BIEB 166 Lecture 25 (WI13)

4 Pages
Unlock Document

Biol/Ecology, Behavior, & Evol
BIEB 166
James Nieh

Lecture 25 Reception of olfactory signals Tiger - The male was rubbing his face towards a tree - Female smells that, and when it encounters the actual male, she has to make sure the male is the one left the odor marks - Olfactory receptor cells have the highest turnover of any sensory cells ○ Most survive only for days to weeks Mechanism - Odor molecule binds to receptor - Same for all types of olfactory receptors - Receptor in a membrane - Odorant molecules bind to the receptor - Triggers cascade of events/open a channel to allow other ions to pass through - molecule binding to receptor - Oldest form: basic mechanism involved in regulating a wide variety of processes - Can be used specifically for communication Insect olfactory sensillum - Multipurpose sensors - Bent by a particle of a near-field sound - Pores inside the hair to allow odor molecules to diffuse inside - Often surrounded by a kind of liquid that the molecule must diffuse through before they can really enter to the receptors in the membrane Nose - Terminate at the olfactory cilia - Mucus ○ Surrounds the cilia, and allow the molecules to diffuse through ○ Protects the cilia ○ Not easily dried out Olfactory cells may be narrowly tuned to a single chemical 1. “Labeled line coding” - 1 cell class sensitive to a single odor - Binds onto the receptor cells, and transfer to the glomeruli ○ Collect information from multiple sensory neurons - Bring information to the olfactory bulb - Similar to light perception Advantage Disadvantage Very sensitive Very inefficient -More olfactory apparatus is more focused -Need a different set of neurons to detect on a single odor different types of molecules -Silk moth/tick -Evolve a new class of neurons to sense new odors Better at detecting a signal from a noisy chemical background 2. "Across neuron pattern coding" - Broadly tuned to many chemicals such that odor quality is a function of the combination of receptor cell types stimulated - Each sensory neuron is capable of detecting multiple odors and the identity of odors is encoded in the olfactory lobe by the pattern of neuron activation - Similar to sound perception - Similar to sound perception - Multiple neurons in the olfactory lobe is turned on ○ Specific neurons response to specific odors Honeybee - Antennal lobe - Calcium sensitive voltage guide ○ Cause change in Ca flux when the cell is active - Response to multiple odors Mixed odors -> mixed pattern - Few odors are pure - Summing up the different patterns, and can recognize the different combination of different molecules - Brain does add up the different odors Concentration difference - The bees are able to differentiate between two odors when one is 1.5x of the other - The brain is more activated in one area than the other Receptive organs Contact organs - Require direct physical contact with the surface carrying the odor molecules 1. Tongue - Bitter - Sweet - Salty - Sour - Umami ○ Response to glutamic acid ○ Meat/protein/soy beans ○ Adaptation of being an omnivore - Taste buds ○ Small openings ○ Molecules coming in can contact with the short, stiff microvilli that are sticking out  Less fragile ○ Human perception is a complex mix of the contact organ and our nose Fly proboscis - Labellum - Sensitive to very few things ○ Salt ○ Sugar Medium-borne organs - Can detect odor molecules dispersed or dissolved in a medium 1. Human nose - Cilia ○ Embedded in the
More Less

Related notes for BIEB 166

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.