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BIOS TEST 3 > Animal Sensory Systems > Flashcards

Animal Sensory Systems Flashcards

1
Q

Sensory System

A
  • detects signals from the external environment and communicates them to the body via the nervous system
  • relies on specialized sensory receptor cells and transduces external stimuli into changes in membrane potentials
  • these can induce an AP through afferent division neurons for the CNS to send a response to the PNS
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2
Q

Sensory Receptor Cells

A

transduce (convert into changes in membrane potential) incoming signals + either DEPOLARIZE of HYPERPOLARIZE in response to the stimulus, depending on the sensory system. CAN BE EITHER
- specialized neurons (receptor cell is also a neuron)
- specialized sensory cells that synapse with a neuron (the receptor cell secretes neurotransmitters to stimulate changes in membrane potential in the synapsed neuron)

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3
Q

Vertebrate Sensory Systems

A

each system transmits signals to a different specialized portion of the brain, where the signal is integrated and interpreted to produce a response via the PNS

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4
Q

Receptor Cell Types

A

each is specialized for different stimuli types and are categorized by the stimulus type they detect:
- Mechanoreceptors
- Photoreceptors
- Chemoreceptors
- Nociceptors
- Thermoreceptors

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5
Q

Mechanoreceptors

A

respond to physical deformation of the cell membrane from mechanical energy/pressure; detect:
- touch (somatosensorial)
- sound (auditory sensation)
- balance (vestibular sensation

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6
Q

Photoreceptors

A

respond to radiant energy
- visible light in vertebrates - visible and UV light in insects
- present in all types of animal eyes, ranging from cup, compound, to camera eyes

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7
Q

Chemoreceptors

A

respond to specific molecules, often dissolved in a specific medium (EX: saliva/mucus), or airborne molecules; allow animals to taste and smell
- oldest of the sensory receptors
- chemo sensation evolved before animals did
- chemoreception and chemosensory systems have been identified in all living organisms

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8
Q

Nociceptors

A

respond to “noxious” stimuli, or anything that causes tissue damage; detect tissue damage - not pain - our brain interprets perceived tissue damage as painful

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9
Q

Thermoreceptor

A

respond to heat/cold

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10
Q

Vertebrate Special Senses

A
  1. Olfaction (smell)
  2. Gustation (taste)
  3. Equilibrium/Vestibular (balance + body position)
  4. Vision
  5. Hearing

ALONG with the general somatosensorial senses

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11
Q

Encoding + Transmission of Sensory Information

A

sensory stimuli may vary in intensity, yet the AP it is transmitted into does not vary in degrees - the stimuli intensity is therefore encoded by either:
1. Rate/frequency of AP produced by the sensory receptor
2. Number of receptors activated
3. Which specific receptors are activated

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12
Q

Encoding Sensory Information: ONE

A

The rate/frequency of AP produced by the sensory receptor
- the intensity of the RATE OF PRODUCTION OF AP - not the speed at which they travel down the axon or amplitude of the AP
- EX: an intense stimulus will produce a more rapid series of AP, and reducing the stimulus will likewise slow the production of AP

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13
Q

Encoding Sensory Information: TWO

A

Number of receptors activated
- EX: an intense stimulus might initiate AP in a large number of adjacent receptors, while a less intense stimulus might stimulate less receptors

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14
Q

Encoding Sensory Information: THREE

A

Which specific receptors are activated
- EX: a low pitch will initiate AP in one set of sensory neurons, while a high pitch initiates AP in a different set

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15
Q

Mechanoreceptors: Touch, Sound, Balance

A

sense stimuli due to the PHYSICAL DEFORMATION of their plasma membrane
- contain mechanically gated ion channels whose gates open and close in response to pressure, touch, stretching, and sound
- used for sensory systems that DETECT CHANGES IN PRESSURE

