Lecture 2 Flashcards
What are receptors?
Proteins that have binding sites for signal molecules
What are signal molecules?
Molecules that bind to receptors (proteins)
What are the two types of receptors?
Transmembrane receptors and intracellular receptors
What are ion channels?
Receptors that can bind to a signal molecule and open up to allow different ions to come through
What are ion channels?
Receptors that can bind to a signal molecule and open up to allow different ions to come through
What are ion channels?
Receptors that can bind to a signal molecule and open up to allow different ions to come through
What is a ligand?
Stimulus molecule
What does a pump do?
Actively moves ions
In an Na+-K+ pump, Na+ is ___ and K+ is ___
out, in
In an Na+-K+ pump, Na+ is ___ and K+ is ___
out, in (preferred high Na+ concentration outside of cell and preferred high K+ concentration inside of cell)
What do ions move along?
The concentration gradient (high to low)
What is a leak channel?
Leak K+ channel: constantly open, lets K+ ions out of cell
What are gated Na+ channels?
Channels that only open in certain conditions (ex. too much positive charged ions outside of cell), lets Na+ ions inside cell
What are gated Na+ channels?
Channels that only open in certain conditions (ex. too much positive charged ions outside of cell), lets Na+ ions inside cell
What is the charge of a membrane potential in a regular cell?
Negative (because of K+ leak channel). More positive charges outside; interior more negative
How is the membrane potential determined?
By electrical charges
What are the names of the closed channels for Na+ and K+?
Voltage-gated Na+ channels, chemically gated K+ channels
What is the resting potential?
Membrane potential at a steady state; more negative inside because more K+ goes outside, so the membrane potential is around -60mV
What is action potential generated by?
By excitable cells/by the action of different neurons or muscle cells
When does action potential happen?
When voltage-gated Na+ channels open
What is another name for action potential?
Depolarization–driving force for actions so we can do things. Polarized to less polarized/more positive –> called depolarization
What happens during action potential?
Inside will become less negative because voltage-gated Na+ channels open. Causes a rise in membrane potential because more positive are coming in (above 50mV).
Why does action potential happen so fast?
Because channels open very fast when the limit of positive cells is reached.
How is there restoration of the resting potential?
By opening the voltage-gated K+ channels. Too much + inside the cell –> let K+ out –> more - inside the cell –> action potential will drop
Why does restoration of the resting potential occur?
Because there are too many positive charges coming into the cell
What is hyperpolarization?
When the membrane potential becomes more negative before it comes back to resting potential because the gates are closing slowly.
What is hyperpolarization?
When the membrane potential becomes more negative before it comes back to resting potential because the gates are closing slowly.
What is the sensory system made up of?
Sensory cells (carry receptors), sensory organs (nose–>sensory cells inside cells), and neural network (sense something–>electrical signal back to brain)
What is the sensory system made up of?
Sensory cells (carry receptors), sensory organs (nose–>sensory cells inside cells), and neural network (sense something–>electrical signal back to brain)
What are the three different stimuli, and what do they activate?
Chemical stimuli, mechanical stimuli, and light. Activate chemoreceptors, mechanoreceptors, and photoreceptors
Which senses are involved in chemoreceptors?
Smell (olfactory) and taste (gustatory)
Which senses are involved in mechanoreceptors?
Touch and pressure (somatosensory), sound (auditory), equilibrium-making (vestibular)
Which senses are involved in photoreceptors?
Visual system
Which senses are involved in photoreceptors?
Visual system
What senses are in the somatosensory system?
Touch and pressure
What senses are in the vestibular system?
Equilibrium-making
What senses are in the vestibular system?
Equilibrium-making (balance, movement)
How do sensory receptors respond to stimuli?
By directly or indirectly opening or closing ion channels
What is ionotropic?
Directly affecting (opening/closing) ion channels
What is metabotropic?
Indirectly affecting (opening/closing) ion channels through messengers
What are ionotropic sensory receptors?
Mechanoreceptors, thermoreceptors, and electroreceptors
What are metabotropic sensory receptors?
Chemoreceptors and photoreceptors
What are metabotropic sensory receptors?
Chemoreceptors and photoreceptors
What are metabotropic sensory receptors?
Chemoreceptors and photoreceptors
What is the stimulus for mechanoreceptors?
Pressure–> pressure-sensitive cation channel
What is the stimulus for thermoreceptors?
Warmth attaches to a protein attached to the channel –> temperature-sensitive cation channel opens
What is the stimulus for electroreceptors?
Electrical charges –> opens voltage-gated Ca2+/Na+/K+/etc channel
What is the stimulus for electroreceptors?
Electrical charges –> opens voltage-gated Ca2+/Na+/K+/etc channel
What happens with a chemoreceptor?
A taste/smell molecule binds to a receptor –> triggers change in the G protein (messenger) –> triggers change in the second messenger –> opens Na+ or K+ ion channel
What happens with a photoreceptor?
Light stimulates a photoreceptor –> triggers change in G protein –> triggers change in second messenger –> opens cGMP-gated Na+ channel
What happens with a chemoreceptor?
A taste/smell molecule binds to a receptor –> triggers change in the G protein (messenger) –> triggers change in the second messenger –> opens Na+ or K+ ion channel Signal transduction events happen to affect ion channel indirectly
What happens with a photoreceptor?
Light stimulates a photoreceptor –> triggers change in G protein –> triggers change in second messenger –> opens cGMP-gated Na+ channel Signal transduction events happen to affect ion channel indirectly
What happens with a photoreceptor?
