Nervous System Perception Notes (Olfactory, Gustatory,

Five Senses

sight, taste, smell, touch and hearing

Functions of Sensory Systems 1

Gather information about the world around us

Functions of Sensory Systems 2

Build an accurate internal representation of the external world

Mechanoreceptors

pressure, bending, or stretch opens an ion channel

Thermoreceptors (touch)

temperature opens the ion Chanel

Chemoreceptors (taste, smell)

a chemical binds to a receptor and opens the ion channel

Photoreceptors

light alters the form of a receptor and opens the ion channel

Goal of Taste

For survival, not to eat poison but also consume nutritious food

Papillae

mounds/ bumps on tongue that most people believe are taste buds

Taste Buds

3-5 taste buds on each papillae

Taste Receptor Cells

chemoreceptors that are activated by one of the five different types of taste (mostly); 50 taste receptor cells on each taste bud

5 Tastes

sweet, salty, umami, sour and bitter

Capsaicin

the colorless compound found on the seeds of hot peppers which give the peppers their spiciness

Odorants

volatile organic compounds that stimulate the olfactory system

ORN (odorant receptor neuron)

chemoreceptor neuron/cell in the olfactory epithelium that detects odorants and sends action potentials to the brain

Each ORN expresses only 1 odorant receptor

Principle of Odor Coding 1

One odorant binds to many receptors

Principle of Odor Coding 2

one odorant receptor neuron (ORN) binds to many odorants

Principle of Odor Coding 3

High concentrations of odorants activate more odorant receptor neurons

Main Concept

The brain is looking for specific patterns of activation and inactivation which acts as a combination code for smells

Olfactory Pathway

ORN —> Olfactory Bulb —> Pyriform Cortex —>
1. Amygdala 2. Hippocampus 3. Orbitofrontal Cortex

Olfactory Pathway

Innervations (connections) with the amygdala, hippocampus and orbital cortex accounts for strong connection with emotional salience and memory, regulates flavor perception, responsible for conditioned flavor aversion