Study Guide Nervous System and Pain PDF

Study guide Nervous System and Pain Week 1 - Nervous system composed of CNS and PNS. - Nervous system high energy and requires glucose and blood llow. Disruption of nutrients and O2 can lead to neuronal cell death. - Ascending pathways carry sensory info from periphery to CNS - Desc...

Study guide Nervous System and Pain Week 1 - Nervous system composed of CNS and PNS. - Nervous system high energy and requires glucose and blood llow. Disruption of nutrients and O2 can lead to neuronal cell death. - Ascending pathways carry sensory info from periphery to CNS - Descending pathways carry info from CNS to periphery. - Brainstem includes midbrain, pons, and medulla. - Cerebellum involves functions in coordinating movement. - Thalamus serves as relay station for body senses. - 3 deep nuclei of brain are basal ganglia, hippocampus, and amygdala - Basal ganglia -- helps regulate movement - Hippocampus -- involved in memory - Amygdala -- involved in emotions fear, fighting, food, and mating - Neuron smallest unit of nervous system. - Calcium needed for synapses. - Glial cells help support functionsof neurons. They include oligodendrocytes, astrocytes, and microglia - Astrocytes help from blood brain barrier and synthesize neurotransmitters. - Glioblastomas most malignant form of primary brain cancers. - Oligdendrcytes synthesize yelin in CNS - Schwan cells sntehzie myelin in PNS. - Microglial cells help after neuronal injury and serve as scavenger to cela up debris. - Spinal reflexes ave different types of neural circuit scuh as feedforward excitation, feedforward inhibition, and convergence. Week 2 - Senosry transduction process couples stimulus detection to the opening or closing of ion channels. Direct generation of membrane potentials in receptor endings of sensory neurons. This may lead to threshold change in membrane potential of sensory neuron that can trigger an action potential. - Somatosensation provdes information about what is happening on surface of our bodies as well as internally. - For somatosensation tehre are - touch and position pathways - mechnaoreceptors - pain and tempertarue pathways - temperature, chemical, painful touch, painful chemical, painful temperature. - Mechanoreceptors -- sensations of light touch, pressure, and vibration are caused by movent of skin by external stimulus. - Mechanoreceptors could have lemallase to magnify movement or just free nerve endings. - 4 types of mechanoreceptors - Messiner corpuscle -- motion stimulus, found near epidermis, rapidly dapting. Meissner = person who is messy is all over the place and constantly moving. Motion stimulus. Energy up near surface. - Pacinian corpuscle -- vibration, found deep within skin, rapidly adptin. Mneumonic Pacinian copuscle = rhymes withvibration so vibration felt. - Merkel cell neurite complex -- goot at detecting static motion, near skin, slow adapting. Mneumonic murky water stands still so good for static. - Ruffini corpuscle -- tells you about constant presence of smothing like skin stretch,, in the middle depthwise, slow adapting. Mneumonic when you play rough you constantly strentch something so stretching of skin for period of time. - Sensory receptors can tell you about intensity duration, location, and modality of stimulus. Think MILD for different types of things sensory receptors can tell you. - Size of receptive field varies. Greater density of receptors, the smaller the receptive field. Greatest 2 point discrimination and point locatlization accuracy is in skin areas with smallest receptive fields and afferent nerve highest density. Ex. fingers have small receptive fields so precise location can be identified. Back has larger receptive fieldsm less likely ot distinguish where feeling is coming from. - Paresetheisa -- weird feeling on skin tingling or numbness - Anesthesia -- total loss of sensation - Hyposthesia -- reduced sense of touch or sensation - DCML- information about touch from mechanoreceptors. Decussation in medulla. Uses A beta fibers. - ALS /spinothalamic pathway -- infromation about pain and temperature from free nerve endings. Decussation in spinal cord. Uses A delta and C fibers. - Somatosensory information from face travels along trigeminal system. - DCML pathway -- fasciculus gracilis caries sensory information from lower part of body and is found more medially. Fasciculus cuneatus caries sensory information from upper part of body and is found more lateally. - Second order neurons in DCML pathway travel in pathway called medial lemniscus. - Second order neurons snapse in