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Marian M. Miguel-Lagundino, MA

Instructor

SENSATION

EXTERNAL SENSATION

A process of knowing material, concrete stimuli through

external senses namely: vision, audition, olfaction,

gustation and cutaneous sensation.

If there is no sensation, there is no perception.

CONDITIONS

If one of these elements is absent, there is no sensation.

General conditionsStimulus

Any aspect of the world that influences our behavior

Must be strong enough to elicit a sensation

Threshold stimulus: minimum amount of stimulus that is capable of producing a sensation

A subminimal stimulus can elicit a sensation if applied repeatedly on the same receptor

Receptor

Any structure in the body that is excitable to stimuli

A peripheral termination of sensory fibers

Exteroceptors: found at the external surface of the body

Proprioceptors: found in muscles, joints and tendons

Interoceptors: found in visceral organs

Transmissor

Fiber tracts: Bundles of nerve fibers that convey sensory impulses from one neuron to the next

Transmits the sensory impulses to the brain

Brain Center

Houses the primary sensory area located in different lobes

Also contains secondary and association areas

VISUAL SENSE

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Stimulus: light waves

Receptor: rods and cones

Transmissor: optic nerve

Brain center: primary visual area

http://www.tutorsglobe.com/CMSImages/52_Visual_pathway.jpg

POINTS OF DIFFERENCE CONES RODS

Shape Conical Tubular

Distribution in the retina Center Periphery

Function Daytime vision Nighttime vision

Sensitivity to color Sensitive Not sensitive

FOVEA BLIND SPOT

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcSXxe6cyqQ0R4OS73YdZYD5CpxLwSGk4jfFdb2BRwW9OWAyvn4gaQ

AUDITORY SENSE

Stimulus: sound waves

Receptor: hair cells

Transmissor: auditory/cochlear nerve

Brain center: primary auditory area

http://www.daviddarling.info/images/organ_of_Corti.jpg

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OLFACTORY AND GUSTATORY SENSES

Stimulus: chemical substances

Receptor: olfactory cells

Transmissor: olfactory nerve

Brain center: primary olfactory

area

http://www.medical-look.com/systems_images/Olfactory_sense.gif

Stimulus: chemical substances

Receptor: taste buds

Transmissor: facial and

glossopharyngeal nerves

Brain center: primary gustatory

area

CUTANEOUS SENSE

Stimulus: mechanical energy

Receptor: somatosensory

receptors

Transmissor: ascending nerve

fibers

Brain center: primary

somatosensory area

http://1.bp.blogspot.com/_kaQ5P19FVgk/SlYj8SW_S7I/AAAAAAAADSo/cVLxJASLnNo/s400/SomaticSensoryCortex1.

JPG

http://www.corpshumain.ca/en/images/SensorielFaisseauxDorsal_en.jpg

Somatosensation Receptor

Touch Merkels disk

Pressure Pacinian Corpuscles

Pain Free nerve endings

Coldness Krauses Corpuscles

Warmth Ruffinis Endings

Kinaesthesia Proprioceptors

http://www.rci.rutgers.edu/~uzwiak/AnatPhys/ChemicalSomaticSenses_files/image020.jpg