Lecture 2 nervous ppt Flashcards
What are the 5 elements of neurons?
1) Cell body
2) Dendrites
3) Axons
4) Myelin sheath around some axons
5) Synapse
What is the mnemonic to help remember the order of the cranial nerves?
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1) What type of neuron cell bodies tend to be in the CNS?
2) What about the PNS?
1) Motor tend to be in CNS (UMN, LMN)
2) Sensory tend to be in PNS (DRG)
1) What do dendrites do?
2) What do axons do?
1) Dendrites: impulses from receptors to neuron
2) Axons: impulses from neuron to site of action
What do synapses do?
Communicate with neurotransmitters (excite or inhibit)
What do neuroglia do?
Support, insulate, & nourish neurons
What are the 3 functions of myelin?
1) It acts as an electrical insulator for the neuron
2) Prevents depolarization
3) It speeds up conduction/ transmission of an electrical impulse
What does the CNS do?
Integrate and coordinate signals to and from soma (body) & central nervous system
1) Define nucleus and give an example
2) Define ganglia and give an example
3) Define tracts and give 2 examples
1) Nucleus: collection of nerve cell bodies within CNS (lateral geniculate nucleus in thalamus)
2) Ganglia: collection of nerve cell bodies outside of the CNS (paravertebral sympathetic ganglia)
3) Tracts: bundle of nerve fibers (axons) connecting nuclei in CNS.
-Ex: corticospinal tract or corticobulbar tract
1) Define gray matter
2) Where’s it’s located?
3) What are the parts of this location?
1) Nerve cell bodies
2) The brain and grey matter horn (H) in spinal cord
3) Parts of horn: anterior (motor), dorsal (sensory), lateral (sympathetic and parasympathetic)
1) What is white matter?
2) What are the 3 layers of meninges?
3) Where is the CSF?
1) Fiber tracts
2) Pia, arachnoid, dura mater (split in cranium)
3) Subarachnoid space
1) A collection of nerve cell bodies within CNS is called?
2) A collection of nerve cell bodies outside of the CNS is called?
3) A bundle of nerve fibers (axons) connecting nuclei in CNS is called?
1) Nerves
2) Ganglia
3) A tract
How many cranial nerves are there?
12 pairs
List the order of the spinal nerve sections and how many nerve are in each section
Cervical-8
T-12
L-5
S-5
Coccygeal-1
What are the functional components of the nervous system? Define each.
What may both have?
1) Sensory (afferent): toward brain
2) Motor (efferent): away from brain
3) Somatic (voluntary) and visceral (involuntary) components
What are the two structural categories of the nervous system? Define each
1) CNS: brain and spinal cord
2) PNS: cranial and peripheral nerves “outside” the CNS
1) What is the gray matter of the CNS made of?
2) What is the white matter of the CNS made of?
3) What are the nerve cell bodies of the PNS called?
4) Does the PNS have fiber tracks?
1) Nerve cells, nuclei
2) Fiber tracks
3) Ganglia
4) Yes
1) Define the somatic nervous system
2) What does it provide, and what to? What are the exceptions?
3) What 4 things does it transmit?
4) What does it stimulate?
1) Somatic parts of CNS and PNS
2) General sensory and motor to all parts of body (soma)
-Except: viscera in body cavities, smooth muscle, and glands
3) Touch, pain, temperature, proprioception
4) Skeletal (voluntary) muscle contraction
1) Define visceral nervous system
2) What does it provide? To where?
3) What are its 3 functions?
4) What 3 things does it stimulate?
1) Visceral (autonomic) parts of CNS and PNS
2) Visceral sensory and motor innervation to viscera, smooth muscle, and glands
3) Visceral sensory pain, reflexes, regulates visceral function
4) Smooth muscle in walls of vessels and organs, modified cardiac muscle (intrinsic stimulating and conducting tissue), and glands
What is the mnemonic to help remember whether a cranial nerve is sensory, motor, or both?
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1) What CN nerve(s) arise from the brain?
2) Which CN nerve(s) arise from the spinal cord? What part of the spinal cord and where does it/they go?
1) CN I-X and XII arise from brain
2) CN XI (spinal accessory n.) from cervical spinal cord to transverse foramen magnum into skull
1) What are the 2 types of cranial motor nerves?
2) What are the 3 types of cranial sensory nerves?
1) Somatic and visceral (aka autonomic)
2) Somatic, visceral, special (vision, hearing, taste, balance)
1) How many pairs of spinal nerves are there?
2) List the number in each section of the spine
3) Where do they originate and emerge?
4) What does each nerve do?
1) 31 pairs
2) C8, T12, L5, S5, Co1 (differ than vertebral count)
3) From the spinal cord
4) Follows a defined path and serves a specific region of the body
1) The specific region innervated by each somatic spinal nerve is called what?
