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MCAT > concept 6a > Flashcards

concept 6a Flashcards

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1
Q

sensation

A

transduction of physical stimuli into neurological signals

performed by receptors in the peripheral nervous system which forward stimuli to central nervous system

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2
Q

transduction

A

the conversion of physical, electromagnetic, auditory, and other info from our internal and external environment to electrical signals in the nervous system

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3
Q

perception

A

processing of this information to make sense of its significance
helps us make sense of the world

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4
Q

sensory receptors

A

neurons that respond to stimuli and trigger electrical signals
encode multiple aspects of a stimulus
differ from one sense to another

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5
Q

common sensory receptors

A 
photoreceptors 
hair cells 
nociceptors
thermoreceptors 
osmoreceptors 
olfactory receptors 
taste receptors
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6
Q

photoreceptors

A

respond to electromagnetic waves in the visible spectrum (sight)

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7
Q

hair cells

A

respond to movement of fluid in the inner ear structures

hearing, rotational and linear acceleration

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8
Q

nociceptors

A

respond to painful or noxious stimuli
somatosensation
sense pain

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9
Q

thermoreceptors

A

respond to change in temperature

somatosensation

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10
Q

osmoreceptors

A

respond to the osmolarity of the blood

water homeostasis

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11
Q

olfactory receptors

A

respond to volatile compounds

smell

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12
Q

taste receptors

A

respond to dissolved compounds

taste

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13
Q

ganglion

A

collection of neuron cell bodies found outside the central nervous system
receive the stimulus and transmit the data to the central nervous system

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14
Q

projection areas

A

areas in the brain that further analyze the information from the ganglia
once transduction occurs the electrochemical energy is sent to projection areas by neural pathways

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15
Q

threshold

A

the minimum amount of a stimulus that renders a difference in perception
3 types: absolute threshold, threshold of conscious perception, and the difference threshold

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16
Q

absolute threshold

A

the minimum of stimulus energy that is needed to activate a sensory system
threshold of sensation
determines if the sensation is enough to be converted into action potentials
*minimum intensity at which a stimulus will be transduced

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17
Q

threshold of conscious perception

A 
subliminal perception (limina means threshold)
perception of a stimulus below a given threshold 
stimulus arrives at the central nervous system but does not reach he higher-order brain regions that control attention and consciousness
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18
Q

difference threshold

A

just-noticeable difference (jnd)
minimum difference in magnitude b/w 2 stimuli before one can perceive this difference
if the difference b/w stimuli is small then they will be perceived as the same

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19
Q

Weber’s law

A

states that there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus
(change needed/original stimulus) gives percent of jnd

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20
Q

signal detection theory

A

focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context
perception can be affected by non sensory factors, such as experiences (memory), motives, and expectations

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21
Q

response bias

A

refers to the tendency of subjects to systematically respond to a stimulus in a particular way due to non sensory factors

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22
Q

signal detection experiments

A

consists of many trials where a stimulus may or may not be presented
trials when signal is presented are called catch trials
when signal is not presented called noise trials
after each
subjects asked to indicated whether or not signals was given
leads to 4 different results

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23
Q

results of signal detection experiments

A

hits: subject correctly perceives the signal
misses: subject fails to perceive a given signal
false alarms: subject seems to perceive a signal when none was given
correct negatives: subject correctly identifies that no signal was given
proportion of misses and false alarms indicate response bias

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24
Q

adaptation

A

decrease in stimulus perception after a long duration of exposure
detection of a stimulus can change over time
have both a physiological (sensory) component and a psychological (perceptual) component

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25
Q

sclera

A

thick structural layer covering exposed portion of the eye
white of the eye
doesn’t cover the front of the eye

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26
Q

choroidal vessels

A

complex intermingling of blood vessels b/w the sclera and the retina
along with the retinal vessels
both sets of vessels supply eye with nutrients

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27
Q

retina

A

innermost layer of the eye
contains photoreceptors that transduce light into electrical information the brain can process
like a screen consisting of neural elements and blood vessels

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28
Q

cornea

A

clear, domelike window in the front of the eye

gathers and focuses incoming light

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29
Q

anterior chamber

A

lies behind the cornea in front of the iris

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30
Q

posterior chamber

A

between the iris and the lens

contains aqueous humor

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31
Q

iris

A 
colored part of eye
composed of 2 muscles: the dilator pupillae and the constrictor pupillae 
continuous with the ciliary body 
iris contracts--> enlarge pupil 
iris relaxes--> constricts pupil
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32
Q

dilator pupillae

A

opens the pupil under sympathetic stimulation

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33
Q

constrictor pupillae

A

constricts the pupil under parasympathetic stimulation

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34
Q

ciliary body

A

produces aqueous humor that bathes the front part of the eye before draining into the canal of Schlemm

