Flashcards in Week 1 Deck (91):
What part of the neurone receives inputs from other neurones and convey graded electrical signals passively to the soma?
What is the synthetic and metabolic centre of the nuerone?
Soma - integrates incoming signals that are conducted passively to the axon hillock
Where in a neurone is the site of initiation of the all or none action potential
Axon hillock and initial segment
What part of a neurone conducts output signals as actin potentials to other nuerones, mediates transport of materials between the soma and presynaptic terminal and vice versa?
What things exploit retrograde transport to infect neurones?
Give an example of a unipolar neurone?
Peripheral autonomic neurone
Give an example of a pseudounipolar neurone?
Dorsal root ganglion neurone
Give an example of a bipolar neurone?
Retinal bioplar neurone
Give an example of a multipolar neurone?
Lower motor neurone
What has a constant amplitude?
What does the distance over which current spread depend on?
Mmebrane resistance and axial resistance of the axoplasm
What provides myelin in the PNS?
What provides myelin in the CNS?
What is the term given for when AP leap from one node of ranvier to the next?
Saltatory conduction in myelinated axons
What is the most common type of synapse?
What two classifications do synapses fall into?
Inhibitory and excitatory
What is the transmitter in excitatory synapses?
What is the transmitter in inhibitory synapses?
Glycine. aminobutyric acid (GABA)
What transmitter activates cation ( positive) selective receptors?
What transmitter activates anion selective receptors?
Name the three major amino acid neurotransmitters in the CNS?
Glutamate, GABA and glycine
What are released from synaptic esicles?`
Amino acids and amines
What are released from secretory vesicles?
What do GABA and amines require to be synthesised by the neurones specifically?
What direction do K channels flow?
Outwards of cells (hyperpolarisation, inhibitory)
What shape are glutamate receptor channels?
What shape are GABA, glycine and nicorinic ACh gates channels?
What is the role of metabotropic glutamate receptors?
Modulation of neurotransmission (e.g. presynaptic inhibition (inhibition of Ca channels))
What channel is operated in ionotropic GABA a receptors?
What channel is operated in metabotropic GABA b receptors?
Which is slower - ionotropic receptors or metabotropic (gprotein couples) receptors?
Because the slow actions of metabotropic receptors (gprotein couples) cannot trigger APs - what do they do instead
Modulate synaptic actions
In relation to a graded potential - what can increase the amplitude and allow it to travel further?
Give an example of a strategy to increase quantal (neurotransmitter) release - extensive innervation?
Purkinje cell - inferior olivary neuron synapse
In relation to the somatosensory system: what do low threshold units respond to?
Low intensity - non-damaging and non-painful stimli
In relation to the somatosensory system: what do high threshold units (nociceptors) respond to?
High (noxious, potentially damaging) stimuli
What response do strethc receptors give?
Slow adapting tonic/static
What response does hair follicle afferents give?
Rapidly adapting phasic/dynamic
What type of axon from skin is thick and involved in proprioceptors of skeletal muscles?
What type of axons from skin are mechanoreceptors of skin?
What type of axons from skin are pain, temperature?
What type of axons from skin are temperature, pain and itch?
What term is given to the region that when stimulated with adequate stimulus causes a response in that afferent neurone?
What can be said about regions with the highest discriminative capacity?
They have the smallest receptive fields (finger tips)
Where are krause end bulbs found?
At the border of dry skin and mucous membranes
Where are ruffini endings found?
Within dermis and also joint capsules
What fibre group is C mechanoreceptor involved in stroking, social and erotic touch?
Fibre group C
What name is given to the area of skin innervated by the left and right dorsal roots of a single segment?
What is shingles due to infection of?
Dorsal root ganglion neurones
What fibre class are nociceptors and where do they terminate?
Terminate in laminae I and II
What fibre class are LTMs and where do they terminaste?
Terminate in laminae III - IV
What fibre class are proprioceptors and where do they terminate?
