Neuro system


2 Medicine Flashcards on Neuro system, created by James Murdoch on 07/02/2016.
James Murdoch
Flashcards by James Murdoch, updated more than 1 year ago
James Murdoch
Created by James Murdoch about 8 years ago

Resource summary

Question Answer
Cells that myelinate the nerve cells in the CNS/PNS? Oligodendrocyte/Schawnn cells
PSNS vs SNS differences? PSNS longer pre ganglionic neurone PSNS neurotransmitter always ACh
What decreases the risk of NTD? Folic acid
Number of layers in the cortex? Neurones break through which plate to reach cortical plate? 6 Subplate
Where do the two dura layers spilt? When brain fissures at falx cerebra
The superficial layer is different to the deep layer how? Not continuous with the spinal cord
What allows the CSF to drain into the sinuses at the Falx cerebri? Arachnoid Villi
Tentorial herniation occurs why? and damages what? SOL (tumour) causing dura to exert pressure on the brain leading to Brainstem/cerebral and cranial nerve damage
Collections of arachnoid villi are called? Granulations
CSF produced by what cells? Choroid plexus
Haemorrhage types and what vessels burst? Extra dural- meningeal arteries Sub dural-cerebral veins Subarachnoid-Cerebral artery
Four differences in CSF and blood? Low glucose and potassium Protein and cholesterol
Describe CSF circulation? Lateral to 3rd to 4th into subarachnoid space
What happens when CSF is continuosly produced? Hydrocephalus
What areas lack the BBB? Areas around 3th and 4th ventricle
Dicenphalon is? Thalamus/hypothalamus
Hypothalamus connected to, functions? Connected to pituitary gland, maintains drinking eating and circadian rhythms
Functions of the amygdala and hippocampus? Social behaviour and emotion memory
Functions of temporal/occipital/parietal Auditory/visual and sensory and motor functions
Explain the loop involving the basal ganglia and SMA Basal ganglia to the ventral nucleus which is in the thalamus, this directs info to the SMA that distributes it amongst the cortex then back to basal ganglia
Lentiform nucleus/striatum are composed of? LN is lateral or medial to the internal capsule Putamen/GP Putamen and caudate nucleus Lateral, GP most medial then putamen
Connections from the BG to the thalamus are? Internal segments of the GP and substantia nigra (pars reticulate)
Dopamine containing neurones are? pars compacta
Direct and indirect pathways function? Describe each pathway briefly? Direct activate movement Indirect inhibit movement GABA inhibition of IGP so no longer inhibits thalamus, Glutamate stimulation of IGP so increases tonic inhibition of thalamus
Parkinsons disease is caused by degeneration in what part of the brain? Substantia nigra
Huntingtons disease Lost of striatal neurones and then lost of cortical neurones
Ballism is caused by? Damage to subthalamic nuclei, and it excites the IGP that inhibits movement.
The vertebral arteries branch off where? Subclavian
Describe what part of the brain each branch of COW supplies? ACA-Parietal and frontal MCA-temporal PCA-occipital
Lower limb,Upper limb and face motor and sensory arterial supply? Anterior supplies lower limb and middle supplies upper limb
Describe a watershed infarct? When perfusion pressure is low can occur where blood supply overlaps?
