Lecture 1

Question 1

funcitons of smell

Answer 1

1. flavor, eating (anticipation & consumption)
2. social communication (perfum,hygiene)
3. safety, warning

Question 2

anatomy nose

Answer 2

1. odor molecules from environmental enter our ose
2. bind to odorant receptors in the olfactory epithelium
3. signal travels via nerve fiber/ olfactory nerves to glomeruli in the olfactory bulb
   - each glomerulus has it’s own color/odor

Question 3

how does odor bind to odor receptors

Answer 3

1. one receptor, one shape, one smell
2. GPCR family
   - 1 oddur molecule can connect with different/multiple receptors
   - receptor recognize small structural features on each molecule
   - 1 odor can activate multiple receptors, and 1 receptor be activated by multiple odors

Question 4

how does odor bind to glomeruli

Answer 4

each receptors activated an subset of receptors on the nasal epithelium, it also activates a subset of glomeruli in the olfactory bulb
- with 400 receptors we can detect many more odor molecules (ROSE vs. ORANGE)

Question 5

from nose to brain

Answer 5

• not contralater
• no thalamus
  1. starts in the olfactory bulb
  2. directly routed to piriform cortex (primary olfactory cortex)
  3. goes to orbital prefrontal cortex (secondary olfactory cortex)
  4. then insula activated: smell and taste are integrated

Question 6

measuring olfactory function

Answer 6

1. sniffen stick: identify, discriminate and detection
2. UPSIT: identify smell from 4 otpions
3. olfactometer: test without researcher

Question 7

odor interaction

Answer 7

• humans are bad at guessing smell intensity & identify
• better at detecting and discriminating
• large nose/olfactory bulb: better detection/identification

Question 8

dual sensory modailty

Answer 8

orthonasal, but also retronasal (during eating swallowing you smell as well)
- both internal and externa
- retronosal only when consuming (so weaker effect)

Question 9

what is the trigeminal system

Answer 9

• chemical irritation in nose and mouth
• part of somatosensation: deals with touch and pain
• causes sensation like: irritation/cooling/tingling
• mediated by nerves/receptors (TRP & K+)

Question 10

anatomy of the trigeminal system

Answer 10

1. face has trigeminal nerves going to the eyes, nose and mouth (largest crianial nerve)
2. signals send to trigeminal nucleas (in brain stem)
3. dual stream
   
   1. going to primary –> secondary somatosensation cortex (touch. temperature, pain)
      2. going to insula –> orbitofrontal cortex (flavor perception)