bascis of olfaction and the OE

Question 1

What are the principles of sensory systems?

Answer 1

1. Physical stimulus interacts with receptors in the periphery
2. Signals are transduced and encoded into electrical signals
3. Electrical signals are relayed via synaptic transmission to
   higher order brain centers&raquo_space;» give rise to conscious
   perception

Question 2

What are the four qualities of a sensory stimulus

Answer 2

1) Modality (Five sensory modalities)
Vision, hearing, touch, taste, smell
2) Location
Awareness of spatial aspects depends on spatial
distribution of activated receptors
3) Intensity
signaled by firing rate
4) Duration
signaled by time course of response
*slowly adapting
*rapidly adapting

Question 3

What are the chemical senses

Answer 3

• Gustation (taste)
• Olfaction (smell)

They detect environmenal chemicals

Question 4

What are chemoreceptos?

Answer 4

• chemically sensitive cells
• distributed throughout the body
• Warn about irritating chemicals and internal state
  (CO2 and O2 levels in blood, acidity in muscles,
  etc..)

Question 5

What is the olfactory system?

Answer 5

a system that process information
about the identity, concentration, and
quality of odorants

Question 6

What are odorants?

Answer 6

• small, volatile molecules
• diverse structures
• perceived as having different odors
• least acute of the senses

humans can sense
10,000 to 100,000 chemicals as
having a distinct odor

Question 7

What are the 3 main cell types in the Olfactory Epithelium (OE)?

Answer 7

1. Olfactory receptor cells (odorant receptor neurons:
   ORNs)—site of transduction
   * Constantly regenerated throughout life
2. Supporting cells—produce mucus (Bowman’s
   Gland)
3. Basal cells—source of new receptor cells (stem
   cells)
   Olfactory Epithelium

Question 8

Describe the Olfactory Epithelium

Answer 8

• sensory stimuli (odorants) interact with receptors and are transduced and
  encoded into electrical signals
• Cribriform plate: thin sheet of bone through which small clusters of axons
  penetrate»>course to olfactory bulb

Question 9

What is the connection between COVID and the Olfactory Epithelium?

Question 10

Which of the following statements about the olfactory epithelium (OE) is TRUE?

Basal cells produce mucus and are affected
by COVID
B. Olfactory axons are large diameter and
heavily myelinated
C. Receptors for odorant molecules are located
on the cilia of Odorant receptor neurons
(ORN)
D. Odorant receptor neurons (ORN)s have
multiple dendrites from which cilia protrude

Answer 10

C. Receptors for odorant molecules are located
on the cilia of Odorant receptor neurons

Question 11

Describe Olfactory Transduction

Question 12

A mutation in adenylyl cyclase in ORNs causes them to be constitutively (constantly) active. Which of the following is not true regarding signal transduction in these ORNs?

A. There is less Na+ and Ca2+ entering the ORN compared with a wild-type ORN
B. Cl- efflux from the ORN will be increased compared with a wild-type ORN
C. The ORN will fire more action potentials compared with a wild-type ORN
D. There is more Na+ and Ca2+ entering the ORN compared with a wild-type ORN
E. cAMP levels will be increased compared with a wild-type ORN

Answer 12

A. There is less Na+ and Ca2+ entering the ORN compared with a
wild-type ORN

Question 13

Describe Olfactory Receptor Proteins

Question 14

You provide an antagonist that binds to only one type of olfactory receptor in the olfactory epithelium. Which of the following is the likely effect on the sense of smell?
A. Affects the sense of only one odorant
B. Complete anosmia
C. Affects the sense of several odorants
D. Normal sense of smell

Answer 14

C. Affects the sense of several odorants

eaach receptor responds to several different odorants