Sensory Receptors

Front 1

types of sensory receptors

Back 1

-chemoreceptors
-mechanoreceptors
-photoreceptors
-electroreceptors
-magnetoreceptors
-thermoreceptors

Front 2

sensory receptors range from_________to_____________. All transduce incoming stimuli into_________________

Back 2

simple neurons, complex sense organs, changes in membrane potential.

Front 3

classification of sensory receptors based on stimulus location. The three classifications are:

Back 3

1. Telereceptors
2. Exteroceptors
3. Interoceptors

Front 4

Telereceptors

Back 4

detect direct stimuli eg. vision and hearing

Front 5

Exteroceptors

Back 5

detect stimuli on the outside of the body eg. pressure and temperature

Front 6

Interoceptors

Back 6

detect stimuli inside the body, eg. blood pressure and blood oxygen

Front 7

classification of sensory receptors based on stimuli receptors can detect. The classifications are:

Back 7

-chemoreceptors: chemicals (smell, taste)
-mechanoreceptors: pressure/movement (hearing, touch, balance, blood pressure)
-photoreceptors:light (vision; detect photons)
-electroreceptors: electrical fields
-magnetoreceptors: magnetic fields
-thermoreceptors: temperature

Front 8

adequate stimulus

Back 8

preferred or most sensitive stimulus modality

-many receptors will respond to other stimuli if sufficiently large

Front 9

polymodal receptors

Back 9

naturally more sensitive to more then one stimulus

Front 10

nociceptors

Back 10

sensitive to strong stimuli
e.g. pain, many are polymodal receptors

Front 11

stimuli are converted into action potentials in the ________________

Back 11

primary afferent neurons

Front 12

sensory receptors must encode 4 types of information:

Back 12

-stimulus modality
-stimulus location
-stimulus intensity
-stimulus duration

Front 13

action potentials code stimulus intensity through_____________

Back 13

changes in frequency, ex high frequency = strong stimulus

Front 14

dynamic range

Back 14

range of intensities for which receptors encode a stimuli

Front 15

threshold detection

Back 15

weakest stimulus that produces a response in receptor 50% of the time

Front 16

saturation

Back 16

top of the dynamic range, all available proteins have been stimulated.

Front 17

linear across long range of intensities

Back 17

large range of stimulus causes a small change in AP frequencies=large dynamic range and poor sensory discrimination

Front 18

linear across small range of intensities

Back 18

small change in stimulus causes large change in AP frequencies=small dynamic range and high sensory discrimination

Front 19

range fractionation

Back 19

groups of receptors work together to increase dynamic range without decreasing sensory discrimination

Front 20

phasic receptors

Back 20

- encode stimulus duration
-produce APs only at beginning or end of the stimulus
-encode changes in stimulus but not stimulus duration (threat or irritant)

Front 21

Tonic receptors

Back 21

-produce APs as long as the stimulus continues
- receptor adaptation-AP frequency decreases if stimulus stays at same level

Front 22

pain and itching are mediated by________

Back 22

nocireceptors

Front 23

itch comes from

Back 23

nocireceptors in the skin. higher pathways of itch not understood

Front 24

no pain stimulus

Back 24

c fiber is connected to secondary neuron but inhibitory neuron is tonically active
-no ascending pain pathway siganl

Front 25

painful stimulus

Back 25

c fiber is connected to secondary neuron and inhibitory neuron is blocked
-ascending pain pathway siganl-strong pain signal

Front 26

modulation of pain

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c fiber is connected to secondary neuron and inhibitory neuron is blocked
the A fiber is stimulated by touch or non painful stimuli
Pain signal is decreased by modulation

Front 27

neurons communicate by

Back 27

neurotransmitters

Front 28

chemoreception

Back 28

-most animals can sense incoming chemical signals
-animals have many chemoreceptors
-multicellular typically use taste and smell

Front 29

olfaction

Back 29

sense of smell, detection of chemicals in the air

Front 30

gustation

Back 30

sense of taste, detection of chemicals emitted from ingested food

Front 31

chemoreception is

Back 31

-preformed by several sense organs
-use differential sense organs
-use different signal transduction mechanisms
-are processed in different integrating centers