thalamus in ventral posterior lateral nucleus of the thalamus. - ALS pathway - Pain transmission is called nociception. Nocicpetors trigger pain. - Thermal receptors are free nerve endings in the skin that respond to warmth or coolness. Transduction involves ion channels on thermoreceptor called transient receptor potential channels. - Change in temperatyre causes change in TRVP1 receptor protein. - TRVPV2 receptor detcts noxious heat above 125 F. V for very hot. - TRPV1 receptor detects heat, capsaicin above 109 F. V for very hot. - TRPA1 receptor detects noxious cold below 64 F. A for antarctica. - Hysiciological (nociceptive)pain -- nervos system doing its job as we respodnd to noxious stimuli. - Neuropathic (intractable) pain -- result from injury to PNS or CNS and ccurs when nervous system is damaged. Body thinks there is pain, but there is not actually pain. - ALS pathway decusates in spainal cord. Second order neuron axons terminate in ventral posteriorlateral thalamus and synapse into third order neurons. Then go to primary somatosensory cortex. - Trigenothalamic tract -- primary aoxons from pain and temperature in face go to mid pos, descend to medulla and then to spinal trigeminal nucelus or spinal nuclues of V. Then they synapse with second order neurns and decussate. Then ascend to ventral trigeminal thalamic tract to ventral posterior medial nuclus of thalamus to synapse with third order neurons. - Spinothalamic Tract (STT): - This pathway carries information about pain, temperature, and crude touch from the body. - It projects to the ventral posterior lateral (VPL) nucleus of the thalamus. - Dorsal Column-Medial Lemniscal (DCML) Pathway: - This pathway transmits fine touch, vibration, and proprioception from the body. - It also projects to the VPL of the thalamus. - Trigeminothalamic Tract: - This pathway carries sensory information (pain, temperature, touch, and proprioception) from the face. - It projects to the ventral posterior medial (VPM) nucleus of the thalamus. - Central pain processing: pain matrix -- S1 informs pain, intensity, modality, and location, but other brain region activites closely correlated to experience of pain. - Anterior cingulate cortex -- part of limbic system involved in emotional learning. - Insula -- self-awareness, snese of self in pain, sense of visceral pain. - Refrontal cortex -- anticipation of pain -- activated during placebo effect with PAG. - Periaqueductal grey (PAG)- important side of endogenous inhibition. The periaqueductal gray (PAG) is a key structure in the propagation and modulation of pain, sympathetic responses as well as the learning and action of defensive and aversive behaviors. - The periaqueductal gray (PAG) receives inputs from higher brain centers and is capable of activating a powerful analgesic (can help relieve pain) effect. The rostroventromedial medulla (RVM) can both facilitate or inhibit nociceptive inputs and acts as a final relay in the control of descending pain facilitation. - Opiods can help relieve pain in dorsal horn of spinal cord. - Neuropathc pain is pain asscaited with damae or disease to nervous system. - Neuropathic pain involves peripheral and central sensitivation. - Peripheral sensitization -- reduction in threshold and increase in responsiveness of peripheral ends of nocicpetors. - Central sensitization is increase in excitability of nerous in CNS. Alters strnegh of synaptic connections. Makes lower threshold for stimulus so we feel more apin. - Hyperaglasia -- nocictors becomes oversensitive to pain. - Allodyinia touch receptors cross over and talk to pain nerusons. Feel pain where you shouldn't. - Basal ganglia and cerebellum help modulate motor ouput by influencing upper motor neurons to improve movement efficiency, corrdate timing between muscle groups to produce fluid movemnts, and make movements adaptable in real time. - Basal ganglia include a group of nuceli which function to select and intiate a collection of relevant movements for a given takes and inhibit competing movements for that task. - Basal ganglia and cerebellum have slightly different functions - The basal ganglia - ensures that the correct movements are initiated and maintained, while unwanted movements are suppressed  - the cerebellum - guarantees that movements take place in a smooth and coordinated way  - Basal ganglia neurons fire before movement happens. - At rest, basal ganglia neurons tonically (continuously) inhibit the thalamus - When the neurons of the basal ganglia are stimulated, the direct or indirect pathways are activated. - Direct pathway - disinhibits (releases inhibition) thalamic neurons that could stimulate wanted mortor programs can now fire. - Indirect pawthway - reinforces inhibition so the thamaic neurons that could stimulate unwanted motor programs will not fire. - Input nuclei of the basal ganglia are called the striatum and include the caudate and putamen. - Output nuclei of basal ganglia is globus pallidus. Includes globus palidus internal segment more medially and the external segment more laterally. - GPi works to inhibit thalamus in resting state. - Modulatory nuceli in basal ganglia are globus pallidus external, subtha,amic nucleus, and substantia nigra. - Usually, GPi inhibits thalamus so movement doesn't occur. When movement wants to occur, substantia nigra releases dopamine which stimulatews striatum. Striatum then inhibits globuss palidus internal. With GPi inthibited, excitatory projections stimulate movmenet in the cerebral cortex. The motor program is then activated. - - Loss of stimulatory drive from substantia nigra because dopamine not released results in slower or absent movements. This occurs in Parkinson's. - Parkinson's disease. Mnemonic Parkinson's you park directly in the spot so direct pathway. when you park uou are slow s Parkinson's accoicated with trouble wit movements, slower movements. Diffculties initialing movement in parkinsons because indirect pathway not doing its job to control when movements occur. When you park you have slower movements of car, car can shake a little or just not move as quickly. - Symptoms of parkinson's include tremor, rigidity, lack of ovemnt, slowrr movements, shuffing with reduced arm swing, and postural changes. - Indirect pathway reinforces inhibitory drive to thalamus, repressing movement that is unwanted. Indirect pathway greater stimulus to the GPi, - Indirect pathway summary -- cortical neurons excite the striatum, striatum inhibits GPe which now cannot inhibit subthalamic nucleus. Subthalamic nucleus exictes GPi. Gpi inhibits the thalamaus veen more. Thalamus is inhibited no unwanted movement occurs. - Huntington's disease cuase degeneration of neurons in striatum -- results in unwanted movemnetnts such as chorea -writing and twisting movements or rigidity. Mneumic Huntington's you indirectly kill an animla hunting through use of gun so indirect pathway. Hunter's can be erratic and violent so think Huntington's disease complications. Has uncontrolled spasmodic movements, impaired coordination and balance muscle rigidity, diffuclty speaking and sawlloing. Neurodegeneration. Basal ganlia affected. - Neurons of substantia nigra use dopamine as neurtotransmitter and help with direct and indirect pathwawy. D1 dopamine reectpors for direct pathway. D2 domapine receptors for indreict pathway. Thus substantia nigra can both excite the direct pathway and inhibit the indirect pathway. - Crebellum helps with coordination and balance. - Loss of coordination is called ataxia - Cerebellum helps with error ccorrection and motor learning - Motor commands not initiated in cerebellum but help modify them. - 2 cerebellar hemispheres connected by the vermis - 3 lobes -- aneterior, posterior, and flocculonodular - 2 fissures - Primary and posterolateral - Cerbellar gray matter found as deep nuceli called dentate, emboliform, globuse, and fastigial. - Dentate most laterally and fastigial most medially. - Cereballar white matterf found in inferior, middle, and superior peduncles. - 3 main arteries to cerebellum -- superior cerebellar artery branches from rostral basilar artery, anterior inferior cerebellar artery branches from caudal basilar artery, and posterior inferior cerebellar artery branches from vertebral artery. - Dentate nucleus relates to cerebrocerebellum - Interposed nuclei relate to spinocerebulleum - Fastigial nucleus relates to spinocerebellum or vestibulocerebellum. - Functional subdivisions of cerebellum - Spinocerebellum -- functions in error correction. Have to have a strong spine to differentiate between plan and movement. Output to UMN of medial motor tracts. Vermis of spinocerebellum coordinates movements of central body. Paravermis coordinates movements of distal muscles. Midline cerebellar damage results in truncal ataxia and wide, unsteady gait. - Vestibulocerebellum -- corrections to stability and balance both continuous and anticipatory. Contributes to vestibular ocular reflex and smooth pursuit eye movement. Bypasses deep cerebellar nuclei and utputs directly to vestibular nuclei. Damage to flocculondular lobe is truncal ataxia and nystagmus. - Cerebrocerebellum -- motor learning adapts motor