The first sense that ill be going to discuss is the Eye. There are External structures of the eye. Lacrimal apparatus includes a series of ducts and the lacrimal glands that produce tears, which washes and lubricates the eyeball. Eyelids protect the eyes associated with eyelids that prevent gross particles to enter the eye. The conjunctiva is a mucous membrane that covers the anterior eyeball and lines the eyelids. The sclera is the outer, tough, protective layer. Its anterior portion is the cornea, which is transparent to allow light to enter the eye. The choroid is the middle layer, which provides nutrition to the internal eye structures and prevents light's scattering in the eye. Anterior modifications include the iris which controls the size of the pupil). The retina is the innermost layer, which contains the photo pigments. Rods are dim light receptors. Cones are receptors that provide for colour vision and high visual acuity. The fovea centralis, on which acute focusing occurs contains only cones. The blind spot (optic disk) is the point where the optic nerve leaves the back of the eyeball. The lens shape is changed by the ciliary muscle for close focus. Anterior to the lens is the aqueous humour; posterior to the lens is the vitreous humour. Both humours reinforce the eye internally. The aqueous humour also provides nutrients to the lens and cornea. Errors of refraction include myopia, hyperopia, and astigmatism. All are correctable with specially ground lenses.
Next to be discussed is the sense of hearing. The ear is divided into three major areas. Outer ear structures are the pinna (auricle), external auditory canal, and tympanic membrane (eardrum). Sound entering the external auditory canal sets the eardrum into vibration. Middle ear structures are the ossicles and auditory tube within the tympanic cavity. The ossicles are malleus, incus, and stapes which transmit the vibratory motion from the eardrum to the oval window. The auditory tube allows pressure to be equalized on both sides of the eardrum. These structures are also involved with sound transmission only. Inner ear, or bony labyrinth, consists of bony chambers namely cochlea, vestibule, and semicircular canals in the temporal bone. The bony labyrinth contains perilymph and membranous sacs filled with endolymph. Within the membranous sacs of the vestibule and semicircular canals are equilibrium receptors. Hearing receptors are found within the membranes of the cochlea. The organ of Corti is receptor for hearing within the cochlea it is stimulated by sound vibrations transmitted through air, membranes, and fluids. Deafness is any degree of hearing loss. Conduction deafness results when the transmission of sound vibrations through the external and middle ears is hindered. Sensorineural deafness occurs when there is damage to the nervous system structures involved in hearing.
Lastly to talk about is the sense of smell and taste. The olfactory (smell) receptors are located in the superior aspect of each nasal cavity. Sniffing helps you to bring more air (containing odours) over the olfactory mucosa. Olfactory pathways are closely linked to the limbic system; odours recall memories and arouse emotional responses. Gustatory (taste) cells are located in the taste buds, primarily on the tongue. The four major taste sensations are sweet, salt, sour, bitter. Taste and appreciation of foods is influenced by the sense of smell and the temperature and texture of foods.
All throughout the reporting, the lesson was clearly discussed by the reporter and my professor. The reporter did a good job in preparing his visual aids. Our teacher gave us an activity in which we have to draw the anatomy of the eye which I enjoyed a lot because I’m somehow good in drawing .
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