1. Senses (Hearing & Taste)
Zulcaif Ahmad
03444737311

2. Hearing sense and Equlilbrium
Two important functions of the ear
It enables us to hear
It functions as the sensory organ of balance or
equilibrium
Location of one ear on each side of head
produces binaural hearing
Hearing from both sides

3. The External Ear
External Ear
 Visible portion of the ear not contained within the head
 Auricle or pinna
Cartilaginous flap that has a fleshy, lower portion called
the ear lobe
 External auditory canal
Tube leading from the auricle to the middle ear
Lined with tiny hairs called cilia which aid in transmitting
sound waves inward
 Tympanic membrane (eardrum)
Separates external ear from middle ear

4. Structure:

5. The Middle Ear
The tympanic cavity
 A small, air-filled space
 Located within the petrous portion of the temporal bone
Medial wall is penetrated by
 Oval window
 Round window
Pharyngotympanic tube (auditory or eustachian
tube)
 Links the middle ear and pharynx

6. Structures of the Middle Ear

7. Structure:
Middle Ear
Contains three tiny bones known as the
auditory ossicles
Malleus
Resembles the shape of a hammer
Connected to tympanic membrane and transmits
sound vibrations to second auditory ossicle
Incus
Resembles the shape of an anvil
Transmits sound vibrations from malleus to third
auditory ossicle

8. Structure:
Middle Ear (continued)
Stapes
Shaped like a tiny stirrup
Transmits sound vibrations from incus to the inner
ear
Eustachian tube
Connects the middle ear to the pharynx
Also called the auditory tube
Oval window
Separates the middle ear from the inner ear
Base of the stapes fits into the oval window

9. Structure:

10. The Inner (Internal) Ear
Inner ear – also called the labyrinth
Lies within the petrous portion of the
temporal bone
Bony labyrinth – a cavity consisting of
three parts
Semicircular canals
Vestibule
 Cochlea

11. Structure:
Vestibule
Central portion of the inner ear
Located next to stapes and between cochlea and
semicircular canals
Contains the utricle and saccule-membranous
pouches or sacs that aid in maintaining balance
Cochlea
Snail-shaped bony structure
Contains endolymph and perilymph
Auditory fluids that aid in transmission of sound
vibrations

12. The Cochlea

13. The Cochlea

14. Inner Ear (continued)
 Organ of Corti
 True organ of hearing
 Contained within the cochlea
 Here, sound vibrations are converted into nerve
impulses that are transmitted to the brain
Components of Organ Of Corti
i. Hair cells
ii. Tectoral membrane
iii. Nerve fibers

15. Inner Ear (continued)
Semicircular canals:
Located behind the vestibule
Three bony, fluid-filled loops that help to maintain one’s balance.
 Lie posterior and lateral to the vestibule
 Anterior and posterior semicircular canals
 Lie in the vertical plane at right angles
 Lateral semicircular canal
 Lies in the horizontal plane
Membranous labyrinth
 Series of membrane-walled sacs and ducts
 Fit within the bony labyrinth
 Consists of three main parts
Semicircular ducts
Utricle and saccule
Cochlear duct

16. Inner Ear (continued)
Membranous labyrinth (continued)
Filled with a clear fluid – endolymph
Confined to the membranous labyrinth
Bony labyrinth is filled with perilymph
Continuous with cerebrospinal fluid

17. Auditory Pathway

18. Structure:

19. Sense of Taste

20. Sense of Taste
Taste receptors are chemo receptors that
are stimulated by molecules in the solution
in the mucous in the nose and saliva in
the mouth
The sense that distinguish the sweety,
sour, salty and bitter qualities of dissolved
substances in contact with the taste bud
on tongue

21. Sense Of Taste(cont.0
Taste sensation Unami
4 primary 5th basic taste
Sweet – tip Deliciousness
Sour – sides
Salty – tip and
sides
Bitter – back

22. Classification:
Salty (Cl of Na + and K+ Ca++ and Mg++
and many other halides like sulphate,
nitrate etc)
Sour (H+, strong inorganic acids like HCl,
Sulphuric acid etc)
Sweet (organic compound like sugar
some polysaccharides, glycerol,
aldehydes, ketones etc)
Bitter (Alkolloids, Brucine, Nicotin)

23. Structure (Taste buds):

24. Taste Buds:
 Collection of 50 –100 epithelial cells
 Contain three major cell types (similar in all special senses)
 Supporting cells
 Gustatory cells
 Basal cells
 Contain long micro villi – extend through a taste pore
 LINGUAL PAPILLAE
 Types of papillae (with taste buds)
 Fungi form papillae (Large round and mostly occur at the tip and
edges, contain 2-5 taste buds)
 Circumvallate papillae (Large size dome shaped, on the back of tongue,
contain 100-250 taste buds)
 Faliate papillae (present on lateral border of the tongue)
 Filiform papillae do NOT contain taste buds
• Filiform papillae help you appreciate texture of food

25. Structure (Taste buds):

26. Gustatory Pathway from Taste Buds