SENSE ORANS ARE THE SPECIALIZED ORGANS COMPOSED OF NEURONS , WHICH HELPS US TO PERCEIVE AND RESPOND TO OUR SURROUNDINGS . THERE ARE FIVE SENSE ORGANS – EYES : SENSE OF SEEING EARS : SENSE OF HEARING NOSE :SENSE OF SMELL TONGUE : SENSE OF TASTE SKIN : SENSE OF TOUCH, PAIN etc. Human ears are sense organ of hearing and equilibrium , that detects and analyses sound by transduction (the conversion of sound waves into electrochemical impulse) and maintaining the sense of balance(equilibrium). PARTS OF EAR: Human ear is divided into three parts that is:- i) External ear ii) Middle ear iii) Inner ear. THE HUMAN EYES ARE SENSE ORGAN ADAPTED TO ALLOW US VISION BY REACTING TO LIGHT . OUR PAIRED EYES ARE LOCATED IN SOCKETS OF THE SKULL CALLED ORBITS . THE ADULT HUMAN EYEBALL IS NEARLY A SPHERICAL STRUCTURE . THE WALL OF EYE BALL IS COMPOSED OF THREE LAYERS : i) SCLERA ii) CHOROID iii) RETINA.

1. HUMAN SENSE ORGANS
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2. SENSE ORGAN :
EAR

3. EAR
 Human ears are sense organ of
hearing and equilibrium , that
detects and analyses sound by
transduction (the conversion of
sound waves into electrochemical
impulse) and maintaining the sense
of balance(equilibrium).
PARTS OF EAR:
Human ear is divided into three parts
that is:-
1. External ear
2. Middle ear
3. Inner ear

4. EXTERNAL EAR:
 It is consist of external pinna and s.

5. MIDDLE EAR
 Tympanic membrane (ear drum) or tympanum:-
It is consists of skin(outside), connective tissue
(middle), and mucous membrane (inner side).
 Eustachian tube:-It is also called
pharyngotympanic tube. Its helps to
equalization of pressure on two side of
tympanic membrane.
 Ear ossicles : These are also known as
auditory ossicles-
1. Malleus (Hammer)
2. Incus(Anvil)
3. Stapes(Stirrup) .
 The Malleus is attached to the tympanic
membrane and the Stapes is attached to oval
window of cochlea .
 Eustachian tube: It is the connecting tube
between the middle ear and pharynx .

6. INNER EAR
 The fluid filled inner ear called Labyrinth consists of two parts :
1. The Bony Labyrinth
2. The Membranous Labyrinth .
 The Bony Labyrinth is a series of channels . Inside these channels lies
Membranous Labyrinth, which is surrounded by a fluid called Perilymph .
 The Membranous Labyrinth is filled with a fluid called Endolymph .
 COCHLEA:
 The coiled portion of the Labyrinth is called Cochlea .
 The membranes constituting Cochlea, Reissner’s Membrane & Basilar
Membrane , divide the surrounding Perilymph filled Bony Labyrinth into –
1. Upper Scala Vestibuli
2. Lower Scala Tympany
3. Scala Media – the space within Cochlea filled with Endolymph .

8. Organ corti
 It is present above Scala
tympani or on the top of the
basilar membrane in the Scala
media.
 It contains hair cells that act
as auditory receptors.
 It is peripheral receptors of
sense of hearing.
 The hair cells are present in
rows on internal side of the
Organ of Corti .
 Above the rows of hair cells is
a thin elastic membrane is
present known as Tectorial
membrane .

9. VESTIBULAR APPARATUS
 The inner ear also contains a
complex system called Vestibular
Apparatus, located above the
cochlea .
 The vestibular apparatus is
composed of
 Three Semi-Circular Canals and
 The Otolith .
 Each Semi-Circular canal is lies in a
different planes at right angles to
each other .
 The Cristal and Macula are the
specific receptors of the vestibular
apparatus responsible for
maintenance of balance of the body
and posture .

10. Nerve supply
of Ear cells:
 Cochlear division of 8th
Cranial Nerve [ AUDITORY
NERVE OR VESTIBULI-
COCHLEAR NERVE ] .

12. INTRODUCTION
 SENSE ORANS ARE THE SPECIALIZED ORGANS
COMPOSED OF NEURONS , WHICH HELPS US TO
PERCEIVE AND RESPOND TO OUR SURROUNDINGS .
 THERE ARE FIVE SENSE ORGANS –
1. EYES : SENSE OF SEEING
2. EARS : SENSE OF HEARING
3. NOSE :SENSE OF SMELL
4. TONGUE : SENSE OF TASTE
5. SKIN : SENSE OF TOUCH, PAIN etc.

13. EYES
 THE HUMAN EYES ARE SENSE ORGAN ADAPTED
TO ALLOW US VISION BY REACTING TO LIGHT .
 OUR PAIRED EYES ARE LOCATED IN SOCKETS OF
THE SKULL CALLED ORBITS .

