Chapter 12 Nose and Smell

Question 1

Olfaction

Answer 1

the sense of smell

Question 2

olfactory receptor cells

Answer 2

embedded in the nasal epithelium; dendrites branch into cilia containing olfactory receptor proteins

Question 3

olfactory stem cells

Answer 3

cells with enough flexibility to differentiate into the various different types of olfactory receptor cells; allow the receptor cells to be regularly replaced, something that happens about everyone 1-2 months

Question 4

Cilia

Answer 4

dendrites of olfactory receptor cells that branch out and are populated by olfactory receptor proteins

Question 5

olfactory receptor proteins

Answer 5

GPCRs; humans have about 350 different olfactory GPCRs (on the low end); able to create a huge number of different scents because GPCR amplifes effect

Question 6

Pseudogene

Answer 6

nonfunctional genes that, although appear to code for olfactory GPCRs, are altered in some way so that they do not code for functional receptor proteins; humans have about 600 of these
believed that humans lost function receptors through mutation because they were no longer needed; may serve some unknown regulatory function

Question 7

essential oil

Answer 7

the oily concentrate of aromatic molecules from a plant; frequently includes many of a plant’s medicinal qualities
oily because the aroma-carrying molecules frequently are hydrophobic
often prepared by distillation, the process of heating an extract of the plant and concentrating the more volatile components

Question 8

aroma

Answer 8

derived from the Greek word for “spice”
essential oil contains a complex mixture of chemical components (when smelling, humans are sniffing dozens of different molecules interacting with the 350 different types of olfactory receptors)

Question 9

cinnamon

Answer 9

contains a highly aromatic essential oil, used to impart a distinctive flavor to both savory and sweet foods

Question 10

cardamom

Answer 10

from India, seeds of this plant are used to impart a distinctive flavor to various Indian foods and to tea and coffee beverages

Question 11

black pepper

Answer 11

fruit of another plant native to India, Piper nigrum; its aromatic essence is a mixture of numerous molecules; expensive due to popularity/high demand

Question 12

sulfur, thiols

Answer 12

thiol refers to the sulfur-hydrogen (-SH) group; often smells stinky (i.d. skunks, asparagus pee)

Question 13

specific anosmia

Answer 13

loss of sensitivity to a specific kind of smell (i.e. some people lack olfactory sensitivity to the asparagus-pee aroma)

Question 14

general anosmia

Answer 14

loss of sensitivity to a large variety of aromas, in some vases even a complete lack of olfactory sensitivity; variety of causes ranging from nasal congestion to unknown developmental factors to head trauma to degenerative brain disease

Question 15

hyperosmia

Answer 15

an increased sensitivity to odors; often appear transiently in association with a migraine headache or pregnancy

Question 16

olfactory bulb

Answer 16

part of the brain located immediately above and adjacent to the nasal cavity; receives axons from the olfactory receptor cells; axons form synapses with dendrites of mitral cells in olfactory bulb

Question 17

pheromones

Answer 17

chemicals that carry signal information related to social communications between members of the same species; discovered and most extensively studied in insects (have been shown to play important roles in identity, social status, mate attraction, territorial and trail marking, signaling of danger)

Question 18

vomeronasal organ

Answer 18

neural pathway that responds somewhat selectively to pheromone molecules