Olfaction Flashcards

Electrophysiology

The study of the electrical properties of nerve cells, including their ion channels and transmembrane voltages.

Action Potentials

Rapid changes in transmembrane voltage that occur when a neuron fires.

Current Clamp

A technique used to record voltage changes by controlling the current flowing into the neuron.

Voltage Clamp

A method that allows the researcher to hold the voltage across the membrane constant while measuring ionic currents.

Ohm's Law

A principle stating that Voltage (V) equals Current (I) times Resistance (R).

Faraday Cage

A shield made of conductive material that protects sensitive electronic equipment from external electrical noise.

Air Table

A stable surface designed to reduce vibrations by suspending the equipment on a cushion of air.

Microscopic Currents

Small electrical currents flowing through individual ion channels.

Macroscopic Currents

Total currents measured from many ion channels opening simultaneously.

Odorants

Chemical substances in the air that can bind to receptors and trigger a smell sensation.

Olfactory Epithelium

A specialized tissue located in the nasal cavity that contains olfactory receptor neurons.

Transduction

The process of converting a sensory stimulus (such as a smell) into an electrical signal that the nervous system can process.

Pseudogenes

Nonfunctional sequences of DNA that resemble functional genes but do not produce proteins.

G Protein Coupled Receptors (GPCRs)

A large family of receptors that detect molecules outside the cell and activate internal signal transduction pathways.

Signal Transduction

The process through which a cell translates external signals (like odorants) into a response.

Cribriform Plate

A bony structure in the skull that supports the olfactory bulb and allows odorants to access the olfactory neurons.

Olfactory Bulb

A neural structure involved in processing the information received from olfactory receptor neurons.

Bacterial Molecular Nose

A term referring to the ability of bacteria to detect airborne chemicals, likened to a sense of smell.

Olfactory Epithelium

The thin layer of tissue at the back of the nasal cavity where odorants bind to receptors.

Neurogenesis

The process of creating new neurons, which occurs actively in the olfactory epithelium every four to eight weeks.

Olfactory Receptor Neurons (ORNs)

Specialized neurons located in the olfactory epithelium that detect odorants.

Basal Cells

Cells in the olfactory epithelium that differentiate into new olfactory receptor neurons.

Supporting Cells

Modified epithelial cells in the olfactory epithelium that provide metabolic support for olfactory receptor neurons.

Cilia

Thin membranous protrusions on the dendrites of olfactory receptor neurons that contain odorant receptors.

Cribriform Plate

A porous bony structure that allows bundles of olfactory nerve axons to pass into the olfactory bulb.

Olfactory Bulb

The brain structure where olfactory information is processed before being sent to the cortex.

G Protein-Coupled Receptors (GPCRs)

A large family of receptors, including odorant receptors, that activate intracellular signaling pathways upon binding with ligands.

Cyclic AMP (cAMP)

A second messenger generated by the activation of adenylyl cyclase during olfactory signal transduction.

Calcium-Activated Chloride Channels

Chloride channels that open in response to increased intracellular calcium, contributing to membrane depolarization in olfactory neurons.

Broad Tuning Curves

The ability of olfactory receptors to respond to multiple different ligands.

Mucus Layer

The sticky layer in the olfactory epithelium that traps odorant molecules for detection by receptors.

Ionic Current

The flow of ions through channels in the cell membrane, crucial for generating electrical signals in neurons.

Threshold for Detection

The minimum concentration of an odorant required for detection by olfactory receptor neurons.

Pattern of Firing

The varying electrical activity of olfactory receptor neurons in response to different ligands, important for odor discrimination.

Ligand

A molecule that binds to a receptor, initiating a response in the cell.

CNG Channel

Cyclic nucleotide gated channel that allows ions to pass in response to cyclic AMP.

Glomerulus

A spherical structure in the olfactory bulb where synaptic connections are made between olfactory receptor neurons and second-order neurons.

Signal Transduction

The process by which a signal outside the cell is converted into a functional response within the cell.

Lateral Inhibition

A process where excited neurons inhibit the activity of their neighbors to enhance contrast in sensory perception.

Granule Cells

Inhibitory neurons in the olfactory bulb that mediate lateral inhibition and synapse with mitral and tufted cells.

Mitral Cells

Output neurons of the olfactory bulb that convey olfactory information to the brain.

Tufted Cells

A type of excitatory neuron in the olfactory bulb that, along with mitral cells, send information to the primary olfactory cortex.

Cribriform Plate

A thin, porous bone that separates the olfactory epithelium from the olfactory bulb.

Action Potential

A rapid change in the electrical membrane potential of a neuron, leading to the transmission of a signal.

Lateral inhibition

A process in which interconnected neurons inhibit their neighbors, enhancing contrast and sharpness in sensory perception.

Olfactory bulbs

Structures in the brain that receive neural input about odors from the olfactory receptors and process this olfactory information.

Mitral cells

Major output neurons of the olfactory bulb that carry olfactory information to the primary olfactory cortex.

Tufted cells

Another type of output neuron in the olfactory bulb, involved in transmitting olfactory information to the cortex.

Anosmia

The complete loss of the sense of smell, which can be caused by various factors, including infection or injury.

Olfactory adaptation

A temporary inability to detect an odor after prolonged exposure, allowing the sensory system to free up attention for new stimuli.

Granule cells

Inhibitory interneurons in the olfactory bulb that play a significant role in lateral inhibition.

Thalamic relay

A necessary stage in the processing of sensory information, except for olfactory information which bypasses this relay.

Primary olfactory cortex

The first brain area to receive processing olfactory information directly from the olfactory bulbs.

Orbitofrontal cortex

A brain area involved in the processing of olfactory and gustatory information, important for the perception of flavor.

Chemical communication in animals

The process in which olfactory signals influence mating behavior, particularly through pheromones.

Hippocampus

A brain region associated with memory and spatial awareness, involved in processing olfactory information.

Amygdala

A brain structure associated with emotional responses and fear conditioning, also involved in processing olfactory information.

Calcium mediated olfactory adaptation

A theoretical process where increased calcium levels in olfactory neurons lead to decreased sensitivity to sustained odors.

GABAergic neurons

Neurons that use gamma-aminobutyric acid (GABA) as their primary neurotransmitter, often involved in inhibitory signaling.

Hebbian plasticity

A theory that proposes an explanation for the adaptation of neurons during learning, often summarized as 'cells that fire together wire together.'

Piriform cortex

The primary region of the cerebral cortex involved in olfactory processing, receiving direct input from the olfactory bulbs.

Olfactory receptor neurons

Specialized sensory neurons responsible for detecting odor molecules and initiating the sense of smell.

Chemokines

Proteins that mediate cellular signaling and can influence various physiological responses, including those related to olfaction.