Bio 219: Chp. 10 Sensory Systems

Front 1

sensory receptors

Back 1

detect & respond to a specific stimulus
-act as transducers - convert stimulus energy into changes in membrane potential
-sensory information is communicated via action potentials carried by sensory neurons

Hint 1

monitor specific conditions within body or in external environment:
arriving information is called a sensation
awareness of a sensation is a perception

Front 2

Each receptor responds best to ______ of stimulus.

Back 2

Each receptor responds best to a specific type of stimulus.

Front 3

transduction

Back 3

conversion of one form of energy into another

Front 4

sensation

Back 4

arriving information

Front 5

perception

Back 5

awareness of a sensation

Front 6

general senses

Back 6

pain, temperature, touch, pressure, vibration

Front 7

special senses

Back 7

olfaction (smell), vision (sight), gustation (taste), equilibrium (balance), and hearing

Hint 7

located in specific sense organs → structurally more complex

Front 8

general senses receptors

Back 8

throughout body, relatively simple structure; most cell processes (dendrites) that monitor conditions in body & environment

Front 9

smaller receptive field =

Back 9

more precise location

Front 10

What are the classes of sensory receptors?

Back 10

photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors, nociceptors

Front 11

photoreceptors

Back 11

light

Front 12

mechanoreceptors

Back 12

touch, pressure, stretch, vibration, sound, acceleration

Hint 12

use mechanically gated ion channels

Front 13

chemoreceptors

Back 13

monitor chemicals (taste, olfaction, pH O₂)

Hint 13

use chemically gated ion channels (ligand-gated)

Front 14

thermoreceptors

Back 14

warm, cold

Front 15

nociceptors

Back 15

pain

Front 16

Sensory receptors produce _______ (depolarization or hyperpolarization) in response to sensory stimuli

Back 16

Sensory receptors produce graded receptor potentials (depolarization or hyperpolarization) in response to sensory stimuli
-caused by opening/closing of ion channels

Hint 16

greater the stimulus = greater the change in membrane potential

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Front 17

sensory receptors can be:

Back 17

modified nerve endings or separate sensory cells

Front 18

What is an example of modified nerve endings

Back 18

touch receptors in skin

Front 19

What is an example of separate sensory cell

Back 19

photoreceptors in the eye

Front 20

sensory unit

Back 20

1 sensory unit + all sensory receptors associated with it
-each sensory neuron is associated with one type of receptor

Front 21

receptive field

Back 21

area of body supplied by 1 sensory neuron
- smaller receptive fields results in greater acuity (e.g. two point discrimination threshold)

Front 22

tonic receptors

Back 22

non-adapting or slowly adapting

Hint 22

fairly constant response to sustained stimulus (e.g. muscle stretch receptors)

Front 23

phasic receptors

Back 23

rapidly adapting

Hint 23

respond to initial change in stimulus, then decrease response (e.g. olfactory receptors)

Front 24

Sensory Pathways to CNS

Back 24

First Order Neuron
sensory neuron (receptor) delivers sensation to CNS cell body located in dorsal root ganglion

Hint 24

Second order neuron
axon of sensory neuron synapses on interneuron in CNS; from spinal cord/brainstem to thalamus
Third order neuron
if sensation is to reach our "awareness," the second-order neuron synapses on a third-order neuron in the thalamus and thalamus relays info to the cerebral cortex for "perception"

Front 25

Third order neuron

Back 25

thalamus relays info to the cerebral cortex for "perception"

Front 26

somatosensory cortex

Back 26

(perception of somatic sensations) parietal lobe (postcentral gyrus)

Front 27

visual cortex

Back 27

(vision) occipital lobe

Front 28

auditory cortex

Back 28

(sound) temporal lobe

Front 29

olfactory cortex

Back 29

(smell) temporal lobe

Front 30

gustatory cortex

Back 30

(taste) parietal lobe

Front 31

3 layers (tunics) of eye

Back 31

fibrous, vascular, sensory

Front 32

fibrous tunic

Back 32

forms outermost coat of eye, composed of: opaque sclera and clear cornea

Hint 32

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Front 33

vascular tunic

Back 33

three regions:
choroid, ciliary body, iris

Hint 33

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Front 34

iris

Back 34

2 smooth muscle layers

Hint 34

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Front 35

sensory tunic

Back 35

retina

Hint 35

neural tissue with photoreceptors (cells that detect light waves)
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Front 36

Internal cavities filled with ______.

