivation, lacrimination, urination, digestion, defication
-decrease heart rate, diameter of airways , decrease diameter or pupils
– support body functions that conserve and restore body energy during times of rest and recovery
– In quiet intervals between period of exercise parasympathetic impulses to the digestive glands and the smooth muscle of the GI tract predominate over sympathetic impulses.
Autonomic Reflexes & Reflex Arcs
– responses that occur when nerve impulses travel over and autonomic reflex arc
– a neural pathway that elicits a relfects and contains a receptor, sensory neuron, integrating center, motor neuron, and effector
Intergration and control of Autonomic Functions : receptor, sensory, intergrating, motor, effector
Receptor – distal end of a sensory neuron, responds to stimuli and produces a change that will ultimately trigger nerve impulses
Sensory Neuron – Conducts nerve impulses form receptors to CNS
Integrating center- interneurons within the CNS that relay impulses from sensory to motor neurons (most autonomic found in hypothalmus and brain stem)
Motor Neuron – nerve cell that carries messages away from the central nervous system towards the muscles and glands; efferent neuron
Effector- in the autonomic reflex arc they are smooth, cardiac muscle, and glands
which of the following statements is true for the parasympathetic division of the autonomic nervous system?
b) the PNS forms craniosacral flow
Which of the following cranial nerve nuclei is not a site of cell bodies of preganglionic neurons of the parasympathetic division
b) V
which of the following statements about gray rami is false ?
A) they carry preganglionic neurons form the anterior rami of the spinal nerves to the trunk ganglia
which of the following is not a sympathetic ganglion?
a ) ciliary
The ANS provides the chief nervous control in which of these activities ?
D) digesting food
White Rami communicants connect :
e) the anterior ramus of a spinal nerve wita sympathetic trunk ganglia
Cholinergic fibers are thought to include:
e) all the above
Which of the following statements wouldnt be included in a description of the sympathetic trunks?
c) each trunk receives preganglionic fibers from the thoracic and sacral regions of the spinal cord
which of the following could not be a result of the binding of acetylcholine to nicotinic receptors?
D) increase hear rate
______ nerves are extensions of preganglionic sympathetic axons that pass through sympathetic trunk ganglia and extend to preventrebral ganglia
splanchnic
organs such as the heart of stomach that recieve impulses from both divisions of the ANS are said to have _______ innervation
dual
Norepinephrine is enzymatically inactivated by COMT or ______
MAO
The two types of adrenergic receptors are _____ and _____
alpha and beta
The two types of cholinergic receptors are ____ and _____
nicotinic and muscarinic
The endocrine gland stimulated direclt by sympathetic preganglionic neurons is the _____
adrenal medulla
Nearly 80 percent of the craniosacral outflow of the parasympathetic division is conducted via preganglionic axons leaving the brain with the ____
Vagus nerve
In fight or flight response , blood glucose levels increase T or F
True
a major difference between autonomic ganglia and posterior root ganglia is that only autonomic ganglia contains synapses
true
The ganglia that make up the sympathetic trunks are also called prevertrebral of collateral ganglia
False – the ganglia that makes up the synaptic trunks are also called paraventrebralor ventrebral chain ganglia
Postganglion neurons begin in the spinal cord and extend to effectors
FALSE- postganglionic neurons begin in the autonomic ganglia
One event occuring during the fight or flight response is increased urine production due to blood being shunted to the kidneys
FALSE – One event occuring during the fight or flight response is DECREASED urine production due to blood being shunted AWAY FROM kidneys
All sympathetic and parasympathetic preganglionic neurons release the neurotransmitter norepinephrine
FALSE- All sympathetic and parasympathetic preganglionic neurons release the neurotransmitter acetycholine ACh