Lecture notes: Gustation and Olfaction

Question 1

gustation

Answer 1

a. taste buds (some on papillae) contain many chemoreceptors (taste sensors)
b. pore on tast buds allow molecules to reach microvilli on taste sensors
c. taste buds are replaced every few days
d. molecular shape + charge + binding receptors= triggers an AP and the release of a neurotransmitter
e. detection of tastes depends on the combined effect of olfaction and gustation

Question 2

Olfactory sensory neurons

Answer 2

a. dendrites with olfactory hair extend into upper nasal cavity
b. protected by mucus

Question 3

olfaction

Answer 3

a. impulses from axons directly to olfactory bulb of brain
b. large numbers of genes coding for different receptor proteins
c. each cell only expresses one type of receptor
d. odorant may bind to different receptors
e. glomeruli group axons of olfactory sensory neurons with same receptor
f. different odorants excite a different combination of glomeruli
g. increased number of odorants binding to receptors, increase in number of AP, increased intensity of smell

Question 4

Steps leading to olfaction

Answer 4

1. odorant fits receptor protein, activates g protein (lock and key system)
2. activation of adenylate cyclase (enzyme) , increase in cAMP(secondary messenger)
3. opening of sodium channels creates an AP