The Ear (Its Structure, Nature and Mechanism) And Mechanism of Smell

1. THE EAR- ITS STRUCTURE,
NATURE AND MECHANISM
OF SMELL

2. PARTS OF EAR
1. Outer Layer or External Ear-
the pinna or concha is the external
protruding ear part that assembles the
sound vibrations to the auditory canal
or meatus, to the tymphaic membrane
(eardrum)
 Pinna – it collects the sound waves
which enter the external meatus.
 Meatus – a hole where the pinna is
attached to the head.
 Eardrum- divides the outer ea
from the middle ear.

3. 2. Middle Ear
is a cavity filled with air.
It contains the tree
bones: the hammer or
malleus, the anvil or
incus, and the stirrup or
stapes. The latter is
attached to the oval
window.

4. 3. Inner Ear- inside the inner ear are two structures – the
semi – circular canal at the upper part and the cochlea
which contains the sensitive structure for hearing. It is a
snail – like structure with three canlas.
 Vestibular Canal – is separated from the cochlear
canal by the Reissner’s membrane filled with a liquid
called perilymph and the cochlear with endolymph.
 Cochlear- is separated from the tymphanic membrane
by the basilar membrane which contains the Organ of
Corti.
 Tymphanic – filled with a liquid called perilymph and
the cochlear with endolymph like Vestibular Canal.

6. FUNCTION OF THE EAR
 They bring us in contact with the
pleasures of enjoying aesthetic
experiences.
 They make possible a judgment of
relative distance from which a
stimulus originates.

7. Sound waves have three attributes which make
them different from one another this are:
 Pitch- is the highness or lowness of a sound. The lower the
frequencies produce lower pitch while higher frequencies produce
higher pitch. The number of frequencies that human ear can hear
is from 20 to 30,000 hertz.
 Loudness- sometimes known as intensity. Is the function of
sound pressure that activates the eardrum. It depends on the
amplitude of the sound wave, amplitude is the degree of the
vibrating body form the resting position. It is measured in terms of
bel- named in Honor of Alexander Graham bell, the inventor of the
telephone
 Timbre – is the characteristic quality of a musical tone. It is the
timer of the tone that tells whether it being played in the piano or
on a violin

8. AUDITORY DISORDERS
 Conduction deafness – is caused when the
ossicles or the three tiny bones get stiff or do not
work because of age. It is due to a disturbance in the
condition of air waves from the outer to the inner ear
due to the ear may be stopped up, the eardrum may
be ruptured.
 Nerve deafness - is a type of hearing loss. It occurs
from damage to the inner ear, the nerve that runs
from the ear to the brain (auditory nerve), or the
brain.

9. MECHANISM OF SMELL
1. Olfaction - The sense of smell can give you varied experiences of
pleasantness and unpleasantness, pleasant, as when you smell
flowers, perfume of good food, unpleasant, as when you smell foul
odor as decaying matter.
2. Olfactory Receptors in human beings are long threadlike nerve
tissues extending from the olfactory bulbs down into the nasal
cavities. They lie in the olfactory epithelium. This nerve tissue is
found on top of the nasal cavity.
- Anything that is sniffed must first be dissolved in the air.
- Receptors Cells – detect the molecules dissolved in the air as they
are sucked up through the nasal cavity and moved up to the olfactory
bulbs of the brain
- According to Hemming’s there are six distinct odors namely ,
flowery, putrid, fruity, spicy, resinous and burned

10. Odor Examples
Flowery odors of flowers like the
sampaguita, rose
Putrid odor of decaying meat or fish
Fruity odor of oranges, apples, guavas
Spicy odor of cloves
resinous odor of turpentines
Burned smell of anything burning