;Chapter 18-General and Special Senses Flashcards Preview

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Flashcards in ;Chapter 18-General and Special Senses Deck (72)
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1

sensory receptor

-specialized receptor that sends sensations to CNS
-tonic receptor
-phasic receptor

2

tonic receptor

always sending signals to CNS

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phasic receptor

becomes active only with changes in the conditions they monitor

4

types of receptors

chemoreceptors
-taste
-smell
nociceptors
-cell damage (mechanical, electrical, thermal)
thermoreceptors
-thermal
mechanoreceptors
-hearing
-stretching
-body position
photoreceptors
-light

5

receptor characteristics

receptive field: area monitored by a single receptor cell
receptor specificity:
-each receptor responds to a specific stimulus
-example: photoreceptor will no respond to a chemical stimulus
more receptor fields=more precise responses

6

sensation vs perception

sensation:
-sensory information arriving at the CNS
Perception:
-conscious awareness of sensation
--all nerve impulses are identical (just action potentials)
--brain interprets impulses
--"feeling" that occurs when sensory impulses are interpreted
sensation=perception?

7

sensory adaptation

-occurs when sensory receptors are subjected to continuous stimulation
-results in a reduction of sensitivity
-at some point along the pathway, impulses are conducted at a decreased rate
-several types

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types of sensory adaptation

-peripheral adaptation
-central adaptation

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peripheral adaptation

when sensory receptors decrease their level of activity

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central adaptation

-sensory neurons are still active
-CNS causes reduced perception

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sensory limitations

sensory information from receptors is incomplete
-do not have receptors for every stimulus
-other animals can detect things we cannot: infrared, ultraviolet, ultrasound, etc.
-receptors have limited ranges
-stimulation requires a neural event that is interpreted

12

general vs special senses

general senses
-do not have specialized receptor cells or sensory organs
special senses
-can have specialized receptor cells separate from the sensory neuron
-structurally more complex
-receptors localized in sense organs

13

general senses

3 major groups
-exteroceptors
-propriocepts
-interoceptors

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exteroceptors

relay info about external environment

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proprioceptors

-depict body position in space

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interoceptors

monitor the internal environment

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nociceptors

-sense tissue damage
-perceived as pain
-free nerve endings with large receptive field
--found everywhere except brain
--provide a protective function
--do not adapt well (do not want to prolong injury)
deters behavior that is damaging

18

types of pain

fast pain: quick, inducing a reflex usually; end when stimulus unds
slow pain (burning): begins later; persists longer; ache
referred pain
-visceral pain that feels like it is coming from a more superficial region
-due to superficial structures being innervated by the same spinal nerves as damaged viscera
-"brain freeze"

19

thermoreceptors

-invovle heat and cold
--no difference in structure between the two
-free nerve endings in skin
-quick to adapt
-felt as pain
--if temp goes above 45C
--if temp goes below 10C

20

mechanoreceptors

-sensitive to mechanical forces that cause tissues to be deformed
-types:
-tactile
-baroreceptors
-proprioceptors

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tactile receptor

touch, pressure and vibration

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baroreceptors

pressure changes in walls of vessels, etc

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proprioceptors

position of joints and muscles

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tactile receptors: two categories

unencapsulated (3 types)
encapsulated (3 types)

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tactile receptors: unencapsulated

free nerve endings
-in papuillary of dermis
-general touch
root hair
-monitor distortions and movement across body surface
tactile sic
-expand nerve terminal that synapses with merkel cell
-sensitive to fine touch

26

tactile receptors: encapsulated

tactile corpuscles
-found where tactile sensitivities are very well developed
-hands
lamellated corpuscle
-respond to deep pressure
-squeeze arm
ruffini corpuscle
-in dermis
-detect pressure with little adaptation

27

baroreceptors

-stretch receptors
-monitor changes in pressure
--detect stretching of tissue walls
-regulates autonomic activities
--digestive tract
--bladder
-carotid sinus
--lung
-colon
--major arteries
similar to ruffini corpuscles but difference is location

28

proprioceptors

-monitor position of joints, tension in tendons, state of muscle contraction
-everywhere, skeletal muscle
-no adaptation to stimulus

29

types of proprioceptors

muscle spindle: monitor length of muscle
golgi tendon organ
-monitor tension in a tendon during contraction

30

chemoreceptors

-respond to substances dissolved in surrounding fluids
-monitor chemical composition of body fluids
--example: sensitive to pH, CO2 changes
-found:
--inside CNS, medulla
--aortic bodies
--carotid bodies