Neurology Flashcards
What is the most common pathophysiology of stroke?
Blockage of blood vessel.
Haemorrhage is often associated with…
Hypertension
What causes changes in membrane potential?
The electrochemical and concentration gradients.
How are ion channels generally closed?
By hyperpolarisation/ repolarisation
What returns a cell to its resting membrane potential?
Potassium efflux from cell.
What is Saltatory conduction?
Electrical conduction moving from one node of ranvier to another to speed up conduction.
Name two factors which affect conduction velocity
Myelination and axon diameter
Will conduction velocity be faster in a smaller diameter or a larger diameter?
Larger; less internal resistance
What is the main issues in Multiple Sclerosis? Apart from this what else may you see under a microscope?
Demyelination of axons. Can also see a lower cell density.
What is the neuromuscular junction?
A specialised synapse between a motor neuron and a muscle fibre.
What is the characteristic pathology of Multiple Sclerosis?
Inflammation and Loss of myelin within the CNS.
Are receptors on the pre-synaptic or post synaptic membrane?
The post-synaptic membrane
Which is the neurotransmitter for voluntary striated muscle?
Acetylcholine
What are MEPPs?
Miniature end-plate potentials = Small potentials at rest caused by individual vesicles releasing ACh.
What is the name of the cytoplasm within the muscle?
The sarcoplasm
What is the sarcolemma?
The plasma membrane which covers the myofibre.
Estimate the diameter of the myofibre.
1-2um.
What is another name for the dark band?
The A band
What is another name for the light band?
The I band
Does the A band’s length change during contraction?
No. The A band remains at the same length.
What is the name of the neuromuscular disease which does not allow ACh to be released into the synaptic cleft?
Botulism.
Which is the neuromuscular disease which causes antibodies to bind to ACh receptors on the post synaptic cleft?
Myasthenia Gravis
What is Lambert Eaton Myasthenia syndrome?
An autoimmune disorder where channels at the pre-synaptic cleft do not allow calcium in.
What is an electromyogram?
Records action potentials in the skeletal muscle.
What is Lambert-Eaton Myasthenic syndrome associated with?
Lung Cancer
Define Multiple Sclerosis
A chronic inflammatory disease of the CNS causing oligodendroglial and axonal pathology.
What two diagnostic components are involved in diagnosing Multiple Sclerosis?
MRI and CSF analysis to show inflammation
Name x5 neurological diseases
Stroke, Multiple Sclerosis, Epilepsy, Parkinson’s, Carpel Tunnel syndrome
A 50 year old man who smokes and has high blood pressure collapses at work. He is unable to speak, and move the right side of his face. He is unable to move his right arm or leg. Where is the problem?
Brain
Name the two types of stroke and which is more common?
Ischaemic - 80%
Haemorrhagic - 20%
What is the word used to describe symptoms felt on the opposite side of the brain legion?
Contralateral
Which side of the brain is responsible for language?
The left side
Which artery is most commonly affected in strokes?
The Middle cerebral artery
What sign is most commonly seen in middle cerebral artery strokes?
Weakness and loss of sensation contralaterally
What sign is most commonly seen in posterior cerebral artery strokes?
Visual Loss contralaterally
What sign is most commonly seen in anterior cerebral artery strokes?
Leg weakness contralaterally
Which part of the brain is affected in Parkinson’s Disease?
The Basal Ganglia
Name x3 clinical features of Parkinson’s Disease
Rigidity, Tremor and Bradykinesia
What does bradykinesia mean?
Reduced movement
What is the name of the chemical affected in Parkinson’s which does not cross the blood brain barrier?
Dopamine
Absent reflexes are associated with a lesion situated where?
The Lower motor neurone
Present reflexes are associated with a lesion situated where?
The Upper motor neurone
Name x2 common causes of acute neuromuscular weakness
Guillain Barre Syndrome and Acute Inflammatory Demyelinating Polyneuropathy (GBS/AIDP)
To measure Cerebrospinal fluid, what diagnostic method is used?
Lumbar puncture
From which part of the brain do seizures arise?
The Cerebral cortex
What is the cause of epilepsy?
A decrease in the inhibitory action of GABA or an increase in excitatory action of Glutamate.
What are anticonvulsants?
A group of treatments used to prevent seizures e.g. glutamate receptor antagonist.