2) Where are dermatomes guaranteed to end?
3) Why is this important?
1) A dermatome
2) The midline
3) Meningitis sometimes will remain on one side because of dermatomes
Give 4 examples of what special cranial sensory nerves are responsible for
Vision, hearing, taste, balance
1) Are spinal nerve roots sensory, motor, or both?
2) What does is the posterior ramus innervate?
1) Both sensory and motor
2) Mid back
What 3 things are found within the anterior ramus of a spinal nerve?
1) White ramus communicans
2) Sympathetic truck (also runs through posterior)
3) Gray ramus communicans
1) Where does the anterior ramus go?
2) True or false: Peripheral nerves are mixture of modalities
1) Continues to remainder of soma (body)
2) True
What are the 3 types of fibers found within peripheral nerves?
Afferent, efferent, and postsynaptic sympathetic fibers
If you feel touch just above your mid back, what ramus is this going to?
Posterior ramus of spinal nerve
If you feel touch in your arm, what ramus is this going to?
Anterior ramus of spinal nerve
1) What type of ganglia are closer to their target organ?
2) What kind is further?
1) Parasympathetic
2) Sympathetic
What is the difference in origin between an upper motor neuron (UMN) and a lower motor neuron (LMN)?
1) UMNs: originate in the cerebral cortex, travel down to the spinal cord or brainstem
2) LMNs: begin in the spinal cord.
1) If there’s a peripheral nerve injury, what do you know has survived if function is able to be restored?
2) What happens around the lesion? Why?
1) Neurons
2) Axons degenerate distal to the lesion because of loss of “life support”
1) Describe how healing peripheral nerves from a crush injury works
2) Describe how healing peripheral nerves from a severed (cut) nerve injury works
3) What may a vasa nervorum injury result in?
1) If nerve cell body survives and connective tissue coverings of nerve intact, they guide regenerating axon to their destination
2) Surgical repair often needed for apposition of the severed ends of the connective tissue “guide” to direct axons growth to their correct destination
3) Ischemia may result in damage to nerves
Sympathetic (thoracolumbar) division of motor innervation:
1) Where does it come from and go?
2) What is its primary function?
3) Is it catabolic or anabolic? Why?
1) Outflow from CNS to T1-L3
2) Regulate BP (also has other functions)
3) Generally catabolic; to prepare for flight or fight
What are the two divisions of visceral (autonomic) motor innervation?
Sympathetic (thoracolumbar) and parasympathetic (craniosacral)
Parasympathetic motor innervation:
1) Where does it come from and go?
2) Is it catabolic or anabolic? Why?
1) Outflow from the CNS to CNs 3,7,9,10 and S2-3-4
2) Generally anabolic, because it’s promoting normal function and conserving energy
1) Do sympathetic and parasympathetic usually innervate same structures, or different structures?
2) Where are the visceral presynaptic (preganglionic) neurons located? Where do they terminate?
3) Where are the visceral postsynaptic (postganglionic) neurons located? Where do they terminate? Give examples
1) Usually same structures, but have contrasting/coordinating effects
2) Grey matter (nuclei) in CNS; their axons synapse with 2nd neuron
3) Outside of CNS in ganglia (paravertebral ganglia); their axons terminate at effector organs
Exs: smooth muscle, glands, cardiac conduction tissue, etc
Sympathetic motor division:
1) Where are its presynaptic neurons? Where do their fibers outflow?
2) Where are its postsynaptic neurons? What are they conveyed by?
1) Lateral Horn of spinal cord; via thoracolumbar nerves (T1-L3)
2) In paravertebral and prevertebral ganglia; by all branches of the spinal nerves
1) What is the primary function of the sympathetic motor division?
2) What does symp. motor innervate?
3) Are parasympathetic motor fibers related to spinal nerves? If so, how?
1) Modulate BP
2) Smooth muscles of blood vessels, sweat glands, erector pili m. of the skin, cardiac conduction tissue
3) Have limited association with spinal nerves (S 2-3-4)
1) Where are the sympathetic presynaptic neurons found?
2) What part of the spine is this?
1) Paired left and right IMLs (aka lateral horns/ grey matter of cord)
2) T1-L2/L3
What are the two locations of sympathetic postsynaptic neurons? (hint: both ganglia)
1) Paravertebral ganglia
2) Prevertebral (preaortic) ganglia
1) Define paravertebral ganglia
2) What is located here?
3) What is the most superior paravertebral ganglia? Where is it?
4) What is the most inferior? Where is it?
1) Symp.trunks/ chains on either side of vertebral column
2) Symp. postsynaptic neurons
3) Superior cervical ganglia; base of cranium
4) Ganglion impar; where two chains unite at level of coccyx
1) Where are prevertebral (preaortic) ganglia found? (4 places)
2) What is found within them?