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35
Q

lens

A

lies behind the iris
helps control the refraction of incoming light
connected to suspensory ligaments

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36
Q

suspensory ligaments

A

connected to the lens

when the ciliary muscle contracts it pulls on the ligaments and changes the shape of the lens

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37
Q

accommodation

A

the change shape of the lens from the suspensory ligaments and the ciliary body

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38
Q

vitreous humor

A

transparent gel that supports the retina

lies behind the lens

39
Q

duplicity theory of vision

A

states that the retina consists of 2 kinds of photoreceptors:
those specialized for light and dark detection
those specialized for color detection

40
Q

cones

A

photoreceptors used for color vision
sense fine details
6 million in the retina
most effective in bright light and comes in 3 forms: short or blue, medium or green, long or red

41
Q

rods

A 
photoreceptors used for light and dark vision 
contain small pigments called rhodopsin 
low sensitivity to detail 
permit light vision 
120 million in the retina
42
Q

fovea

A

central section of the retina (macula)

contains only cones

43
Q

bipolar cells

A

connects rods and cones

highlight gradients b/w adjacent rods and cones

44
Q

ganglion cells

A

synapse with bipolar cells

group together to form the optic nerve

45
Q

amacrine and horizontal cells

A

receive input from multiple retinal cells in the same area before the information is passed on to ganglion cells
accentuate slight difference b/w the visual info in each bipolar cell
important for edge detection

46
Q

visual pathway

A

right visual field goes to left hemisphere
left visual field goes to right hemisphere
through the optic nerve to the optic chiasm to the optic tract
information goes to several different places in the brain: the lateral geniculate nucleus (LGN), visual cortex, and the superior colliculus

47
Q

processing areas

A

lateral geniculate nucleus (LGN) in the thalamus
visual cortex in the occipital lobe
superior colliculus, which controls some responses to visual stimuli and reflexive eye movements

48
Q

parallel processing

A

ability to simultaneously analyze and combine information regarding color, shape, and motion
then they can be compared to our memories to determine what is being viewed

49
Q

parvocellular cells

A

detects shape
have high color spatial resolution
work with stationary or slow-moving objects so they have low temporal resolution

50
Q

magnocellular cells

A

detect motion
high temporal resolution
low spatial resolution
provide blurry but moving images

51
Q

pinna

A

or auricle
where sound wave first reaches cartilaginous outside of ear
channel sound waves not the external auditory canal which directs sound to the tympanic membrane

52
Q

tympanic membrane

A

eardrum
membrane vibrates in phase with the incoming sound
frequency of wave determines pitch
intensity corresponds to amplitude of vibration
divides the outer ear and the middle ear

53
Q

ossicles

A

housed in the inner ear
3 smallest bones in the body
help transmit and amplify the vibrations from the tympanic membrane

54
Q

middle ear

A

malleus (hammer) affixed to the tympanic membrane, and acts on the incus (anvil), which in turn acts on the stapes (stirrup)
the base plate of the stapes rests in the oval window

55
Q

Eustachian tube

A

connects the middle ear to the nasal cavity

helps equalize pressure b/w the middle ear and the environment

56
Q

inner ear

A

sits within a bony labyrinth
contains the cochlea, vestibule, and semicircular canals
all continuous with each other and form the membranous labyrinth filled with endolymph
also contains perilymph that transmits vibrations and cushions the inner ear structure

57
Q

cochlea

A

spiral-shaped organ divided into 3 parts called scalae that run the entire length of the cochlea
middle scala houses organ of corti and contains endolymph
other 2 scalae filled with perilymph

58
Q

organ of corti

A

actual hearing apparatus
housed in the middle scala
lies on a thin, flexible membrane called the basilar membrane
composed of thousands of hair cells that are bathed in endolymph
on top is immobile membrane called tectorial membrane

59
Q

round window

A

membrane covered hole in the cochlea

permits perilymph to actually move within the cochlea

60
Q

vestibule

A

portion of the bony labyrinth the contains the utricle and saccule
sensitive to linear acceleration
part of balancing apparatus

61
Q

semicircular canals

A

sensitive to rotational acceleration (x,y, and z planes)
arranged perpendicularly to each other
ends in a swelling called an ampulla, where hair cells are located