Commonest site for an ischaemic stroke and why? Middle cerebral artery, connected to ICA, so emboli elsewhere in the body can reach the MCA
CBF=, how much of the CO does the brain use? CPP/CVR 15% CPP=MAP-ICP
Range of brain auto regulation? 50-170
CBF maintained by what 3 things? Neural/metabolic/myogenic Neuronal control is weak
PSNS/SNS control arises from where? Facial and superior cervical ganglion
Metabolic control? Decreasing pH and increases CO2 pressure causes VD Increases in K+ causes VD
Reduction in O2 supply triggers production of what chemical Adenosine within 5 secs
Myogenic control does what to vessels Constricts them
Marker used for fMRI gadolinium
Final type of brain imaging PET
Three components of the skull Brain tissue/blood/csf
Average ICP 20mmHg True is between 5-13mmHg
CPP/mean BP/ ICP equation CPP=MAP-ICP
Cardiac arrests causes what at watershed zones? Hypoperfusion causes ischeamic
Four causes for raised ICP? Edema/hydrocephalus/bleeding/SOL
S&S of raised ICP? Headache papillodema vomiting Pupil changes/hemiparesis
Types of intracranial herniation? Subfalcine/transtentorial/foramen magnum
Effects of a transtentorial herniation? Compressed PCA/Crn 3
Berry anerysm occurs which intracranial space? Sub arachnoid
Secondary tumours of the brain come from where? lung/breast/skin/renal + colon
Primary tumours relatively affect which demographic the most? children Medulloblastoma Pilocytic astrocytoma
Two types of hydrocephalus? Non-communicating=blockage Communicating=thickening of arachnoid villi
Are neurones terminally differentiated? Yes
Human brain consumes what % for each of the following: CO/02/Glucose 15/20/25 percent
The nernst Equation tells us what? The equilibrium potential for to be no net movement of that particular ion
Goldmanns equation uses what three variable? Conc gradient Voltage gradient Membrane permeability
If the RMP becomes closer to Nernst potential what has happened to the permability? It has increased for the ion, Na+ it depolarises
Where are the action potential generated? Axon hillock
For saltatory conduction which is more important for the speed of the impulse myelination or diameter? Diameter
Astrocytes have what functions? Metabolising neurotransmitters/bridging between blood vessels and neurones/regulating ionic conc
The WBC of the brain are called? Microglia
What lines the ventricles? Ependymal cells
Number of cells it myelinates Schawnn and oligodendrocytes? 1/10
Microplagia form amyloid plaques in what disease? Alzheimers
Summation allows? Single EPSP not adequate to reach threshold potential
How do neurones pass info? By rate of coding, this controlled by the synapse
Sensory discrimination is sharpen by? Lateral inhibition
EEGS release frequencies what does delta/theta/alpha/beta indicate sleep/memory/restfullness/active concentration
Dopamine depletion occurs where? striatum
Levodopa is given with what other drug? Commonest side effect with levo dopa? Carbonic anhydrase inhibitor dyskinesias
+/- of direct dopamine agonists? bypasses nigrostriatal neurons activation of peripheral dopamine receptors
What cant you consume when on a MAO-B inhibitor such as selegiline? Tyramine/tricylics anti depressants
Dopamine depletion leads to what? cholinergic overactivity give you dry mouth
Deep brain stimulation implant is located where? subthalamic nucleus/GP/thalamus
Gene therapy use what? Neurotrophins-BDNF
Huntington disease is causes by increases numbers of what codon? Glutamine
CAG repeat length determines what? Onset however rate of progression does not!