Front 32

Vertebrate olfactory system

Back 32

-can distinguished thousands of odorants
-located in the roof of the nasal cavity
-mucus layer to moisten olfactory epithelium
-receptor cells are bipolar neurons and covered in cilia
-odorant receptor protiens are located in the cilia

Front 33

odorant binding proteins

Back 33

allow lipophillic odorants to disolve in the mucus

Front 34

odorant receptor are G proteins

Back 34

-each olfactory neuron expresses only one odorant receptor protien
-each odorant receptor can recognize more then one odor

Front 35

steps in olfactory signaling

Back 35

1. odorant binds to receptor and causes a conformational change
2. activated g protein activates enzyme Ad cyclase
3. AD cyclase converts ATP in cAMP (cAMP is the second messenger)
4.cAMP opens gated ion channels
5. Calcium and sodium enter the cell creating a greater potential
6. calcium opens calcium activated Cl- channels and Cl- leaves cell increasing depolarization
7. localized depolarization (makes more positive)
8. voltage gated sodium channels open
9. action potential to CNS where it is intergrated

Front 36

Vemeronasal organs

Back 36

-detect pheromones
-structurally and molecularly distinct from the primary olfactory epithelium
-located near septum
-cAMP is a second messenger
-Phospholipase C signal transduction system is activated and leads to increase in IP3 and DAG

Front 37

taste buds

Back 37

-group of taste receptor cells
-located on tongue, soft palate, larynx and esohagus
-have hair like projections
-have basal (interior) and apical side
-taste cells form a chemical synapse with sensory neurons that project from brain to tongue

Front 38

basic steps of taste cell

Back 38

1. ligands/chemicals bind to the receptor
2. activates taste cell-requires depolarization
3. increase in ca2+ in the taste cell by activation of voltage gated calcium channels or from release of intracellular stores
4. triggers release of NT (seritonin)
5. NT is released
6. action potential
7. information is sent to the brain

Front 39

steps in gprotein and Adenylate cyclase

Back 39

1. ligand binds to stimulating gprotien=conformational chnage
2.alpha subunit binds gtp and releases gdp then moves through membrane to activate Ad cyclase
3. activated Ad cyclase converts ATP into cAMP
4.cAMP binds to regulatory subunit of PKA which dissociates from the catalytic subunit and activates it
5.activated kinase can phosphorylate protiens and cause a response
6. phosphoed protiens are quickly dephosphorlyated by serine/threonine phosphotases terminating the response
7. if ligand binds to inhibitory gprotien the subunit inhibits activation of Ad cyclase inhibiting the signal transduction pathway

Front 40

inositol-phospholipid signaling

Back 40

-inc in phospholipase C which cleaces PIP2 into IP3 + DAG
-leads to second messengers IP3 and DAG
-IP3 + pi = IP4
-IP3 opens calcium channels, calcium binds to calmodulin-diverse effects
-DAG activates protien kinase C-phosphorylates protiens

Front 41

amiloride

Back 41

diuretic that causes a increase in urination and used when people have a high blood pressure

Front 42

Salt taste

Back 42

-sodium enters the cell through passive amiloride sensitive sodium channel
-found in kidneys and frog skin
-entery of sodium cases cell to depolarize
-need large concentration of sodium to trigger sufficient depolarization to signal the post synaptic neuron

Front 43

steps in salt taste signaling

Back 43

1. sodium enters the cell and makes the cell more positive
-localized depolarization opens voltage gated calcium channels
-influx of calcium leads to NT release

Front 44

Sour Taste

Back 44

-works different then salt taste
-taste response produced by excess protons
-positive ions enter a H+ cation specific ion channel and in turn depolarize the cell
-K+ channels always open (leak) and are blocked by the H+ and so K+ cannot leak out and cell becomes more positive....depolarization

Front 45

sweet taste

Back 45

-not ligand gated ion channels but instead are metabotropic receptors
-stimulates a g protien that activates PLC
-PLC breaks bout PIP2 into IP# and DAG
-IP3 binds and activated calcium ion channel----calcium influx and depolarization leads to AP

