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144 Cards in this Set
- Front
- Back
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What ion causes hyperpolarisation at the synapse? |
Cl- |
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Functions of astrocytes? (4) |
Reactive astrocytosis - response to tissue damage Help form the blood brain barrier Neurotransmitter modulation - soak up excess NTs Attach to arterioles and venules - can increase blood flow to the brain |
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Function of oligodendrocyte? |
Myelin synthesis |
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Function of microglial cells? |
Immune function - phagocytosis |
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Function of ependymal cells? |
Line the ventricles and secrete CSF from the choroid plexus |
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What type of lesion would Broca's aphasia be seen with and in what area? |
Destructive cortical lesion Frontal left lobe |
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What are the signs of a temporo-parietal left destructive cortical lesion? (5) |
Acalculia Alexia Right-left disorientation Homonymous field defect Wernicke's aphasia |
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What are the effects of an irritative lesion to the frontal lobe? (2) |
Deviation of the eyes and head away from the lesion Partial seizures |
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What are the effects of an irritative lesion to the temporal lobe? (3) |
Seizures Hallucinations Memory problems |
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Effects of an irritative lesion to the parietal lobe? |
Contralateral limb seizures |
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What size are the pre and postganglionic neurones in sympathetic fibres? |
Short pre-ganglionic Long post-ganglionic |
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What is the telencephalon? |
Cerebrum |
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What is the myencephalon? |
Medulla |
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What is the metencephalon? |
Pons and cerebellum |
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What is the mesencephalon? |
Midbrain |
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Describe the two layers of the dura mater |
Endosteal layer - continuous with the periosteum under the skull Meningeal layer |
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What are the valves in the nervous system and what is their function? |
Arachnoid villi One-way valves to drain CSF into the sinuses |
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Other than CSF, what lies in the subarachnoid space? (2) |
Blood vessels and cranial nerves |
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What is an extradural haemorrhage the damage of? |
Damage to meningeal arteries and veins |
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What is a subdural haemorrhage the damage of? |
Rupture to cerebral veins |
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What is the a subarachnoid haemorrhage the damage of? |
The cerebral artery circle |
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What are the 5 main pathways across the BBB? |
Paracellular aqueous pathway Transcellular lipophilic pathway Transport proteins Transcytosis Absorptive transcytosis |
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Where are blockages most likely to occur in the brain to cause hydrocephalus? (2) |
Interventricular foramen Cerebral aqueduct |
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Main functions of the midbrain (2) |
Auditory and Visual components Motor function (substantia nigra) |
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Main functions of the pons (2) |
General reptilian functions (sleep, breathing, swallowing etc.) Major input to the cerebellum |
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Main functions of the medulla (3) |
Cardiovascular and respiratory control centres Aid in conveying corticospinal tract fibres Nuclei that relay info about hearing, taste and control of head/neck muscles |
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What are the main functions of the thalamus? (3) |
Transfer all sensory information except Olfaction Regulates basal ganglia Attention and consciousness |
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Mathematically define ICP |
Mean BP - Cerebral Perfusion Pressure (CPP) |
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What is a normal ICP? |
5-20 mmHg |
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Describe the early signs of raised ICP (3) |
Headaches - distortion of meninges and BVs Vomiting - distortion of the CTZ (medulla) Papilloedema - compression of the optic nerve |
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Describe the late signs of raised ICP (4) |
Pupillary changes - compression of the occulomotor nerve Occipital infarction - compression of the posterior cerebral artery Hemiparesis/plegia - compression of the cerebral peduncle Increased BP, Decreased HR and oedema - compression of the medulla |
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What is a thunderclap headache the clinical sign of and what is it the result of? |
Berry aneurysm, subarachnoid haemorrhage |
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What demographic is more susceptible to subdural haemorrhages? |
Elderly people with low force |
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How is the resting membrane potential maintained? |
Active transport of Na+ ions out and K+ in the cell via 3Na+/2K+ATPase to keep a -ve membrane potential |
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What are the physiological features of Hypokalaemia? (3) |
More -ve RMP Harder to trigger APs (far from threshold) Muscle problems |
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What are the physiological features of Hyperkalaemia? (3) |
More +ve RMP Easy to trigger APs (close to threshold) Hyperexcitability |
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What are the physiological features of Hyponatraemia? |
SIADH (syndrome of innapropriate ADH secretion) Results in overabsorption of water by the kidneys so plasma becomes hypo-osmolar |
