Sensation- awareness or mental process which is aroused due to stimulation of a sense organ.

ACQUIRING SENSORY AWARENESS1ST CONDITION:1.Stimulation – anything which rouses a sense

organ to activity. 2 types of stimulus

1. physical energy2. chemical form energy

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”

2nd Condition: Presence of Receptor Cell

- the sense organ detect stimuli from the environment and transmit information to the appropriate areas of the brain.

3rd 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 1. Vision - 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 impulseReceptor

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).

Cones – thicker / cone shape ; interprets color. ( 6 million) Function: Daytime vision , enable one to discriminate brightness ,

hue or color. See the color of the spectrum ( 3 types of cones) Sensitive to A. red B. green C. blue

3 dimension of colors 1. Hue - name of colors

red- longest wave length.violet – shortest wave length.blue , green , yellow – intermediate wave length.

2. Brightness – energy of the source of lightcoloring range from bright to dim.intensity of the stimulus.

3. Saturation – purity or richness of color.highly saturated color – pure hues ( no tint of gray

added)low saturation – close to gray

note: Saturation of any color is reduced by mixing it with white.

Visual defects 1. myopia 2.Hyperopia 3.Presbyopia 4. Astigmatism 5. Diplopia 6. Scotoma

Parts of the retina:

Fovea – in the central region, the point of clearest and sharpest vision

Blind spot – are where all the nerve fibers converge to form optic nerve which

carries impulse to the brain.2 kinds of Blind spot1. Dichromatic – 2 or 3 primary colors2. Achromatic – no cones in the retina

2. AUDITION Sound Waves 1. pitch – highness or lowness of a

sound. 2. loudness – intensity sound pursue

that activates the eardrum. 3. timbre – quality of musical tone.

Mechanism of the hearing

3 major parts: 1. outer / external serves to collect sound

waves. 2. middle ear – transmit the sound waves. 3. inner ear – has sensitive receptors for

hearing.

How do we hear? Sound waves travel and collected by

pinna

Funneled by the

auditory canal

Ear drum

Changes in air pressure

Middle ear Tiny bones

hammer

anvil

Stirrup ( to vibrate)

3 tiny bones conduct the sound impulse inward to

the inner ear:Hammer – eardrum-

stirrupOval windows

cochleaAuditory portion of

the inner ear ( pressure Changes ,

fluid displace

Receptor cells

Hair cells (receptor cells of

organ of corti)Auditory

nerve Brain

II. Proximal Distance:

1. Olfaction – sense of smell stimulus substance : gaseous

substance( must be dissolved in the air “ vaporous form.

Mechanism of Smell: RECEPTOR – Olfactory receptor – long

thread like nerve tissue from

Olfactory bulb

Nasal cavity

Process: 1. Anything that is sniffed must best

dissolved in the air. 2. Receptor cells detect the molecules

dissolved in the air that is sucked up in the nasal cavity.

3. Move up to the olfactory bulbs of the brain.

4. Physical Energy is transduced in the olfactory epithelium to be able to reach the brain.

2. Gustation “ Tongue” organ for the sense of taste Stimulus – chemicals – must transform into

soluble substance to penetrate into the taste cells.

Receptor – taste receptorPapillae – tongue elevationTaste buds – lie between the papillae ( taste

receptor)Pore – opening of the taste buds.

Mechanism of taste: The food is transformed into soluble form .

Depolarized liquid substance can penetrate into the taste cells:

depolarized

Will incite the nerve fiber

Give rise to nerve impulse

Gustatory nerve

Brain