Name x5 anti-epileptic drugs
Valproate, Phenobarbital, Benzodiazepines, Vigabatrin, Tiagabine.
Which class of anti-epileptic drugs enhance GABA action
Benzodiazepines e.g. Diazepam and Phenoarbitals.
What is the mechanism of action of Vigabatrin?
Inhibits GABA transaminase
What is the mechanism of action of Tiagabine?
Inhibits GABA reuptake
What is the mechanism of action of Phenobarbital?
Enhanced GABA action
What is the mechanism of action of Valproate?
Weak effect on GABA transaminase and Na+ channels
Which anti-epileptic medications are used on all forms of epilepsy?
Benzodiazepines and Vigabatrin.
Which anti-epileptic medication can be used in all forms of epilepsy apart from absence seizures?
Phenoarbital
Which anti-epileptic medication is used on focal seizures?
Tiagabine
What is the name of the enzyme which converts GABA to glutamate?
GABA Transaminase
What are spines?
Protrusions which sit on the dendrite. These protrusions receive the majority of synapses.
What are axons made up of?
Intermediate filaments and microtubules
What are the three types of neurone synapses?
Axo-dendritic, axo-somatic and axo-axonic.
What is the range length of an axon in humans?
um-1m
What is the cytoskeleton made up of?
Microfilaments, intermediate filaments and microtubules.
What are the differences between Golgi I multipolar and Golgi II multipolar neurones?
Golgi I multipolar neurones = long axons
Golgi II multipolar neurones = short axons
What is the group name of astrocytes, schwann cells, oligodendrocytes and microglia
Neuroglia
Which is the most abundant nerve cell in the human body?
Astrocytes
Give x5 functions of astrocytes
- Formation of blood-brain barrier
- Removal of neurotransmitters
- Axonal Growth during development
- Glial Scar formation
- K+ buffering
Which receptors on astrocytes allow glutamate in?
EAAT-2 receptors
Which are the myelin forming cells of the CNS?
Oligodendrocytes
Describe the structure of oligodendrocytes
Small nuclei, few thin processes, many ER and GA
What is the main function of microglia?
Immune function. Present antigens to invading immune cells, act as macrophages.
Which is the phagocytic nerve cell?
The microglia
Which are the myelin forming cells of the PNS?
The Schwann cells
What is the average length of time between two action potentials?
2ms
Name the three stages of synaptic transmission
- Biosynthesis, packaging and release of neurotransmitter
- Receptor activation
- Inactivation
Glutamate and GABA are examples of what type of neurotransmitter?
Amino acid neurotransmitter.
Noradrenaline = amine
Which ion is essential for neurotransmitter release?
Ca2+
Approximately how many molecules are there per synaptic vesicle?
4000- 10,000
How do vesicles release neurotransmitters into the synaptic cleft?
The vesicle fuses with the membrane and release their neurotransmitters via exocytosis.
How do vesicles rapidly release neurotransmitters?
Interaction between the synaptic vesicle and synaptic membrane proteins = rapid response. The vesicle is docked in a ‘prime’ zone close to Calcium channel. Entry of calcium through channel activates a sensor in the protein complex.
What is the protein complex made up of?
The synaptic vesicle, proteins and membrane.
Which transmission is faster - impulses through ion channel receptors or G-Protein coupled receptors?
Ion channel receptors
ACh at nicotine receptors moves through which type of receptor?
Ion channel receptors
ACh at muscarinic receptors moves through which type of receptor?
G-Protein coupled receptors
Compare the ion flow through Glutamate receptors Vs GABA receptors
Glutamate = Na+ flow GABA = Cl- flow
GLUR, AMPA and NMDA receptors are examples of what type of receptor?
Glutamate receptors
Which receptor is the fast excitatory synapse receptor?
AMPA
Which receptor is the slow excitatory synapse receptor?
NMDA
Where are glutamate and GABA transporters found?
On the Glial cell
What is the name of the glutamate transporter on the glial cell?
EAAT - Excitatory amino acid transporter
What does glutamate break down to?
Glutamine
What is the name of the GABA transporter on the glial cell?
GAT - GABA Transporter
What chemical does GABA break down to and by which enzyme?
Succinate semialdehyde (SSA) via GABA Transaminase.