programs to make furtue movements more accurate. Outputs to UMN of lateral movement pathways. - Incoming fibers synapse in cerebellum in deep cerebellar nuclei and purjunke cells. - Cerebellar cortex projects to deep cderebellar nucleu and then deep cerebellar nuclei project to toher parts of the brain. All pathways leavin cerebellum project to upper motor neurons. Many travel through superior cerebellar peduncle. - Main fibers in cerebellar cortex - Mossy Fibers - Originate from multiple sources, such as the spinal cord, brainstem, and pontine nuclei. Synapse with granule cells in the granular layer. Provide the majority of input to the cerebellar cortex. - Climbing Fibers - Arise exclusively from the inferior olivary nucleus. Synapse directly on Purkinje cell dendrites in the molecular layer. Exert a powerful excitatory influence. - Most cerebellar lesions are ispilalterally affected becayse crossovers happen twice before they interact with lower motor neurons. - Damagae to vermis and fastigial nuclei are bilaterally affecting because happen in midline. Week 3 - Facial nerve provides motor innervation for muscles of facial expression. - Facial nerve innervates frontal elly of occipitfrontalis, orbicularis oculi and oris, zygotmticus, leveator/depressor labii, buccinator, platysma, stapedius. - Facial nerve involves with sensation of taste to anterior 2/3 of tongue via chorda tympani nerve. - Facial motor nucleus in pons. CN VII loop around abducens nucleus before exiting pontomedullary junction so sometimes issue with CN 6 and CN 7 happen together. - CN VII goes through posterior cranial fossa to pass through internal acoustic meatus. - UMN axons project -\> corona radiata -\> internal capsule -\> CN VII nucleus. - CN VII motor pathway - UMN lesions cause contralateral issue on lower face. UMN sparing of forehead. - CN VII motor pathway -- LMN lesions cause ipsilateral issue to whole side of face. - Ex. bells palsy is lower motor neuron lesion and resultsin complete facial paralysis. - Stroke is upper motor neuron lesion and results in sparing of the forehead. - CN VII parasympethtics secretomotor innervation to submandibular and sublingual glands. Also innervates palatine, nasal, and lacrimal glands. - Autonomic nervous system has a craniosacral origin and is a 2 order neuron system. - CN VII supplies parasympathtiecs to pterygopalatine ganglion which innervates lacrimal, nasal, and palatine glands and the submandibular ganglion which innervates sublingual and submandibular glands. - Parasympatheic supply by facial nerve -- pontomedullary junction -\> posterior cranial fossa-\> internal acoustic meatus -\> splits into rgreater petrosal nerve -\> pterygopalatine ganglion and chorda tympani -\> lingual nerve -\> submandibular ganglion - Know what is affected when lesions occur throughout pathway -- if lesion at stylomastoid foramen then muscles of facial expression effected, if lesion at middle ear cavity than submandibular and sublingual glands are affected, if lesion at geniculate gablion than taste, salivation, muscles of facial expression, and hearing would all be affected. If lesion at internal acoustic meatus occurs then issues with lacrimation, salviation, taste, facial palsy and hyperacusis. - Facial canal located in petrous portion of temporal bone. CN VIIII vestibuloclear nerve is in close proximity. With lesion to CN VII could come with lesion to CN VIII loss of hearing and dizziness. - A lesion in the pons could damage both the abducens nerve and the facial nerve due to their proximity. Improtnat to use cranial nerves neary to localize a lesion. - Trigeminal nerve comes out of mid pons. - V1, V2, V3 have general sensation for face. V3 lso has motor innervation to muscles of mastication, anterior belly of digastric, mylohyoid, tensor veli palatini, and tensor tympani. - V1 is ophthalmic division and is only sensory innveration to forehead, upper eyelid, top prt of face. - V2 is maxillary divison and is sensory to lower eyelid and its conjunctiva, inferior posterior posrtion of nasal cavity, cheeks and maxillary sinus, lateral nose, upper lip, teeth, and gingiva, and superior palate. - V3 mandibular divion is facial skin in lower third of face, including chin and lowr lip, inferior row of teeth and gingiva, and the anterior two thirds of tongue (pain only). - V3 provides motor innervation to muscles of mastication which includes temporalis, masseter, medial pterygoid, and lateral pterygoid. - UMN axons project -\> corona radiata -\> internal capsule -\> CN V nucleus - Since UMN innervation to motor nucleus of V is