Week 8 Flashcards
lateral inhibition
inhibiting neighboring signals for sharper contrast of a message
mechanical lateral inhibition
activating neighboring receptors to suppress an area of pain (itch around mosquito bite)
crossing over
right side of the body is controlled by the left side of the brain etc.
inhibitory efferent nerves
block afferent pathways for messages that are deemed unnecessary (ex. don’t feel watch after a certain period of time)
what type of info does the somatosensory nervous system gather?
skin, muscles, joints, bones, tendons
what type of neurons are used in the somatosensory NS?
afferent neurons, 1st design
what types of receptors are used in the somatosensory NS?
thermoreceptors, mechanoreceptors, noiceceptors
what is visual stimuli?
electromagnetic waves
how are electromagnetic waves measured?
photons
do human eyes detect all kinds of electromagnetic waves?
no (ex. UV rays)
what kind of receptors are used in our visual system?
photoreceptors
what kind of adequacy do our photoreceptors have?
low adequacy
what components of the eye help us focus our sight?
cornea and lens
what part of the eye transforms electromagnetic waves?
retina
what version of receptors are in the retina?
2nd version
what is the “problem” with the design of our retinas?
afferent neurons are in front of the receptors, information moves back and forth
why do we have blind spots?
axons of ANs in the retina exit and block receptors
how does the brain make up for blind spots?
makes up what it should look like
what are the types of receptors that encode info in the retina?
rods and cones
rods
seeing shades of grey, more sensitive because they are larger
cones
smaller and less sensitive, seeing “colors”
what type of cones do we have?
red, green and blue
how do we see other colors?
based on the ratio of the cones that are activated, combination of info sent to the CNS by cones causes specific color
what causes color blindness
lack of a certain type of pigment or certain cones behave more like another
what is the most common type of color blindness?
red-green
what is red-green color blindness
green cones acting more like red cones
what is the problem with traffic lights at night and color blindness?
hard to see which light is on top and can’t tell color
what type of auditory stimuli do we receive?
pressure waves
what type of receptors do we have in our auditory system?
mechanoreceptors
what are the names of mechanoreceptors in our ear?
stereocilia and cochlear hairs
what are the components of the ear?
external auditory meatus/canal, tympanic membrane, middle ear, and cochlea
what is the tympanic membrane
the ear drum
what is the middle ear?
air canal, connects to the throat
why do our ears pop at high altitudes?
increased pressure in the middle ear on the tympanic membrane, equalized by opening the jaw and letting air out through connection to the throat
cochlea
converts air waves to water waves
how is auditory stimuli sent to CNS?
stereocilia to nerves via 2nd design
how do waves become messages to CNS?
water waves in cochlea push mechanoreceptors, bending causes opening of mechanically gated K+ channels
what happens after K+ channels are opened from movement of water waves?
influx of K+, depolarization occurs, threshold causes voltage-gated Ca2+ to open
what happens when voltage-gated Ca2+ channels are opened?
Ca2+ causes neurotransmitters to be exocytosed, received by afferent neuron which sends to CNS
what is loudness in terms of pressure waves?
increased amplitude
what does loudness cause in stereocilia?
greater bend in hairs
how do we detect pitch/frequency?
which stereocilia are hit by water waves in cochlea
high pitch
stereocilia are hit early/near base of cochlea
low pitch
stereocilia are hit later/near apex
what causes the quality/timbre of sound?
how mixed the waves are
cerebral geometry
angle at which waves are coming
vestibular system
head position and motion
what type of receptors are in vestibular system?
mechanoreceptors (stereocilia)
what are the components of the vestibular system?
semicircular canals (3), and otolith organs
why do we have 3 semicircular canals
measure in all 3 dimensions
how do semicircular canals function?
measure the bending of stereocilia based on movements of water
what do semicircular canals detect?
rotation and acceleration (speeding up and slowing down)
what serves as the reference point for semicircular canals?
movement of water by gravity
what makes up otolith organs?
utricle and saccule
what are in the otolith organs?
Ca2+ based stones
how do otolith organs function?
determine how head is tilting or accelerating relative to gravity based on the movement of the stones
why is it difficult to know which way is up under water?
no effects of gravity on otolith organs
chemosensory system
detecting dissolved chemicals (internal and external)
what type of receptors are used in the chemosensory system?
chemoreceptors
where are chemoreceptors found?
mouth, throat, GI, lungs
what are the primary tastes?
salty, sour, sweet, bitter, umami and fat
salty
Na+ binds to chemoreceptors and causes an influx of Na+, depolarization to signal that Na+ is present
sour
registering pH or H+
why is spoiled meat sour?
when proteins are broken down H+ is released
sweet
binding of glucose
bitter
about 30 different receptors that bind different compounds, typically basic (alkaloids and toxins)
what is a toxin?
something that can cause harm if too plentiful
umami
“pleasant savory,” binding of glutamate (A.A.)
why is glutamate important?
indicator of proteins and can act as a neurotransmitter
fat
binding of fats to chemoreceptors
what primary tastes were historically of critical need?
fat, sweet (glucose), and salty (Na+)
what is olfaction?
sense of smell
where are the receptors for olfaction?
3cm patch on the roof of the nasal cavity
what do we need to dissolve compounds and detect them?
water
how often are olfactory receptors changed?
every 2 months
what causes noseblindness?
receptors that sense common smells are not always replaced
where does processing of smells take place?
olfactory bulb
olfactory bulb
processes smells and sends necessary info to the brain
primary olfactory cortex
coordinates with behavior
orbitofrontal cortex
where small is finally registered
vomeronasal organ
weak organ that registers pheromones
