Friday 2 - fitz sensory physiology & somatosensation Flashcards
(18 cards)
Two “essential” steps in transduction
- conformational change in transducer protein
2. Opening of ion channel (or closing)
When a receptor is the primary afferent in a system (i.e. free nerve endings), where does the first action potential in that system occur?
At the first node of ranvier
What is one type of “inadequate” stimulus in a neurological system
pushing on your eyes and seeing stars, stimulating a nerve ending in a way that it is not used to and getting an effect that it thinks it is “supposed” to be.
Acuity
The ability to precisely localize a stimulus
The more intense a stimulus, the (Less or more?) precisely it can be localized.
less
Two ways in which “stimulus intensity” is encoded.
Frequency coding - firing rates of sensory neurons increase as the intensity of the stimulus increases
Population coding - Number of primary afferents increases (recruiting)
Define the process of adaptation in neurons and two types of adaptation with regards to how fast they happen
Adaptation is the process by which the response of a receptor to a CONSTANT stimulus DECLINES over time. If the change in receptor potential occurs SLOWLY, the response is called TONIC; if it occurs RAPIDLY, it is called PHASIC.
What maintains acuity in the face of a large stimulus?
Lateral inhibition of neurons.
3 types of pain from class and how they happen
Nociceptive (acute) - sensation = perception. TRP V1 receptors
Inflammatory - tissue dmg
neuropathic - synapses change
example of Allodynia
person with a peripheral neuropathy reports sharp pain when a brush is lightly passed over his skin.
example of Hyperalgesia
person reports being more sensitive to pain for an extended period of time after being stung (by a platypus)
molecular mech of benzos and barbituates
sensitize chloride channels
3 ways to activate TRP V1 gated channels
H+
>43C
capsacin
2 ways to sensitize TRP V1 channels
- Prostaglandins (NSAIDS block this)
2. Bradykinins
Is there a change in “adequate stimulus” with “referred pain”
NO
What is referred pain
Pain from the heart, lungs, gut, etc gets transported to the spinal cord where it is perceived as pain from the skin, muscle, etc.
What order of neuron (i.e. primary, secondary, or tertiary) do inhibitory neurons work on?
second order
What function is first to be blocked by low concentration of a local anaesthetic?
pain
