The special senses Flashcards
Where is information from sense organ processed?
-CNS- conscious or unconscious
What are the special senses?
-Sight, hearing, taste, smell
What system deal with taste?
-Gustatory
What system deals with smell?
-Olfactory
What are the accessory structures of the eye?
-Eyebrows, eyelids, eyelashes, conjunctiva, lacrimal, apparatus, extrinsic eye muscles
What is the lacrimal apparatus?
-Gland that is responsible for tears a part of the PNS
What is the conjunctiva?
-Transparent mucous membrane covering the cornea
What are the three tissue layers of the eye wall?
-Fibrous layer (outer), vascular layer and nervous tissue layer (inner)
What does the fibrous layer of the eye contain?
-Sclera (white of the eye) and cornea (front of the eye)
What does the vascular layer of the eye contain?
-Choroid (melanin containing cells), colliery body (cilliary muscles to change thickness of lens), iris (coloured and control pupil size)
What does the nervous tissue layer of the eye contain?
-The retina, outer pigmented to prevent light reflection and inner sensory retina
What are the chambers of the anterior segment?
-Anterior chamber, posterior chamber
How does light pass through the eye?
-Iris allows light into the eye, focused by the cornea, lens and humors onto the retina through the vitreous humour,between sons, ganglion cells and bipolar cells to photoreceptors next to the pigmented layer. Ganglion cell axons run on internal surface and converge at posterior of the eye to form optic nerve
What are the two types of photoreceptors ?
-Rods and cones
What are the features of the rod cells?
-More sensitive to light, allow vision in dim light by only black and white and not sharp
What are the features of cone cells?
-High acuity, so bright light needed. Colour vision, separated into 3 subtypes-blue, red and green
What is the anterior chamber?
-Chamber between cornea and iris
What is the posterior chamber?
-Chamber between iris and lens
What is the chamber in the posterior segment?
-Vitreous chamber
What is the vitreous humor?
-Jelly like tissue that maintains and refracts in the posterior cavity
What is the aqueous humor ?
-Fills the anterior segment-it is a watery liquid that is continuously replaces and refracted light and maintains pressure
What are the regions of the retina?
-Macula and optic disc
What is the macula?
-Area of high rod and cone density and contains the fovea which contains the highest density of cones
What is the optic disc?
-Where blood vessels enter the cell
What are the layers of the retina?
-Outer pigmented layer and inner neural layer
What are the features of the outer pigmented layer of the retina?
-Produce melanocytes and contain melanin
What are the features of the neural layer of the retina?
-Contain 3 main types of Neuron-photoreceptors, bipolar cells and ganglion cells
What are the regions of the posterior retina?
-Macula-high res colour vision, contains fovea where highest density of cones for focused vision
-Optic disc-where blood vessels enter the eye, axons from the retina meet and exit as the optic nerve - no photoreceptors
Explain the process of phototransduction?
-Rhodopsin is composed of opsin and retinal, light causes retinal to change shape activating the rhodopsin which changes cells resulting in vision. Retinal detached from opsin and ATP is needed to bring retinal back to its original form and the process repeats
What are the parts of the ear?
-Outer ear, middle ear, inner ear
What does the outer ear contain?
-Pinna and external auditory canal
What does the middle ear contain?
-Tympanic membrane, malleus (hammer), incus and stapes
What does the inner ear contain?
-Mechanoreceptors for hearing and balance, vestibular apparatus, semicircular canals, cochlea (organs of corti)
What are the features of the middle ear?
-Air filled, oval and round window connect to the inner ear
-TM causes ossicles middle ear to mover malleus (attached to TM), incus, stapes (touches window), ossicles for a lever system, transmits vibrations from TM to fluids of inner ear
What are the 3 chambers of the inner ear?
-Cochlea, hearing
-Vestibule, equilibrium
-Semicircular canals, equilibrium, filled with perilymph and endolymph fluids
What canals make up the cochlea?
-Vestibular, tympanic and cochlear canals separated by basilar membrane
What are the features of the organ of corti?
-Specialised sensory hair cells called sterocilia, seated of basilar membrane, reach to tectorial membrane, base of hair cells attached to neurone
How does the cochlea work?
-Soundwaves cause the basilar membrane to move and the tectorial membrane to stay rigid which causes the sterocilia to bend which causes the mechanoreceptor to depolarise and neurotransmission occurs in connective neuron through the cochlea nerve
Explain the process of sound transmission through the ear?
-Sound waves vibrate the tympanic membrane, auditory auspices vibrate causing amplification, stapes connected to oval window sends vibration into cochlea, press pushes on basilar membrane and energy waves dissipate at round window, hair cells bend and transmission of signal occurs, neurotransmission activates sensory neurons and action potentials are sent to the brain
Explain the auditory pathway in the brain?
-Sensory axons from the cochlear ganglion terminate in the brainstem, axons from the neurons in the cochlear nucleus project to other brainstem nuclei or inferior colliculus, axons from the inferior colliculus project to the thalamus and thalamus neurons project to the auditory cortex