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What is optic neuritis and what is a typical sign? |
Inflammation of the optic nerve with pain on eye movement and some kind of visual defect |
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Name 4 demyelinating diseases |
MS Optic neuritis Central pontine myelinosis HTLV-associated myelopathy |
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What are the main catecholamines? (3) |
Dopamine Adrenaline Noradrenaline |
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What are the main monoamines? (3) |
Histamine 5-HT ACh |
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What is the purpose of lateral inhibition? (2) |
To increase the strength of an impulse To increase discrimination |
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What type of cell are primary afferent neurones? |
Pseudo-unipolar neurones |
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What type and classification of fibres detect cold temperatures? |
Ad fibres (III) |
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What type and classification of fibres detect warm temperatures? |
C fibres (IV) |
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Which fibres detect nociception? (2) |
Ad and C fibres |
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What type of fibres have the largest diameter? |
Type Ia/b |
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What type of fibres are found in the Golgi Tendon Organ? |
Type Ib |
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Which type of fibres have high thresholds? (2) |
Ad and C fibres |
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What type of fibres are cutaneous mechanoreceptors? |
Type II (Ab) |
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What do Pacinian Corpuscles detect and where are they found? |
Vibration Hairy and non-hairy skin |
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What do Meissner's Corpuscles detect and where are they found? |
Light touch Non-hairy skin |
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What do Merkel cells detect and where are they found? |
Light touch and shape and texture discrimination Found in skin and oral and rectal mucosa |
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What do Ruffni endings detect and where are they found? |
Tissue stretch Hairy/non-hairy skin and ligaments |
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What type of receptors does heat activate? |
TRPV4 |
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What type of receptors does cold activate? |
TRPV8 |
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What type receptor fulfills the role of Meissner's Corpuscles in hairy skin? |
G-hair cells |
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What is the TRPV1 receptor and what does it respond to? |
The capsaicin receptor Found at C-fibre terminals and detect capsaicin, acid pHs and 45+ temperatures. The spicy feeling |
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After a nociceptive stimulus is detected what will the nerve endings release and why? |
Substance P and CGRP They increase vasc. perm. and trigger inflammatory mediators to be released |
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Which regions of the brain detect "where" a stimulus has occured? (2) |
Primary somatosensory cortex (contralateral) Association cortex (bilateral) |
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Which region of the brain detects the "intensity" of pain? |
Insular cortex |
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What are the three sites of analgesic opoid action and what is their mechanism? |
1. At the presynaptic terminal of primary afferent neurones - reduces glutamate transmission 2. Post-synaptic neurones - inhibit the spinothalamic tract by K+ channel activation = hyperpolarisation 3. Periaqueductal grey |
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What is hyperalgesia? |
Hypersensitivity to a noxious stimulus |
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List the main local anaesthetics (7) |
Lidocaine Procaine Bupivicaine Mepivicaine Prilocaine Tetracaine Articaine |
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What 3 chemical features are needed for all local anaesthetics? |
Aromatic ring (lipophilic and hydrophobic) Ester or amide group how quick it's metabolised) Amino group (determines Na+ channel blocking) |
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How does the amine group change to enter the cell and to block the Na+ channel? |
To enter - the amine group needs to secondary (uncharged) For Na+ blocking - needs to be tertiary (+vely charged) |
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Name two atypical local anaesthetics? |
Benzocaine QX-314 |
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What region of a local anaesthetic determines it's half life? |
The ester/amide group |
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How can the duration of certain local anaesthetics be increased? |
Some LAs have vasodilatory properties for rapid absorption so are given with a vasoconstrictor (adrenaline) to prolong action. |
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What are the main opioid receptors (3) and what antagonises them? |
Antagonised by naloxone: MOP KOP DOP |
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Which type of opioid receptor is not antagonised by naloxone? |
Nociceptin receptor |
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List all the full MOP receptor agonists? (5) |
Morphine Diamorphine Codeine Fentanyl Methadone |
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Name the partial MOP receptor agonist and why shouldn't it be given to a morphine overdosed patient? |
Buprenorphine Will antagonise a full agonist so can immediately cause withdrawal |
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List all the general anaesthetics which are administered via inhalation (5) |
Isoflurane Desoflurane Sevoflurane Enflurane N2O |
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List all the general anaesthetics which are administered via IV (4) |
Propofol Thiopental Etomidate Ketamine |
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What is dantrolene given for and whats it's action? |
Inhaled GAs (-flurane drugs) to counteract the hypermetabolism due to immense Ca2+ release from the sarcoplasmic reticulum. RyR1 receptor antagonist. |
