Test 2 - Other Senses Flashcards
Odorant
chemicals/molecules that lead to olfactory perception (ligand)
Olfactory bulb
first olfactory processing center in the brain
Glomerulus
axon endings of ORN terminate here where they form synapses
Olfactory cilia
dendrites into open space/external environment
What happens when an odorant binds to an olfactory receptor?
- odor molecule binds to GPCR (GDP-> GTP & activates effector)
- Adenylylcyclase (AC - effector) makes cAMP
- cAMP binds to CNG - Ca & Na enter cell & depolarize
- signaling goes to cell body & results in action potential of cell neuron receptor located in olfactory cilia (dendrite)
Explain the mechanisms of recovery and adaptation in olfaction.
built-in cut off
1. Ca binds to CAM -> CAMKII shuts of AC & stops making cAMP ->
2. activates PDE -> cuts of CAMP -> cuts up cAMP
Recovery
fast hyperpolarization for responding to future olfactory cues
Adaptation
modification of sensation due to prior experience
Why are recovery and adaptation important and what is important factor in both?
Both use Ca - and they make sure you can respond to future smells
Why is it possible one person can perceive a smell as sweet and another person perceives it as disgusting?
Polymorphisms (androstenone - incomplete dominance - people with both copies can smell sweet vanilla sometimes and sickening smell other times - depending on what protein they are expressing at a given time) - also epigenetics
What do we know regarding the ORN to golmerulus to mitral cell connectivity?
each ORN expresses a single odorant receptor - to one glomerulus - to one mitral cell
Explain the purposes of olfactory information landing in the anterior olfactory nucleus
emotional connection to smell
Explain the purposes of olfactory information landing in the piriform cortex
smell associated with words
Explain the purposes of olfactory information landing in the entorhinal cortex
gatekeeper for access to hippocampus
Explain the purposes of olfactory information landing in the olfactory tubercle
reward based (dopamine) output to smell
Explain the purposes of olfactory information landing in the cortical amygdala
emotional & smell input integrated (innate behavior & transgenerational)
What do periglomerular cells do in regards to olfaction?
interneurons that receive input from ORN axons to spread inhibition to nearby glomeruli - used in lateral inhibition
What do granule cells do in olfaction?
input from mitral cells - used in lateral inhibition
What are the 5 taste types?
- sweet (glucose)
- salty (Na)
- Sour (protons)
- bitter (multiple)
- umami (glutamate)
How is taste different from flavor?
taste - only 5
flavor - can be a combo of the 5
What are taste buds and where are they located?
taste buds are bumps on different location of the tongue that contain taste pores
What is the flow of information from the taste bud?
taste bud is made up of taste pores (down the side of the bud) -> made up of taste receptor cells (TRCs) -> travel by gustatory nerve -> to dorsal root ganglion
Are certain tastes limited to certain regions of the tongue?
No they are no - not sure how we know (maybe because we can taste a taste all over the tongue and not just one region)
Describe the path of taste info. from gustatory nerve to insular cortex
gustatory nerve (via peripheral axon) -> gustatory ganglion (w/in DRG) (via central axon) -> brainstem -> nucleus of solitary tract -> thalamus -> insular cortex
Insular cortex
taste perception region
What type of receptor detects sweet?
GPCR - T1R2 + T1R3
What type of receptor detects umami?
GPCR - T1R1 + T1R3
What type of receptor detects bitter?
GPCR - over 30 T2R
What type of animal has a pseudogene for T1R1?
obligate herbivores (panda bears)
What type of animal has a pseudogene for T1R2?
obligate carnivores (wolves & big cats)
Why do some people perceive substances as bitter while others might perceive it as sweet?
There are so many T2R GPCR receptors that there is an increased possibility of receptor mutations - very sensitive can lead to picky eaters since all food can taste bitter
How do you perceive salty?
Na+ ion channels - ENaC
How do you perceive sour?
proton ion channels - Trp channels (PKD2L1 + PKD2L3)
Why do you only taste salty things when you need salt?
because taste receptors only respond to Na+ when it’s low
Describe the audition mechanism from sound waves coming to the outer ear to the auditory nerve.
- sound waves enter through external auditory canal
- vibrates eardrum -> ossicles -> fluid movement in cochlea
- fluid movement disturbs hair cells, which cause stereocilia to pivot/bend
- once bent, tip-link proteins pop open mechanical-gated K+ channels
- K+ goes down gradient leading to depolarization
- leads to voltage-Ca channels opening
- Ca promotes NT release and spiral ganlion peripheral neuron axons collection glutamate
By what mechanisms are we able to distinguish pitch?
Postsynaptic spiral gangion neurons
How do individual auditory fibers respond to frequency?
- sensitive to a certain frequency
- frequency based on cochlear location (thick/flexible = low frequency & thin/rigid = high freq.)
How do individual auditory fibers respond to intensity?
inner hair cells
1. affected by # SGNs activated
2. firing rate of SGNs
By what mechanism do we recognize auditory amplification?
motility of outer hair cells
1. positive deflection (open mechanotransduction channel and increase Ca)
2. electromotility (shortening of cell which is mediated by Prestin)
Describe the sound mechanism from auditory nerve to auditory cortex.
cochlea -> auditory nerve -> cochlear nuclei (ventral) -> superior olivary nuclei -> lateral lemniscus -> inferior colliculus -> medial geniculate nucleus -> auditory cortex (cognition)
How do we perceive sound from differing directions?
horizontal plane determination by:
1. ITD (time) hear before in on ear than other by medial superior olivary nucleus
2. ILD (level) sound louder on closer ear - lateral superior olivary nucleus
- one side gets it and inhibits the other from hearing the same thing
How does the ear function in perception of head placement, movement, and angular velocity?
cupula bends in the direction so flow of liquid goes against the angular velocity - otolith movement as well (forward/back)
Proprioception
body positioning/movement
Thermosensation
temperature
Nociception
forms of touch perception and pain
Pruriception
itching
Interoception
internal organ function
Which somatosensory nerve fiber types are heavily myelinated?
Aalpha & Abeta
Which somatosensory nerve fiber types are lightly myelinated?
Adelta
Which somatosensory nerve fiber types are not myelinated?
C
What is the Aalpha fiber involved with?
proprioreception (ventral horn)
What are the Abeta, Adelta, C fibers involved with?
touch, temperature, pain, itch (dorsal horn)
Where do you find proprioceptive neuron endings?
- muscle spindles
- tendons
- joints
Me lo