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16
Q

Somatosensation

A

sense of touch; occurs all over the exterior of the body and some interior locations as well
- detected by a variety of different mechanoreceptors in the skin, mucous membranes, muscles, joints, internal organs, and cardiovascular system
- a light touch only activates mechanoreceptors near the skin’s upper layer, while a firmer touch activates those in deeper as well as on the upper layer
- a firmer touch will activate more receptors, and may induce more frequent AP in the receptors than a lighter touch

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17
Q

Mechanoreceptor Locations in the Skin

A

Touch in humans includes 4 primary tactile mechanoreceptors in the skin:
- some are in the upper layers of the skin, and more sensitive to light touch, and can precisely localize gentle touch precisely
- some are in the deeper layers and are only activated by stronger pressure and are not as sensitive to identify the precise location of the touch

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18
Q

Mechanoreceptors: Auditory System

A

auditory stimuli are SOUND WAVES - mechanical pressure waves that move through a medium (air/water)

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19
Q

Frequency (SOUND)

A

number of waves/unit time; heard as PITCH
- related to wavelength, where higher frequency sounds are higher pitched + shorter wavelength

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20
Q

Amplitude (SOUND)

A

dimension of a wave from peak to trough, in sound is heard as VOLUME
- waves of louder sounds have greater amplitudes than softer sounds
- volume is measured in decibels (dB)

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21
Q

THE EAR AND SOUNNNNND

A
  1. The outer ear collects sound waves, which travel through the auditory canal and cause the ear drum to vibrate
  2. Vibrations transmit sound to the middle ear, where 3 small bones (ossicles - unique to mammals) amplify them and transmit them to the inner ear
  3. In the inner ear, the vibrations create PRESSURE inside the cochlea
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22
Q

Cochlea

A

fluid-filled, “whorled” structure that contains the auditory mechanoreceptors that allow us to perceive pressure waves in the air as sound

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23
Q

Basilar Membrance

A

flexible membrane that lines the length of the cochlea and contains HAIR CELLS; located within the cochlea

24
Q

Hair Cells

A

transduce sound waves into action potentials; have tiny hair-like protrusions called STEREOCILIA
- important for both the mammalian vestibular and auditory system, but these hair cells are located in different places and are activated in different ways