bilateral, damge to one side of corticobulbar pathway will usually not produce symptoms. - Damage to LMNs can be detected due to ipsilateral loss of muscle function. Ex. muscles of mastication damaged then deviate to injured side. Tensors veli palatini and tympani can be damaged results in ipsilateral loss of function. - Mesncephalic nucleus relates to proprioception - Main sensory nucleus to touch, pressure, and vibration - spinal nucleus to pain and temperature - Trigeminal pain pathway -- 1^st^ order neurons synpase on spinal nucleus of CN V which conveys pain. Trigenothalamic tract decussates and go to thalamus where 3^rd^ order neurons synapse. End at post-central gyrus for sensory information. - CN V no innate parasympathetic fibers. It oes have a role in the various parasympathetic apthways - CN IIIsynapse in ciliary anglion and postganglionic parasympathetics hitchhike on short ciliary nerve (CN V1). - CN VII synpase in pterygopalatine ganglion. Postaglionic parasympathetics hitchhike on CN V2 and V1 branches to lacrimal gland. - CN VII synpase in subpandibular ganglion. Postaglionic parasympathetics hitchhike on lingual nerve V3 to submandibular and sublingual glands. - CN IX synapse in otic gland. Postaglionic parasympathetics hitchhike on auriculotempral nerve CN V3 branches to lacrimal gland. - Jaw jerk reflex -- with upper motor neuron lesions, there is a hyperactive or repeating reflex (clonus). With lower motor neuron lesions, the reflex is absent. - Jaw clonus is rhythmic, oscillatory contraction of jaw muscles. - Normal blink reflex checks afferent limb CN VI and efferent limb CN VII. There should be a direct response and a consensual response. Week 4 Trigeminal nerve emerges from pons Fissure/formina within middle cranial fossa function Ganglia in middle crania fossa/nuclei within pons Cortex ------------------------------------ --------------------------------------------- ------------------- ---------------------------------------------------- ------------------------------------------------------------------ V1 opthalmic Superior orbital fissure sensory Trigeminal sensory ganglion Parietal lobe, postcentral gyrus V2 maxillary Foramen rotundum sensory Trigeminal sensory ganglion Parietal lobe, postcentral gyrus V3 mandibular Foramen ovale Sensory and motor Trigeminal sensory ganglion; motor nucleus in pons Parietal lobe, postcentral gyrus, frontal lobe, precentral gyrus A white grid with black text AI-generated content may be incorrect. - Cell membrane is selectively permeable and has transport proteins - Cell membranes regulate the ntracellualr environment by creating and maintaining concentration differences of solutes between intracellular and extracellular solutions. - Hydrophobic solutes like oils, fatty acids, and fat soluble vitamins and drugs can divvolve in phospholipid bilayer and diffuse across. - Hydrophilic solutes like ions, hydrophilic solutes, and water can't dissolve in phospholid bilayer and must diffuse across. Require channels and pores. - Fluid mosaic model of membrane structure says that proteins are immersed in sea of phospholipids. - Plasma membrane is 7.5-10nm thick. It is a thin memebrane. - Much higher K+ inside cell than outside. - Much higher Na+, Ca2+, Cl- outside cell than inside. - ECF is slightly alkaline (basic) and ICF is closer to neutral. - Osmolarity of ICF and ECF are normally equal to each other. - Both the ICF and ECF are electronically neutral. Solute Concentration in ECF ------------ ---------------------- Na+ 142 mM K+ 4 mM Ca2+ 1mM Cl- 105 mM H+ 40 nM pH 7.4 Osmolarity 290 millimoles/L - A common phosopholipid is phosphatidylcholine. - Cholesterol composes 19-50% of all membrane lipid and helps stabilize membrane. - Phospholipds are amphilic molecules with a polar, hydrophilic head group and two nonpolar hydrophobic fatty acid tails. - Channels are made of one or more integral protein subunits that span the membrane. Channels can be regulated. - Pores are hydrophilic pathways through the membrane that are not requlated like achannels. Aquaporins is an example of a pore. Allow movement of water through cell membranes. - Princles of diffusion - Net diffusion is always from high to low concentrations - Movement is random - Movement related to heat in the solution - Concentration difference is the driving force - If no barriers, such a membranes, the process of diffusion results in equilibrium in which concentrations are the same everywhere - No energy source (such as ATP) is needed - The physical characteristic of the particle that effects its rate of diffusion across the