Potential therapies for Hungtindons? coenzyme Q10/creatine(2care crest-e)
Somatosensory conveys all sensory to the CNS apart from? Methods of obtaining info? Special senses Extero/Intero/Proprio
Where do sensory afferent neurones decussate? What cell type? Synapse where? In the spinal cord Pseudouni-polar Dorsal horn
Sensory ganglia are found where? In cranial nerves? Dorsal root ganglion trigeminal ganglion
Peripheral neuropathy presents in what fashion? Glove and stocking
The stimulus strength is indicated by what? The rate of AP
5 variables for sensory afferent neurones? Modality/Threshold/Adaptation Conduction velocity/Receptive field
What is an adequate stimulus? Type of energy that the receptors respond to most effectively
Low versus high threshold types? Low-touch/warm/cool High-Nociceptors
Slowly/rapidly adapting fibres? Stretch receptors are SA RA react to movement/acceleration
Are A fibres myelinated? C fibres run in what? Yes Run in remak bundles
Receptive field in primary afferent neurones? site of projection of the peripheral terminal
Which fibres have the slowest and quickest conduction velocity? Aa fastest C slowest
Non-nociceptive cutaneous fibre class? AB
Pacinian corpuscle? Fibroblasts/modified schwann cell RA/deep
Meissners corpuscle? What plays the role of these in hairy skin Mechanoreceptor and low frequency vibration Only in glabrous (no hair) RA/superficial G cells
Merkel cells? Special senses/touch cells SA/superficial
Ruffini? Tissue stretch sensor Deep/slowly adapting
LTM stand for and what fibre type? Low threshold mechanoreceptors c fibre
Two types of muscle afferents, general characteristics? 1a dynamic adaptation/change in stretch II static adaptation/tonic stretch
Type 1&2 tendon and joint receptors Ruffini and Pacinian corpsule
4 types of processing in the ascending pathway? Convergence/divergence/lateral inhibition/centrifugal control of neuronal facilitation(accurate transmission of sense/awareness of part of body)
Lateral inhibition releases what NT? GABA
Define nociception? Detection of stimulus that is potentially harmful
Pain is transmitted in what fibres, where to the cell bodies of these sit? C and Adelta Dorsal root ganglion/nodose/cranial
Cutaneous nociceptors have? Sharp pricking pain versus slow burning pain? Free unmyelinated ending Adelta is sharp pain C is slow dull pain
TRPV-1 is found where? Describe its action Located in C-fibre terminals Ion channel activated by capsaicin, cation so leads to depolarisation
Why does a burn continue to hurt at room temp? TRPV-1 Threshold to heat decreased by prostaglandins/bradykinin/histamine which are released during inflammation. So more are active at lower temperatures
Nociceptors release what substances? Glutamate-main excitatory CGRP/Substance P-Modulatory role slow EPSP
Central sensitisation Where does windup occur? WINDUP constant stimulation of C-fibres that lead to more evoked AP's in WDR neurones Lamina V
Give a few differences between high and low threshold primary afferents? Nociceptives=smaller/higher threshold/large peptide content (substance P CGRP) Slowly adapting
Gate control theory stimulates what fibre to counter act pain? AB
Spinothalamic tract where does it decussate? Immediately
Cortical areas active in pain? Primary sensory cortex/association cortex Anterior cingulate cortex
Interoceptive activates what? Insular cortex, also where we imagine pain and the intensity of pain
PAG/Amydala/hypothalamus role in pain? FIght/flight fear/anger/anxiety nausea and cvs affects
Descending control of nociception? via PAG Uses neurotransmitters like serotonin/na/opioid peptides
Major sites of analgesic opioid actions? Presynaptic terminal depresses glutamate release Post synaptic, inhibits spinothalamic activity K+ channel activation PAG
Neuropathic pain? De afferentation pain? Stimulus origanates somewhere along pain pathways phanton limb
Referred pain? Pain is perceived at a location other than the site of painful stimulus
Define Hyperalagesia/allodynia? Increased pain from noxious stimulus pain from non-noxious stimulus(sunburn)
LA two effect on NA Channels? Block Na channels and prolong Na channel inactivation
Small or large fibres blocked more readily? Small fibres, pain is transmitted via Ad+C fibres
Two drugs that exhibit LA properties at high concentrations? Propanolol/morphine
