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1. Chemical Senses-Smell Macrosmatic (Dog) vs
Dogs are 300 to 10K more sensitive (e.g. bomb, cadaver, fish, drug detecting dogs)
Microsmatic (Human)
Sensitivity varies w the number of receptors not sensitivity of individual receptors (10 million in humans vs 1 billion in dogs)
Anosmia
2. Chemical Senses-Smell
3. Chemical Senses-Smell Receptors
4. Smell Overview
5. Chemical Senses-Smell Receptors
6. Chemical Senses-Smell Olfactory Receptors (OR) are part of the membranes of cilia of the ORNs
Consist of proteins that cross through the membrane
There are approx 1,000 different ORs that respond to the same class of molecules
The ORs on a particular ORN are the same
10K of each type of ORN; 10 Million ORNs
7. Chemical Senses-Smell Olfactory Receptors (OR)
Response of the ORs in a section of the Olfactory Mucosa. Two receptors respond to both substances
8. Chemical SensesSmell Response of Frog receptors to different substances
There is a pattern of receptor responses to each substance
9. Olfactory Mucosa has four zones. ORNs from each zone communicate to a zone on the Olfactory Bulb. Each Glomerulus receives 5-10K ORNs. Each Glomerulus receives one type of ORN.
The bulb becomes a map of the types of substances detected by smell.
10. Chemical Senses-Smell Response of Olfactory Bulb to different substances
There is a position associated with each substance
11. Chemical Senses-Smell CNS Pathways
12. Chemical Senses-Smell Responses of Two Neurons in the Orbital Frontal Cortex to different substances
13. Chemical Senses-Smell Smell Naming and Memory
The perception of a particular smell is influenced by memory associations for the name of the smell.
If a subject is given an ambiguous smell stimulus and told it is smell X, then the subject will perceive the smell as X.
14. Chemical Senses-Smell Identifying others by smell
Humans can generally identify males vs females by smell alone. This works for body and breath odor.
Women who synchronize the menstrual cycle likely do this using smell.