By Jasmine Luck, Brianna Hebert,
Nicole Hickman, Molly Spitters,
Ashkan Shahbandi
Per. 3
Sensation- A feeling that occurs when brain
becomes aware of sensory impulse
Perception- A person’s view of the stimulus; the
way the brain interprets the information
Projection- Process in which the brain projects the
sensation back to the apparent source
Sensory adaptation- ability to ignore unimportant
stimulus
Chemoreceptors- respond to changes in chemical
concentrations
Pain receptors- (nociceptors) respond to tissue
damage
Thermoreceptors- respond to changes in
temperature
Mechanoreceptors- respond to mechanical forces
Photoreceptors- respond to light
• General senses: Joint, muscle, skin, visceral senses.
• Three groups: exteroceptive (body surface senses),
visceroreceptive (changes in viscera), and proprioceptive
(muscle/tendon changes)
• Touch and Pressure Senses: Free nerve endings (sense
itching), Meissner’s corpuscles (fine touch), and Pacinian
corpuscles (heavy pressure and vibrations)
• Warm recepetors (sensitive above 25⁰C, unresponsive
above 45 ⁰C)
• Cold receptors (sensitive between 10⁰C and 20⁰C)
• Pain receptors (respond below 10⁰C and above 45⁰C)
• Visceral Pain is “referred pain”
• Acute pain fibers (A-delta fibers)
• Chronic pain fibers (C fibers)
Olfactory System:
• Pathway: Olfactory nerves -> olfactory bulbs ->
olfactory tracts -> limbic system -> olfactory
cortex
• Olfactory code: a hypothesis about how
certain odors stimulate a set of receptor cells
and its associated receptor cells and proteins.
Sense of Taste
• Taste Buds: located on papillae of tongue, roof of mouth,
linings of cheeks, walls of pharnx
• Taste receptors: Taste cells (chemoreceptors)+Taste hairs
(microvilli that protrude from taste cells)
• Primary taste sensations: sweet, sour, salty, bitter (spicy
activates pain and sour receptors)
• Cranial nerves=>medulla oblangata=>thalamus=>gustatory
cortex
Hearing
• External ear: auricle, external auditory meatus, tympanic
membrane
• Middle ear: tympanic cavity, auditory ossicles, oval window
• Auditory tube: eustachian tube connects middle ear to
throat (maintain equal pressure on both sides of tymp.
membrane)
• Inner ear: osseous (perilymph)+membranous (endolymph)
labyrinth; cochlea, semiciruclar canals, vestibule
• Cochlea composed of scala vestibuli + tympani, cochlear
duct, vestibular membrane, basilar membrane
• Organ of Corti: hair cells on surface of basilar membrane,
different frequencies of vibration move different parts of
membrane
Equlibrium
Static Equilibrium: Vestibule (utricle, saccule,
macula); sense position of head when body is
not moving
Dynamic Equilibrium: semicircular canals
(ampulla, crista ampullaris); sense rotation and
movement of head and body
Visual
• Eyelid: papebra (skin, muscle, connective tissue,
conjunctiva), orbicularis oculi (closes), levator
palperbrae superioris (opens), conjunctiva (mucous
membrane)
• Lacrimal Apparatus (lacrimal gland => canaliculi =>
lacrimal sac => nasolacrimal duct)
• Extrinsic eye muscles (superior rectus rotates
up+medially, inferior rectus rotates down+medially,
medial rectus rotates medially, lateral rectus rotates
laterally, superior oblique rotates down+laterally,
inferior oblique rotates up+laterally)
Visual Cont.
• Outer tunic: cornea (light refraction), sclera (protection)
• Middle tunic: iris (controls light intensity), ciliary body
(holds+moves lens), choroid coat (vascular region)
• Anterior portion of eye filled with aqueous humor
• Lens: transparent, biconvex, lies behind iris
• Accommodation: changing lens shape to view objects
• Pupil: hole in iris
• Inner tunic: retina (visual receptors), macula lutea (yellowish spot in
retina), fovea centralis (sharpest vision), optic disk (blind spot),
vitreous humor in posterior cavity (thick gel holds retina against
choroid coat)
• Vision: cornea=>aqueous humor=>lens=>vitreous humor=>retinal
layers=>photoreceptor cells
Visual Cont.
• Retinal neurons: Receptor cells, bipolar cells, and ganglion
cells (provide pathway for impulses)
• Horizontal cells and amacrine cells (modify impulses)
• Refraction: bending of light
• Convex causes convergence (hyperopia), concave causes
divergence (myopia)
• Rods (more sensitive, colorless vision, dark+dim light,
blurry), cones (colored vision, sharp)
• Rods: rhodopsin
• Cones: erythrolabe (red), chlorolabe (green), cyanolabe
(blue)
• Stereoscopic vision: perception of distance+depth