Chemoreception

Question 1

Synaptic facilitation
Synaptic depression

Post-tetanic potentiation

Answer 1

Buildup of Ca2+ following AP causes more neurotransmitter release and larger response

Depletion of pre-synaptic vesicles, reduced response

After train of high freq APs
- Build up of Ca2+ causes more pre-synaptic vesicles to dock

Question 2

Cell type diversification vs fusion

Answer 2

Diversification - Be more fine tuned to stimuli

Fusion - Be more efficient

Question 3

Sensory neuron -> Generator pot
Epithelial sensory receptor -> Receptor potential

Question 4

Sensory receptors based on stimulus location
Telereceptors
Exteroceptors
Interoceptors
Proprioceptors

Answer 4

Distant stimuli (vision, hearing)

Stimuli outside of body (pressure, temp)

Stimuli inside body (blood pressure, blood oxygen)

Position and orientation of body

Question 5

Sensory receptors based on stimulus modality
Chemoreceptors
Mechanoreceptors
Photoreceptors
Electroreceptors
Magnetoreceptors
Thermoreceptors

Answer 5

Chemicals
Pressure, movement, touch, balance
Light
Electrical fields
Magnetic firlds
Temperature

Question 6

Theory of labeled lines

Answer 6

Discrete path from sensory cell to integrating center
- Receptor location encodes both stimulus modality and location
- Receptive field organized into cortical sensory areas to form topographical maps

Question 7

Weber-Fechner law

Answer 7

Resolution of perception diminishes for stimuli of greater magnitude

Question 8

Vertebrate taste buds
Type I
Type II
Type III

Answer 8

Type I:
- 50% of cells in taste bud
- Salty
- Eliminate neurotransmitters in extracellular space

Type II:
- 1/3 of cells
- Sweet, umami, bitter
- Multiple receptors to respond to more than one taste

Type III:
- 20% of cells
- Sour
- Differing amount in certain areas of tongue

Question 9

Taste activation pathways
Salty - Unknown transmitter
Sour - Serotonin, GABA, norepinephrine
Sweet - ATP and Acetylcholine
Bitter - ATP and Acetylcholine

Answer 9

Salty: Activates ionotropic receptor
- Na+ ion enters, depolarizes, Ca2+ enters, neurotransmitter release

Sour: Blocks + Ionotropic receptor
- H+ ions enter and block K+ channel (Prevents K+ from leaving cell)
- Depolarization, Opens Ca2+ channel, influx of Ca2+ causes neurotransmitter release

Sweet: Activates GPCR (gustducin)
- Sweet substance bunds, G protein gustducin activates adenylate cyclase, ATP to cAMP, protein kinase phosphorylates and closes K+ channel, depolarization, Ca2+ causes neurotransmitter release

Bitter: Activates GPCR (transducin)
- Bitter substance binds, G protein transducin activates phospholipase C, PIP2 to IP3, causes release of Ca2+ from intracellular stores, influx cause’s neurotransmitter release