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What are NMJ blockers used for and what are the two types? |
Paralyse reflexes e.g. gag reflex for intubation Depolarising and Non-depolarising |
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What is the main depolarising NMJ blocker and how does it work? |
Suxamithonium Binds to nicotinic NMJ receptors to inactivate Na+ channels. |
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What are the main non-depolarising NMJ blockers and how do they work? (3) |
Atracurium Vecuronium Pancuronium Antagonise the nicotinic NMJ receptor |
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Which cranial nerves don't have nuclei in the brainstem? |
Optic and olfactory |
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Through which foramen does the optic exit the skull through? |
Optic canal |
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Where does the vestibulocochlear nerve enter the brainstem? |
Cerebellopontine angle |
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What are the signs of trochlear nerve palsy? (3) |
Diplopia on a vertical gaze Associated head tilt Hypertropia (misalignment of right eye on left gaze) |
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Through which foramen does the facial nerve exit the skull? |
The stylomastoid foramen |
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Which muscle of the pharynx does the glossopharyngeal nerve innervate? |
Stylopharyngeus |
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What are the 3 sources a-motor neurones receives input from? |
Upper motor neurones Sensory input from muscles Interneurones |
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What part of the muscle does the a-motor neurone stimulate? |
Extrafusal fibres (body) |
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What part of the muscle does the y-motor neurone innervate? |
Intrafusal fibres (mainly at the poles) |
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Where are Ia fibres found and what is their function? |
In the muscle spindle and detect muscle stretch |
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What is the crossed-extensor reflex? |
Maintains body equilibrium and balance |
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What are renshaw cells? |
A type of inhibitory interneurone which inhibits a-motor neurones via -ve feedback |
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What is the purpose of the supplementary motor area? |
To evoke more complex/purposeful movements |
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What is the main purpose of the premotor area? |
"planning" movements |
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The corticobulbar tract receives bilateral innervation to the face and neck except for what? (2) |
Facial and hypoglossal nerves |
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What are the main signs of lateral corticospinal tract damage? (3) |
Hypertonia/reflexia +ve Babinski Weakness in distal muscles (fingers) |
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What are the main signs of medial corticospinal tract damage? (3) |
Reduced tone in axial muscles Frequent falling Loss of the righting reflex |
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What are the main signs of a LMN lesion? |
Hypotonia/reflexia Muscle weakness/atrophy Fasciculations Fibrillation |
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What will be seen with a lesion at level C1? |
Flaccid paralysis - loss of tone and volition |
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What will be seen with a lesion at the colliculi (separating upper and lower brainstem)? |
Decerebrate posture |
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What will be seen with a lesion at the reticular formation (dividing upper brainstem from cerebrum)? |
Decorticate position |
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What is the blood supply to the motor cortex and what will happen if it's damaged? |
Middle cerebral artery - Decorticate, decerebrate posture and spinal paralysis |
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What are the four deep intracerebellar nuclei? |
Dentate Globose Emboliform Fastigial |
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In general, what information does the spinocerebellar tract carry? |
Unconscious proprioception |
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Which tracts convey unconscious proprioception from the lower limbs? (2) |
Dorsal and Ventral spinocerebellar tracts |
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Which tracts convey unconsciousness proprioception from the upper limbs? (2) |
Rostral and Caudal spinocerebellar tracts |
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All the spinocerebellar tracts convey information through the inferior peduncle, which one doesn't? |
The ventral spinocerebellar tract - superior peduncle |
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What is the function of Purkinje cells and what NT do they release? |
Regulate and coordinate motor movements by releasing GABA (inhibits certain neurones) |
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Where do climbing fibres originate from and where do they terminate? |
Inferior olivary nucleus to the Purkinje cells |
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What information do climbing fibres convey to the cerebellum? (3) |
Visual Somatosensation Cortical information |
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What information do mossy fibres convey? (2) |
Sensation from the periphery Cortical information |
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Where do mossy fibres originate and where do they terminate? |
Brainstem nuclei and the spinal cord to granule cells |
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Foetal alcohol syndrome can result in the destruction of what neurological structure? |
Purkinje cells |
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Cerebellar control of posture, balance and co-ordinated eye movement originates from which region and passes through which nucleus? |
Flocculo-nodular lobe Fastigial nucleus |