Two pathways that LA use? Hydrophobic/hydrophilic Hydrophobic diffuses from cell membrane directly into the receptor. Hydrophilic diffuses across the membrane into the cytosol and then binds to the receptor
What LA is only used experimentally and give an example of LA that uses the hydrophobic pathway? QX-314 (100% ionised) Benzocaine
Explain use dependance? The more the nerve fibres fire the greater the effect of the LA
Metabolism mechanisms of LA/Does LA VC or VD? Ester-Plasma Amide-Liver potent VD
Clinical uses of LA (6)? Surface/infiltration/IV/Nerve block/spinal/epidural
Side effects of LA? Respiratory depression/decreased heart contractility Hypersensitivity Toxic metabolite-prilocaine causes methaemoglobinaemia
Opioid vs Opiate? Opioid acts on opioid receptors Drugs derived from juice of opiates
Where do C fibres terminate? What tract to nociceptors use? Dorsal horn Spinothalamic tract
What inhibits pain transmission in substantia gelatinosa? Causes local release of what? System is activated by what drug? PAG Dynorphin Opiates
List the four opioid, what are three inhibited by? MOP/KOP/DOP/NOP Naloxone
Problem with giving morphine orally? When do u give morphine orally? FPE poor absorption Oromorph for cancer patients
Side effects of morphine? Miosis(pupil constriction) Respiratory depression/alveolar hypoventilation anti-tussive
With what and where is morphine metabolised, where is it excreted? glucoronic acid, liver. In the kidney
Most potent, given to help with opioid addiction,prodrug and life saving antagonist? Fentanyl/methadone/codeine/naloxone (much shorter half-life than morphine)
Two types of anaesthetics? inhalation and intravenous FLURANE=inhalation
MAC stands for? Minimum alveolar concentration that produces surgical anaesthia in 50% of patients
Entonox? Side effects? N20 mixed with O2 (50%) Inactivates B12 neuropathy Low solubility in blood so blood becomes easily saturated
First halogenated ethers in Uk? Potential side effects of modern fluranes? Halothane no longer in use as causes liver toxicity Malignant hyperthermia
malignant Hyperthermia is caused by a problem with what receptor? Abnormal ryanodine receptor massive increase in ca2+ in SR Give dantrolene
What do you give to stop malignant hyperthermia? Dantrolene
What drug can you not give to people with a peanut/soya allergy? Propofol
Thiopental suppresses what production? Used to treat what? Cortisol Status epilepticus
What do you give to people with Status asthmaticus? ketamine
Side effects of Ketamine Ulcerative cystitis
Two types of NMJ blockers? Depolarising-Sux Binds to receptor/4min t1/2/malignant hyperthermia/pseudochol Non-depolarising-curium/curonium Antagonists/40min t1/2/neostigmine/tachycardia and hypotension
Which cranial nerves do not synapse in the brainstem? Olfactory/Optic
Edinger Westschal nuclei for which cranial nerve? Oculomotor
Functions of the cranial nerves? SSA/SVA/SVE GSA/GVA/GSE/GVE
Optic and Vestibulocochlear Only associated with SSA
Three symptoms of damage to the CR8 Ataxia,loss of balance and nystagmus
The olfactory nerve is unique cause? Only nerve that is only associated with SVA
GSE motor nerves? Hypoglossal/oculomotor/Trochlear/abducens/accesory
Ptosis/lateral strabismus is damage to what nerve? oculomotor
Hypoglossal nerve palsy deviates to side? Same side as lesion
4 nerves that are involved in both sensory and motor? For trigeminal which lesion causes damage to jaw? Trigeminal/facial/Glossopharnygeal/Vagus LML
Special about the forehead muscles? What causes bells palsy? Bi-lateral innervation LML damage of facial nerve
What part of the cranial innervates the SCM/traps and what does the other part do? Spinal Roots to the pharynx/larynx
Bilateral corticonuclear connections present in all cranial nuclei except? Lower part of the face Hypoglossal nucleus that supplies the genioglossus muscle
Motor neuron location in ventral horns of ventral and dorsal? Flexors-Dorsal Extensor-Ventral
3 sources of input of the motor a neuron? Difference between A & Y fibres Motor unit? Muscle length determined by what? Inter-neurones/Upper motor neurones/sensory input from muscles A innervates skeletal muscle fibres, Y innervate intrafusal muscle fibres/adjust sensitivity of muscle spindles Muscle fibres and respective a neurone Muscle spindles
Monosynaptic reflex maintains what? Exaggerated reflex indicates? Gamma motor neurones do what to the spindles? Muscle tone Upper motor lesion Cause contraction when the muscle contracts