Front 46

metabotropic receptor

Back 46

linked to ion channel by g-protien

Front 47

Other way sweet taste can work

Back 47

-g protien can activated AD cyclase
-leads to increase in cAMP
-cAMP activated PKA which phosphorylates the k+ channels and caused them to close
-k+ cannot leak out so depolarization occurs

Front 48

bitter taste

Back 48

-metabotropic receptor
-some use g protien gustducin to activate PLC>IP3>calcium influx (unique because needs no depolarization)
-some bitter chemicals bind to and block K+ channels thus result in depolarization

Front 49

amino taste

Back 49

have multiple ways to taste
1. amino acids bind to specific ligand gated channels
2.activate metabotropic receptor glutamate receptor
3.activate one of the other 2 metabotropic receptors>activate PLC>generate IP3

Front 50

mechanoreceptors

Back 50

-transform mechanical stimuli into electrical signal
-all organisms can sense and respond to mechanical stimuli

Front 51

two types of mechanoreceptors

Back 51

type 1: ENac epithelial sodium channels
Type 2: transient receptor potential =ion channels
both have anchors which change shape

Front 52

baroreceptors

Back 52

interoceptors that detect pressure
-within body and important for clood pressure

Front 53

tactile receptors

Back 53

externoceptors thats detect touch and pressure and vibration on body surface

Front 54

proprioceptors

Back 54

monitor the position of the body

Front 55

Type 1 external surface have two common types of sensilla (sensory organ)

Back 55

1. trichoid=hair like
2. campaniform=bell shaped

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Type 2 Internal surface

Back 56

-scolopidia=bipolar complex neuron and complex accessory cell
-can be isolated or grouped to form chordotonal organs
-most fucntion in proprioception
-can be modified into tympanal organs for sound detection

Front 57

vertebrate tactile receptors

Back 57

-widely dispersed
-function as isolated sensory cells
-free nerve endings or enclosed in accessory structure.

Front 58

proprioceptors-monitor the position of the body
3 major groups are

Back 58

1. muscle spindles=located on surface of muscle and monitor length
2.golgi tendon organs=located at junction between tendons and muscles to monitor tendon tension
3. joint capsule receptors= located in capsules that enclose joints and detect pressure, tension and movement in joint

Front 59

equilibrium and hearing

Back 59

-utilize mechanoreceptors

Front 60

statocysts

Back 60

-organ of equilibrium in invert
-hollow fluid filled caviety with mechanosensory neurons
-contain statoliths-dense particles of calcium carbonate

Front 61

Hair cells

Back 61

-mechanoreceptor cells used for hearing and balance in vertebrates
-are modified epithelial cells
-have extensive structures and cillia that extend from apical end (sterocillia)

Front 62

kinocillium

Back 62

not in adult mammals instead just have one long sterocilia

Front 63

signal transduction in hair cells

Back 63

-detect movement and direction
- mechanically gated K+ channels

Front 64

signal transduction in hair cells
at rest

Back 64

slightly depolarized and continuously firing a AP but AP freq is intermediate

Front 65

signal transduction in hair cells when signal causes sterocilia to move towards long sterocilia

Back 65

-opens more K+channels and AP freq inc

Front 66

signal transduction in hair cells when signal causes sterocilia to move away from long sterocilia

Back 66

-channels close but not 100%
-decrease in AP freq

Front 67

neuromasts in fish

Back 67

-is a hair cell and accessory cupula (is filled with viscious gel)
-detect water movement
-gel orientation moves the hair cells cilia

Front 68

lateral line

Back 68

array of neuromasts in pits and tubes along side of fishes body that sense h20 pressure and electrical fields

Front 69

Outer Ear

Back 69

auditory canal

Front 70

middle ear

Back 70

Incus
stapes
mallous

Front 71

inner ear

Back 71

semicircular canals(vestibular apparatus)
cochlea=contains hair cells and is important for hearing

