Week 8 - olfactory system

Question 1

name the traditional five senses

Answer 1

• smell (olfaction)
• sight (vision, ophthalmoception)
• hearing (audioception)
• taste (gustatory, gustaception)
• touch (tactioception)

Question 2

What are the extra senses?

Answer 2

temperature (thermoception)
kinesthetics sense (proprioception)
pain (nocioception)
balance (equilibriocetpion)
various internal stimuli (eg. chemoreceptors)

Question 3

What cranial nerve is related to smell?

Answer 3

olfactory CN1

Question 4

What cranial nerve is related to sight?

Answer 4

optic CN2

Question 5

What cranial nerve is related to hearing?

Answer 5

vestibulocochlear CN8

Question 6

What cranial nerve is related to taste?

Answer 6

facial CN7, glsph CN9, vagus CN10

Question 7

What cranial nerve is related to touch?

Answer 7

trigeminal CN5

Question 8

Describe the olfactory signal initiation and transmission

Answer 8

• schematic of the mammalian olfactory system
• olfactory receptor neurons are bipolar cells within the olfactory epithelium
• ciliated ending contain odorant receptors that detect odours
• axons project to glomeruli in olfactory bulb
• moral/ tufted cells send info to higher Brian centres

Question 9

Describe the organisation of the glomerular layer

Answer 9

• neurons with same receptor poorest to the same glomerulus
• mitral cells and tufted cells sundaes ponta single glomerulus
• periglomerular cells inhibitory interneuorns that synapse within and between glomeruli
• granule cells inhibitory interneurons that synapse between mitral/tufted cells
• inhibitory cells use GABA/Dopamine/glycine as neurotransmitters

Question 10

How are olfactory neurons connected in mammals?

Answer 10

• olfactory neurons send axons to olfactory bulb
• composed of layers
• peripheral layer is glomerular layer where axons of olfactory neurons terminate
• many axons converge on a single glomerulus
• activation of different receptors leads to activation of different glomeruli
• combination of activated glomeruli encodes smell

Question 11

Explain the terminal areas of the main olfactory pathway in humans

Answer 11

• from POC (primary olfactory cortex) in uncus -> medial thalamus -> orbitofrontal cortex -> olfactory tubercle -> hypothalamus
  through anterior commissure to other hemisphere