;Chapter 18-General and Special Senses Flashcards Preview

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

sensory receptor

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

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tonic receptor

always sending signals to CNS

3

phasic receptor

becomes active only with changes in the conditions they monitor

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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

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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

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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"

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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

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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

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proprioceptors

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

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types of proprioceptors

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

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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

31

special senses

next ones

32

olofaction

-sense of smell
-olfactory organ
--located within the nasal cavity on either side of nasal septum
--covers the cribiform plate of ethmoid
--made up of olfactory epithelium

33

olfactory cells

olfactory epithelium consists of
-olfactory receptors: chemoreceptors
-supporting cells: surround the receptors
-basal cells: stem cells that grow new cells
covered in secretions from olfactory glans

34

olfactory receptors

-highly modified bipolar neurons
-have cilia that extend into mucus secreted by olfactory glands
-odorous particles dissolve into mucus and cause depolarization

35

olfactory nerve pathway

-impulses travel along axons of receptor cells
-pass through openings in cribiform plate
-go to olfactory bulb and cranial nerve I
-unique in that the impulse does NOT go through the thalamus
-travel along tracts to limbic system
--smells can trigger strong emotions
-interpreted as smell in temporal lobe and base of fronts

36

olfactory discrimination

-no structural difference in receptor cells
-olfactory can turn over (reproduce)
--but numbers decrease with age
-50 primary smells
--combinations allow us to distinguish thousands of smells
-adapt quickly

37

gustation

-taste
-chemoreceptors in structures called taste buds
-taste buds on superior surface of tongue in papillae
-gustatory receptors found in taste buds found in papillae found on your tongue

38

papillae

-epithelial projections
-taste buds lie along papillae
-three types of papillae
-filiform
-fungiform
-cicumvallate

39

taste buds and receptors

-gustatory cells: receptor clusters
--about 40 per bud
-also have basal cells
--replace receptors every 10-12 days
-gustatory cells extend microvilli called a taste hair into taste pore

40

gustatory pathway

-uses cranial nerves VII, IX, and X
-afferent fibers synapse with nucleus solitarius in medulla
-goes to thalamus and cerebral cortex

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gustatory discrimination

primary tastes
-sour
-sweet
-salt
-bitter
-water
-umami-meat
-individual differences in taste
-number and sensitivity decrease with age

42

external ear

-auricle: external structure supported elastic cartilage
-external acoustic meatus: canal to middle ear
--ceruminous glands: make wax
--hairs
-ends at tympanic membrane

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middle ear

consists of tympanic cavity
-air filled space between external and inner ear
tympanic membrane
-thin, transparent connective tissue sheet
auditory tube
-when open
--middle ear equalized to atmospheric pressure
--can be induced by chewing or yawning
--allows for microbes to get in and cause an 'ear infection'

44

middle ear ossicles and muscles

-tiny bones in middle ear
-transfer vibrations from the tympanic membrane to inner ear
-includes: malleus, incus, stapes
muscles:
-tensor tympani muscle
--inserts on malleus
-stapedius muscle
--inserts on stapes

45

inner ear

-a series of tubes and cavities
-split into two sections:
--vestibule (balance)
--cochlea (hearing)

46

layers of inner ear

-memranous labyrinth
--contains endolymph fluid
-bony labyrinth
--dense bone layer of the temporal
--contains perilymph fluid

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cochlea

-converts vibrations to sound
-contacts the stapes at the oval window
-coiled tube with cochlear duct
-divided into three ducts
--vestibular duct: divided by vestibular membrane
--cochlear duct: divided by basilar membrane
--tympanic duct

48

organ of corti

found on the basilar membrane
-mass of epithelial cells
contains:
-hair cells: mechanoreceptors with stereocilia (stick out in order to be deformed, send signals to dendrites)
-cranial nerve VIII: cochlear branch contacts hair cells
-tectorial membrane: positioned right above hair cell stereocilia, deforms sterocilia

