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Sensory- Smell
Dr. Ellis Smell Lecture
44
Other
Graduate
10/21/2010

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Cards

Term
What are the receptor cells for smell sensation?
Definition
Olfactory cells
Term
Where are the olfactory sensory neurons located?
Definition
Within the olfactory epithelium
Term
Where do the olfactory sensory neurons project to__________?
Definition
To the olfactory bulb of the brain
Term
What are the 3 cell types of the olfactory epithelium?
Definition

1. Olfactory sensory neurons

2. supporting cells

3. basal stem cells

Term
Why does the supporting cells secrete mucus?
Definition

1. to bathe the odorant receptors

2. to provide the molecular and ionic environment for odor detection

Term
Odorant receptors are located on the
Definition
cilia
Term
What is the function of the basal stem cells?
Definition
To make new olfactory sensory neurons
Term
The olfactory sensory neuron dendrite projects into the __________
Definition
Nasal cavity
Term
Where does the dendrite terminate at?
Definition

At a knob that has 10 - 20 cilia,

the cilia has the odorant receptors

Term
When an odor binds to its receptor on the cilia what happens?
Definition

1. Signals a cascade

2. Creates an action potential in the sensory axon

Term
How many axons project from each neuron to the olfactory bulb?
Definition
1
Term
What must the axons of the neurons pass in order to enter the olfactory bulb?
Definition
The cruciform plate
Term
How many different smells are there?
Definition
Over 10, 000
Term
How many odorant receptors do we have?
Definition
1000
Term
All the receptors are coupled to a _____?
Definition
G-Protein
Term
What happens when an odor binds to its receptor?
Definition

1. G-protein dissociates

2. alpha subunit activates the adenylate cylcase

3. cAMP is made

4. cAMP binds to cation channels

5. Cation channels open so Ca2+ moves inward

6. Action Potential occurs

Term
Olfactory receptor cells can project to different______________?
Definition
Olfactory glomerulus
Term
In the Olfactory glomeruli the olfactory sensory neurons axons synapse to _____________
Definition
The dendrites of the mitral and tufted cells
Term
The axons of the mitral and tufted cells go into the ____________
Definition
olfactory cortex
Term
What connects glomerulus together?
Definition

Periglomerular cells

(they are inhibiting neurons)

Term
__________ synapses with the lateral dendrites of the mitral and tufted cells
Definition
Granule cells
Term
How do the mitral and tufted cells excite the granule cells?
Definition
By releasing glutamate
Term
How do the granule cells inhibit the mitral and tufted cells?
Definition
By releasing GABA
Term
What are the regions that the mitral and tufted cells terminate on?
Definition

1. Anterior olfactory nucleus

2. Olfactory tubercle

3. Piriform cortex

4. Amygdala

5. Entorhinal Cortex

6. Orbitofrontal cortex

Term
What kind of function does the Amygdala serve?
Definition
As an emotional response
Term
What function does the frontal or orbitofrontal cortex serve?
Definition
Discrimination of odors
Term
Other mammals and rodents have what organ in their olfactory epithelium?
Definition
Vomeronasal organ
Term
Animals perceive odors as_________
Definition
Pheromones
Term
In other animals, besides humans, the olfactory sensory neurons project to where?
Definition
accessory olfactory bulb
Term
Where does the neurons go after the accessory olfactory bulb in other animals?
Definition
primarily to the amygdala and hypothalamus
Term
The vomernasal organ has ____________ that differ from the rest  that are on the olfactory epithelium
Definition
100 G-coupled odorant receptors
Term
What two things are shown to be closely related?
Definition
Smell and sexual function
Term
What 5 sensations can we mainly smell?
Definition

1. Floral

2. Musky

3. Pepperminty

4. Pungent

5. Putrid

Term
Why does the smell seem to cease when exposed to it continously?
Definition
We have adapted to it or have become desentisized
Term
Adaptation is mediated by ______ ions acting via calmodulin on ___________ ion channels.
Definition

1. Ca2+

2. cyclic nucleotide gated (CNG)

Term
True/False: Only a small amount of the agent is needed to elicit a smell sensation.
Definition
True
Term
Methylmercaptan (garlic) has a _____ threshold, only needing __________ in a mL air
Definition

1. Low

2. 1/25 trillionth of a gram

Term
Anosmia
Definition
Is an inability to smell
Term
Hyposmia or Hypesthesia is when you have deminished ____________
Definition

Olfactory sensitivity

 

 

Term
Hyperosmia is when you have _______________
Definition

Enchanced olfactory sensitivity

(heightned sense of smell)

Term
What can lead to a decrease in smell?
Definition

1. nasal congestion

2. fractures of the cruciform plate

3. tumors

4. infections

5. Alzheimers

6. Aging

7. Damage to the olfactory nerve

Term
What % of people over the age of 80 have a decreased ability to identify smells?
Definition
75%
Term
Dysosmia is when your sense of smell is ___________
Definition
distorted
Term
Dysosmia can be caused by
Definition

1. sinus infection

2. partial damage to the olfactory nerve

3. poor dental hygiene

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