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. 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 .

1. Represented By WASIM AKRAM
BSc Nursing
ADWIKA INSTITUTE OF NURSING

2. 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.

3. 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 .

4. 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

5. 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.

6. 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 .

7. 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.

8.  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.

9. 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.

10. 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 .