49

the path of vibrations

1. auricle funnels vibrations into meatus
2. tympanic membrane vibrates
3. transmits to ossicles
-malleus to incus to stapes
4. stapes connected to oval window
-transmits vibrations to inner ear
5. oval window vibrates; perilymph moves
6. membranous labyrinth vibrates
-cochlear duct vibrates within
7. basilar membran bounces
-hair cell stereocilia contact tectorial membrane
-become deformed and creates depolarization
-transmits an action potential down of CN VIII

50

pathway for auditory sensations

-carried by cochlear branch of cranial nerve VIII
-goes to cochlear nucleus of medulla
-travels through thalamus
-processed in auditory cortex of temporal lobe
mechanoreceptors detect different pitches of sound in different portions of the cochlea

51

vestibule

consists of:
semicircular canals
utricle and saccule

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semicircular canals

-three total: anterior, posterior, lateral
-surrounding semicircular ducts
-ampulla (swellings) at base: each possess cristae that attaches to a cupula (inside critae, creates action potential)

53

utricle and saccule

-paired membranous sacs
-connected by endolymphatic duct
-saccule possess maculae (creates action potential

54

semicircular canals

-contains fluid thats pulled on by gravity
-cupula has hair cells
-head rotation:
--causes fluid to move through canals
--fluid moves cupula
-hair cell stereocilia bends
-depolarization occurs

55

utricle and saccule

deal with head orientation
Maculae consists of
-hair cells
-otolith:
--small calcium carbonat ecrystals
--gel like substance
Head orientation changes
-gravity pulls on crystals
-moves otolith
-deforms hair cell stereocilia
-depolarization occurs

56

pathway for balance sensation

hair cells
-activate neurons of vestibular branch of cranial nerve VIII
-synapses with vestibular nuclei

57

eye accessory structures

-eyelids or palpebrae
-tarsal glands
-conjunctiva
-lacrimal apparatus

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eyelids or palpebrae

-protect and lubricate
-epidermis, dermis, CT

59

tarsal glands

-oily secretions keep lids from sticking together

60

conjuctiva

-thin protective mucus membrane-what you see when you look at eye
-palpebral (eyelid) and bulbar (on eye)
-stopes at coneal edge
-dilated BV--bloodshot

61

lacrimal apparatus

-produce tears
consists of:
-lacrimal gland: produces tears
-lacrimal punctum: drains tears into lacrimal canaliculi
-lacrimal canaliculi: passageway that leads to the lacrimal sacc
-lacrimal sac: fills groove on lacrimal bone, connects to the nasolacrimal duct
-nasolacrimal duct: delivers tears to nasal cavity

62

eye layers

3 layers
-fibrous tunic
-vascular tunic
-neural tunic

63

fibrous tunic

outer
-sclera
--white of eye
--dense irregular CT
-Cornea
--transparent layer

64

vascular tunic

iris
-smooth muscles and pigments
choroid
-vascularized, pigmented layer
lens
-layered proteins
-refracts light

65

vascular tunic: ciliary body

-below the iris
-has ciliary processes
--attach to suspensory ligaments
--attach to lens
-ciliary muscles change the lens shape
--focus

66

vascular tunic: functions

-route for BV's
-regulate amount of light
-secrete and absorb aqueous humor
-control shape of lens

67

neural tunic

-inner most layer
-retina
-5 groups of retinal neurons

68

retinal neurons

-receptor cells
--rods and cones
--detect light
-bipolar neurons
--synapse with above
-ganglion cells
--synapse with above
-amacrine cells
--modulate communication between bipolar and ganglion cells

69

rods and cones

rods
-very light sensitive
-do not discriminate color
-require less light
cones
-color vision
-three types: red, blue, green
-give sharper image

70

neural tunic: regions of the retina

-macula lutea: area of no rods
-fovea centralis: area of most cones, within macula
-optic disc: beginning of optic nerve, "blind spot"

71

visual pathway

-photoreceptors to
-bipolar cells to
-ganglion axons converge on optic disc into optic nerve (cranial nerve II)
-optic tract to optic chiasm
-relayed to lateral geniculate nucleus
-on the visual cortex of occipital lobe-finally see, associate it with previous sights

72

cavities

posterior cavity (behind lens)
-contains gelatinous vitreous body-gel like
anterior cavity( between leans and cornea)
-contains clear aqueous humor-watery