Neurology Flashcards
What are the two types of neurotransmitter receptors?
Metabotropic
Ionotropic
What type of receptor are the majority of neurotransmitter receptors?
Metabotropic
Name four neurotransmitters that act generally.
Glutamate
Gamma-amino butyric acid (GABA)
Glycine
Acetylcholine
Where is glutamate the main excitatory neurotransmitter?
In the CNS
Name the 3 ionotropic receptors for glutamate and state what they are permeable to.
AMPA - sodium
NMDA - calcium and sodium
Kainate - sodium and calcium
What does prolonged activation of glutamate receptors result in?
Hyperexcitability, leading to seizures and excitotoxicity
Give 2 examples of what blocks glutamate receptors and what does this cause?
Ketamine and alcohol
Results in sedation
Where in the body in GABA the main inhibitory neurotransmitter?
In the CNS
What are the two types of GABA receptor?
GABA A - ionotropic receptor that conducts Cl
GABA B - metabotropic receptor
What does activation of GABA A result in?
Sedation
Name 2 substances that activate GABA A receptors.
Alcohol and benzodiazapines, such as lorazepam
What does activation of GABA B receptors result in at the synapse?
Presynaptic inhibition of GABA release
What is the effect of positive allosteric modulators on GABA?
Potentiates the effect of GABA on GABA A receptors
What do GABA analogues do and what are the clinical signs?
Increase the amount of GABA available
Have a relaxing, anti-anxiety and anti-convulsive effect
Why are glia important for glutamate and GABA?
Important for the synthesis of them and also “mop up” excess neurotransmitter
What type of of neurotransmitter is glycine: inhibitory or excitatory?
Inhibitory
What type of receptors does glycine act on?
Ionotropic receptors that conduct chloride ions
What are glycine receptors blocked by?
Strychnine
Where is glycine mainly active?
Brainstem and spinal cord
Where in the brain is the principal source of serotonin?
Raphe nuclei
How many Raphe nuclei are there, and where are they found?
7-8
Located near the midline of the brainstem and around the reticular foramen
What is serotonin implicated in?
Depression Appetite control Nausea Sleep Sexual arousal Analgesia
What type of receptors are serotonin receptors?
All are metabotropic G-protein coupled receptors, except 5-HT 3 which is ionotropic
How is serotinergic action primarily terminated?
By reuptake of serotonin, which is down through SERT (a specific monoamine transporter for serotonin) on the presynaptic neuron
What is special about drug targets for serotonin?
All 5 elements in the life of a neurotransmitter are drug targets for serotonin
Name a drug type that can block transporters of serotonin.
SSRIs
What drug can activate receptor 5-HT 1B and what is this drug used to treat?
Sumatriptan
Treats migraines
Name a type of drug that activates 5-HT 2A receptors.
Hallucinogenic drugs
Name a type of drug that blocks 5-HT 2A receptors.
Atypical antipsychotics
Name a drug that blocks 5-HT 3 receptors and what is it used to treat?
Odansetron
An anti-emetic
Where does serotonin exist outside the nervous system?
In vast stores in enterochromaffin cells in the lining of the GI tract
What parts of the brain make acetylcholine and where do they project to?
Basal forebrain- project to cortex and hippocampus
Brainstem tegmentum - project to thalamus, brainstem and cerebellum
Which subdivision of the nervous system is acetylcholine the main neurotransmitter for?
Autonomic nervous system
What are the receptors for acetylcholine and what type of receptors are they?
Nicotinic - ionotropic
Muscarinic - metabotropic
Which part of the brain synthesises dopamine?
Ventral midbrain - substantia nigra and ventral tegmental area
What is the substantial nigra thought to be involved in?
Movement control
What is the ventral segmental area involved in?
Reward
Novelty
Motivation
In what disorders is there thought to be something wrong with the dopaminergic system?
Schizophrenia
Drug addiction
Tourettes
Parkinsons disease
What are the receptors of the dopaminergic system and what type are they?
D1 - excitatory metabotropic
D2 - inhibitory metabotropic
What type of drugs block dopamine receptors and name 2.
Antipsychotic medications - haloperidol and quetiapine
What part of the brain produces noradrenaline?
Locus coeruleus
What type of receptor are adrenergic receptors?
Metabotropic
What part of the brain produces histamine and where does it project to?
Hypothalamus -projects throughout brain
What are the 3 major types of endogenous opioid peptides?
Endorphins
Enkephalins
Dynorphins
What are endorphins similar to and what are their effects?
Like morphine
Have endogenous analgesic effect
Where in the brain are endogenous opioids synthesised, and what as?
By hypothalamus as propeptides
Once synthesised, where are endogenous opioids projected to?
Periaqueductal grey
Brainstem
What and where is the periaqueductal grey?
Grey matter located around the cerebral aqueduct within the tegmentum of the midbrain
What is the main function of endogenous opioids?
Neuromodulators that regulate the release and activity of other neurotransmitters
What does damage to CN VIII result in?
Unilateral hearing loss, tinnitus and vertigo
What is the function of V1?
Sensation from the cornea, skin of forehead, scalp, eyelids, nose and mucosa of nasal cavity
What does damage to CN XI cause?
Paralysis of sternocleidomastoid and trapezius muscle causing drooping of shoulder
What is CN IV called?
Trochlear nerve
How does cranial nerve I exit the cranium?
Through the cribiform plate
What is the pons involved in?
Sleep Respiration Swallowing Posture Taste
What is CN XI and what is its function?
Spinal accessory nerve - motor innervation to sternocleidomastoid and trapezius muscle
Through which space and then which sinus does CN IV run on its way to the orbit?
Through the subarachnoid space and then through the cavernous sinus
What is CN VIII?
