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MCAT > 6A: Sensing the environment > Flashcards

6A: Sensing the environment Flashcards

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MCAT flashcards
1
Q

What is a threshold?

A

The minimum amount of stimulus required to cause an action potential

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2
Q

What is the absolute threshold?

A

The minimum intensity of a stimulus that one can detect

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3
Q

What is the difference threshold?

A

The minimum difference in intensity between two stimuli that one can detect; also known as the just noticeable difference

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4
Q

What does Webers Law indicate?

A

There is a constant ratio between the change in stimulus to produce a difference threshold and the magnitude of the original stimulus;

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5
Q

What is Weber’s constant/fraction?

A

1/5 or 2%

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6
Q

What is Signal Detection Theory?

A

It states that nonsensory factors can influence thresholds; it focuses on changes in our perception of the same stimuli depending on psychological and environmental context;

The ability to discern between stimuli and noise

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7
Q

What are the parts of a signal detection experiment?

A

Consists of catch trials (where stimuli is present) and noise trials (where stimuli are absent)

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8
Q

What are the outcomes of a signal detection experiment?

A

HIT = signal present and detected
MISS = signal present and not detected
FALSE ALARM = single absent and detected
CORRECT NEGATIVE/REJECTION = single absent and not detected

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9
Q

What is sensory adaptation?

A

It is the ability of our bodies to become accustomed to a stimulus after repeated application of the stimulus; both the physiological and psychological component get decreased

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10
Q

What does sensory adaptation allow us to do?

A

It allows us to differentiate meaningful information from the background; unable to feel clothing after getting dressed

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11
Q

What do sensory receptors do?

A

They respond to stimuli and trigger electrical signals

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12
Q

What are sensory pathways?

A

Sensory pathways are nerve endings or sensory cells that receive stimuli and carry the information through sensory ganglia and arrive at the CNS

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13
Q

What are Ganglia?

A

Ganglia are found outside of the CNS and they are group of neuron cell bodies

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14
Q

What are Projection Areas?

A

Projection areas are portions of the brain that analyze the sensory input

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15
Q

What are the major sensory receptors?

A

Hair cells, Photoreceptors, Thermoreceptors, Mechanoreceptors, Osmoreceptors, Nocireceptors, Olfactory receptors, Chemoreceptors

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16
Q

What do Hair cells detect?

A

Movement of fluid in the inner ear

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17
Q

What are simple receptors?

A

Neurons with free nerve endings

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18
Q

What are complex neural receptors?

A

Nerve endings that are enclosed in connective tissue capsules

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19
Q

What are special senses receptors

A

These are neurons that release neurotransmitter onto sensory neurons that initiate action potentials

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20
Q

Which lobe of the brain is devoted to vision?

A

Occipital lobe

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21
Q

How does the eye receive nutrients?

A

Choroidal and retinal vessels

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22
Q

What is the duplicity theory of vision?

A

This theory posits that the retina contains two kinds of photoreceptors which are specialized for light and dark detection

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23
Q

What is the function of Rods? What kind of pigment(s) do they contain?

A

It functions in reduced illumination and allow for sensation of light and dark; they have a low sensitivity to detail; pigment = rhodopsin

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24
Q

What is the function of Cones? What kind of pigment(s) do they contain? How does the Fovea relate to cones?

A

It functions in color detection and sensing of fine detail; contain S, M and L pigments; Fovea only has cones so its important in visual acuity and sensitivity to daylight vision

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25
Q

What is the function of amacrine & horizontal cells?

A

They receive input from many of the retinal cells before it is passed onto the ganglion cells; they focus the slight differences between the visual information in each cell increases the perception of stimuli

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26
Q

What are the two muscles of the iris and what do they do?

A

Dilator pupillae = opens the pupil under sympathetic stimulation
Constrictor pupillae = constricts pupil under parasympathetic stimulation

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27
Q

What is the Choroid and what is its function?

A

It is a continuous structure of the iris along with the ciliary body; it produces aqueous humor and washes the anterior chamber of the eye

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28
Q

Where is the lens of the eye located and what is its function?

A

It’s located behind the iris and controls the refraction of entering light

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29
Q

What is the function of the ciliary muscle (part of the ciliary body)?

A

It contracts under parasympathetic stimulation to change the shape of the lens (known as accommodation)

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30
Q

What is the function of vitreous humor?

A

It’s a transparent gel that supports the retina behind the lens

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31
Q

What is the function of the Macula and where is it located?

A

It’s responsible for detailed central vision, it is located in the central section of the retina

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32
Q

What is the pathway for visual information?

A

Optic nerve -> optic chiasm -> optic tracts -> lateral geniculate nucleus -> visual radiations -> visual cortex (occipital lobe)

33
Q

Where does the right visual field project?

A

Onto the left half of the retina and the left side of the brain

34
Q

Where does the left visual field project?

A

Onto the right half of the retina and the right side of the brain

35
Q

What is parallel processing?

A

The ability to simultaneously analyze and combine information; includes color, shape, depth and motion - correlated with feature detection;

Features are compared to memories to determine what is being viewed

36
Q

What processes color, shape and motion?

