smell

Question 1

transduction

Answer 1

sensory cells translating chemical, electromagnetic, mechanical stimuli into action potentials that our nervous system can make sense of

Question 2

receptors needed for touch and hearing

Answer 2

mechanoreceptors

Question 3

receptors needed for taste and smell

Answer 3

chemoreceptors in nasal passages and taste buds

Question 4

when are chemical senses sharpest?

Answer 4

at birth

Question 5

hyperosmia

Answer 5

an overwhelming sensitivity to smells
(and taste since they are connected by the olfactory system)

Question 6

causes of hyperosmia

Answer 6

• pregnancy
• migraines
• neurological conditions
• autoimmune diseases

Question 7

petrichor

Answer 7

• the earthy smell when rain falls on dry soil
• stems from streptomycete bacteria in the soil

Question 8

compound produced by streptomycete bacteria in the soil

Answer 8

geosmin

Question 9

what is the requirement to be able to smell something?

Answer 9

the odorant must be volatile, or in a gaseous state so it can be absorbed by the nostrils

Question 10

journey of molecules smelled

Answer 10

majority of molecules are filtered out before reaching the nasal cavity by protective nose hairs

Question 11

what is the destination of molecules in the nose?

Answer 11

olfactory epithelium

Question 12

olfactory epithelium

Answer 12

• main organ of the olfactory system
• located on the roof of the nasal cavity
• small, yellowish patch of tissue

Question 13

what’s inside the olfactory epithelium

Answer 13

• contain millions of olfactory sensory neurons surround by insulating columnar supporting cells

Question 14

the pathway of electrical signal out the nose

Answer 14

• airborne molecules dissolve in the mucus coating the olfactory epithelium
• once dissolved, molecules can bind to receptors on the olfactory sensory neurons
• if molecules hit their binding threshold, olfactory sensory neurons are activated, firing action potentials
• action potentials travel up the neurons’ long axons, pass through the ethmoid bone, then reach the olfactory bulb in the brain

Question 15

specificity of olfactory neurons

Answer 15

each olfactory neuron has receptors for a specific smell

Question 16

glomerulus

Answer 16

a complex of tangled fibers that transforms nose information into brain information

• where axons from smell-specific neurons converge