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BSCI 1511 > Sensory Systems > Flashcards

Sensory Systems Flashcards

1
Q

What are the four aspects of sensory processes?

A
  1. Sensory reception
  2. Transduction
  3. Transmission
  4. Perception
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2
Q

What happens in sensory reception?

A

Detection of a stimulus by a sensory receptor cell.

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3
Q

What happens in transduction?

A

Conversion of stimulus energy to a change of membrane potential in a sensory receptor cell.

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4
Q

What happens in transmission?

A

Traveling of sensory information via neurons.

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5
Q

What happens in perception?

A

Interpretation of sensory input by the brain.

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6
Q

What are the two types of sensory receptor cells?

A
  1. Sensory neurons
  2. Non-neuronal cells that regulate a neuron.
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7
Q

How are neuronal receptors and non-neuronal receptors different?

A

Neuronal receptors are made of afferent neurons. Non-neuronal receptors regulate afferent neurons.

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8
Q

What are the two ways in which sensory cells can be arranged?

A
  1. Alone
  2. Arranged into sensory organs.
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9
Q

Describe the sensory reception step.

A

Sensing a stimulus opens or closes ion channels. Non-neuronal sensory receptor cells form chemical synapses with afferent neurons.

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10
Q

Describe the sensory transduction step.

A

Stimulus is converted to a change in the membrane potential: receptor potential.

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11
Q

Describe the sensory transmission step.

A

Receptor potential (a graded potential) initiates an action potential that is transmitted from the PNS to the CNS (a nerve impulse). The frequency of action potentials encodes the strength of the stimulus.

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12
Q

What is a receptor potential?

A

Receptor potentials are graded potentials that by summation, trigger action potentials.

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13
Q

How is the size of the receptor potential related to the intensity of the stimulus?

A

The size of the receptor potential increases with the intensity of the stimulus.

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14
Q

How is the size of the receptor potential controlled in sensory neurons vs in non-neurons?

A

In sensory neurons, the size is controlled by the summation of graded potentials. In non-neurons, size is controlled by the amount of neurotransmitter released.

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15
Q

What dictates the meaning of a signal?

A

The path the signal takes. Specific neurons are dedicated to conveying specific information, so the brain can interpret the signal based on the specific neuron the signal passed through.

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16
Q

What is amplification?

A

The strengthening of a sensory signal during transduction; may involve second messengers.

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17
Q

What is sensory adaptation?

A

A decrease in responsiveness following continuous stimulation.

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18
Q

What do mechanoreceptors sense?

A

They sense physical deformation caused by mechanical energy: pressure, touch, stretch, motion, and sound.

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19
Q

What are mechanoreceptors, and where are they found?

A

They are typically ion channels that open or close when structures bend or stretch, and they are usually embedded in connective tissue.

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20
Q

What do nociceptors sense?

A

Extreme conditions, and they trigger defensive reactions such as withdrawal from danger.

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21
Q

What are the two types of chemoreceptors?

A
  1. General receptors
  2. Specific receptors
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22
Q

What do general chemoreceptors do?

A

Transmit information about total solute concentration (for example, osmoreceptors that trigger thirst)

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23
Q

What do specific chemoreceptors do?

A

Transmit information about specific molecules (for example, glucose, oxygen, CO2, amino acids, volatiles, and pheromones).

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24
Q

What do electromagnetic receptors do?

A

They detect electromagnetic energy, such as light, electricity, and magnetism. They are used in vision, to detect prey, to guide migratory patterns, etc.