Back 36

Internal cavities filled with ______.
(vitreous humor and aqueous humor)

Front 37

vitreous humor

Back 37

posterior cavity (clear gel) helps maintain shape

Front 38

aqueous humor

Back 38

anterior cavity (clear fluid) nourishment

Front 39

lens

Back 39

biconvex, transparent, flexible, avascular structure

Hint 39

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Front 40

fovea centralis

Back 40

region of retina where image focuses

Hint 40

highest density of cones (no rods)

Front 41

optic disc

Back 41

"blind spot" exit for optic nerve → no photoreceptors

Front 42

Visual pathway

Back 42

photoreceptors → bipolar cells → ganglion cells → optic nerve → crosses at optic chiasm → optic tracts → thalamus → visual cortex

Front 43

6 extrinsic eye muscles →

Back 43

allow eyes to follow a moving object while maintaining image on fovea centralis

Front 44

visual acuity and astigmatism

Back 44

light rays → bend (refraction) as they pass through convex cornea & lens
• passing from air to higher density structures (pass through slower)
• cornea is fixed; shape of lens is adjustable

Hint 44

concave and convex

Front 45

concave

Back 45

surfaces diverge light waves

Front 46

convex

Back 46

surfaces converge light waves to a focal point

Front 47

emmetropia

Back 47

• normal eye has good visual acuity (sharpness of vision)
• incoming light is sharply focused on fovea centralist of retina
• lens inverts image on retina
∙ left side of visual field → projected only right side of retina
∙ upper portion of field → projected downward

Front 48

myopia

Back 48

(nearsightedness) eyes are too long, light rays focus in front of retina
• individuals can see near; not far
• corrected with a concave lens
• tested for with Snellen chart

Front 49

snellen eye chart

Back 49

tests for myopia

Hint 49

normal vision - person can read to line marked 20/20
20/40 vision - individual must stand 20 ft from line that normal person can see at 40ft

Front 50

hyperopia

Back 50

(farsightedness) eye is too short light rays focus behind retina
• individuals can see far; not near
• corrected with a convex lens

Front 51

astigmatism

Back 51

visual defect produced by abnormal curvature of cornea or lens or irregularity on their surface
• vision is distorted & blurred
• corrected with uneven lens
• tested with an astigmatism chart

Front 52

accommodation

Back 52

ability of eye to focus on objects at different distances

Front 53

lens is flattened for distant vision →

Back 53

ciliary muscles are relaxed & suspensory ligaments are taut

no PNS stimulation

Front 54

lens is more spherical for close-up vision →

Back 54

ciliary muscles are contracted & suspensory ligaments are relaxed

PNS stimulation

Front 55

presbyopia

Back 55

("old eyes") ability to lose focus on close objects decrease with age
• decline in elasticity of lens
• tested by measuring the closest point at which an individual can focus clearly
• e.g. 10 year old near pt of vision ~ 8cm; 70 year old ~ 100cm

Front 56

6 extrinsic eye muscles →

Back 56

allow eyes to follow a moving object while maintaining image on fovea centralis
• 3 cranial nerves control muscles

Front 57

nystagmus

Back 57

if tone of 1 muscle is weak or nerve is damaged → eye can drift slowly in 1 direction, followed by rapid movement in opposite direction to correct position

Front 58

ophthalmoscope

Back 58

used to observer posterior portion of eye

Front 59

macula lutea

Back 59

"yellow spot"
• no rods
• fovea centralis - highest concentration of cones
• optic disc - blind spot

