Lecture Notes: Special Senses

Special cenes The different sensations perceived by the hurren bety are groupel into two rigor categories: these concerned with general sensations and those concerned with special sensations. Olfaction The olfactory organ is located in the Mucous Meribrone lining the uppernest pat of the roof of the nasal cavity. From the roof. the offat day epithelium cxtende down both sides of the nalal cavity to cover most of the superior concha laterally and Icm of nasal septon redially. Man is a Microsmatic animal in whom the surface area of olfactory Imucous membrore in both nostrile is small. Saste!- esticrated that one vallatte papilla of the tongue contains 200 taste buds on its side and about 50 buds in the wall of the trench opposi Vallate ond pungi form papillae of the tongue, taste buds are found the soft palate, propharynx and epigllatis. She taste buds contains neuro lepithelial and supporting celles. There are approximately 4 to 20 receptor The gustatory sense organs in higher vertebrates are limited to to cavity of the mouth. The serlary digon of taste is the taste bus, in is pale, ovoid etoucture within the stratified squamous epithelon. It is the papilla she nucber decreases progressively with age. In addition to cells in the centre of ech torte bud. The apex off each receptor call realipiad into microvilli, which increase the receptor surful and project into opening, the taste pore Receptor celle decrease in nurrber with age. the nevro epithelial celte are stimulated by substances in solution. Vision Vision is for the most important of Man's senses. Most of our percepti of the environment around us comes through our eyes. Our visual syster. capable of adopting to extreme changed in light intensity to allow us to see clearly; it is also capable of colour discriccination and depth perception The digon of vision is the eye, accessory structures include the eyelids. lacrimal glands and extrinsic eye muscles. The eye has four functional compon a protective coat a nourishing lightproof coat, a dioptric syster and a receptive interating layer the protective coat is the tough, opaque sclera which covers the posterior five sixths of the it is co eyeball, it continuous with the duraratter around the optic nerve. The anterior one sixth is covered by the transparent cornea, which belongs to the diprotic system. The nourishing coat is made up of the vascular choroid, which supplies nutriente to the retina and because of ite rich content of relanocytes, acts as a light absorbin layer It corresponds to the pia-Inchnoid layer of the nervous system. Audition- The organ of hearing is located in the scala media of the inner ear ond is seperates prom the underlying scala tyreponi by the basilar membrane. Sound waves reaching the tympanic membrane will initiate vibrations that are transmitted through the boxy ossicles of the middle car to the oval window. Vibrations of the oval window are transmitted to the perilyny in the scala vestibuli and across the vestibular membrane to the endolyreph of the cochlear duct. Such induced pullations in the endo lyroph will displace the barilar merebrand on which the organ of Corti ties and alter the relationship of the tectorial membrane, which overlies the organ of Corti, to the hairs of the hair cells. Thus bending or stretching of the hair acts as a stirulas to the hair cells, causing release of a chemical nesmotransmitter, generation of a receptor potential, and subsequent development of on action potential in the peripheral processes of bipolar neurons of the spiral ganglion. The central processes of bipolar neutrons constitute the auditory components of the eight cranial nerve, which projecte centrally to the cochlear nuclei. Position and Moverment The internal ear consiste of Vestibular apparatus which is having 3 sericircular conale and I sac like structures called witiculus and saculus nesocinted with balancing. Vestibular apparatus The vestibular apparaties is differentiated into & chambers these are wrticulus and soculus. Urticulus is upper wide charcher and sacculus is lower smaller chacher Shey are connected with each other by a small sacculo uiticular duct. Shove sericircular conals are attacked to witiculus. There are 1. Anterior vertical canal 2. Posterior vertical canal 3. Horizontal canal. The place of origin of canak become swollen and called as orpulla. All are filled with endolyreph. On the inner surface of witiculus and Sacculus there are sensory hairs like celle called maculae. They are alssiatk with otholith or ear stones and tiny particles of caloz. Functions Urticulus, sacculus and semicircular conals serve to detet the positione of the body with respect to gravity and the motion of the body. These tructures transit the detected data to the CNS in the form of Mpulkes.