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Cerebellar control of motor execution originates from which region and passes through which nucleus? (5) |
Vermis and paravermal cortex Fastigial, globose and emboliform nucleus |
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Cerebellar control of pre-programming movements originates from which region and passes through which nucleus? |
Lateral hemispheric cortex Dentate nucleus |
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Is cerebellar damage contralateral or ipsilateral? |
Ipsilateral due to double crossing |
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What are the two ouput regions of the basal ganglia? |
The internal part of the globus pallidus Pars reticulata of substantia nigra |
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Functions of the basal ganglia? (4) |
Initation of voluntary movement Emotion Behaviour Learning routines |
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Which part of the substantia nigra has dopamine containing neurones and where do the fibres project to? |
Pars compacta To the striatum |
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What is the function of the nucleus accumbens? (2) |
Motivation Reward |
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What does the direct pathway between the cortex and basal ganglia do and describe its steps |
Direct pathway = allows a movement to occur 1. The cortex projects to the striatum via glutamate to secrete GABA to the internal globus pallidus. 2. The internal Golbus pallidus has a constant inhibitory signal to the thalamus so it's stopped by the GABA. 3. The internal Globus pallidus will also release GABA on to itself to further increase the strength of the signal. 4. The thalamus is now active so releases glutamate on to the motor cortex. |
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What is the purpose of the pars reticulata on the direct pathway? |
To release dopamine on to the striatum to enhance it's activity |
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What does the indirect pathway between the cortex and basal ganglia do and describe its steps
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Indirect pathway = inhibition of a movement 1. The striatum inhibits the external globus pallidus via GABA 2. The external globus pallidus inhibits it's inhibitory signal to the subthalamic nucleus and also releases GABA to further inhibit itself. 3. The subthalamic nucleus is now activated and releases glutamate on to the internal globus pallidus. 4. This strengthens the inhibitory signal to the thalamus |
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What are 3 most common diseases which are due to dysfunction of the basal ganglia? |
Parkinson's Huntingdon's Ballism |
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What is Parkinson's? |
Destruction of substantia nigra Results in trouble initiating willed movements bc. of increased inhibition to the thalamus |
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What are the main symptoms of Huntingdon's patients? (2) |
Hyperkinesia Chorea (spontaneous, jerky movements) |
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What is ballism and how is it caused? |
Ballistic movements of the limbs Damage to the subthalamic nucleus |
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What is the pathophysiology of Parkinson's? |
Accumulation of synuclein resulting in the formation of Lewy bodies within the dopamine cell bodies resulting in basal ganglia dysfunction |
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How can idiopathic parkinsons disease be identified? |
Flourine-18 PET scan (binds to dopamine so will be less bright with parkinsons) |
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What classes of drugs are given to Parkinson's patients? (5) |
Dopamine agonists Dopamine metabolism inhibitors Memantidine Amantidine Anticholinergics |
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What type of drug is L-dopa? What is it given for and what's its mechanism? |
Dopamine agonists for IPD Dopamine can't pass BBB so this is given with decarboxylase inhibitor to limit peripheral decarboxylation. |
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What is the difference between dopamine receptor agonists and L-dopa? (2) |
DRAs have a longer half life and can reduce dyskinesia assc. with L-dopa |
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What are the dopamine metabolism antagonist drugs and how do they work? (4) |
MAO inhibitors: a) Selegnine b) Rasagline These allow dopamine to stay in the striatum for longer. COMPT inhibitors: a) Entacapone b) Tolacapone |
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What are the anticholinergic drugs and how do they work? (3) |
Benztropine Ethopropazine THP Dopamine depletion = cholinergic overactivity Reduce the tremor and rigidity |
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What is memantidine? |
NMDA receptor antagonist |
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What effect will demyelination have with respect to APs? |
Reduces conduction velocity |
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What effect will axon damage have with respect to APs? |
Reduces AP amplitudes |
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What are the two main immune-mediated peripheral demyelinating diseases? |
Guillain-Barre syndrome Chronic Immune Demyelinating Polyneuropathy (CIDP) |
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What is Uhthoff's phenomenon? |
Worsening neurological symptoms during hot weather |
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What is Lhermitte's phenomenon? |
Inflammation of the cervical spine (tingling is felt when turning neck) |
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What form of MS is the most common? |
Relapsing remitting (secondary progressive)-70% Multiple relapsing symptoms which are gradually getting worse |
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What is primary progressive MS and how common is it? |
Gradually getting worse after the first symptom 20% |
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What is benign relapsing-remitting MS and how common is it? |
Repeated relapses of the same severity 10% |
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What are the features of optic neuritis? (3) |
RAPD Uhthoff's phenomenon Peri-ocular pain |
