Chapter 9.3 - The Olfactory System

Limbic system

Action potentials for smell and taste propagate to the ______ ______

Rapidly

Adaptation (decreasing sensitivity) to odors occurs ______

Decreasing

Another mechanism of adaptation (decreasing sensitivity) occurs by _________ the opening of cAMO-gated cation channels, causing the olfactory transduction process to be less responsive to odorant

Nonmotile cilia

Extending from the dendrite of an olfactory cell receptor are several _____ _____, which are the sites for olfactory transduction

Neurons

Olfactory receptor cells are ______

Olfactory (I) nerves

On each side of the nose, bundles of axons of olfactory receptor cells form the right and left ____ (__) ______

Limbic system

Other axons of the olfactory tract project to the _____ _____; these neural connections account for our emotional responses to odors

Temporal

Some of the axons of the olfactory tract project to the olfactory cortex in the _______ lobe, where conscious awareness of smell occurs

Olfactory epithelium

The receptors for olfaction, the sense of smell, are located in a 5-cm^2 patch called the ______ ______ in the upper part of the nasal cavity

Phosphorylation

At the receptor level, adaptation seems to involve the _______ of odorant receptor proteins by a protein kinase This reduces the sensitivity of the olfactory receptor to odorant binding

Odorants

Chemicals that bind to and stimulate the receptors in the olfactory cilia are called _______

Olfactory receptor

Each glomerulus receives input from only one type of ______ ______ This allows the mitral cells of a particular glomerulus to convey information about a select group of odorants to the remaining parts of the olfactory pathway

Orbitofrontal cortex

From the olfactory cortex, a pathway extends via the thalamus to the _______ ______ in the frontal lobe, where odor identification and discrimination occur

Frontal

From the olfactory cortex, a pathway extends via the thalamus to the orbitofrontal cortex in the _______ lobe, where odor identification and discrimination occur

Low

Olfaction, like all of the special sense has a _____ threshold Only a few molecules of certain substances need be present in air to be perceived as an odor

Thalamus

Olfactory sensations are the only sensations that reach the cerebral cortex without first synapsing in the _________

Receptor

Only one type of ______ is found in any given olfactory receptor cell

Olfactory cortex

Some of the axons of the olfactory tract project to the ______ _____ in the temporal lobe, where conscious awareness of smell occurs

Olfactory receptor cells

The _____ _____ _____ are the first-order neurons of the olfactory pathway

Olfactory tract

The axons of the mitral cells form the _____ ______

Olfactory glands

The olfactory epithelium also contains ____ _____ which produce mucus that moistens the surface of the olfactory epithelium and dissolves odorants so that transduction can occur

Olfactory receptor cells

The olfactory epithelium consists of three types of cells: 1.) 2.) Supporting cells 3.) Basal cells

Supporting cells

The olfactory epithelium consists of three types of cells: 1.) Olfactory receptor cells 2.) 3.) Basal cells

Basal cells

The olfactory epithelium consists of three types of cells: 1.) Olfactory receptor cells 2.) Supporting cells 3.)

Olfactory bulbs

The olfactory nerves extend to parts of the brain known as the ______ _____, which contain ball-like arrangements called glomeruli

Glomeruli

The olfactory nerves extend to parts of the brain known as the olfactory bulbs, which contain ball-like arrangements called _______

Mitral cells

The olfactory nerves extend to parts of the brain known as the olfactory bulbs, which contain ball-like arrangements called glomeruli Within each glomerulus, axons of olfactory receptor cells converge onto _____ ______ - the second-order neurons of the olfactory pathway

Olfactory cilia

Within the plasma membranes of the ______ ____ are olfactory receptor proteins that detect inhaled chemicals

Olfactory receptor proteins

Within the plasma membranes of the olfactory cilia are ______ ______ ______ that detect inhaled chemicals

Olfactory receptor cells

______ ____ _____ are sensory neurons that respond to olfactory stimuli

Supporting cells

______ _____ provide physical support to the olfactory receptor cells and help detoxify chemicals that come in contact with the olfactory epithelium

Basal cells

______ ______ are stem cells that continually undergo cell division to produce new olfactory receptor cells, which live for only about two months before being replaced

Olfactory

_______ sensations are the only sensations that reach the cerebral cortex without first synapsing in the thalamus