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Sence organs ear and nose

a human being has different types of senses, which includes the sense of smell, touch etc. but the are organs that are responsible for this senses.

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Sence organs ear and nose

  1. 1. UNIT 3: SENSE ORGANS – NOSE AND EARS • Chemical senses •Sense of hearing and balance Campbell et.al, 2010 – CHAPTER 50
  2. 2. 1. SENSE OF SMELL Receptor cells of smell are OLFACTORY CELLS Olfactory cells are located within olfactory epithelium high in the roof of the nasal cavity.
  3. 3. SENSE OF SMELL
  4. 4. PERCEPTION OF SMELL The gas molecules in the air dissolves in the mucus of the nasal cavity. It stimulates the microvilli of olfactory cells. This cause an impulse to be send from olfactory cell through the sensory nerve fibers, to the olfactory bulb in the temporal lobe of the cerebrum. Smell is integrated and perceived.
  5. 5. PERCEPTION OF SMELL
  6. 6. 2. THE SENSE OF HEARING AND BALANCE The ear has two sensory functions: Hearing and Balance. The sensory receptors for both of these is located in the inner ear, and each consist of hair cells and cillia which are sensitive to mechanical stimulation. They are called machanoreceptors.
  7. 7. THE HUMAN EAR
  8. 8. FUNCTIONS OF DIFFERENT PARTS OF THE EAR OUTER EAR MIDDLE EAR INNER EAR
  9. 9. THE OUTER EAR Pinna – Concentrate sound waves in the direction of the external auditory canal. External Auditory canal – Transport sound waves from the pinna to the tympanic membrane. - Contain fine hairs and cerumin glands that secrete cerumin (earwax) to help guard the ear against foreign material and insects. (smell)
  10. 10. THE OUTER EAR Tympanic membrane – A thin membrane that covers the opening between the inner- and middle ear. - Converts soundwaves into vibrations. (starts to vibrate)
  11. 11. MIDDLE EAR 3 Bony ossicles e.g.: (start to vibrate): - Malleus – transmit vibration to incus - Incus – transmit vibrations to stapes - Stapes – transmit vibrations to oval window (fenestra ovalis) Oval window – start to vibrate and cause waves in liquid (perilymph) in cochlea. Eustachian tube – Equalize the pressure between the atmosphere and the inside of the ear. (Connected with the pharynx).
  12. 12. MIDDLE EAR
  13. 13. INNER EAR Cochlea: - Snail shaped canal. - Divided in 3 canals separated by membranes 1. Vestibular canal (scale vestibuli) – top canal, filled with perilymph. Receives vibration from oval window, form waves in perilymph, causes Reissner membrane to form waves.
  14. 14. 2. Cochlear canal (Scala media) – middle canal, filled with endolymph. Form waves in endolymph, that causes Basilar membrane to wave up and down. Contains the receptor cells for hearing: Organ of Corti - which pushes the stereocilia against the tectorial membrane, causes an impulse which is send through the cochlear nerves to the temporal lobe of the brain for integration.
  15. 15. 3. Tympanic canal (Scala tympani)– bottom canal, filled with perilymph. Form waves which are carried to the round window (fenestra rotunda). Round Window: absorb excess sound waves to prevent echoing in the ear.
  16. 16. COCHLEA Cross section through cochleaCochlear unrolled
  17. 17. 3. INNER EAR: SEMI CIRCULAR CANALS Contain machanorecepters (cristae) – detect rotational or angular movement of the head. Cristae- located in the ampulla (enlarged base of semi circular canals)in the endolymph found in the semi circular canals. - Consist of hair cells, supporting cells, stereocillia imbedded in a gelatin capsule called cupula, and nerve fibers.
  18. 18. INNER EAR: SEMI CIRCULAR CANALS Movement of the head causes the endolymph to move around in the ampulla, the cupula moves, bending the stereocilia, causing an impulse send through the vestibular nerve to the cerebellum of the brain for integration.
  19. 19. CRISTAE
  20. 20. 4. INNER EAR: UTRICULUS AND SACCULUS Enlarged area below the semi circular canals. Contain mechanoreceptors (macula) – that detects straight line movement of the head in any direction – gravitational equilibrium. Macula:  Consist of hair cells with stereocilia embedded in a gelatin membrane called otolithic membrane with otoliths (crystals) ontop, supporting cells and vestibular nerves.
  21. 21. 4. INNER EAR: UTRICULUS AND SACCULUS If a person stops suddenly, the endolymph in the utriculus and sacculus move around,  the otolithic membrane moves, bending the stereocilia, which sends an impulse through the vestibular nerves to the cerebellum of the brain to maintain balance.
  22. 22. MACULA FOUND IN SACCULUS AND UTRICULUS
  23. 23. PROCESS OF HEARING
  24. 24. PROCESS OF HEARING
  25. 25. PROCESS OF HEARING
  26. 26. Fig. 50-8 Hair cell bundle from a bullfrog; the longest cilia shown are about 8 µm (SEM). Auditory canal Eustachian tubePinna Tympanic membrane Oval window Round window Stapes Cochlea Tectorial membrane Incus Malleus Semicircular canals Auditory nerve to brain Skull bone Outer ear Middle ear Inner ear Cochlear duct Vestibular canal Bone Tympanic canal Auditory nerve Organ of Corti To auditory nerve Axons of sensory neurons Basilar membrane Hair cells
  27. 27. SENSE OF BALANCE
  28. 28. Fig. 50-11 Vestibular nerve Semicircular canals Saccule Utricle Body movement Hairs Cupula Flow of fluid Axons Hair cells Vestibule

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