Sensory System and Pain Flashcards
How do anticonvulsant drugs effect GABA
agonists to chloride conductance, blocking GABA reuptake or inhibiting its metabolism by GABA transaminase
Why is the ear drum larger than the oval window
to allow the wave frequency to be transferred through the fluid of the cochlea
describe the A delta fibres
fast
large myelinated
up to 10m/sec
sharp stabbing pain
True or false: Low plasma drug = low Vd = drug not widely distributed
False
What happens when glutamate binds to a mGlu receptor
Gαq
PLC –> IP3 + DAG –> Ca2+ via IP3 R on ER–> Ca2+ + DAG –> PKC
State the 3 ionotropic glutamate receptors
NMDA
AMPA
Kainate
What are the two types of spontaneous pain
continuous and paroxysmal (intermittent) pain
What does ketamine antagonise to cause effects
NMDA- , which prevents excitatory stimuli inducing a state of euphoria/sleep
What do thermoreceptors sense
Temperature
Explain the steps of photoreception
Light activating photoreceptors –> conformational change –> decreased glutamate release
What does the organ of corti contain
hair cells and the auditory nerve
What is GABA converted to for breakdown
succinate
Describe non-depolarising neuromuscular blockers
Curare Derivatives
No Na influx, muscle is relaxed
Prevents ACh binding to receptors
Inhibits respiratory muscle such as the diaphragm
Give effects of opioids
analgesia, constipation, sedation, respiratory depression, and mood alteration
What are anticonvulsant drugs
a diverse group of drugs used in the treatment of seizures such as epilepsy. They suppress excessive rapid firing of neurons during seizures and prevent the spread through the brain.
What does Gi inhibit
adenylate cyclase
What is the role of glycine
potentiate NMDA signalling
What do photoreceptors sense
vision
What is the calculation for the volume of distribution
(amount of drug in body (dose))/(plasma concentration (extrapolated))
Does the ear canal or cochlea have cells with cilia
cochlea
When light hits the excitatory portion of the receptive field, what happens
the photoreceptor becomes hyperpolarised, and the process of photoreception occurs
What are the three layers of the retina
- epithelial cells
- photoreceptors
- bipolar/ganglion/amacrine cells
Describe the withdrawal reflex
- Pain signal travels along the Ad fibre, to the dorsal root ganglion
- travels across an interneuron to the anterior horn cell
- travels along a motor neuron to move e..g the hand
Define Peripheral sensitisation
sensory neuron expression of α-adrenoreceptors, so more stress means more pain, and overexpression of V-G Na+, which increases AP production and increases stimuli above the original injury.
describe the C fibres
slow
small unmyelinated
1.2m/sec
aching burning pain
How is the activity of NMDA receptors controlled? A. voltage-gated B. ligand-gated C. enzyme antagonist D. all of the above
D
NMDA receptors are both voltage-gated and ligand-gated: they will only open the ion channels if the membrane is depolarized and the neurotransmitters glutamate and glycine are attached. When the membrane is not depolarized the activity of the NMDA receptors is blocked as Mg2+ acts as an enzyme antagonist.
How does neostigmine work
inhibits AchE activity, so Ach is not broken down in the synaptic cleft and continues to activation the nicotinic ACHR, for Na+ to cause depolarisation and contraction.
what are the two types of pain conduction
fast response - A delta fibres
slow response - C fibres
What is the purpose of GABAa channels
Causes hyperpolarisation which reduces excitability
what is the pain pathway
injury –> peripheral nerve (afferent neurone, excitatory (glutamate and ATP release)) –> spinal cord - receptor binding, AMPA (fast), NMPA (slower, release block of prolonged depolarisation) –>
thalamus –>
cortex
What is glycine
Glycine is an inhibitory neurotransmitter
What is the retina
a thin layer of tissue, lining the back of the eye. It receives the light that the lens has focused and converts it to neural signals, sending these to the brain for visual recognition.
What type of channels are GABAa
Ligand gated chloride channels
what is a precursor of glutamate
glutamine