Front 72

vestibular apparatus

Back 72

-detects moventments and is important for balance and equilibrium
-consists of 3 semicircle canals with enlarged region at one end (ampulla) and 2 sac like swellings (utricle and saccule)
-all reagions contain hair cells

Front 73

utricle and saccule

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-contain otoliths suspended in a macula covering tons of hair cells

Front 74

ampullae

Back 74

lack otoliths and have cristae

Front 75

cristae

Back 75

-hair cells suspended in a cuplula
-detect angular acceleration
-neuromast sense pressure
-moving head changes pressure in the endolymph to one side moving sterocilia
-move towards long one get inc in AP
-move away from long one get dec in AP

Front 76

macule

Back 76

detect linear acceleration and tilting
-constantly partially depolarized when not moving
-move forward and sterocilia move towards long sterocilia and inc AP

Front 77

sound detection in fish

Back 77

-sound detected in inner ear
-incoming sound waves cause otoliths to move which bend cilia of hair cells
-some fish use swim bladder to amplify sound

Front 78

terresterial vertebrates sound detection

Back 78

-hearing involves, inner, outer and middle ear

Front 79

since sound passes poorly from air to fluid filled earl we must amplify sound by

Back 79

-pinna acts as a funnel to collect more sound
-middle ear bones increase the amplitude of vibrations

Front 80

vibrations travel from....to

Back 80

malleus>incus>stapes>oval window>cochlea where lots happens

Front 81

mammalian inner ear

Back 81

-specialized for sound detection
-cochlea is coiled
-perilymph and endolymph
-ogran of corti

Front 82

perilymph

Back 82

fills vestibular and tympanic ducts and is similar to extracellular fluid

Front 83

endolymph

Back 83

fills cochlea duct and is high in K+ and low in Na+

Front 84

organ of corti

Back 84

contains hair cells and sits on basilar membrane

Front 85

two types of hair cells are

Back 85

inner hair cells that detect sound
and outer hair cells that amplify sound

Front 86

sound signal transduction steps

Back 86

1. incoming sound
2. oval window vibrates
3. waves in perilymph of vestibular duct
4.basal membrane vibrates
5.sterocilia of hair cells bend
6.depolarization
7.release of neurotransmitter (glutamate) via calcium
8.excite sensory neurons

Front 87

round window

Back 87

is a membrane that acts as a pressure valve. It moves outwards and improves sound clarity by preventing sound waves from traveling backwards

Front 88

sound encoding
basilar membrane is stiff and narrow at proximal end (at round/oval windows) and flexible and wide at distal end

Back 88

if freq is high>stiff end vibrates
if freq is low> flexible end vibrates

Front 89

loudness

Back 89

loud sounds increase movement of basilar membrane and increase depolarization of cell which increases AP freq

Front 90

outer hair cells

Back 90

chnage shape in response to sound instead of releasing NT
chnage in shapes cause basilar membrane to move more and causes longer stimulis to inner hair cells
-leads to sound amplification

Front 91

sound location

Back 91

sound in right ear is on the right ect.

brain uses time lags and differences in intensities

Front 92

ciliary photoreceptors

Back 92

have single highly folded cilium; folds firm disks that contain photopigments

Front 93

rhabdomeric photoreceptors

Back 93

apical surface is covered with multiple out foldings called macularvillar projections

Front 94

photopigment

Back 94

-molecules that absorb energy from photons
-have 2 covanlently bonded parts
chromphore (pigment that is derivative of vitamin a) and opsin(g coupled protien)

Front 95

vertebrates have 2 types of ciliary receptors they are

Back 95

rods and cones

Front 96

rods

Back 96

are more sensitive to dim light and found more in nocternal animals

Front 97

steps in photo reception

Back 97

1. chromophore absorbs energy
2.chromophore changes shape
3.photoreceptor protien chnages shape
4.signal transduction cascade
5.chnage in membrane potential

Front 98

no light

Back 98

retinal binds to opsin

Front 99

bleaching

Back 99

when retinal no longer binds to opsin and thereby activate opsin and leads to increase in AP