Golgi tendon does what? Helps protect what? Opposite monosynaptic to prevent tendon damage
Flexor reflex receives stimulus from what types of fibres? Maintenance of balance is done how? If your left arm flexes your right arm will? Nociceptives (ad+C) Crossed extensor reflex, maintained by the central pattern generator (excitatory and inhibitory interneurones) Extend
Convergence is what, causes three things? Multiple nerves into one nerve Summation/Facilitation/Occlusion
Basal nuclei function? Initiation and control of movements
Rubrospinal synapse? Red nucleus
Describe the pathway that the basal ganglia are involved Motor cortes/PFC to Basal ganglia to ventral tegmental nuclei to SMA then down spinal tracts
Striatum is,separated by what? Lentiform nucleus? Output regions of basal nuclei? What is NA involved in and what carries dopamine from substantia nigra? Putamen/caudate internal capsule Globus pallidus/Putamen Internal segments of GP and pars reticula of SN Reward, Pars compacta
Which pathway allows movement? Direct
Describe basal ganglia pathway? Removes tonic inhibition of IGP on thalamus by the striatum inhibiting it
Indirect pathway? Inhibition of the thalamus above normal level, Inhibition of EGP tonic inhibition of Subthalamic nucleus that excites IGP
Parkinsons disease causes and symptoms? Loss of pars compact in substantia nigra, trouble initiating movements, bradykinesia
Hungtingtons disease? Loss of striatal neurones thus loss of cortical neurones dementia/movement problems
Damage to subthalamic nucleus causes? Ballism cause this excites the IGP so if you remove this you have no control of movements
Commonest causes of ballism? Stroke
Motor areas can produce movements how? Lowest stimulus intensity
Primary motor cortex neurones fire before or at the same time as movement? before
Describe the location of the SMA? Pre-SMA differs from SMA proper how? Directly anterior to Primary motor cortex Connected to PFC not strongly connected to other motor areas
Which pathway lateral or medial controls proximal and distal muscles? Lateral thus medial control axial muscles
Lateral pathways/medial pathways? lateral corticospinal/rubrospinal Vestibulospinal/reticulospinal/tectospinal/ corticospinal
Percentage of corticospinal neurones that decussate? and where? Lateral innervates what? 85% medullary pyramids Limbs
Corticobulbar fibres involved in cranial nerve functions, what nuclei do not receive bilateral innervation from cortex? Facial muscle below eye and hypoglossal
When does rubrospinal tract decussate?What does it innervate? Immediately Upper limb
Motor that innervate flexors are dorsal or anterior to those that innervate extensors? Dorsal
Head orientation is received from tract? Innervation to muscles? Vestibulospinal tract bilateral innervation
Where does tectospinal tract originate? Function? Superior colliculi Control head position
Which tract is involved with muscle tone? Ipislateral or contralateral? Reticulospinal tract ipislateral
Consequences of upper motor injury? Increased muscle tone/hyperactivity Barbinski sign/weakness in digits
Barbinski sign is normal in infants because? Of lack of myelination of corticospinal tract
Most prominent sign of impairment to the corticospinal tract? Weakness in digits
In a LML what affect on spasicity and reflexes? Decreases muscle tone and reflexes
Difference between decorticate and decerebrate postures? Decorticate-Cerebrum from brainstem Arms abducted and flexed (on chest) Decerebrate- Separates upper and lower brainstem Arms extended/wrist pronated arms are by the side
Two things you get with LML that you don't get with UML? Fasciluations/atrophy
Left and right hemisphere joined by what? Anterior and posterior lobe separated by what? Median vermis Primary fissure
4 inputs into the cerebellum? Types of input fibres? 3 inferior peduncle vestibular/reticular/inferior olivary nucleus 1 middle peduncle Cerebral cortex Climbing and mossy Climbing used for inferior olivary nucleus
Number of outputs of cerebellum to the spinal cord? Flocculo-nodular lobe? 0 Loss of balance and co-ordination
Hereditary disease associated with the cerebellum? Fredreich's ataxia
Clinical signs of cerebellar damage? D-Dyskine A-ataxia N-nystagmus I-intention tremor S-Slurred speech H-Hypotonia P-Past pointing
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