1) In plexuses that surround origins of the main branches of the abdominal aorta (celiac ganglia) and the aortic, hypogastric, and pelvic plexuses that descend from them
2) Sympathetic postsynaptic neurons
1) Where do symp. presynaptic motor fibers that provide autonomic innervation within the head, neck, body wall, limbs, and thoracic cavity go?
2) Where do they exit and go?
3) Where do symp. presynaptic fibers innervating viscera within the abdominopelvic cavity pass through? Where do they synapse?
1) Either ascend within the paravertebral ganglia at current level, ascend or descend then synapse
2) Via grey communicans; into the spinal nerves.
3) Sympathetic chain; within the prevertebral (preaortic) ganglia (then to their effector organ)
What are the two structural divisions of the nervous system?
CNS and PNS
What are the two functional divisions of the nervous system?
Motor (efferent) and sensory (afferent)
Describe the path of the symp. postsynaptic motor fibers that innervate below the head (3 steps)
1) Paravertebral ganglia of sympathetic trunk, then through Gray rami communicantes
2) To adj. anterior rami of spinal nerves
3) Then enter all 31 spinal nerves (incl. posterior rami)
Do sympathetic postsynaptic motor fibers enter all spinal nerves?
Yes, they enter all 31, including their posterior rami
Give 3 examples of things done by postsynaptic somatic motor fibers
1) Regulate blood pressure via of blood vessels tone; vasomotor tone
2) Erector pili muscles in skin (goose bumps)
3) Diaphoresis (sweating)
Define diaphoresis
Sweating
What would happen if sympathetic postsynaptic motor neurons stopped working? (3 things)
You would lose all vasomotor tone (so die), not be able to form goosebumps, and not be able to sweat
What is the path of sympathetic motor fibers that go to the head? (3 steps)
1) They all have their post synaptic cell bodies in superior cervical ganglion
2) Ascend into cranium via periarterial plexus of nerves following branch of the carotid artery
3) Hitch a ride with cranial nerves to target organ (eye via CN III, oculomotor nerve).
Define splanchnic
Internal abdominal organs
1) What do sympathetic splanchnic nerves convey?
2) Where do the postsynaptic symp. splanchnic motor fibers go?
3) Where do the presynaptic symp. splanchnic motor fibers go?
1) Visceral efferent and afferent nerves to & from the viscera of the body cavities
2) Thoracic cavity viscera
3) Abdominopelvic cavities viscera
1) What is the path splanchnic postsynaptic symp. motor fibers take to the viscera of thoracic cavity?
2) Where do they terminate? (3 places)
3) What do they form?
1) They course through the cardiopulmonary splanchnic nerves
2) Enter cardiac, pulmonary and esophageal plexuses
3) Peri-arterial plexuses following arterial branches to target organs
1) What nerves do splanchnic presynaptic symp. motor fibers use to innervate the viscera of abdominopelvic cavities?
2) Where do they terminate? List all 6 places
1) Abdominopelvic splanchnic nerves (greater, lesser, least, and lumbar splanchnic nerves)
2) Prevertebral (preaortic) ganglia: celiac, aorticorenal, superior& inferior mesenteric, aortic, hypogastric, & pelvic ganglia
What is the suprarenal gland also called?
Adrenal gland
1) What is the suprarenal gland innervated by? What is the path it takes to get there (2 steps), and where do these nerve fibers terminate?
2) What do the cells the nerve fibers terminate on function as? What do they release?
1) Presynaptic sympathetic fibers:
A) Pass through sympathetic ganglia chain B) And through prevertebral (aorticorenal) ganglia to terminate directly onto adrenal medulla cells
2) Function as postsynaptic neurons; release neurotransmitter (NE) directly into blood stream for widespread sympathetic response
What do adrenal medulla cells act as?
Postsynaptic neurons
What type of fibers innervate the suprarenal gland?
Presynaptic sympathetic fibers
What are the two types of parasympathetic outflow?
Cranial and sacral
What are the two groups of places parasympathetic cranial outflow goes?
1) The head
2) The thoracic and abdominal viscera
1) How many nerves does parasympathetic cranial outflow use to innervate the head? List them
2) How many pairs of ganglia does parasympathetic cranial outflow use to innervate the head? List them and what each effects.
1) 3 CN: #s 3, 7, 9)
2) 4 pair of ganglia:
A) Ciliary ganglia (pupil)
B) Terygopalatine (lacrimal gland)
C) Otic (parotid gland)
D) Submandibular (Sublingual and submandibular salivary glands)
1) How many nerves does parasympathetic cranial outflow use to innervate the thoracic and abdominal viscera? List them
2) What is innervated?
1) CN X, Vagus n.
