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Benefits Neet - Subscription TARGET NEET_UG 2022 LET’s ACE NEET_UG EXAMS WITH INDIA’s MOST INNOVATIVE LEARNING PLATFORM BENEFITS NEET - SUBSCRIPTION Full Access to All Subjects: Biology, Taught in English LIVE Courses Physics, chemistry and Hindi Instant In-class Master concepts Learn safely from Doubt Solving with India's Best home on any Teachers device UNDERSTAND YOUR VEDANTU NEET PRO-SUBSCRIPTION 5000+ Hours of LIVE Tests & Assignments Continuous review of Online Teaching with 10,000+questions areas of Improvement 20+ Teachers with 5+ Option to Learn in Cover all needs with years of experience English or Hindi Micro & Crash Courses NEET - SUBSCRIPTION PRICES SUBSCRIPTION ORIGINAL DISCOUNTED PER MONTH PER DAY MODEL-- PRICE PRICE PRICE PRICE 1 MONTH Rs.5,000/- Rs.4,000/- Rs.4,000/- Rs.133/- 3 MONTH Rs.13500/- Rs.10800/- Rs.3600/- Rs.120/- 6 MONTH Rs.24000/- Rs.19200/- Rs.3200/- Rs.107/- 12 MONTH Rs.42000/- Rs.33600/- Rs.2800/- Rs.93/- WHAT ARE YOU WAITING FOR ? BUY NOW @ https://vdnt.in/YTPRO USE COUPON CODE:- Sense of Hearing The organ of hearing, the ear, has outer (external), middle, and inner (internal) sections. The ear has two sensory functions: hearing and balance (equilibrium). Middle Ear Inner Ear Outer Ear Stapes Semicircular Canals Incus Malleus Vestibular Nerve Pinna Cochlear Nerve Tympanic cochlea Membrane Auditory Canal Round Auditory Earlobe Window Tube OUTER EAR Gathers sound waves Consists of the pinna (external flap) and the auditory canal Opening of auditory canal is lined with fine hairs and glands OUTER EAR Auricle Collects sounds waves External Auditory Meatus Lined with ceruminous glands Carries sound to tympanic membrane Terminates with tympanic membrane Tympanic Membrane Vibrates in response to sound waves MIddle EAR Amplifies sound waves Begins at tympanic membrane (Eardrum) Ends at a bony wall containing two small openings covered by membranes called oval window and round window Three small bones lie between the tympanic membrane and oval window called ossicles, individually they are malleus (hammer), incus (anvil), and stapes (stirrup) MIddle EAR TYMPANIC CAVITY Air-filled space in temporal bone Middle Ear Incus AUDITORY OSSICLES Malleus Stapes Vibrate in response to tympanic membrane Malleus, incus and stapes Hammer, anvil and stirrup OVAL WINDOW Auditory Opening in wall of tympanic cavity Tube Stapes vibrates against it to move fluids in inner ear MIddle EAR Middle Ear Auditory Tube Incus Malleus Stapes Also known as the Eustachian tube Connects middle ear to throat Helps maintain equal pressure on both sides of tympanic membrane Auditory Usually closed by valvelike flaps in Tube throat INNER EAR Filled with fluid Semicircular canals and also the vestibule are both concerned with balance The cochlea is concerned with hearing INNER EAR Complex system of labyrinths • Osseous Labyrinth Bony canal in temporal bone Filled with perilymph • Membranous Labyrinth Tube within osseous labyrinth Filled with endolymph INNER EAR Three (3) parts of labyrinths: • Cochlea Functions in hearing • Semicircular canals Functions in equilibrium • Vestibule Functions in equilibrium COCHLEA • Scala Vestibuli Upper compartment Leads from oval window to apex of spiral, Part of bony labyrinth • Scala Tympani Lower compartment Extends from apex of the cochlea to round window, Part of bony labyrinth COCHLEA • Cochlear duct Portion of membranous labyrinth in cochlea • Vestibular membrane Separates cochlear duct from scala vestibuli • Basilar membrane Separates cochlear duct from scala tympani Organ of Corti • Group of hearing receptor cells (hair cells) • On upper surface of basilar membrane • Different frequencies of vibration move different parts of basilar membrane • Particular sound frequencies cause hairs of receptor cells to bend • Nerve impulse generated MECHANISM OF HEARING Sound waves enter the external acoustic meatus. ↓ Waves of changing pressures cause tympanic membrane to reproduce vibrations coming from sound wave source. ↓ Auditory ossicles amplify and transmit vibrations to the end of stapes. ↓ Movement of stapes at oval window transmits vibrations to perilymph in scala vestibuli. ↓ Vibrations pass through vestibular membrane and enter endolymph of cochlear duct. ↓ Different frequencies of vibration in endolymph move specific regions of basilar membrane, stimulating specific sets of receptor cells. ↓ MECHANISM OF HEARING ↓ A receptor cell depolarizes; its membrane becomes more permeable to calcium ions. ↓ In presence of calcium ions, vesicles at base of receptor cell release neurotransmitter. ↓ Neurotransmitter stimulates ends of nearby sensory neurons. ↓ Sensory impulses are triggered on fibers of the cochlear branch of the vestibulocochlear nerve. ↓ The auditory cortex of the temporal lobe interprets the sensory impulses. SENSE OF TASTE In mammals, taste receptors are a type of chemoreceptor located in taste buds There are at least four primary types of taste Sweet, sour, salty, and bitter A fifth taste, called umami, may exist for certain flavors of cheese, beef broth, and some seafood SENSE OF TASTE Taste buds for each of these tastes are located throughout the tongue Certain regions may be most sensitive to particular tastes Tip of the tongue is most sensitive to sweet tastes Margins to salty and sour tastes Rear of the tongue to bitter tastes SENSE OF TASTE Sweet → Stimulated by carbohydrates Sour →Stimulated by acids Salty → Stimulated by salts Bitter → Stimulated by many organic compounds TASTE BUDS • Organs of taste • Located on papillae of tongue, roof of mouth, linings of cheeks and walls of pharynx Taste Receptors • Chemoreceptors • Taste cells → Modified epithelial cells that function as receptors • Taste hairs → Microvilli that protrude from taste cells; sensitive parts of taste cells TASTE GUSTATION Sugar molecules enter the taste bud ↓ Sugar molecules bind to sweet receptors, specific protein molecules embedded in a taste receptor cell membrane ↓ The binding triggers a signal transduction pathway that causes some ion channels in the membrane to close and others to open. ↓ These changes in the flow of ions create a graded change in membrane potential called a receptor potential. 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