Exam Two Flashcards
Taste bud anatomy breakdown
papillae -> multiple taste buds per papilla -> 100 taste receptor cells per taste bud -> 10 different afferent nerve fibers per taste bud
Tastants that pass directly through the ion channels
Salty and Sour
Tastants that activate or block ion channels
Sour
Tastants that bind to G-protein-coupled receptors
Bitter, sweet, umami
Salty transduction steps
- Na+ ions enter via amiloride Na+ channels
- Depolarization amplified by volt-gated Na+ channels
- Ca2+ enters volt-gated Ca2+ channels
- Vesicle fusion, transmitter release
Sour transduction steps
- H+ ions pass through proton channels
- H+ ions block certain types of K+ channels which causes depolarization
Bitter genes
TAS2R
Sweet genes
T1R receptor combo, T1R2+T1R3
Umami genes
T1R1 + T1R3
Cranial nerves involved in taste
VII (facial, anterior 1/3)
IX (glossopharyngeal, posterior 1/3)
X (vagus)
Central taste pathway order
Tongue, cranial nerves, medulla, thalamus, cortex
Receptor Potential
A stimulus-induced shift in Vm. Similar to PSP but caused by an external chemical stimulus, rather than by neurotransmitter release
Temperature, touch, irritation, and pain are encoded by what cranial nerve?
V (trigeminal)
Olfactory transduction steps
GPCR pathway leads to activatino of cyclic-nt-gated cation (Na+/Ca2+) channels and subsequent activation of calcium-gated Cl- channels which causes depolarization
How does adaptation occur?
- prolonged receptor cell activation
- increased intracellular calcium levels
- decreased sensitivity of cAMP-gated cation channels
Macula
Yellowish pigmented area near the center of the retina, responsible for high-acuity and central vision
Retina vertical pathway
Photoreceptors -> bipolar cells -> ganglion cells
Amacrine cells
receive input from bipolar cells; synapse with ganglion cells, bipolar cells, and other amacrine cells
Horizontal cells
receive input from photoreceptors; synapse with other photoreceptors and with bipolar cells
What cells are spiking cells?
ganglion and amacrine cells