CHEMICAL SENSES SMELL AND TASTE OLFACTION SMELL and

CHEMICAL SENSES: SMELL AND TASTE

OLFACTION (SMELL) and GUSTATORY (TASTE) Function is to monitor the chemical content of the environment Smell is the response of the olfactory system to air borne chemicals . Chemical senses Taste id the response of the Gustatory system to chemicals in solution in the oral cavity

. When we are eating , smell and taste act in concert

. In humans the main adaptive role of chemical senses is flavor recognition

In many other species , the chemical senses also play significant role in regulating social interactions Members of many species release pheromones. Pheromones – chemicals that influence the physiology and behavior of “conspecifics” (others of the same species)

Human may release sexual pheromones has received considerable attention because of its financial and recreational potential Olfactory sensitivity of woman is greatest when they are ovulating or pregnant. Humans-particular woman- can tell the sex of a person from the breath or the underarm odor.

Man can judge the stage of the woman’s menstrual cycle on the basis of her vaginal odor.

OLFACTORY SYSTEM

It was widely assumed that there where only a few different types of olfactory receptors Different profiles of activity in a relatively small number of receptor types was thought to lead to the perception of various smells In mammals, each olfactory receptor cells contains only one type of receptor protein molecule. The one-olfactory-receptor-oneneuron-rule

Olfactory receptor proteins are in the membranes of the dendrites of the olfactory receptor cells; where they can stimulated by circulating carbon chemicals in the nasal passages

Piriform cortex- area of medial temporal cortex adjacent to the amygdala � Considered to be primary olfactory cortex, but this designation is somewhat arbitrary

GUSTATORY SYSTEM Taste receptors are found in the tongue Typically occur in clusters of about fifty, called taste buds Unlike olfactory receptors, taste receptors do not have their own axons

Four Primary taste : � Sweet � Sour � Bitter � Salty �Four kinds of taste receptors, one for each primary taste

Several major problems pertaining to simple component-processing theory of taste : It is now clear that there at least five primary tastes; “umami” (meaty or Savoty) is the fifth

Many taste cannot be created by combinations of the primary taste Some taste (salty and sour) seem to have no receptors specific to them

BRAIN DAMAGE AND THE CHEMICAL SENSES ANOSMIA – The inability to smell Common neurological cause of anosmia : �Blow to the head that causes a displacement of the brain within the skull, and shears the olfactory nerves where they pass through the cribiriform plate.

Less complete deficits in olfaction have been linked to a wide variety of neurological disorders including �Alzheimer's disease �Down syndrome �Epilepsy �Multiple sclerosis �Karsakoff’s syndrome �Parkinson's disease

AGEUSIA - The inability to taste Is rare. Because sensory signals from the mouth are carried via three separate pathways

GUSTATORY SYSTEM