62
Q

auditory pathways

A

most info passes through the vestibulocochlear nerve to the brainstem
auditory input –> middle ear–> cochlea–> auditory nerve–> superior olive–> inferior colliculus (thalamus)–> medial geniculate nucleus–> temporal cortex

63
Q

tonotopically organized

A

the cochlea is organized this way

when the hair cells vibrate it gives the brain an indication of the pitch of the sound

64
Q

smell

A

considered a chemical sense

respond to the incoming chemicals from the outside word via olfactory chemoreceptors

65
Q

olfactory chemoreceptors

A

olfactory nerves
located in olfactory epithelium in the upper part of the nasal cavity
chemical signals bind to these receptors to cause a signal

66
Q

olfactory pathway

A

chemicals bind to the olfactory receptors in the olfactory epithelium
signal sent to the olfactory bulb
then sent to higher regions of the brain

67
Q

pheromeones

A

smell that carries interpersonal information
bind to olfactory receptors
play a role in animals social, foraging, and sexual behavior

68
Q

5 basic tastes

A 
sweet
sour 
salty
bitter
umami (savory)
69
Q

taste chemoreceptors

A

detect taste
can sense dissolved compounds (salts) and specific molecules binding to receptors
receptors are groups of cells called taste buds

70
Q

papillae

A

little bumps found on the tongue

this is where taste buds are found

71
Q

taste pathway

A

chemoreceptors on tongue (taste buds on papillae) detect taste
sent to the brain stem
ascend to the taste centers in the thalamus before traveling to higher brain regions

72
Q

somatosensation

A

the sense of touch
complex
has many different receptors

73
Q

4 sensations of touch

A

pressure
vibration
temperature
pain

74
Q

5 receptors

A 
Pacinian corpuscles 
Meissner corpuscles
Merkle discs
Ruffini endings 
Free nerve endings
75
Q

Pacinian corpuscles

A

respond to deep pressure and vibration

76
Q

Meissner corpuscles

A

respond to light touch

77
Q

Merkle discs

A

respond to deep pressure and texture

78
Q

Ruffini endings

A

respond to stretch

79
Q

Free nerve endings

A

respond to pain and temperature

80
Q

somatosensation pathway

A

transduction occurs in the receptors

then sent to the central nervous system and eventually to the somatosensory cortex in the parietal lobe

81
Q

two-point threshold

A

minimum distance necessary between 2 points of stimulation on the skin such that the 2 points will be felt as 2 different stimuli
size of threshold depends on the density of nerves in the particular area of skin being tested

82
Q

physiological zero

A

how temperature is judged
the normal temperature of the skin, b/w 86-97 degrees F
object feels cold bc it is under the physiological zero
object feels hot bc it is above the physiological zero

83
Q

gate theory of pain

A

proposes that there is a special “gating” mechanism that can turn pain signals on or off
this affects whether or not we perceive pain
spinal cord is able to preferentially forward the signals from other modalities of touch to the brain reducing the sensation of pain

84
Q

kinesthetic sense

A

proprioception
ability to tell where one’s body is in space
knowing where limbs are in space
receptors are found mostly in muscles and joints
play role in hand-eye coordination, balance, and mobility

85
Q

bottom-up processing

A

data driven
refers to object recognition by parallel processing and feature detection
brain takes the individual sensory stimuli and combines them together to create a cohesive image before determining what the object is

86
Q

top-down processing

A

conceptually driven
driven by memories and expectations that allow the brain to recognize the whole object and then recognize the components based on expectations
brain quickly recognize objects without needing to analyze specific parts

87
Q

perceptual organization

A

ability to use these processes to create a complete picture or idea

88
Q

Gestalt principles

A 
ways for the brain to infer missing parts of a picture when a picture is incomplete 
law of proximity 
law of similarity 
law of good continuation
subjective contours 
law of closure
89
Q

law of proximity

A

elements close to one another tend to be perceived as a unit

90
Q

law of similarity

A

objects that are similar tend to be group together

91
Q

law of good continuation

A

elements that appear to follow the same pathway tend to be grouped together

92
Q

subjective contours

A

perceiving contours and shapes that are not actually present in the stimulus
may arise from the law of good continuation

93
Q

law of closure

A

when a space is enclosed by a contour it tends to be perceived as more complete (or closed) than they really are

94
Q

law of prägnanz

A

perceptual organization will always be as regular, simple, and symmetric as possible
governs the Gestalt principles

MCAT (18 decks)

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