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25
What do thermoreceptors do?
They detect heat and cold, are used to detect prey, to thermoregulate, etc. Some are activated by chemicals in our diet (such as capsaicin in hot peppers or cooling menthol).
26
What does the outer ear do?
It focuses the sound waves into the ear through the auditory canal.
27
What happens when sound waves hit the tympanic membrane at the end of the outer ear?
The pressure waves are going to hit the tympanic membrane and make it vibrate. Those vibrations are then transmitted into the middle ear.
28
In what order do the three small bones of the middle ear vibrate?
1. Malleus 2. Incus 3. Stapes
29
What happens when vibrations reach the stapes?
It pushes against the oval window, which transmits the sound waves into the cochlea of the inner ear.
30
What is a major difference between the outer/middle ear and the inner ear?
The outer and middle ear portions are in the air while the inner ear is in fluid.
31
Describe the direction of sound waves in the cochlea.
Sound comes up the vestibular canal, through the cochlear duct, and back out via the tympanic canal.
32
What causes the tectorial membrane of the ear to vibrate?
The transmission of sound waves through the vestibular canal, cochlear duct, and tympanic canal causes the tectorial membrane to vibrate.
33
What happens when the tectorial membrane vibrates?
It vibrates against hair cells, depolarizing them by opening or closing ion channels and causing a signal that can be integrated into a sound.
34
What does the organ of Corti contain?
The mechanoreceptors of the ear, with hairs projecting into the cochlear duct.
35
When do the pressure waves of sound transition from being in air to being in fluid?
The stapes vibrates against the oval window, causing this transition.
36
What happens when pressure waves push on the cochlear duct and basilar membrane?
The hair cells, which originate in the basilar membrane and attach to the tectorial membrane, vibrate up and down.
37
After stimulating the hair cells, where does the signal go?
To the auditory nerve, which allows the sound to be sensed by the brain.
38
What is hearing?
The transduction of a mechanical stimulus into impulses the brain perceives as sound.
39
What determines the volume of sound?
Volume is determined by the amplitude of the sound wave. Higher amplitudes result in a higher frequency of action potentials.
40
What is dissipation in the context of hearing?
Pressure waves dissipate when they strike the round window, preventing an echo.
41
What determines the pitch of sound?
The frequency of the sound wave determines pitch, and different areas of the cochlea are receptive to different pitches because of different membrane thicknesses.
42
What do the utricle and saccule of the ear do?
They detect position in terms of gravity or linear movement.
43
How do the utricle and saccule use hair cells with signaling?
Bending of hairs by the otoliths signals the angle of the head.
44
What are otoliths, and where are they found?
The utricle and saccule contain hair cells that project into a gel that contains calcium carbonate particles called otoliths.
45
What do the three fluid-filled semicircular canals of the ear do, and where are they found?
They detect turning of the head and rotational acceleration. They are connected to the utricle.
46
How are the utricle and the saccule oriented?
The utricle is oriented horizontally and the saccule vertically.
47
How do the semicircular canals of the ear detect rotational movement?
There is fluid in the canals, and when movement of the head or body occurs, the fluid also moves. This causes the cupula (a gel-like structure) to bend, activating it and causing a signal. The semicircular canals are different from the utricle and saccule in that they do not have otoliths.
48
Why are there three semicircular canals?
Each canal corresponds to one axis: x, y, or z.
49
What type of eyes do planaria have?
Eyespots that direct the direction of light.
50
What are the compound eyes of insects and crustaceans composed of, and how does this create vision?
These compound eyes are composed of ommatidia, each detecting light from a small portion of the visual field. Each ommatidium provides a slightly different view. This is excellent for detecting movement.
51
How does the vision of planaria work?
On each, there is a shaded (pigmented) region and a non-pigmented region so that they can detect where the light is coming from.
52
How do ommatidia work?
Light passes through the lens and the cornea to the photoreceptor cells, which then pass the signal to the brain.
53
How is light focused in the eyes of invertebrates, amphibians, and fish?
The lens moves forward and backward to focus the light on the retina.
54
How is light focused in the eyes of mammals, birds, and most reptiles?
Light is focused by changing the shape of the lens.
55
Put these three structures in the order with which they interact with light: pupil & iris, photoreceptors, and lens.
1. Pupil & iris 2. Lens 3. Photoreceptors
56
What is the sclera?
The sclera is the outside part of the eye. It is composed of connective tissue and is white-colored.
57
What is the iris?
It is the part of the choroid that regulates pupil size and can be seen from the outside.
58
Why is it important for the cornea to be clear?
This allows light to pass through into the eye.
59
What is the choroid?
The choroid wraps around the eye and is the pigmented layer.
60
What is the pupil?
The gap in the choroid that allows light to pass through.
61
Where are the photoreceptors located?
The retina.
62
What are the two kinds of photoreceptors?
1. Rods 2. Cones
63
What do rods do?
They detect monochrome information and decide whether or not there is light.
64
What do cones do?
They detect color information.
65
What are the three types of cones?
1. Red-detecting 2. Green-detecting 3. Blue-detecting
66
Where is the retina?
It wraps all the way around the eye, except for at the optic nerve.
