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pheromone
signal between individuals that causes change in physiology or behavior
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transduction
convert external stimulus to internal signal
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How do you sense the environment?
- 1. transduction
- 2. amplification of signal
- 3. transmission to central nervous system
- 4. integration
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nocireceptors
sense dangerous stimuli
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thermoreceptors
sense temp
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mechanoreceptors
sense touch or pressure
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chemoreceptors
sense specific molecules/class of molecules
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photoreceptors
sense specific waves of light
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electroreceptors
detect electrical fields
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depolarized
the interior of the cell becomes more positive
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hyperpolarized
interior more negative than resting potential
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How does the action potential react to changes in intensity of the sensory input?
it increases in firing rate
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How does the brain interpret all of the electrical signals?
- receptor cells are very highly specific
- each sensory neuron sends its signal to a specific portion of the brain
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frequency
number of pressure waves per second
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pitches
different sound frequencies
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statocyst
- helps to maintain correct orientation in space
- ex. if a crab is flipped over, the calcium-rich particle (statolith) presses against nerve hairs (setae) that signals the body to flip the crab back over
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Effect of direct pressure on plasma membrane
- causes the ion channels to distort, either closing or opening the way for ion flow
- bending causes ions to open
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Hair cells
- comprised of many stiff outgrowths (sterocilia) and one kinocilium
- depolarization due to pressure causes inflow of calcium, increasing amount of neurotransmitter released
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Three main parts of the ear
- Outer ear
- Middle ear
- Inner ear
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Fxn of outer ear
funnel sound into ear canal
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tympanic membrane
- "eardrum"
- vibrates back and forth due according to sound wave
- vibrations pass to the ear ossicle (3 bones in middle ear)
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Oval window
- separates middle and inner ear
- carries vibrations into the fluid inside a chamber called the cochlea
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Fxn of middle ear
- amplifies sound
- tympanic membrane larger than oval window (same force, smaller size is more heavily affected)
- three ossicles act as levers, amplifying the vibrations
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Basilar membrane
- membrane in middle chamber of cochlea
- certain parts vibrate differently according to the different frequencies
- brain receives signals from different hair cells and interprets them differently
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How do elephants communicate?
infrasonic sounds (very low) that can travel very far
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Echolocation
using sound echoes (sonar) to navigate
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Compound eye
composed of hundreds of ommatidia (functional units of insect eyes)
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Structure of vertebrate eye
- cornea - transparent sheet of connective tissue
- iris - colored, round muscle; controls amt of light entering the eye
- pupil - hole in the middle of iris
- retina - back of the eye; contains photoreceptor cells (rods or cones)
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What is special about the vertebrate eye?
- the photoreceptors are placed in the far end of the eye, allowing light to pass through many layers of neurons before it reaches the cells
- this creates a blindspot where the axons have to exit the eye
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Rod cells (in eye)
detect dim light
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Cone cells (in eye)
detect color
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fovea
place in retina that only has cones
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opsin
transmembrane protein that contains retinal (pigment)
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What causes color blindness?
- a deficiency in specific opsin (they only sense distinct wavelengths of light)
- blue, green, red (short, medium, long)
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Gustation
sense of taste (through chemoreceptors)
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umami
"meaty" sense from MSG
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glomeruli
little balls that sense smell
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