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MCAT Behavioral Sciences > Ch 2: Sensation and Perception > Flashcards

Ch 2: Sensation and Perception Flashcards

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MCAT flashcards
1
Q

sclera

A

thick structural layer covering the eye (the white of the eye). Dies not cover the cornea

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2
Q

Two sets of blood vessels that supply the eyes with nutrients

A

Choroidal vessels

Retinal Vessels

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3
Q

Retina

A

innermost layer of the eye, contains the photoreceptors that transduce light into electrical signals

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4
Q

anterior chamber of the eye

A

portion before (in front of) the iris

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5
Q

posterior portion of the eye

A

portion behind the iris

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6
Q

iris

A

the colored portion of the eye

composed of two muscles: the dilator pupillae and the constrictor pupillae

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7
Q

Dilator pupillae

A

dilates the iris of the eye

under sympathetic stimulation

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8
Q

Constrictor pupillae

A

constricts the pupil of the eye under parasympathetic stimulation

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9
Q

Ciliary Body

A

produces aqueous humor which drains into the canal of schlemm

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10
Q

accommodation (vision)

A
  • the ciliary muscle, a component of the ciliary body, changes the shape of the lens by contracting and pulling on suspensory ligaments
  • under parasympathetic control
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11
Q

Vitreous humor

A

transparent gel that supports the retina

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12
Q

duplexity or duplex theory of vision

A

stated that the retina contains two types of photoreceptors: those specialized for light and dark color detection and those specialized for color detection

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13
Q

Cones

A
  • used of color vision and fine details

- absorb blue (short) green (medium) and red (long) light

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14
Q

Rods

A
  • used to see black and white in low light situations

- use rhodopsin

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15
Q

fovea

A
  • the center most point of the macula (central section of the retina)
  • contains only cones
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16
Q

Bipolar cells

A
  • connect rods and cones
  • rods &cones –> BP Cells –> ganglion cells
  • highlight gradients between adjacent rods and cones
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17
Q

Amacrine and Horizontal cell function

A

-important in edge detection as they increase contrast perception

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18
Q

Visual pathway

A
  • enter the eye through the lens and pupil
  • light from the nasal visual field projects onto the temporal side of the retina and vise versa
  • nasal-side optical fibers cross at the optic chiasm but temporal optical fibers do not, meaning all information from the left visual field project into the right side of the brain and vise versa
  • visual pathways are called optic tracts once they leave the chiasm
  • info then moves to lateral geniculate nucleus (LGN) in the thalamus and the superior colliculus
  • info moves to the visual cortex of the occipital lobe from here via radiations
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19
Q

Parallel Processing (feature detection)

A
  • the ability to simultaneously analyze and combine information regarding color, shape, and motion
  • these features can then be compared to our memories to determine what is being viewed
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20
Q

parvocellular cells

A
  • able to detect shape
  • high color spatial resolution, low temporal resolution
  • can only work with stationary objects though because of their low temporal resolution
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21
Q

magnocellular cells

A
  • detect motion of objects

- high temporal resolution, low spatial resolution meaning no rich detail, sometimes blurry

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22
Q

responsibilities of the ear

A
  • hearing

- rotational and linear acceleration (vestibular sense)

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23
Q

pinna or auricle

A

the cartilaginous outer part of the ear

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24
Q

Pathway of sound waves into the ear

A

pinna–> external auditory canal –> tympanic membrane (eardrum) –> malleus –> incus –> stapes –> oval window
of cochlea –> vibrations in perilymph –> vibrations in endolymph –> organ of corti –> vestibulocochlear nerve –> CNS

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25
Q

tympanic membrane

A

eardrum
separates the outer and middle ear
vibrates in phase with incoming soundwaves causing transmission of the soundwave through the ossicles into the inner ear

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26
Q

Eustachian tube

A

connects the middle ear to the nasal cavity

helps equalize pressure between the middle ear and the environment

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27
Q

Composition of the inner ear

A
  • Begins with the oval window to the cochlea and contains the cochlea, vestibule, and semilunar canals
  • membranous labyrinth is filled with endolymph and surrounded by perilymph within the bony labyrinth
28
Q

vestibule

A

portion of the bony labyrinth that contains the utricle and saccule which are responsible for balance and determining one’s orientation in 3D

29
Q

Otoliths

A

used in the utricle and saccule
otoliths are attached to specialized hair cells and resist motion stimulating underlying hair cells and thus sending signals to the brain

30
Q

semicircular canals

A

sense rotational acceleration

31
Q

pathway in the CNS of auditory signals

A

vestibulocochlear nerve –> brainstem –> medial geniculate nucleus (MGN) of thalamus –> auditory complex in temporal lobe

32
Q

difference between LGN and MGN?

