Pheromones Flashcards
What are pheromones?
- molecules released by one animal to signal something to another member of the same species
- strongly influence the behaviour of many organisms
Do pheromones exist in humans?
- their existence in humans is controversial
Are behavioural responses to pheromones innate?
- yes, they are largely innate
What are pheromones used to do?
- attract or repel other members of the same species
- signal attractiveness and sexual receptivity
- mark a path to follow
- signal danger
Where are pheromones released?
- in liquid like urine or tears
Where does the initial transduction and processing of pheromones occur in mammals?
- in the vomeronasal organ and accessory olfactory bulb
Where are the vomeronasal organ and accessory olfactory bulb?
- next to but distinct from the regular olfactory epithelium and main olfactory bulb
What are the regular olfactory epithelium and main olfactory bulb?
- process regular odors
What are pheromones detected by?
- metabotropic vomeronasal receptors
What are metabotropic vomeronasal receptors?
- distantly related to the olfactory receptors that detect normal odors
Do humans have functional vomeronasal
organs?
- humans, apes, and birds do not have functional vomeronasal organs
- only have regular olfactory epithelium that detects normal odors
How are pheromones detected?
- must be actively sniffed or tasted to be detected
What does pheromone detection influence?
- sexual behaviour
What is female to male pheromone signaling?
- how does female urine change male behaviour
- especially powerful
- male mice will only attempt to mate with female mice that are in heat
What happens if the male vomeronasal system is damaged?
- they try to mate indiscriminately with any mouse, male or female
What is male to female pheromone signaling?
- how does male urine change female behaviour
- effects are more subtle
- females prefer males that have healthy testosterone levels (vs. castrated males)
- presumably because of testosterone-induced male sex pheromone signaling
What are the types of male to female pheromone effects?
- lee-boot effect
- whitten effect
- vandenbergh effect
- bruce effect
What is the lee-boot effect?
- when female mice are housed together (without any male urine present), their estrous cycles slow down and eventually stop
What is the whitten effect?
- pheromones in the urine of male mice can trigger synchronous estrous cycles in groups of female mice
What is the vandenbergh effect?
- earlier onset of puberty seen in female animals that are housed with males
What is the bruce effect?
- the tendency for female rodents to terminate their pregnancies following exposure to the scent of an unfamiliar male
What type of urine does not produce effects in female mice?
- urine of castrated males