membrane. - Nonelectrolytes are lipophilic. - Diffusion without partition because substance dissolvs equally well in membrane and aqeuois. - Non-electrolytes through a porous membrane - The net flux is directly proportional to concentration difference. A membrane with a bigger surface area will allow more flow. - Fick's first law of diffusion (without partitioning) -- J= D\*delta C/ delta x - Fick's law says that a thicker membrane will be more of a barrier to diffusion so there will be less flow. - Fick's law holds for diffuson through membranes and also diffusionin free solution - Diffusion is the process whreby particles in a gas or liquid tend to intermingle due to their spontaneous motion caused by thermal agitation. - Diffusion driven by concentration difference. Direction is from high to low. - Net flux is directly proportional to concentration difference delta C. - Fick's law is a way to quantitate diffustion through membranes and also diffustion in free solution. - Hydrophilic solute needs carrier mediated transport to cross membrane. - Different solubility of solute in oil and water is called partitioning. Kp is the partition coefficient. - Kp = solubility in oil/solubility in water. - Fick's law of diffusion with partitioning hydorphobic (lipophiloc) solutes cross membrane by diffusion more easily. - Diffusion is a fast process over short distances. Diffusion is a slow process over long distances. - Einstein time course of diffusion. The distance a particle moves is proportional to sauare root of time. Diffusion is a fast process over short distances. Diffusion is a slow process over long distances. - Fat soluble substances dissolve in phospholipid bilayer and diffuse across - Ions go through channels and pores. - Glucose goes through specific glucose transporter mechanism. - Water goes through aquaporins. - Cell volume regulated by movement of solutes across membrane by transport of ions by active transport. - Osmosis is flow of water through semi-permeabele membrane from compartment where solute concentration is lower to side of membrane were solute concentration is higher. Water flows from region of higher water concentration to side with lower water concentration. - Cells survive because Na+/K+ pup is constantly pumping Na+ out of cell, making it effecitvel impermeable. - Difference between osmosis and diffusion -- diffusion means dissolving in phospholipid biayer. Can be slow. Osmosis menas moving water through membrane pores (aquaportins) as hydraulic flow. Can be very fast. - Similartieis between osmosis and diffusion -- both are spontaneous and arise from random molecular movements. Both are where net flow of matter is from high concentrations to low concentrations. The direction of both processes is to abolish concentration differences. - Reflection coeffceint relates to how a semipermeable membrane can reflect solute particles from apssing through. A value of zero results in a ll particles passing through. A value of one is that no aprticles can pass. - Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent inward flow of wwater across semipermpeable membrane. - Van't Hoff equation ofr osmotic pressure difference across a embrane -- delta pi =nRT\*delta C. N is most important number in this equation. N is number of partiles solute dissociates into. - Osmosis refers to flow of water through membrane. - Osmotic pressure refers to pressure that can drie osmotic flow. - Osmolarity is property of solution itself. - Osmolarity is concentration of particles in solution. - Normal osmolarity of plasme is 290 mosm. - Tonicity is efined as concentration of particles in solution outside cell that cannot cross membrane. Tonicity is a property of a solution that determines whether it will maek a cell shrnk, swell, or maintain its original size, depends on concentration of impermeable solutes. - Semi-permeable membrane is a memebrane that is permeable to wetaer and imprermeable to solute. - Iso-osmotic -- two solutions with the same osmolarity. - Hyperosmotic a solution with a greater osmolarity - Hypo-osmotic a solution with lesser osmolarity. - Isotonic a cell paced in an isotonic solution and will maintain its volume - Hypertonic a cell placed in a hypertonic solutiona dn will shirnk - Hypotonic a cell placed in a hypotonic solution and will swell. - For osmolarity problems, sucrose cannot cross cell membrane, part of urea in solution will remain outside cell and other part will center the cell, - Predict volume changes of cells placed into different bathing solutions. Cells wll either stay the same, swell, or shrink.