Front 60

optic disc

Back 60

blind spot
• area where axons of all ganglion cells gather to form optic nerve (no rods or cones)
• normally we are unaware of blind spot → brain "fills in" missing visual field

Front 61

phototransduction

Back 61

conversion of light energy into electrical signals
• carried out by rods and cones
• outer segment - molecules in disks that absorb light
• inner segment - nuclei & organelles
• synaptic terminal - storage & releases of chemical messengers

Front 62

4 photoreceptor types

Back 62

• 1 rod type
• 3 cone types
∙ blue cones
∙ red cones
∙ yellow cones

Front 63

photopigments

Back 63

organic compounds that absorb light waves
•derivatives of rhodopsin

Front 64

rhodopsin

Back 64

made of opsin (protein) bound to retinal (pigment) synthesized from vitamin A

Front 65

retinal pigment

Back 65

same in rods & cones

Front 66

opsin

Back 66

differs in each cone type
• opsin type within a cone determines which wavelength will be absorbed

Front 67

phototransduction

Back 67

retinal can assume various 3-D shapes (called isomers)
• When bound to opsin - retinal is kinked (11-cis-isomer)
• When pigment absorbs light - twists into different shape (all-trans isomer)
• Retinal = activated → ultimately causes AP to be transmitted down optic nerve

Front 68

bleaching

Back 68

rhodopsin breaks down into retinal & opsin
• regeneration requires ATP & takes time

causes lingering visual impression

Front 69

afterimage

Back 69

appears after "bleaching" of the visual pigment of affected receptors

Front 70

Humans have _____ color vision

Back 70

Humans have trichromatic color vision
• color vision → provided by stimulation of 3 cone types

Front 71

colorblindness

Back 71

can be cause by:

Hint 71

Genetic defect in photopigments (typically red and green)
• located on X chromosome
• more common in males (inherited by mother)
• females would have to inherit from mother and father

Front 72

auditory system

Back 72

responsible for hearing

Front 73

vestibular system

Back 73

responsible for balance or equilibrium

Front 74

What are the two sensory systems?

Back 74

auditory system and vestibular system

Front 75

Both sensory systems (auditory and vestibular) rely on ___ to detect movement of fluid within the cavities of the ear

Back 75

Both sensory systems (auditory and vestibular) rely on hair cells (mechanoreceptors) to detect movement of fluid within the cavities of the ear
-causes a receptor potential → afferent neuron → CNS

Front 76

Hair cells in the ___ detect vibration produced by sound waves

Back 76

Hair cells in the cochlear detect vibration produced by sound waves

Front 77

Hair cells in the ______ respond to acceleration (motion and gravity)

Back 77

Hair cells in the vestibular system respond to acceleration (motion and gravity)

Front 78

Tympanic membrane

Back 78

(eardrum)
• thin connective tissue membrane that vibrates in response to sound
• transfers sound energy to the middle ear ossicles
• boundary between outer and middle ears

Front 79

What are components of the external ear?

Back 79

tympanic membrane

Front 80

What are components of the middle ear?

Back 80

auditory tube, ear ossicles (malleus, incus, stapes), oval window, round window

Front 81

Middle ear

Back 81

small, air-filled cavity
flanked laterally by the eardrum; medically by the oval & round windows

Front 82

Auditory (eustachian) tube

Back 82

connects middle ear with pharynx (or throat)
• helps maintain normal pressure in middle ear

Front 83

What are the ear ossicle?

