Taste and Smell

Question 1

pheromones

Answer 1

• molecules released in urine- sensed by other animals
• specialized olfactory cues
  = chemical signal that is released by 1 member of the species and is sensed by another member of the species –> triggers an innate response
• mating, fighting, communication (territory

Question 2

accessory olfactory epithelium

Answer 2

• sends projections to accessory olfactory bulb
• vomeronasal system- zone
• apical cells, basal cells–> have receptors at the tips of projections that are sensitive to different pheromone molecules–> send projections and eventually goes to the amygdala (emotion/aggression/mating)

Question 3

humans rely very little on pheromones

Answer 3

• we do have vomeronasal but do not have accessory olfactory epithelium

Question 4

olfactory bulb

Answer 4

• between cribiform plate (bone w/ holes) and brain
• bundle of nerves that send projections through cribiform plate into olfactory epithelium
• at end of cells are receptors

Question 5

olfactory receptors

Answer 5

• each one is responsive to a certain molecule
  ex. aromatic ring- benzene molecule binds to receptor on nerve ending in olfactory epithelium–> AP fired to olfactory bulb
• have a bunch of cells synapsing to one particular location in olfactory bulb = glomerulus

Question 6

glomerulus

Answer 6

• destination point of various olfactory cells that are sensitive to the same molecule
• ex. benzene glomerulus- when molecule binds to receptor, cells synapse to that place–> then synapse onto mitral/tufted cell–> projects to the brain

Question 7

how odor molecule binds to olfactory receptor

Answer 7

• molecule enters nasal passage and binds to receptor in the membrane of olfactory sensory cell
• G protein receptor- when bound to causes dissociation
• G protein binds to ion channel, allows + ions and depolymerization which fires AP…
• Odor molecule–> GPCR–>G protein breaks away–> ion channel (depolymerization)–> AP–> cribiform plate–> mitral/tufted cell–> brain

Question 8

tastes (5) (gustation)

Answer 8

• bitter
• salty
• sweet
• sour
• umami (glutamate)

Question 9

taste buds (3)

Answer 9

• throughout tongue
• very highly localized in anterior aspect of tongue
  1. fungiform- anterior
  2. foliate- side of tongue
  3. circumvallete- back of tongue
• each taste bud contains the 5 different taste cells

Question 10

labelled lines model

Answer 10

• all 5 taste cells
• each cell has an axon projected that remain separate and go to the brain
• synapse on different parts of the brain
• each cell has its own dedicated line–> distinction carried all the way to the cortex

Question 11

individual taste cell

Answer 11

ex. sweet cell- has glucose receptors that send AP
- sweet, umami and bitter- have G protein coupled receptors
- sour and salty- rely on ion channels

Question 12

G protein coupled receptors (taste)

Answer 12

• inner membrane protein that has a receptor that undergoes a conformational change that causes a G-protein to dissociate so bond is broken
• G protein can open ion channels via conformational change can cause cell to depolarize and fire AP to brain

Question 13

ion channel (Taste)

Answer 13

• sour and salty
• molecule binds to ion receptor which causes channel to open (ex. NaCl)
• allows + ions outside to flow in–> depolarize–> fires AP to brain