67
What is the fovea?
The point in the eye with the greatest visual acuity. This is where vision is the highest resolution and has the best color resolution due to the high number of cones.
68
What is the vitreous humor?
The fluid inside the eye.
69
What is the aqueous humor?
The fluid contained between the cornea and the iris.
70
What causes glaucoma?
High blood pressure in the aqueous humor.
71
Which cells work in the transmission of visual information?
Photoreceptors, ganglion cells, and bipolar cells.
72
Which cells work in the integration of visual information?
Horizontal cells and amacrine cells.
73
What do rods use as a pigment?
Rhodopsin.
74
What do cones use as a pigment?
The three types of cones each use a different photopsin.
75
What is retinal?
The light-absorbing molecule in both rhodopsin and photopsins.
76
What happens when light hits the retinal molecule?
It converts it from a cis configuration to a trans configuration. This shifts a bond in retinal and activates rhodopsin.
77
When the retinal molecule is in the trans configuration, what does that mean?
It means the molecule is active, and it can send the signal that there is light.
78
What happens when rhodopsin is activated in a photoreceptor?
This activates transducin (a G-protein) since rhodopsin is a GPCR.
79
What happens when transducin is activated in a photoreceptor?
This activates cGMP phosphodiesterase.
80
What happens when cGMP phosphodiesterase is activated in a photoreceptor?
cGMP phosphodiesterase hydrolyzes cGMP to GMP, thus closing Na+ channels in the plasma membrane.
81
What happens when Na+ channels in the plasma membrane are closed in a photoreceptor?
The membrane's permeability to Na+ decreases, and the rod hyperpolarizes.
82
How is rhodopsin different from normal GPCRs?
Instead of having a chemical first messenger, the first messenger is a photon.
83
When will a photoreceptor cell have lots of cGMP?
When the retinal is in the cis configuration and it is dark.
84
Describe the membrane potential and glutamate secretion levels in a photoreceptor cell in the dark.
It is in a depolarized state of about -40 mV. In the dark, the depolarized cell will release glutamate at the synaptic terminals.
85
Describe the membrane potential and glutamate secretion levels in a photoreceptor cell in the light.
When light strikes the retina, the cell is hyperpolarized, causing it to stop releasing glutamate.
86
How do bipolar cells respond to glutamate?
Some depolarize while others hyperpolarize, depending on the glutamate receptors.
87
What happens when a bipolar cell depolarizes in the absence of glutamate (light conditions)?
The bipolar cells that depolarize in the absence of glutamate transmit a signal that indicates "light."
88
What type of receptor do glutamate molecules released in the dark bind?
A metabotropic receptor. This causes the bipolar cell to hyperpolarize.
89
List the order with which a light signal passes through the cells of the retina.
1. Photoreceptor 2. Bipolar cell 3. Ganglion cell
90
How does lateral inhibition work?
When a photoreceptor is activated, horizontal cells inhibit distant photoreceptors and bipolar cells that are not illuminated or only weakly illuminated by diffraction. This is repeated by amacrine cells at the level of the ganglion cell, sharpening the image and increasing contrast.
91
What defines the receptive field?
Information received by each ganglion defines the receptive field. The smaller the field, the sharper the image.
92
Why is the fovea the visual area of the highest resolution?
It is the area of the eye where each ganglion cells receives information from fewer bipolar cells and fewer photoreceptors. The receptive field is small.
93
How are the amacrine cells and horizontal cells different?
They are both doing integration, but the horizontal cells are doing lateral integration at the interface between the photoreceptor and the bipolar cells while the amacrine cells are doing lateral integration at the interface between the bipolar cell and the ganglion cell.
94
Where do the optic nerves from the left and right eyes meet?
They meet at the optic chiasm near the center of the base of the cerebral cortex.
95
After the optic chiasm, where do ganglion cell axons extend to?
The lateral geniculate nuclei, where they synapse with neurons that reach the primary visual cortex.
96
How does focusing occur in the eye?
Focusing occurs by changing the shape of the lens.
97
How is the density of rods related to the distance from the fovea?
The density of rods increases with distance from the fovea.
98
What are the five tastes humans can perceive?
Sweet, salty, sour, bitter, and umami.
99
How are taste receptors organized?
Each taste receptor cell detects only one taste. The cells are organized into taste buds that have cells that detect all five tastes.
100
What are taste receptors?
They are modified epithelial cells--not neurons.
101
Which tastes are GPCRs?
Sweet, umami, and bitter.
102
Which type of receptor is associated with sour taste?
Transient receptor potential (TRP) channel--ion channels.
103
Which type of receptor is associated with salty taste?
Sodium channels that detect the Na+ in NaCl.
104
What are smell receptors?
Odorant receptor neurons. Unlike the photoreceptors of the eye and the taste receptors of the tongue, these are actually neurons.
105
How many human genes encode odorant receptors?
380--about 2% of the genome.
106
How is the sense of smell initiated?
The receptor cells extend cilia into the mucus; an odorant binds and activates an odorant receptor (a GPCR).
107
What happens after an odorant receptor is bound?
cAMP opens Na+ and Ca2+ channels, depolarizing the membrane.
108
What happens after the membrane is depolarized in an odorant receptor cell?
Signals are transmitted to the brain, and olfactory inputs are integrated into a single sensation.

BSCI 1511 (32 decks)

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