14. STRUCTURE OF EYE
 THE ADULT HUMAN EYE BALL IS NEARLY A
SPHERICAL STRUCTURE .
 THE WALL OF EYE BALL IS COMPOSED OF THREE
LAYERS :
1. SCLERA
2. CHOROID
3. RETINA

15. EYE ANATOMY
 SCLERA:
 THE EXTERNAL LAYER IS COMPOSED OF A DENSE CONNECTIVE
TISSUE AND IS CALLED THE SCLERA .
 THE ANTERIOR PORTION OF THIS LAYER IS CALLED THE CORNEA .
 CHOROID:
 THE MIDDLE LAYER , CHOROID , CONTAINS MANY BLOOD VESSELS
AND LOOKS BLUISH IN COLOUR.
 THE CHOROID LAYER IS THIN OVER THE POSTERIOR TWO-THIRDS
OF THE EYE BALL, BUT IT BECOMES THICK IN THE ANTERIOR PART
OF THE EYE BALL TO FORM THE CILIARY BODY.
 THE CILIARY BODY ITSELF CONTINUES FORWARD TO FORM A
PIGMENTED AND OPAQUE STRUCTURE CALLED THE IRIS .
 THE IRIS IS THE VISIBLE COLOURED PORTION OF THE EYE .
 THE EYE BALL CONTAINS A TRANSPARENT CRYSTALINE LENS
WHICH IS HELD IN PLACE BY LIGAMENTS ATTACHED TO THE
CILIARY BODY .
 IN FRONT OF THE LENS , THE APERATURE SURROUNDED BY THE
IRIS IS CALLED THE PUPIL . THE DIAMETER OF THE PUPIL IS
REGULATED BY THE MUSCLE FIBRE OF THE IRIS.

16. RETINA…..
 THE INNER LAYER IS THE RETINA AND IT CONTAINS THREE LAYERS
OF NEURAL CELLS; FROM INSIDE TO OUTSIDE –
1. GANGLION CELLS
2. BIPOLAR CELLS
3. PHOTORECEPTOR CELLS
 RETINAL GANGLION CELLS (RGCs) ARE THE BRIDGING NEURONS
THAT CONNECT THE RETINAL INPUT TO THE VISUAL PROCESSING
CENTRES WITHIN THE CENTRAL NERVOUS SYSTEM .
 BIPOLAR CELLS ARE INTERNEURON TO PROVIDE THE MAIN
PATHWAYS FROM PHOTORECEPTORS TO GANGLION CELLS .

17. RETINA….
 PHOTORECEPTOR CELLS :
 THERE ARE TWO TYPES OF PHOTORECEPTOR CELLS,
NAMELY, RODS AND CONES .
 THESE CELLS CONTAIN THE LIGHT-SENSITIVE PROTEINS
CALLED THE PHOTOPIGMENTS.
 THE DAYLIGHT (PHOTOPIC) VISION AND THE COLOR
VISION ARE FUNCTION OF CONES . AND THE TWILIGHT
(SCOTOPIC) VISION IS THE FUNCTION OF THE RODS .
 THE RODS CONTAIN A PURPLISH-RED PROTEIN CALLED
THE RHODOPSIN OR VISUAL PURPLE, WHICH CONTAINS A
DERIVATIVE OF VITAMIN A .
 THERE ARE THREE TYPES OF CONES RESPOND TO RED,
GREEN AND BLUE LIGHTS.

18.  THE OPTIC NERVES
LEAVE THE EYE AND
THE RETINAL BLOOD
VESSELS ENTER IT AT A
POINT MEDIAL TO AND
SLIGHTLY ABOVE THE
POSTERIOR POLE OF
THE EYE BALL.
 PHOTORECEPTOR
CELLS ARE NOT
PRESENT IN THAT
REGION AND HENCE IT
IS CALLED THE BLIND
SPOT.

19. CHAMBERS OF EYE
 THE SPACE BETWEEN THE
CORNEA AND THE LENS IS
CALLED AQUEOUS
CHAMBER AND CONTAINS A
TIN WATERY FLUID CALLED
AQUEOUS HUMOR .
 THE SPACE BETWEEN THE
LENS AND THE RETINA IS
CALLED THE VITREOUS
CHAMBER AND IS FILLED
WITH A TRANSPARENT GELL
CALLED VITREOUS HUMOR.

20. BLOOD SUPPLY OF EYES
 ARTERIAL SUPPLY:
 THE ARTERIAL INPUT TO THE EYE IS PROVIDED BY
SEVERAL BRANCHES FROM THE OPHTHALMIC ARTERY,
WHICH IS DERIVED FROM THE INTERNAL CAROTID
ARTERY .
 THESE BRANCHES INCLUDE:
 THE CENTRAL RETINAL ARTERY
 THE SHORT & LONG POSTERIOR CILIARY ARTERIES
 THE ANTERIOR CILIARY ARTERIES.
 VENOUS DRAINAGE:
 VORTEX VEINS AND THE CENTRAL RETINAL VEIN, WHICH
MERGE WITH THE SUPERIOR AND INFERIOR OPHTHALMIC
VEINS THAT DRAIN INTO THE CAVERNOUS SINUS, THE
PTERYGOID VENOUS PLEXUS AND THE FACIAL VEIN .