SPECIAL SENSES: [SMELL AND TESTE] and etc.

Chemoreceptors

Stimulated by chemicals in solutions.

Olfactory receptors

roof of nasal cavity

Olfactory receptor cells

known as olfactory hairs detect chemicals

olfactory

chemicals must be dissolved in mucus for detection by chemoreceptors

olfactory nerve (cranial nerve I)

Impulses are transmitted via the olfactory filaments to the

olfactory cortex

Smells are interpreted in the

Locations of taste buds

-most on tongue
-soft palate
-cheeks
-superior part of the pharynx

papillae

TASTE BUDS, tongue is covered with projections called

Gustatory cells

taste receptors,
- Possess gustatory hairs (long microvilli)
- Gustatory hairs protrude through a taste pore
- Hairs are stimulated by chemicals dissolved in saliva

Impulses are carried to the gustatory complex by several cranial nerves because taste buds are found in different areas

- facial nerve
- glossopharyngeal nerve
- vagus nerve

taste buds

are replaced frequently by basal cells

sweet receptors

sugars, saccharine, some amino acids

sour receptors

respond to H+ ions or acids

Bitter receptors

alkaloids

Salty receptors

metal ions

Umami receptors

respond to the amino acid glutamate or the beefy taste of meat

Special sense organs

formed early in embryonic development

age 8 to 9

eye continue to grow and mature until

presbyopia

-"old vision" results from decreasing lens elasticity that accompanies aging
-Causes difficulty to focus for close vision

presbycusis

type of sensorineural deafness

otosclerosis

ear ossicles fuse

Congenital ear problems

usually result from missing pinnas and closed or missing external acoustic meatuses