A

Cones, Parvocellular Cells and Magnocellular cells

37
Q

What are the parts of the outer ear?

A

Pinna/Auricle and Tympanic Membrane

38
Q

What are the parts of the middle ear?

A

Malleus, incus and stapes

39
Q

What are the parts of the inner ear?

A

Cochlea, Vestibule, Semicircular Canals

40
Q

What is the function of the Eustachian Tube?

A

It equalizes pressure between the middle ear and the environment

41
Q

What happens to sound when it enters the cochlea?

A

It passes through the oval window and causes vibrations which allow the hair cells to move and turn the physical stimuli into electrical signals

42
Q

What is the function of the vestibule?

A

It’s sensitive to linear acceleration and it’s used as a part of balancing apparatus and determining 3D orientation

43
Q

What is the function of the semicircular canals?

A

It’s sensitive to rotational acceleration and they contain hair cells in their canals which bend to interpret change

44
Q

What is the auditory pathway?

A

Vestibulocochlear nerve -> brainstem -> medial geniculate nucleus (thalamas) -> auditory cortex (temporal lobe) & inferior colliculus

45
Q

Location, characteristics of Hair Cells

A

Located within the organ of corti in the cochlea, they are epithelial cells with stereocilia on their surface and they rest on the basal lamina

46
Q

Functionality of Hair Cells

A

Vibrations reach the basilar membrane -> hair cells move which opens ion channels that produce action potential and the brain identifies the pitch of the sound

47
Q

4 modalities of somatosensation

A

Pressure, Vibration, Pain and Temperature

48
Q

Pacinian Corpuscles

A

Respond to Deep Pressure and Vibration

49
Q

Meissner Corpuscles

A

Respond to Light Touch

50
Q

Merkle Discs

A

Respond to Deep Pressure & Texture

51
Q

Ruffini Endings

A

Respond to Stretch

52
Q

Free Nerve Endings

A

Respond to Pain & Temperature

53
Q

What is the Two-Point Threshold?

A

The minimum distance necessary between two points of stimulation on the skin to be felt as two distinct stimuli

54
Q

What is Physiological Zero?

A

The point to which temperature is judged, below PZero = cold, above PZero = warm

55
Q

What is the Gate Theory of Pain?

A

There is a special mechanism that can turn pain signals on or off and affect whether or not we receive pain

56
Q

What does the gate theory of pain involve?

A

The spinal cord forwarding stimuli from the various modalities; if non-painful stimuli is detected, the gate closes.

57
Q

What are the five basic tastes?

A

Sweet, Sour, Salty, Bitter & Umami

58
Q

How are tastes detected?

A

By chemoreceptors (they’re sensitive to dissolved compounds)

59
Q

How is taste information processed?

A

Taste buds -> brain stem -> thalamus taste center -> other parts of the brain

60
Q

What is olfaction?

A

Response to volatile or aerosolized compounds

61
Q

What are pheromones?

A

Compounds that carry interpersonal information; play a bigger role in animals than humans

62
Q

What is the olfactory pathway?

A

Olfactory Receptors -> Olfactory Bulb -> Olfactory Tract -> Brain (limbic system)

63
Q

What is proprioception (kinesthetic sense)?

A

Sensing the body’s position in space; involves hand-eye coordination, balance and mobility

64
Q

Where are proprioceptors located?

A

Muscles, Ligaments and Joints; contain stretch receptors

65
Q

What are the two types of object recognition?

A

Bottom-Up and Top-Down Processing

66
Q

What is Bottom Up Processing?

A

It is a data driven process; it occurs via parallel processing and feature detection;

The brain first combines individual sensory stimuli into a cohesive image -> emotional response -> brain cognition -> action occurs

Features are processed before comprehension is achieved

67
Q

What is Top Down Processing?

A

It is a conceptually driven process; occurs via object recognition by memories and expectations; quick recognition of an object occurs first and then analysis of detail occurs

68
Q

What is Perceptual Organization?

A

It is the process of forming a complete picture by applying all sensory ideas about an object through top-down and bottom-up processing; it applies information about depth, form, motion and constancy helps to complete the picture

69
Q

Depth Organization

A

Involves seeing objects in 3D in a 2D space; Binocular cues depend on both eyes
Monocular cues depends on one eye

70
Q

Form Organization

A

Organization of the visual field into objects that make it stand out from the background

71
Q

Motion Organization

A

Seeing the object in motion

72
Q

Constancy Organization

A

Recognizing objects by size, shape and color from different angles

73
Q

What are Gestalt Principles?

A

The way the brain acts to infer the missing parts of a picture when a picture is incomplete

74
Q

GP: Proximity

A

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

75
Q

GP: Similarity

A

Objects that are similar tend to be grouped together

76
Q

GP: Good Continuation

A

Elements that appear to follow in the same pathway tend to be grouped together; tendency to perceive continuous patterns in stimuli rather than abrupt changes

77
Q

GP: Subjective Contours

A

Perceiving shapes that are not actually present in the stimulus

78
Q

GP: Closure

A

When a space is enclosed by a contour it tends to be perceived as a complete figure; certain tend to be perceived as more complete than they really are

79
Q

Law of Prägnanz

A

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

MCAT (31 decks)

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