Ch14: Olfaction

Question 1

What is an odor?

Answer 1

odorants are molecules that olfactory receptors can respond to

Question 2

Describe the detection and identification of odors

Answer 2

perceived intensity of odor increases as concentration of odor increases; change in concentration may change quality of odor (ex: 1-heptanol)

Question 3

What are the measuring thresholds?

Answer 3

detection and difference (75%; JND)

Question 4

How does perception of odor change with age and smoking?

Answer 4

smoking exacerbates age-related decline in olfaction

Question 5

“lack of smell”?

Answer 5

anosmia– occurs as you get older; can lead to hypertension (high BP)

Question 6

Describe adaptation

Answer 6

detects novel stimuli more readily but w repeated exposure, olfactory system responds less strongly

Question 7

cross-adaptation

Answer 7

similar odorants can experience adaptation; if the odorants are molecularly similar (ex: only one diff in carbon chain length, investigation time remains low)

Question 8

what kind of mapping does olfactory system show?

Answer 8

chemotopic mapping (similar molecular structures will be processed in adjacent regions)

Question 9

what are the two pathways into and through the brain?

Answer 9

orthonasal and retronasal (through the pharynx when chewing food)

Question 10

describe the pathway that olfactory info travels?

Answer 10

through nasal cavity, stirred around by turbinates (bony structures), mucus that covers epithelium; if dissolved, interact w cilia where the receptors are (lock and key); if it binds w receptor, activates G protein mediated pathway that opens ion channels, depolarizing the cell; once threshold is reached, action potentials will be sent along the axon; axons of ORN bundle together to form the olfactory nerve

Question 11

cells in the olfactory epithelium

Answer 11

basal cells generate new ORN’s constantly; Bowman’s gland produces mucus; supporting cells– structural support

Question 12

cribiform plate

Answer 12

porous bony structure; w head trauma can experience anosmia, shearing off the axons

Question 13

what happens when the olfactory nerves pass through the cribiform plate?

Answer 13

olfactory bulb (in the brain); glomeruli synapses ORNs to mitral and tufted cells (output of bulb); axons bundle together– olfactory tract; send signals higher into the brain

Question 14

transduction

Answer 14

350 diff types of receptors; open calcium and sodium ion channels

Question 15

Explain what a population code is and its role in olfaction.

Answer 15

unique pattern of responses for each odorant across the receptor types

Question 16

Explain chemotopic organization and where this occurs.

Answer 16

olfactory system is organized by molecular structure; molecules that are similar are processed in adjacent glomeruli in the olfactory bulb

Question 17

odor and memory

Answer 17

evoke more early memories compared to words or pictures

Question 18

odor and emotion

Answer 18

consistent assessment of an odor as pleasant/unpleasant; some reactions learned and some depend on state of learner

Question 19

pheromones

Answer 19

chemical substance emitted by an organism that evoke behavior or hormonal responses in others

Question 20

what’s the evidence for human pheromones?

Answer 20

menstrual cycles and underarm sections; tears from sad women; sweat from opposite sex