Chapter 16 - Special Senses Flashcards

1
Q

What is the difference between sensation and perception relating to senses?

A

Sensation - the raw form in which a receptor sends information to the brain
Perception - the way your brain interpret this information

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2
Q

What are the special senses receptor types and what does each sense?

A
  1. Nociceptors - respond to pain / tissue damage
  2. Thermoreceptors - respond to temperature
  3. Mechanoreceptors - respond to mechanical stimuli (touch and sound)
  4. Chemoreceptors - respond to chemical substances (taste and smell)
  5. Photoreceptors - respond to light energy (eyes/vision)
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3
Q

How is temperature senses? What functions as the sensor?

A

Thermoreceptors - respond to temperature

–Free nerve endings

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4
Q

Class of chemicals which stimulates pain receptors…

A

bradykinins

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5
Q

What important job do bradykinins perform?

A

activates cascade reactions leading to healing

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6
Q

What chemicals have the ability to block pain?

A
  1. Enkephalins (opioid) - bind to the same receptor as morphine
  2. Serotonin - stimulates the release of enkephalins
  3. Endorphins (opioid) - similar to morphine
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7
Q

What is the descending analgesic pathway? In what two ways does it function?

A

Descending Analgesic Pathway - relieves pain after pain has “done its job”

  1. Stops pain signal
    - –Secretes serotonin into inhibitory spinal interneuron (stimulates release of enkephalins)
    - –Secretes enkephalins onto postsynaptic neuron
  2. Hyperpolarizing effect (nerve inhibition)
    - –Synapses with presynaptic neurons –> opens Cl- channels (inhibits entire nerve causing the pain signal)
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8
Q

Where are the olfactory receptors located?

A

Form the olfactory epithelium, at the upper portion of the nasal cavity.

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9
Q

How are odorants sensed?

A

Odorants - stimulate olfactory hairs, which stimulate olfactory receptors

  • -Over 10,000 types
  • -Patterns of activation represent different smells
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10
Q

What are the the parts of an olfactory receptor?

A
  1. Olfactory bulb
  2. Olfactory epithelium (full of olfactory receptors, made by basal stem cells)
  3. Supporting cells - physical support, nourishment, electrial insulation, and detoxification
  4. Cilia (hairs) - project from the tip to sense odorants
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11
Q

How many different odors are we able to distinguish?

A

10,000

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12
Q

What is taste “multi-sensual”?

A

All flavors are combinations of the 5 gustatory receptor tastes.

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13
Q

What are the 5 gustatory receptor tastes?

A
  1. Sour (acids)
  2. Sweet (sugars)
  3. Bitter (alkaloids) - natural aversion to bitter tastes because they are found in toxins + rotten foods
  4. Salty (metal salts)
  5. Umami (amino acids) - “meaty” taste, often found in Japanese cuisine
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14
Q

Describe the structure of the eye.

A
  1. Fibrous tunic - outer layer
    - –cornea
    - –sclera
  2. Vascular tunic - middle layer
    - –area of blood supply, hence “vascular”
    - –Choroid - contains blood vessel that nourish retina
    - –Ciliary body - secretes aqueous humor
    - –Ciliary muscle - pulls on lens for focusing, “squinting”
    - –Lens - focuses the image on the retina
    - –Iris - dilates / constricts to control the amount of light coming through the pupil
  3. Retina
    - –Photoreceptor layer - contains rods + cones
    - –Bipolar cell layer - rods + cones synapse with bipolar cells
    - –Ganglion layer - axons extend posteriorly to optic disc –> exit through the optic nerve
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15
Q

How do rods + cones differ in structure?

Hint: Photopigments

A

RODS

  • Rhodopsin (opsin protein) + vitamin A (retinol)
  • Forms:
  • –Cis form - purple
  • –Trans form - clear

CONES

  • 3 different opsin proteins (that respond to blue, green, and red-orange light) + vitamin A (retinol)
  • -Individual cones only contain one photopigment
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16
Q

How do rod cells sense light?

A

Light causes…
1. Some rhodopsin molecules to split
—Dim light - rods split and recombine (dynamic process)
—Bright light - rods become nonfunctional (takes 40 mins from bright to dim light for rods to function maximally)
2. Rhodopsin to go from Cis form –> Trans form (bleached)
—Cis form - secretes glutamate, which inhibits bipolar cells (allows you to see in the dark)
> Light exposure causes rod to release less glutamate, removing the inhibition of the bipolar cell
—-Trans form - light activates bipolar cell —> creates a local potential –> ganglia depolarizes (releases Na+, becomes excitatory),
> Rod now BLEACHED

17
Q

What are the structure of the outer, middle, and inner ear?

A

OUTER

  • Auricle
  • External acoustic meatus - part of ear where sound passes throught and alters pressure on tympanic membrane
  • Ceruminous glands - produces wax
MIDDLE
-Tympanic cavity 
-3 Auditory ossicles
> malleus
> incus
> stapes
-Tensory tympani and stapedius muscles
-Pharyngotympanic tube - equalizes pressure

INNER EAR
-Labyrinth - complex system of chambers and tubes
-Cochlea - fluid-filled chamber where hearing is sensed
-Semicircular canals - connected to the…
> vestibule
> round window - relieves pressure by bulging in and out in response to vibrations from the stapes

18
Q

Explain the sound pathway

A
  1. Sound vibration causes a portion of the basilar membrane (of the cochlea) to vibrate –> bends stereocilia in that area
  2. Tip link of stereocilia is pulled to open ion channel –> K+ ions flood in, depolarizing cell
  3. Depolarization releases neurotransmitters –> stimulates a nearby sensory nerve
  4. Stimulated sensory nerve sends a signal to the brain
19
Q

Explain how the orientation of the Utricle and Saccule allow for the detection of static equilibrium. Where in the inner ear are these structures located?

A

Static equilibrium - senses the position of the head (standing, lying down, etc.)
-Occurs in the vestibule, which contains otolith organs
> Utricle - has verticle macula
> Saccule - has horizontal macula
(Macula = patches of hair cells)

20
Q

Describe the location and structure of the sense organs for dynamic equilibrium.

A

Dynamic equilibrium - detects motion
-Occurs in the 3 semicircular canals
> Ampulla - at the base of each canal
> Crista ampullaris - sensory organ of rotation, contains stereocilia that position themselves in fluid
—-Movement of fluid puts pressure on the crista ampullaris, moving the hair cells
> Cupula - dome-shaped mass that hair cells extend up into