Terminate in laminae VII - IX
In the dorsal column medial leminscal pathway - (proprioception [Aalpha] and mechanoreceptors [Abeta]) where does decussation occur?
In the spinothalamic tract (pain, thermosensation [c/delta]) where does decussation occur?
At all levels of spinal cord, close to point of entry
What does the dorsal column consist of?
Medial fasciculus gracilis and lateral fasciculus cuneatus
What dorsal column does sesnsory input to T6 and below travel in?
Medial fasciculus gracilis
What dorsal column does sensory input to above T6 travel in?
Lateral fasciculus cuneatus
Whast is the major route in which touch and proprioceptive information ascents to the cerebral cortex?
Dorsal column medial lemniscal
What is general somatic information from the anterior head mediated by?
Two trigeminothalamic pathways
Central terminals of the trigeminal nerve sypnase upon second order neurones in what two nuclei?
Chief sensory - general tactile stimuli
Spinal nucleus - pain, temperature
Once central terminals of trigeminal nerve have synpased on either chief sensory nucleus or spinal nucleus - they then decussate and project where?
To the ventroposteriomedial nucleus of the thalamus
What is located in the post central gyrus of the parietal cortex, immediately posterior to the central sulcus and adjacent to the posterior parietal cortex?
The somatosenosry cortex (SI)
What Brodman areas make up the somatosensory cortex?
1, 2, 3a and 3b
What does the somatosensory cortex receive input from?
The VP thalamus
In the somatosensory cortex - what inputs into BA 3a?
proprioceptors (muscle spindles)
In the somatosensory cortex - what inputs into BA 3b?
Cutaneous and RA receptors (touch
In the somatosensory cortex - what inputs into BA 1
Cutaneous RA mechanoreceptors (texture discrimination)
In the somatosensory cortex - what inputs into BA 2
Joint afferents, golgi tendon organs, deep tissues (object perception)
What does scaling the body surface to the volume of SI cortex devoted to hte representation of a body part give rise to?
What do adjacent strips of the somatosensory cortex map?
The same parts of the body in parallel to eac other. Maps are mirror images of each other
If a finger (D3) is amputated what happens to the area of somatosensory cortex representing the finger?
Utlised by other sensory inputs such as adjacent digits D2 and D4
What cortex receives and integrates information from somatosensory cortex and other cortical areas (visual, auditory) and subcortical areas (thalamus)?
Posterior parietal cortex
Damage to the right parietal cortex can cause what syndrome?
What are the three types of pain?
1. Sensory - discriminative
2. Cognitive - evaluative
3. Affective - emotional
What is the difference between nociceptive pain and neuropathic pain?
Nociceptive - appropriate physiologic response to painful stimuli
Neuropathic - inappropritate response caused by a dysfunction in nervous system
Give a few causes of neuropathic pain?
3. Diabetic neuropathy
Name two non-opiod analgesics?
Name 4 opiod analgesics?
Name two antidepressant adjucants?
Name two anticonvulsant adjucants?
Name two topical analgesic adjucants?
Lidocaine 5% plaster
What type of pain do non-opid analgesics act on?
How do non-opiod analgeiscs (NSAIDS) work?
Inhibition of cyclooxygenase and prostaglandin synthesis decreases
What type of pain do opiod analgeiscs act on?
Nociceptive, only partially effective in neuropathic pain
Name some side effects of weak opiods?
Nausea, vomiting, constipation, dizziness, somnolence, dry skin and itch
What type of pain are antidepressants used for?
Neuropathic - CRPS, tension headache
How do antidepressants work for pain?
Inhibition of neuronal reuptake of noradrenaline and serotonin (5-HT)
Name some side effects of antidepressents?
Constipation, dry mouth, somnolence, heart rate, insomnia, increased appetite
What type of pain are anticonvuldsants used for?
Some side effects of anticonvulsants?
Sedation, dizziness, ataxia, peripheral oedema, nausea, weight gain