Anatomy 101: From Muscles and Bones to Organs and Systems, Your Guide to How the Human Body Works

SENSORY SYSTEM DISEASES AND DISORDERS

When the Signal Doesn’t Get Through

The complex and intricate systems that detect and respond to stimuli can occasionally break down or suffer problems. Injuries, infections, and cancers can affect the senses. Other sensory system diseases and disorders include:

· sensory processing disorder, where the brain receives stimuli but doesn’t organize it in a coherent way

· age-related macular degeneration, where blood supply to the retina is disrupted, causing loss of vision

· nasal polyps, benign (noncancerous) growth in the nose, often caused by allergies or infections

Color Blindness

This condition results from an inadequacy, malfunction, or malformation of one or more types of cones in the retina. The most common type of color blindness is red-green color blindness, when red and green color discrimination is decreased. Affecting about 1 in 12 males, this is a hereditary condition and is termed X-linked, meaning the gene that is the problem is on the X chromosome. This is a recessive mutation. The presence of a dominant gene can overcome the condition and the individual will only be a carrier of the color-blind gene.

Anosmia

Anosmia means a lack of the sense of smell. Smell and taste are intimately linked together to expand the repertoire of each sense. A person lacking the sense of smell has a much less discriminating palate when compared to individuals with a functional olfactory system. Often, temporary anosmia may occur during a sinus infection, and that is usually why the taste of food is dulled during such a sickness.

Vertigo

Vertigo is a result of complications with the functioning of the inner ear, specifically the semicircular canals. The lack of information, or incorrect information, pertaining to balance can result in extreme dizziness, nausea, and vomiting, and increases the likelihood of falling. It is particularly problematic in older individuals.

Motion Sickness

With some of the same symptoms as vertigo, motion sickness (also called car sickness or air sickness) results from crossed signals in the visual centers of the brain. There is confusion between what the brain thinks is happening versus what the balance centers of the brain think is happening.

For example, many people get seasick on a ship when they are inside of a portion of the ship that has no windows. Their visual cortex sees the floor, walls, and ceiling, and relative to the body there is no movement. However, because the boat is moving up and down with the waves, the body is in fact moving and this fact is being detected by the semicircular canals of the inner ear.



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