Back 83

malleus, incus, and stapes

Front 84

Three ear ossicles

Back 84

transmit vibratory motion of the eardrum to the oval window

Front 85

oval window

Back 85

thin membrane that separates air-filled middle ear from fluid filled inner ear

Front 86

round window

Back 86

thin membrane that separates air-filled middle ear from fluid filled inner ear

Front 87

malleus

Back 87

hammer

Front 88

incus

Back 88

anvil

Front 89

stapes

Back 89

stirrup

Front 90

bony labyrinth

Back 90

surrounds and protects membranous labyrinth
• channels worm way through temporal bone

Front 91

bony labyrinth is subdivided into:

Back 91

vestibule
semicircular canals
cochlea

Front 92

endolymph

Back 92

within membranous labyrinth —> potassium-rich fluid

Front 93

perilymph

Back 93

between bony and membranous labyrinth —> similar to extracellular fluid (high in sodium, low in potassium)

Front 94

cochlea

Back 94

spiral bony tube, located withing temporal bone

Front 95

cochlear duct

Back 95

tube within cochlea, contains endolymph lies between 2 chambers:

Hint 95

vestibular duct and tympanic duct

Front 96

vestibular duct

Back 96

contains perilymph

Front 97

tympanic duct

Back 97

contains perilymph

Front 98

vestibular membrane

Back 98

separates vestibular duct & cochlear duct

Front 99

basilar membrane

Back 99

separates tympanic duct & cochlear duct

Front 100

spiral organ

Back 100

(organ of Corti) sensory organ for sound

Hint 100

• located on top of basilar membrane
• contains hair cells & overlying tectorial membrane

Front 101

tectorial membrane

Back 101

attached to inner wall of cochlear duct

Front 102

hair cells

Back 102

stereocilia tips embedded within tectorial membrane

Front 103

Sounds and Mechanism of Hearing

Back 103

sound -

Hint 103

consists of waves of pressure through air or water

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Front 104

Hair Cilia

Back 104

Stereocilia

Hint 104

tips embedded in tectorial membrane

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Front 105

Coding of Sound Intensity and Pitch in the Cochlea

Back 105

pitch -

Hint 105

encoded based on which portion of the basilar membrane vibrates

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Front 106

volume

Back 106

(intensity) encoded by the frequency of action potentials

Front 107

semicircular canals

Back 107

detect rotational acceleration
• 3 canals oriented in perpendicular planes to detect 3-dimensional motion

Front 108

vestibule

Back 108

2 components

Hint 108

utricle & saccule

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Front 109

cupula

Back 109

gelatinous membrane, bends hair cells when fluid moves in semicircular ducts

Hint 109

ADD MORE HERE

Front 110

Utricle and Saccule

Back 110

otoliths

Hint 110

"ear stones" attached to membrane, bend hair cells when head moves

Front 111

utricle

Back 111

detect forward & backward accleration

Front 112

saccule

Back 112

detect up and down linear acceleration

Front 113

conduction deafness

Back 113

middle ear damage (e.g. middle ear infection, ossification of bones)

Front 114

sensory deafness

Back 114

cochlea or vestibulocochlear damage (e.g. infections, prolonged exposure to loud sounds)

Front 115

Tuning Fork Tests:

Back 115

Rinne's Test and Weber's Test

Hint 115

Vibrations from tuning fork are transmitted through skull bones to fluid in cochlea

Front 116

Weber's Test

Back 116

tuning fork placed on midsagittal line

Hint 116

• sound seems louder in conduction deaf ear
∙ cochlear hair cells are stimulated but room noise is excluded
∙ can stimulate with cotton in ear
• sound is louder in normal ear in sensory deafness

Front 117

Rinne's Test

Back 117

tuning fork placed on mastoid process; when sound is gone → place near external ear

Hint 117

• if sound re-appears (=no damage to middle ear/conduction deafness)
• put cotton in ear for 2nd test to stimulate conduction deafness

Front 118

Equilibrium

Back 118

Afferent impulses from vestibular apparatus:

Hint 118

• make us aware of our position in space
• affect efferent somatic motor nerves (e.g. voluntary extrinsic eye muscles)

Front 119

vestibular nystagmus

Back 119

involuntary eye oscillations produced by vestibular activity's affect on extrinsic eye muscles

Front 120

test with swivel chair

Back 120

note: after ~ 20 seconds of rotation →

Hint 120

fluid in semicircular canals has stabalized
• if abruptly stop → causes fluid to move again (activated response)