Front 100

if light

Back 100

retinal activated and no longer binds to opsin>bleaching

Front 101

rhabdomeric receptor signal transduction

Back 101

-via PLC activation
-IP3+DAG
Inc in Ca2+ and Na+
Inc in AP

Front 102

ciliary photoreceptor signal transduction

Back 102

phosphodiesterase hydrolyzes cGMP into GMP which closes sodium channels and hyperpolarizes the (makes more neg) and brain interpets this

Front 103

eyespots

Back 103

single cells or regions of a cell that contain photo senstitive pigment
-eyes are complex organs

Front 104

Flat sheet eye

Back 104

provide some sense of light direction and intensity
most often seen in larvae forms or as accessory eye in adults

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cup shaped eye

Back 105

retinal sheet is folded to form a narrow aperature
better descrimination of light direction and internsity

Front 106

vesicular eyes

Back 106

-use a lens in the aperture to improve clarity and intensity
-lens relects light and focus it on a single point on the retina
-present in most vert

Front 107

convex eye

Back 107

photoreceptors radiate outward and form complex retina

Front 108

compound eye

Back 108

-most complex convex eyes found in anthropods
-composed of ommatidia
form image in 2 ways

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apposition compound eyes

Back 109

ommatidium operate independently, afferent neurons makes interconnections to create image

Front 110

superposition compound eyes

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ommatidiumwork together to form a image on the retina

Front 111

parts of vertebrate eye

Back 111

-sclera=white of eye
-cornea=transparent layer
-choroid=pigmented layer
-tapetum=layer in choriod that reflects light in nocternal animals

Front 112

iris

Back 112

two layers of pigmented smooth muscle that can constrict or dilulate

Front 113

pupil

Back 113

opening in iris

Front 114

lens

Back 114

focuses image

Front 115

ciliary body

Back 115

muscles for chnaging the shape of lens

Front 116

aqueous humor

Back 116

fluid in anterior chamber

Front 117

vitreous humor

Back 117

gelatinous mass in posterior chamber

Front 118

Image formation

Back 118

- refracted 2x by cornea and lens
-both act as converting lens to focus light on retina
-in terrestrial vert most refraction occurs between the air and the cornea

Front 119

accomodation

Back 119

incoming light rays must converge on the retina to produce a clear image

Front 120

focal point

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point at which light converges

Front 121

focal distance

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distance from lens to its focal point

Front 122

distant object

Back 122

light rays are parallel when entering the lens

Front 123

close objecy

Back 123

light rays are not parallel when entering the lens and must be refracted more

Front 124

light rays focused on retina by

Back 124

chnaging shape of the lens
-accomodates image and focus

Front 125

retina

Back 125

-arranged in several layers
-rods and cones at back and tips face backwards
-axons of ganglion cells join to form optic nerve
-optic nerve exists retina at optic disk(blind spot)

Front 126

fovea

Back 126

small depression in center of retina
-contains only cones and provides the sharpest image

Front 127

rods

Back 127

principle of convergence (100s of rods one bipolar cell)
-fuzzy image and large field view

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cones

Back 128

one cone synapses with one bipolar cell which connects to one ganglion cell
-small visual field and high resolution image

Front 129

on and off regions of receptive fields of ganglion cells improve their ability to detect contrasts between light and dark

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retina
on region=depol
off region=hyperpol

Front 130

brain process the visual signal

Back 130

optic nerve>optic chiasm>optic tract>lateral geniculate nucleus>visual cortex

Front 131

color vision

Back 131

detect different wave lengths of light
requires different types of photoreceptors with different maximal sensitivities

Front 132

central thermoreceptors

Back 132

located in the hypothalamus
and monitor body temp

Front 133

peripheral thermoreceptors

Back 133

monitor environment temp

Front 134

thermal nociceptors

Back 134

detect painfully hot stimuli

Front 135

ThermoTRPs

Back 135

TRP ion channel thermoreceptor protiens

Front 136

pit organs

Back 136

found between eye and nostril of pit vipers and can detect radiating heat

Front 137

magnetoreception

Back 137

neurons in the olfactory epithelium of rainbow trout contrain particles that resemble magnetite