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BSCI 1511 > Sensory Systems > Flashcards

Sensory Systems Flashcards

1
Q

What is ionotropic sensory detection?

A

the receptor protein itself is part of the ion channel and opens or closes the channel pore by changing its conformation

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2
Q

What is metabotropic sensory detection?

A

the receptor protein is linked to a G protein that activates a cascade of events that eventually open or close ion channels

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3
Q

Receptor potential

A

a change in the membrane potential of a sensory cell in response to a stimulus

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4
Q

Stretch receptor pathway

A
  1. stretching the muscle = stimulus (that opens ion channels in dendrites)
  2. depolarization spreads to the cell body > receptor potential
  3. RP spreads to the hillock (if strong enough to reach threshold > action potential triggered)
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5
Q

Mechanoreceptors

A

receptors that are sensitive to mechanical forces, involved in many sensory systems

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6
Q

What causes ion channels to open for sensory systems?

A

physical distortion of mechanoreceptor’s plasma membrane

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7
Q

Surface level mechanoreceptors

A

Merkel’s disks and Meissner’s corpuscles

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8
Q

Merkel’s disks

A

surface mechanoreceptors that adapt slowly and provide continuous information

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9
Q

Meissner’s corpuscles

A

surface mechanoreceptors that adapt rapidly and are very sensitive

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10
Q

Deeper mechanoreceptors

A

Ruffini corpuscles and Pacinian corpuscles

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11
Q

Ruffini corpuscles

A

deeper mechanoreceptors that adapt slowly and sense low frequency vibrations

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12
Q

Pacinian corpuscles

A

deeper mechanoreceptors that adapt quickly and sense high frequency vibrations

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13
Q

What is special about hair cells?

A

They are a special kind of mechanoreceptor found in the cochlea of the ear that respond to the vibration induced by sound

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14
Q

What are rhodopsins?

A

a family of photoreceptors that are composed of a pigment (retinal) bound to a protein (opsin)

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15
Q

What are channelrhodopsins and why are they important?

A

a new “optogenic” tool for stimulating neurons developed by single-called plants

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16
Q

Evolution of eyes

A

shows progression of complexity

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17
Q

What is an example of de-evolution?

A

Eastern American mole: vestigial eyes
-they don’t need to create images underground, just differentiate between light and dark

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18
Q

What are ommatidia?

A

compound eyes consisting of many optical units in arthropods; each ommatidium has a lens that directs light onto photoreceptor cells (retinula cells)

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19
Q

What are retinula cells?

A

they contain rhodopsin and their axons communicate w/ the nervous system

20
Q

What kind of view do ommatidia give?

A

broken-up images

21
Q

What does insect vision look like?

A

Mottled impressionist paintings: spots of paint are integrated by our brain into coherent images (Pointillism)

22
Q

Veretebrae eyes have ___ and ____

A

rods and cones

23
Q

What is a rod cell?

A

A modified neuron that has an outer segment, an inner segment, and a synaptic terminal

24
Q

What does the inner segment have?

A

nucleus and many mitochondria

25
Q

What does the outer segment have?

A

a stack of membrane-bound discs that are densely packed w/ rhodopsin

26
Q

What is the role of the discs in the outer segment of vertebrae eyes?

A

Capture photons

27
Q

What does light do to a rod cell?

A

Hyperpolarize

28
Q

Membrane potential of a rod cell (in the dark/light)

A
  1. Rod cell = depolarized resting potential (Na+ channels are partially open)
  2. cGMP keeps Na+ channels open
  3. When light is absorbed by rhodopsin, cell becomes photoexcited and activates a G protein called transducin
  4. Activated transducin activates cGMP phosphodiesterase that converts to cGMP to GMP, causing cGMP levels to fall
  5. Na+ channels close completely
  6. Rod cells hyperpolarizes
29
Q

Organization of the retina

A

Photoreceptors (rods and cones) synapse onto bipolar cells
Bipolar cells (input from PRs, output to ganglion cells)
Ganglion cells (axons project thru the optic nerve to the brain)

30
Q

Dark response

A

depolarized cells release glutamate continuously onto bipolar cells

31
Q

Light response

A

hyperpolarized photoreceptor cells stop releasing glutamate

32
Q

What are Type 2 bipolar cells?

A

They have metabotropic receptors for Cl- channels.

33
Q

How do Type 2 bipolar cells function?

A

When glutamate is released, the Cl- channel in the bipolar cell is open and hyperpolarized (darkness). When glutamate is not released, the metabotropic receptor turns off, closing the Cl- channel. This causes the bipolar cell to depolarize to threshold and fire an action potential

34
Q

Pathway after depolarization

A
  1. Depolarized bipolar cells fire an action potential
  2. Releases neurotransmitter onto ganglion cells
  3. Fires an action potential that goes down the optic nerve to the brain
35
Q

What are the important parts of the eye?

A

cornea, aqueous humor, iris, pupil, lens, vitreous humor, retina

36
Q

What is the blind spot on the retina?

A

An area on the back of the eye where blood vessels and the optic nerve pass through the back of the eye; there are NO photoreceptors

37
Q

What does the lens do?

A

Makes fine adjustments in the focus of images on the photosensitive retina at the back of the eye; mammals and birds alter lens shape to focus

38
Q

What is the most sensitive area of the retina?

A

the fovea

39
Q

What causes near-sightedness (myopia) and far-sightedness (hyperopia)?

A

Changes in the shape of the eyeball that put the focal length outside of the range in which the lens is able to focus

40
Q

What happens to lenses as we age?

A

they become less elastic and we lost the ability to focus on objects close at hand (presbyopia)

41
Q

Rods vs. cones

A

rods: more sensitive to very low intensities of light (provide high sensitivity B&W vision)
cones: respond to diff wavelengths of light for color vision, provide sharpest vision (fovea only has cone cells)

42
Q

What kinds of cone cells do humans have?

A
  1. one that absorbs violet and blue wavelengths
  2. one that absorbs green
  3. one that absorbs yellow and red
43
Q

What wavelengths can humans not see?

A

ultraviolet or infrared

44
Q

Why do squids and octpi might have a more logical eye design?

A

photoreceptors are the first thing the light hits > less light scattering > NO blind spot

45
Q

What do sensory systems represent?

A

What is important for survival and fitness; perception of changes or differences in the environment are emphasized

BSCI 1511 (25 decks)

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