TYPES OF CHEMOSENSORY LOSSES


While taste and smell disorders are associated with a wide variety of conditions (including drug therapy, disease states, normal aging, Alzheimer's disease, and pollution), they can generally be classified by three major types of losses: transport losses; sensory losses, and neural losses. The term sensori­ neural losses is used in situations in which it is difficult in practice to distinguish between sensory and neural disorders.

Sensory losses are caused by damage to the sensory organs themselves. Toxic chemicals, radiation therapy, medications, neoplasms, endocrine and viral infections that reduce cell turnover or directly modify cells, can impair taste and smell functioning. For example, radiation treatment can reduce cell turnover and cause aberrations in the sense of taste. Medications with sulfhydryl groups in their molecular structure such as penicillamine (antirheumatic drug) and captopril (antihypertensive agent) probably cause taste disorders because they interfere with receptor proteins on the surface of taste cells.
Neural losses result from damage to either the peripheral neural pathways that mediate taste and smell information or to the central nervous system. Common causes include head trauma, neoplasms, and surgical procedures. For example, head trauma resulting from an automobile accident can sever the nerve pathways through the cribriform plate to produce olfactory dysfunc­tion.

1. Ageusia: total loss of taste sensitivity to some or all stimulants (tastants). 2. Hypogeusia: decreased taste sensitivity to some or all stimulants (tastants). 3. Dysgeusia (parageusia): distortion of taste for some or all tastants, or
the perception of taste in the absence of any tastants (gustatory hallucina­
tion).
4. Hypergeusia: increased taste sensitivity to some or all stimulants (tastants). 5. Taste agnosia: complete or partial inability to identify, classify, or contrast
a tastant verbally despite ability to recognize and distinguish between tastants.
Smell disorders fall into five similar categories:
1. Anosmia: total loss of sensitivity to odors.
2. Hyposmia: decreased sensitivity to odors.
3. Dysosmia: distortion of smell for some or all odorants, or the perception
of odor in the absence of any odorants (olfactory hallucination).
4. Hyperosmia: increased odor sensitivity to some or all stimulants (odorants). 5. Smell agnosia: complete or partial inability to identify, classify, or contrast
an odorant verbally despite ability to recognize and distinguish between odorants.
 

by the end of this lesson, students should be able to know about

1. different types of chemosensory disorders 

2. Smell disorders

3. Taste disorders 

 

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olfactory-disorders.ppt (2.69 MB )