A 
LGN = Lateral geniculate nucleus; Light
MGN= Medial geniculate nucleus: Music (sound)
33
Q

vestibule

A
  • contains the utricle and saccule
  • sensitive to linear acceleration so they are part of the balancing apparatus and to determine one’s position in 3D space
34
Q

otoliths

A

structures attached to hair cells in the utricle and saccule that resist motion, moving the modified hair cells which send signals to the brain

35
Q

Semicircular Canals

A
  • sensitive to rotational acceleration

- when the head rotates, endolymph in the canals resist motion bending the underlying hair cells

36
Q

superior olive

A

structure of the brain that localizes sound

37
Q

inferior colliculus

A

involved in the startle reflex and helps keep the eyes fixed on a point while the head is turned (vestibulo-ocular reflex)

38
Q

How is a signal transduced at the organ of corti?

A

vibrations of the endolymph from the stapes hitting the oval window of the cochlea cause movement of the basilar membrane underlying the organ of corti. stereocilia attached to the hair cells begin to sway back and forth with the endolymph causing the opening of ion channels –> receptor potential.

39
Q

place theory

A

the location of a hair cell on the basilar membrane determines the pitch perception when that hair cell is vibrated. This means that the cochlea is tonotopically organized (which hair cells vibrating tells brain pitch)

40
Q

High pitches are perceived where in the cochlea? Low pitches?

A

High: close to the oval window
Low: nearer the apex away from the oval window

41
Q

Olfactory pathway

A

chemical signals bind to chemoreceptors in the nasal epithelium –> chemoreceptors are activated upon binding causing them to send signals to the olfactory bulb –> relayed via olfactory tract to higher brain regions (including limbic system)

42
Q

5 basic tastes

A
  • sweet
  • sour
  • salty
  • bitter
  • unami (savory)
43
Q

olfactory sensors are sensitive to

A

volatile or aerosolized chemicals

44
Q

Chemoreceptors responsible for taste are sensitive to

A

disolved compounds

45
Q

taste pathway into CNS

A

chemoreceptors on taste buds –> brainstem –> taste center in the thalamus –> higher-order regions of the brain

46
Q

four modalities of somatosensation

A

pressure
vibration
pain
temperature

47
Q

Receptors of somatosensation

A

pacinian corpuscles: deep pressure and vibration
meissner corpuscles: light touch
merkle cells (disks): respond to deep pressure and texture
Ruffini endings: strech
Free Nerve endings: pain and temperature

48
Q

pathway to CNS for somatosensation

A

transduction at a receptor –> brainstem –> somatosensory cortex in the parietal lobe

49
Q

two point threshold

A

minimum distance necessary between two points of stimulation on the skin such that the points will be perceived as two separate points

50
Q

physiological zero

A

between 86 an 97F is normal temperature of the skin. If an object is warmer than this temp, we perceive it as warm and vice versa with cold

51
Q

Kinesthetic Sense of Proprioception

A

the ability to tell where one’s body is in space. Receptores for proprioception are found mostly in muscles and joints, play critical roles in hand-eye coordination, balance, and mobility

52
Q

Bottom-Up Processing

A
  • Data driven processing
  • object recognition by parallel processing and feature detection
  • the brain combines individual sensory stimuli into a cohesive image before trying to determine what the object is
53
Q

Top-Down Processing

A
  • conceptually driven processing
  • driven by memories and expectations
  • allows us to ID objects without having to analyze their specific parts
54
Q

Perceptual Organization

A

the ability to combine top-down and bottom-up processing along with all other sensory clues about an object to create a complete picture or idea

55
Q

Depth Perception

A

-relies on monocular and binocular cues

56
Q

monocular cues for depth perception

A

relative size of objects
partial obscuring of one object by another
convergence of parallel lines at a distance
lights and shadows

57
Q

primary binocular cues for depth perception

A

slight differences in images projected onto the two retinas and the angle required between the two eyes to bring the object into focus

58
Q

form of an object is determined by…

A

parallel processing

feature detection

59
Q

Gestalt Principles (basic idea)

A

there are ways for the brain to infer missing parts of a picture when a picture is incomplete
images tend to be perceived as more stable, consistent, and simple than they actually are

60
Q

Law of Proximity (gestalt)

A

objects that are close to one another tend to be perceived as a unit

61
Q

Law of Similarity (Gestalt)

A

objects that are similar tend to be grouped together

62
Q

Law of Good Continuation

A

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

63
Q

Subjective Contours

A

perceiving contours and, thus, shapes that are not actually present in the stimulus

64
Q

Law of Closure

A

when a space is enclosed by a contour it tends to be perceived as a complete figure

65
Q

Law of Prägnanz

A

perceptual organization will always be as regular, simple, and symmetric as possible

MCAT Behavioral Sciences (14 decks)

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