On October 23rd, 2014, we updated our
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Receptor Organ – highly specialized part of the body and selecting sensitive to a definite stimulus.
- doorway of the body responsible for all the sensation we experience.
- “sense organ”
2 nd Condition:
Presence of Receptor Cell
- the sense organ detect stimuli from the environment and transmit information to the appropriate areas of the brain.
3 rd Condition:
Sense Receptor is stimulated by certain “stimulus”.
Stimulus must be transferred into a code of electrochemical impulses which is travel to the brain.
Transduction – process of converting physical energy into activity in the nervous system which takes place in the receptor.
QUESTION: When a stimulus is said to be detected?
ANSWER: Stimulus to be detected must be strong enough and to produce sensation.
1. Absolute threshold – stimulus is in the inner limit or does not go or reach beyond the threshold.
2. Subliminal threshold – stimuli are way above the threshold.
3. Terminal threshold – stimuli reach an increased intensity it produces pain and individual uncomfortable.
Sensory Adaptation :
1. Sense Receptor – ability to make adaptation to changes/ adjust to a particular stimulus.
2. Sense Organ:
a. Distal senses – sensitive to stimuli coming from a distance in the outside environment.
b. Proximal senses – bring information when we come direct contact with the objects that stimulates them.
A. DISTAL SENSES
- utilize the physical characteristic of light.
EYE (receptor organ of Vision).
Light Waves ( stimuli for seeing)
waves of radiant energy coming from the sun.
Eye utilizes 2 basic properties of light:
1. brightness – intensity of light (the amount of radiant energy coming from the sun.
2. color – wave length or frequency
Parts of the Eye:
1. Sclerotic coat (SCLERA) – hard and outer most covering , it protects the eye.
2. Choroid coat – full of bloody tissues, gives nourishment to the eye.
3. Retina – inner most covering of the eye. Photosensitive plate of the eye. Regarded as the true organ of vision.
RODS and CONS (receptors cells) embedded on in the coat.
cornea Aqueous humor pupil
IRIS lens retina
connects light energy to nerve impulse
Receptor cells Nerve impulse Optic nerve BRAIN
Receptor cells of the eye:
RODS - slender nerve cells ( 100 million)
Function: used for twilight vision or low light intensity, enable one to make colorless discrimination, sensitive to tiny amount of lights ( dim light ), color blind (they see the world in black and white).