lecture 12 Flashcards
what are the mechanical senses
- audition
- somatosensation
- vestibular sensation
whats an electromagnetic sense?
vision
Briefly explain how the semicircular canals work in the inner ear (vestibular system)
As the head turns otoliths in the fluid bend cilia on hair cells, which produces a neural signal (depolarization) in the hair cells
..these hair cells provide input to Vestibular Nerve Cells
What are the four types of sensory neurons used for somatosensation? Describe each one’s function
Tactile: response to being touched (light and deep touch)
Pain: response to noxious stimulus
Temperature: response to cold/hot
Proprioception: response to position or mechanical movement of muscle/joint
whats a Dermatome
a spinal cord segment
skin area that provides input to a single sensory nerve
Exam question: photoreceptors, rods and cones CANT have dendrites because..
they dont receive information from other cells
(and dendrites do)
Where does somatosensory information go in the brain and how is it represented? (hint:
homunculus)
Somatosensory information is represented in the somatosensory specifically the postcentral gyrus.
Skin areas that are needed for tactile information have a lot more representation in this brain area
than others such as the lips or hands
Briefly describe the phantom limb phenomenon.
Phantom limb is when a limb such as the hand is amputated but the area of cortex that represents
the hand is still intact.
if you can ACTIVATE that area of cortex -> phantom limb
So, HOW can it be activated?
a) cut nerves from the HAND still function, but now are stimulated by the wrist
(i.e., nerve endings are now in wrist)
b) cortical “hand” area gets taken over by inputs from “face”
what is pain?
Invoked by harmful stimulus: cut, chemical irritation, intense heat or cold
Describe the pain reflex arc… does it require the brains input?
Sensory neurons that sense pain send their signals to the spinal cord which in turn sends their
signals back to the muscles to contract away from the aversive stimulus. This pain reflex arc does
not involve the brain but signals for pain also go to the brain.
what are the 3 levels of pain
Sensation of pain (mediated by sensory neurons)
Perception (emotion) of pain (unpleasant vs neutral vs pleasant)
Response to pain
Which neurotransmitter is released in response to pain? What are the post synaptic cells it is
released onto?
Substance P is the pain neurotransmitter and sensory neurons release substance P onto spinal cord neurons.
What endogenous neurotransmitter inhibits the release of substance P?
the endorphin (endogenous morphine), Enkephalin
If you have endogenous neurotransmitter that limits substance P, why do you still continue to feel pain?
because prostaglandins and inflammation increase the
sensitivity of pain neurons allowing them to still respond
which drugs works directly at the site of injury
Aspirin, Ibuprofen
which drugs works on the pain “signal” in the Nervous System
Opiates: agonist for endorphin receptors inhibiting the release of
Substance P,
they also cross the blood brain barrier changing the appraisal of pain.
