smell

Question 1

draw and label the anatomy of the olfactory system

describe

Answer 1

yellow = olfactory epithelium

• contains bodies of olfactory receptor neurons

red = route that molecules take to reach olfactory epithelium

olfactory receptor neurons

• axons go through cribriform plate of ethmoid bone
• GPCR for odour molecules
  
  • smell is more complex than taste - has many different GCPRs

Question 2

what important structure do olfactory receptor cells have?

what is the purpose?

Answer 2

contain microvilli

• extend into fluid of nasal epithelium
• microvilli form a mat on the surface of the nasal epithelium
• odour molecules must dissolve in fluid to reach GCPR olfactory receptors

Question 3

what are mitral cells?

where?

Answer 3

2nd order neurons in the olfactory pathway

• found in olfactory tract
  
  • above ethmoid bone

Question 4

draw and describe the olfactory pathway

Answer 4

1. olfactory receptor cells’ axons pass through cribriform plate and form synaptic connections with dendrites of mitral cells
2. mitral cells have very dense dendrite which form spherical glomeruli
3. mitral cells project along olfactory bulbs to higher brain centres

Question 5

where does perception of complex distinct odours happen?

Answer 5

each glomerulus only relays information about selective structurally related odour molecules that bind a single GPCR

Integration of information from many glomeruli in higher centres develops the perception of complex distinct odours

Question 6

describe the olfactory pathway in higher levels of the brain

Answer 6

1. axons of mitral cells pass along olfactory bulbs and innervate paleocortex and amygdala (gatesways for emotional response to smell

• mitral axons can also decussate
  
  • go from one side of brain to the other to innervate those on the other side

2. neurons in paleocortex project axons to thalamus

• also small strong of information directly from paleocortex to orbitofrontal cortex
• paleocortex can also project axons to hypothalamus
  
  • relays information to brain stem motor nuclei - green

3. thalamus neurons project axons to the orbitofrontal cortex - responsible for conscious response to smell

Question 7

how are olfactory, taste and vision response pathways integrated

Answer 7