Chemical senses: Taste & Smell

Taste Buds

 

•The taste buds are ovoid bodies present on the papillae of tongue.
•Taste buds are also situated in the mucosa of epiglottis, palate, pharynx and the proximal part of esophagus.
•Three types of papillae are located on the tongue.
1.Filiform : They are small and situated over the dorsum of tongue.
2.Fungiform : They are situated over the anterior surface of tongue.
3.Circumvallate papillae : These are large papillae present on the posterior part of tongue and are arranged in the shape of “V”.

Full Text

Read More

Visual sense organ

Structure of eye

uAccommodation is the adjustment of the eye to see either near or distant objects clearly. It is the process by which light rays from near objects are brought to a focus on the sensitive part of retina. It is achieved by , three adjustments made in eyeballs.
u
1.Convergence of the eyeballs due to contraction of the medial recti
2.Constriction of the pupil due to the contraction of constrictor pupillae of iris
3.Increase in the curvature of the lens due to contraction of ciliary muscle.
u
u Involves both skeletal muscle ( medial recti) and smooth muscle (ciliary muscle and sphincter pupillae)
uThe center for accommodation lies in frontal eye field (area 8) in frontal lobe of cerebral cortex. 

Full Text

Read More