Vestibulocochlear nerve
What is the most ventral part of the midbrain?
The paired cerebral peduncles
What does damage to CN XII result in?
Protruded tongue deviates towards affected side
Moderate dysarthria
Disturbance of articulation
How does CN XII leave the skull?
Through the hypoglossal canal
What does damage to CN IX cause?
Loss of taste over posterior third of tongue
Loss of sensation over affected side of palate
Loss of gag reflex on affected side
What 4 nerves exit the skull through the superior orbital fissure?
Oculomotor nerve
Trochlear nerve
Ophthalmic nerve (trigeminal nerve 1)
Abducens nerve
In the brainstem, what does the pons link?
The thalamus to the medulla oblongata
What is CN IX?
Glossopharyngeal nerve
Where does CN VIII originate?
The vestibular nerve in the vestibular ganglion in the brain stem and the cochlear nerve in the spiral ganglion in the brainstem
Where is CN XI formed?
From neurone at the top of the spinal cord
Where does CN IX originate in the brainstem?
Medulla oblongata
What is CN X?
Vagus nerve
What are the motor functions of CN IX?
Somatic - innervation to stylopharyngeus muscle
Visceral - parasympathetic innervation to parotid gland
What is the function of CN IV?
Motor innervation to direct gaze of eye inferomedially
Which cranial nerves do not come off the brainstem?
CN I (olfactory) and CN II (optic)
What is the red nucleus?
A motor nucleus that sends a descending tract to lower motor neurone
Where are the inferior and superior colliculus found?
Tectum of the midbrain
In what disease is the substantial nigra thought to be involved in the pathology?
Parkinson’s disease
What is the function of CN VIII?
Vestibular nerve - vestibular sensation from semicircular ducts, urticle and saccular relating to position and movement of head
Cochlear nerve - hearing from the cochlear
What is the superior colliculus involved in?
Sense of vision
How does the cerebellum play an important role in motor control?
It contributes to coordination, precision and accurate timing
What would damage to CN I lead to?
Loss of smell
What is the special sensory function of CN IX?
Taste from the posterior third of the tongue
What is CN II and what is its function?
Optic nerve - vision
What is CN V and what are its divisions?
Trigeminal nerve - Ophthalmic nerve, Maxillary nerve and Mandibular nerve
Where do the sensory and parasympathetic parts of CN VII originate from?
Nervus intermedius
What is the inferior colliculus involved in?
Sense of hearing
What does damage to CN IV cause?
Inability to rotate an adducted eye inferiorly
What 3 nerves exit the skull through the jugular foramen?
Glossopharyngeal nerve (CN IX) Vagus nerve (CN X) Spinal accessory nerve (CN XI)
What does damage to CN III result in?
Dilated pupils
Ptosis
Eye rotates inferiorly and laterally
What is the medulla oblongata continuous with?
Spinal cord
What is contained in the brain stem?
Midbrain
Pons
Medulla oblongata
What is the visceral motor function of CN VII?
Supplies lacrimal glands and the sublingual and submandibular salivary glands
Where does CN VI leave the brainstem?
At the junction of the pons and the medulla
Along which lateral wall does CN V1 pass along?
Cavernous sinus
What is the chord tympani?
Nerve that originates from the taste buds in the front of the tongue, runs through the middle ear and carries taste messages to the brain
What does the chord tympani join to and where?
With the facial nerve in the facial canal
What is CN VI?
Abducens nerve
How does CN X leave the skull?
Through the jugular foramen
What is the function of CN VI?
Motor function to the lateral rectus muscle to direct gaze laterally
What are the three lobes of the cerebellum?
Anterior lobe
Posterior lobe
Flocculonodular lobe
How does CN V3 leave the skull?
Through the foramen ovale
How does CN II exit the skull?
Through the optic canal
Where do the 3 branches of CN V converge and where is this located?
Trigeminal ganglion - in Meckel’s cave
What autonomic functions are controlled in the medulla?
Breathing
Heart rate
Blood pressure
What 2 nerves exit the skull through the internal acoustic meatus?
Facial nerve
Vestibulocochlear nerve
What is the substantial nigra?
A concentration of neurons that use dopamine and are involved in both motor function and emotion
What is the function of CN III?
Somatic - innervate muscles to raie upper eyelid, and control superior, inferior and medial gaze
Visceral - control constriction of pupil and control accommodation of lens
What is the somatic motor function of CN VII?
innervate muscles of facial expression
What is the function of CN XII?
Motor innervation to muscles of tongue, except palatoglossus
What is CN VII?
Facial nerve
How does CN V2 leave the skull?
Through foramen rotundum
What is the path of CN XI through the skull?
Enters through the foramen magnum and exits via jugular foramen
What cranial nerve is most likely to be damaged if there is laceration or contusion to the parotid region and what does it cause?
CN VII (facial nerve) Bells palsy - paralysis of facial muscles
Where does CN III originate?
Midbrain
What separates the lobes of the cerebellum?
Primary fissure - separates anterior and posterior
Posterior fissure - above flocculonodular
What does damage to CN VI cause?
Inability to rotate the eye laterally with diplopia on lateral gaze
What are the three parts of the midbrain?
Tectum
Tegmentum
Paired cerebral peduncles
How is damage to CN II usually caused?
Trauma
Pressure
Clot
What is CN XII?
Hypoglossal nerve
Where does CN XII emerge from the brainstem?
Medulla
What is CN I and what is its function?
Olfactory nerve - sense of smell
What is the function of CN V3?
Sensation of skin over mandible, including TMJ and mucosa of mouth
Motor innervation of muscles of mastication
What is CN III?
Oculomotor nerve
What is the function of CN V2?
Sensation of skin over maxilla
Where are the pontine nuclei found?
Pons