25
Stereocilia
hair-like protrusions; when sound waves in the cochlear fluid contact the basilar membrane, the basilar vibrates, pressing the hair cell's stereocilia against the TECTORIAL MEMBRANE - this initiates AP in the afferent neurons that communicate sound stimuli to the brain
26
How do we perceive sound?
It is based on HOW MANY HAIR CELLS ARE ACTIVATED - with pitch being perceived by which hair cells are activated - different hair cells are activated by different pitches because the basilar membrane's flexibility changes
27
Basilar Membrane and Sound Perception
- one side of the BM is thicker/stiffer/narrower while the other is thinner/floppier/broader - different regions of the BM vibrate according the the sound's frequency - stiffer region responds to high frequencies - floppier region responds to low frequency - PITCH IS DETECTED BASED ON WHICH REGION OF THE BM VIBRATES
28
Vestibular Systems
detects the position and movement of our head in space; the stimuli associated are linear acceleration (gravity) + angular acceleration and deceleration - mechanoreceptor cells detect gravity based on head position, changes in acceleration and deceleration in response to the turning and tilting of the head
29
Vestibular Hair Cells
located within the VESTIBULAR LABYRINTH (adjacent to the cochlea), detecting stimuli in two different ways
30
Vestibular Hair Cells: Detection Method 1
some hair cells lie below a gelatinous layer, with their stereocilia projecting into the gelatin - embedded in the gelatin are CALCIUM CARBONATE CRYSTALS, which move in response to gravity - when the head tilts, these crystals cause the gelatin to shift, bending the stereocilia - this stimulates neurons, signaling to the brain the lead is tilted, allowing the maintenance of balance
31
Vestibular Hair Cells: Detection Method II
some hair cells project into a gelatinous cap called a COPULA - when the head turns, the fluid in the canal shifts, bending stimuli and sending signals to the brain - when movement stops, the movement of the fluid slows or stops
32
Statocyst
ball-shaped organ lined with inward-facing cells + statoliths - INVERTEBRATE
33
Statoliths
dense particles (similar to the calcium carbonate crystals); any movement causes them to change location inside the statocyst, activating different hair cells - INVERTEBRATE
34
Light
travels in electromagnetic waves that need NO medium - photon is a packet of electromagnetic radiation - humans can perceive just a small slice of the entire spectrum
35
Wavelength (LIGHT)
detected as HUE/COLOR; light at the red end has a longer wavelength while violet has a shorter wavelength
36
Amplitude (LIGHT)
detected as luminous intensity - brightness
37
Photoreceptors in Vision
cells that contain pigment-absorbing molecules that absorb (detect_ light; located in light- collecting organs called eyes - eye types may represent pathways of evolution from a patch of photosensitive cells to "simple" eyes in humans - regardless of eye structure, all photoreception relies on light-absorbing pigment molecules embedded in the photo-receptor cells
38
Eye Cups
dimple-shaped structures that detect the direction of a light source (flatworms)
39
Compound Eyes
multiple lenses that detect shapes, patterns, and movements (arthropods)
40
Pinhole Eyes
no lens and forms simple, low-resolution images (nautilus)
41
Simple Eyes
single lens + form high-resolution images (cephalopods and vertebrates)
42
Cornea
transparent sheet of connective tissue; functions with the lens to focus light on the retina
43
Iris
pigmented ring of muscle that controls amount of light entering the eye
44
Pupil
hole in the center of the iris
45
Lens
crystalline, curved structure that focuses light on the cornea by bending in conjunction with the cornea
46
Retina
thin layer of photoreceptor cells + neurons - photoreceptor cells: light-detecting sensory cells - Fovea: site of retina with only cones, area of highest visual resoltuion
47
Optic Nerve
axons of the ganglion cells
48
Vertebrate Eye
- "inverted retina"(blood vessels and nerves are in front of photoreceptor cells) causes a blind spot - changing the shape of the lens causes loss of resolution and flexibility over time
49
Light Absorbing Molecule
Retinal + Opsin = RHODOSPIN - allows us to detect light and color
50
Retinal
pigment that reversibly changes shape when hit by a photon of light
51
Opsin
protein that holds the retinal pigment and changes shape/activity when the retinal changes in response to light absorption; responsible for the ability to perceive different colors - 3 types: 1. S opsin (short wavelengths) 2. M opsin (medium wavelengths) 3. L opsin (long wavelengths)
52
Photoreceptors in Vision: Cell Types
RODS + CONES contain a unique opsin that causes the cell to be the most sensitive to a specific light wavelength - Retinal is always the same, it is opsin that varies in different photoreceptor cells
53
Cones
contain a single type of color-sensitive opsin, making each cone most sensitive to a particular hue of light - 3 types of cones (3 color-sensitive opsins), but we can detect so much hue variation to do activation of different cone combinations at the same time - require HIGH LEVELS OF LIGHT to work, so we cannot perceive color well in the dark - heavily concentrated at the FOVEA - useful for focusing on important visual details
54
Rods
Contain a 4th type of opsin - ROD OPSIN - which is activated by intermediate light wavelengths; NOT COLOR-SENSITIVE, but are capable of working in low light levels - heavily concentrated at the periphery of the retina - useful for detecting movement in our vision field - why we cannot perceive color well in dim light
55
What happens when a photo activates rhodopsin?
A rod/cone cell HYPERPOLARIZES when its rhodopsin are activated by light and DEPOLARIZES when they are in the dark - LIGHT: Stops releasing neurotransmitters - DARK: releasing neurotransmitters to their synapsed bipolar cells

BIOS TEST 3 (8 decks)

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