2) All thoracic viscera and GI to the splenic flexure of colon
1) Where does parasympathetic sacral outflow (innervates body) come from?
2) Describe the path they take.
3) How many places are innervated by this type of outflow? List them
1) S 2-3-4
2) Lateral horn grey matter via anterior S2-4 spinal nerve, anterior rami to pelvic splanchnic nerves
3)
A) Pelvic viscera
B) Erectile tissues of external genitalia and bladder
C) GI from pelvic flexure of colon distal (descending colon, sigmoid colon, & rectum)
Which’s ganglion are embedded near its target organ, sympathetic or parasympathetic?
Parasympathetic
1) Is sympathetic catabolic or anabolic? Why? What about parasympathetic?
2) Where are sympathetic presynaptic bodies located? What about parasympathetic?
1) Sympathetic is catabolic for flight or fight. Parasympathetic is anabolic to conserve energy
2)
-Sympathetic: in grey matter of the spinal cord.
-Parasympathetic: in cranial gray matter & S2-3-4 lateral horn gray matter.
Are parasympathetic postsynaptic fibers long or short? Why?
Relatively short because they run from a ganglion embedded near or in target organ
1) Where are sympathetic postsynaptic bodies located? What about parasympathetic?
2) Are sympathetic presynaptic fibers long or short? What about parasympathetic?
2) Are sympathetic postsynaptic fibers long or short? What about parasympathetic?
1)
-Sympathetic postsynaptic bodies located in the sympathetic trunk ganglia or prevertebral ganglia.
-Parasympathetic post synaptic bodies in cranial ganglia (4 pair) or walls of the target organ
2) Sympathetic presynaptic sympathetic fibers are relatively short. Parasympathetic presynaptic fibers are for the most part long.
3) Sympathetic postsynaptic fibers are relatively long & extend to all parts of the body. Parasympathetic postsynaptic relatively short running from a ganglion embedded near or in target organ.
1) Does the enteric nervous system rely on the CNS?
2) What modulates the enteric nervous system?
1) Functions autonomously from CNS
2) Parasympathetic and sympathetic input
What makes up the enteric nervous system?
Two interconnected plexuses: myenteric and submucosal
Do the two plexuses of the enteric nervous system function entirely independently of each other?
No, they’re interconnected
List and describe the locations of the plexuses of the enteric nervous system
1) Myenteric plexus: in wall smooth muscle
2) Submucosal plexus: deep to mucosa
What 4 things does the enteric nervous system do?
Controls local input and reflex activity for:
1) Exocrine & endocrine secretion
2) Vasomotion
3) Micro-motility
4) Immune activity of the gut
What part of the nervous system has had its existence debated?
Visceral afferent
1) Are we aware of the actions of the visceral afferent part of the nervous system? What does it do?
2) What two things does it trigger?
1) Usually unaware; gives input to CNS regarding condition of internal environment
2) Visceral and somatic reflexes
When we do perceive visceral afferent input, what is that perception like?
Input that reaches conscious level is often poorly localized PAIN, hunger, or nausea
1) How do we perceive normal visceral afferent activity?
2) How do we perceive pathologic visceral afferent activity? Give an example
1) Usually produces no stimulation of conscious perception
2) Pathologic, such as ischemia, lowers normal threshold and pain is perceived
Give two more examples of perception of pathologic activity of the nervous system
1) MI causes referred pain, nausea
2) Acute distension, spasm or strong contraction of GI tract
Referred pain and nausea caused by a heart attack involves what part of the nervous system?
Visceral afferent
1) What two things travel in visceral afferent fibers that accompany the parasympathetic fibers retrograde?
2) Most visceral pain impulses from the heart and most organs of the peritoneal cavity travel what path? Where do they synapse?
1) Most visceral reflex (unconscious) sensations, and some pain
2) Centrally via visceral afferent fibers accompanying sympathetic fibers retrograde and synapse in DR (dorsal root)
1) Why can you have referred pain?
2) What about with a heart attack specifically?
1) Visceral pain is transmitted retrograde via visceral afferent fibers of sympathetic fibers to the spinal DRG (dorsal root ganglia), so pain can be “referred” to that spinal cord segment’s dermatome
2) T1-4/5 visceral afferent fibers (of sympathetic fibers) transmit pain from the heart to the spinal DRG, so pain is “referred” to the T1-4/5 dermatome
Define myotome
A group of muscles innervated by a single spinal nerve root
1) What does the corticospinal tract run through?
2) How long is it?
1) The lateral column of spine
2) Goes from C1 to L1 or L2
1) Where are the sympathetic presynaptic neurons found?
2) What about postsynaptic?
1) In intermediolateral cell columns (IMLs) aka, lateral horns (grey matter of cord)
2) Paravertebral and prevertebral (preaortic) ganglia
