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BIO 230
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Receptive

field 1

•If you take a fine pen and touch very lightly, you can feel it
sometimes but sometimes you can’t,

Receptive

field 2

Receptive fields

depends on area, if you do it in an area without receptor field will not feel it
• Touch receptor field or it is stimulated; mechanical into chemical so it fires, sends to
spinal cord and produces motor movement

Interpretation of sensory information

• Classification of Receptors
• Tonic receptors
• Always active
• Photoreceptors of the eye constantly monitor body

position
• Phasic receptors-body adapts or reseting if you will, cold at first but body adjusts
• Normally inactive but become active when necessary (for short periods of time)
• Touch and pressure receptors of the skin (for example)

Receptors

• Central Processing and Adaptation
• Adaptation
• Reduction in sensitivity due to a constant stimulus
• bikers without gloves, at first very cold but train yourself to not be bothered by it
• Peripheral adaptation
• Receptors respond strongly at first and then decline
• Central adaptation-when you move around and feel the clothes on skin and realize you are
wearing clothes but after awhile you are not consciously aware of it
• Adaptation within the CNS
• Consciously aware of a stimulus, which quickly 

disappears
• Wants to reduce noise, need to be aware of surroundings but not of the clothes touching
your back

General senses

• Classification of the General Senses
• One classification scheme:
• Exteroceptors: provide information about the external environment, cold you are
feeling, shirt on body, not as common
• Proprioceptors: provide information about the position of the body, where you are in
space, when you do a flip turn underwater, how a figure skater knows where they are
when they are turning in the air, most common
• Interoceptors: provide information about the inside of the body, not as common
• Classification of the General Senses, very common, very important
• Another classification scheme:
• Nociceptors: respond to the sensation of pain
• Thermoreceptors: respond to changes in temperature
• Mechanoreceptors: activated by physical distortion of cell membranes, has
subcategories
• Chemoreceptors: monitor the chemical composition of body fluids
**What do you do when you're hot? Metabolism is increased to utilize more calories and
increase temperature**
• Nociceptors
• Known as pain receptors
• Associated with free nerve endings and large receptor fields
...
2 shows this different referred pains
• Thermoreceptors
• Found in the dermis, skeletal muscles, liver, and hypothalamus (hypothalamus=regulator)
• Cold receptors are more numerous than hot receptors
• Exist as free nerve endings
• These are phasic (you perceive it when you are directly exposed but adapt to it) receptors
• Information is transmitted along the same pathway as pain information
• Mechanoreceptors (Mechanical)
• Receptors that are sensitive to stretch, compression, twisting, or distortion of the plasmalemmae
• There are three types
• Tactile receptors-typically done by name, laminated corpuscles, pascinian corpuscle
• Baroreceptors-for these use barorecptors (barometer, pressure monitor, can respond to
blood pressure, these are very important, golgi tendon organs and muscle tendon fibers)
• Proprioceptors-for these use word proprioreceptors
• Mechanoreceptors- dermal layer
• Tactile receptors
• Provide sensations of touch, pressure, and vibrations
• Unencapsulated tactile receptors: free nerve endings, tactile disc, and root hair plexus
• Encapsulated tactile receptors: tactile corpuscle, Ruffini corpuscle, and lamellated
corpuscle
• Mechanoreceptors
• Unencapsulated tactile receptors
• Free nerve endings are common in the dermis
• Tactile discs are in the stratum basale layer
• Root hair plexus monitors distortions and movements of the body surface- hair on skin
stimulated with movement, when something is touching us like a bug crawling on our
skin
**All nerves common root on slide 16**
**lamellated corpuscle rings are made up of connective tissue**
• Mechanoreceptors
• Encapsulated tactile receptors: Know function, which one responds to what
• Tactile corpuscle: common on eyelids, lips, fingertips, nipples, and genitalia
• Ruffini corpuscle: in the dermis, sensitive to pressure and distortion-when you pull up
your skin and twist it, that pain is the Ruffini corpuscle being fired, sensitive to twisting
• Lamellated corpuscle: consists of concentric cellular layers / sensitive to vibrations
• Mechanoreceptors

• Baroreceptors-mostly important for blood pressure, but for everywhere
• Stretch receptors that monitor changes in the stretch of organs
• Found in the stomach, small intestine, urinary bladder, carotid artery (large artery that
goes up to head, baroreceptor where you can feel pulse, sends blood up to the brain),
lungs, and large intestine (send information that tells brain you are full, to stop
stretching your stomach)
*NEED TO KNOW DIAGRAM ON 24**
• Mechanoreceptors
• Proprioceptors-know these terms
• Monitor the position of joints, tension in the tendons and ligaments, and the length of
muscle fibers upon contraction
• Muscle spindles are receptors in the muscles-what are stimulated in reflex arc,
specialized muscle spindles responds to the stretching of that muscle, if you stress a
muscle its normal response is to contract or shorten(use this word), to a level that it
feels comfortable or a resting length
• Golgi tendon organs are the receptors in the tendons, in muscle tendon unit (muscletendon-bone) inside muscle tendon unit, located pretty close to the junction
...
So muscle is stretched, it wants to contract
...
when one fails we
do not sense them as well, like when you're nose is stuffy
• Equilibrium-fluid in ears
• Hearing-Goes hand in hand with equilibrium
• Vision- Most important, we get most of our sensory input through our vision, we are visual
beings
How you perceive the world is based on your preconceived notions, your brain has filled in with what it
does not know, just like in an optical allusion

Vision-will review most of these in lab
• The Eyes
• Consist of:

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•
•
•
•
•
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Sclera
Cornea
Pupil
Iris
Lens
Anterior cavity
Posterior cavity

• Three tunic (just wrappings):

• (1) fibrous tunic, (2) vascular tunic, and (3) neural tunic

• Retina
• know slide 30 of eyeball where things are circled that we need to know
• Cornea first to anterior chamber filled with aqueous humor aka fluid, then to
pupil (black dot), then to iris (every iris is different, color part of eye), then the
posterior chamber with more aqueous fluid, then you have the lens (connective
tissue), then goes back into posterior cavity which is filled with vitreous humor aka
fluid, then the retina, choroid, sclera, fovea, optic disc, optic nerve, central retinal
artery and vein
• Have sensory cells down in retina who will transmit them into chemically, back to
brain electrically, splits it and sends it to the back of the brain, and then puts it
back together to make a picture of what you are seeing
...
Older people have not as great accommodation, this has to do with
connective tissue and the strength of it, older people do not have great connective
tissue**



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