Special Senses: Introduction and Olfaction Flashcards

Vocabulary practice flashcards covering general and special senses, sensory receptors, adaptation, and the anatomical and physiological components of olfaction.

Sensation

The physical detection of a stimulus by a sensory receptor.

Perception

The conscious awareness and processing of sensory information within the central nervous system.

General senses

Senses detected by simple receptors distributed all over the body, responsible for touch, pressure, temperature, and pain.

Special senses

Senses (vision, hearing, smell, taste, and balance) that utilize complex sensory organs located exclusively in the head.

Exteroceptors

Sensory receptors that monitor the external environment.

Interoceptors

Sensory receptors that monitor the internal environment of the body.

Proprioceptors

Sensory receptors located in synovial joints that monitor body position and balance.

Chemoreceptors

Receptors sensitive to chemical stimuli, monitoring internal chemical parameters such as electrolyte concentration, glucose, and calcium levels.

Nociceptors

Pain receptors that respond to hurtful stimuli and damaged tissue.

Thermoreceptors

Receptors that monitor temperature on the skin or internally within deep body tissues.

Mechanoreceptors

Receptors sensitive to mechanical stimuli involving pressure, touch, or sound wave vibration.

Photoreceptors

Specialized receptors located in the retina of the eye that detect light.

Specialized receptor cell

A non-neuronal cell unique to special senses that manufactures neurotransmitters in synaptic vesicles, depolarizes upon stimulation, and releases neurotransmitters via exocytosis to communicate with a sensory neuron.

Sensory adaptation

A central nervous system phenomenon where responsiveness to a constant, continuous stimulus decreases over time due to pathway inhibition.

Olfaction

The special chemical sense of smell.

Gustation

The special chemical sense of taste.

Odorant

A volatile chemical compound that dissolves in nasal mucosa and binds to chemoreceptors to generate the sensation of smell.

Olfactory organs

Structures located in the superior region of the nasal cavity consisting of olfactory epithelium and underlying connective tissue.

Cribriform plate

A region of the ethmoid bone on either side of the crista galli containing olfactory (cribriform) foramina that allow nerve fibers to pass into the nasal cavity.

Olfactory receptor cells

First-order bipolar neurons located in the olfactory epithelium that directly detect odorant stimuli.

Supporting cells

Columnar epithelial cells that provide structural support within the olfactory epithelium.

Basal cells

Stem cells in the olfactory epithelium that divide to replace bipolar olfactory neurons approximately every $40\text{ to }60\text{ days}$.

Olfactory hairs

Cilia extending from the dendrites of bipolar olfactory neurons that contain chemoreceptors for binding odorants.

Mitral cells

Second-order sensory neurons located in the olfactory bulb that synapse with bipolar olfactory neurons.

Olfactory bulb

A central nervous system structure resting on the cribriform plate containing cell bodies of second-order sensory neurons.

Methyl mercaptan

An odorant added to naturally odorless gases to permit human perception of gas leaks due to a very low threshold for detection.

Hypothalamus (olfactory connection)

Brain structure receiving convergent olfactory signals responsible for triggering visceral reactions to smells, such as gagging or nausea.

Amygdala

A structure within the limbic system that links olfactory information directly to memories, emotional responses, and behavioral reactions.