Light stimulates a photoreceptor –> triggers change in G protein –> triggers change in second messenger –> opens cGMP-gated Na+ channel Signal transduction events happen to affect ion channel indirectly
Example of stimuli to action potential (stretch in muscles)
Stimuli: stretch –> activates opening of ion channels in stretch receptor (ionotropic) –> small changes in resting potentials (voltage from the stretch receptor neuron) –> action potentials generated in the axon hillock –> action potentials travel down the neuron on the axon
What do axons of sensory cells carry, and where do they carry them to?
Action potentials to specific parts of the CNS
What does sensation depend on?
On which part of the CNS receives the sensory messages
What is the intensity of sensation coded as?
The frequency of action potentials (e.g. smell of pizza is stronger the closer you are to it)
What is receptor adaptation?
Diminishing response to repeated stimulation
What does receptor adaptation enable animals to do?
Ignore background conditions but remain sensitive to changes or new stimuli
What is receptor adaptation?
Diminishing response to repeated stimulation Ex. feeling of clothes on your body
What does receptor adaptation enable animals to do?
Ignore background conditions but remain sensitive to changes or new stimuli
Do all sensory cells adapt? If not, which ones don’t?
No. Pain receptors, mechanoreceptors for balance
Do all sensory cells adapt? If not, which ones don’t?
No. Pain receptors, mechanoreceptors for balance
What can generate action potentials?
Receptors and neurons
Why can’t you smell when you’re sick?
The mucus film layer gets thick, so odorant molecules can’t get through and you can’t smell.
Why can’t you smell when you’re sick?
The mucus film layer gets thick, so odorant molecules can’t get through and you can’t smell.
What are glomeruli, and what system are they in?
multiple receptors combined, olfactory system
What are glomeruli, and what system are they in?
multiple receptors combined (combination of complex odorants), olfactory system
What are ORN?
Olfactory receptor neurons in the nose
What type of receptor is a chemoreceptor?
Metabotropic
What type of receptor is a photoreceptor?
Metabotropic
What type of receptor is a mechanoreceptor?
Ionotropic
What type of receptor is a thermoreceptor?
Ionotropic
What type of receptor is an electroreceptor?
Ionotropic
What happens in the opening of ion channels by odorant-olfactory receptor neuron binding (4 steps)?
- Binding of an odorant to its receptor activates a G protein. 2. G protein (GTP) activates synthesis of cAMP on the second messenger (ATP to cAMP) 3. cAMP causes ion channels to open (Ca2+/Na+ enters cell) 4. Changes in ion concentrations inside cell initiate a signal to the brain, which perceives the signal as a scent
Why can many more odorants be discriminated than there are olfactory receptors?
More smells than receptors because they can combine odors (glomeruli)
Why can many more odorants be discriminated than there are olfactory receptors?
More smells than receptors because they can combine odors (glomeruli)
Why can many more odorants be discriminated than there are olfactory receptors?
More smells than receptors because they can combine odors (glomeruli)
What are papilla?
bumps on the tongue
What are the taste bud sensory cells?
Cells on the sides of the papilla
What is the purpose of microvilli?
Increase the sensitivity to sense molecule on the tongue
Why is the structure of sensory cells on the gustatory system the way it is (taste)?
Many sensory cells –> larger surface area, more taste buds can be there. Taste buds can be soaked into one little area –> better contact with tastes
What are the 5 tastes a human can experience? What other two are there, and what do those involve?
Salty, sour, sweet, bitter, and umami Spicy/hot involve heat sensors Minty involves cold sensors
What is umami?
A savory, meaty taste from the amino acid proteins
What does the full complexity of taste involve?
Both gustatory and olfactory receptors Ex. when sick, can’t taste because you can’t smell.
Do humans vary in sense of taste?
Yes. Wine tasters and chefs have more taste sensations because they have more sensory cells
What is the suffix for disorders of smell?
-osmias
What is the name for the disorder in which one cannot smell?
Anosmia
What is the name for the disorder in which one has a lower sensitivity to smell?
Hyposmia
What is the name for the disorder in which one perceives smells differently?
Dysosmia
What is the name for the disorder in which one cannot taste?
Ageusias
What is the name for the disorder in which one has a lower sensitivity to taste?
Hypogeusias
What is the name for the disorder in which one perceives taste differently?
Dysgeusias
What is the suffix for disorders of taste?
-geusias
What senses are in the somatosensory system?
Touch and pressure (somato: body)
What is the suffix for disorders of taste?
-geusias
What kind of stimuli is smell?
Chemical
What kind of stimuli is taste?
Chemical
What kind of stimuli are touch and pressure?
Mechanical
What kind of stimuli is sound?
Mechanical
What kind of stimuli is equilibrium-maintaining?
Mechanical
What kind of stimuli is visual?
Light
What does the somatosensory system involve?
Mechanoreceptors
How does one sense objects externally?
Through touch receptors in the skin–difference in the density of touch receptors along the body.
Where is there a high density of touch receptors, and where is there a low density?
Lips and fingertips; back
How does one sense objects externally?
Through touch receptors in the skin (many varieties of touch receptors)–difference in the density of touch receptors along the body.
Where is there a high density of touch receptors, and where is there a low density?
Lips and fingertips; back
What is the two point discrimination test?
Use 2 toothpicks on the fingertips and back. See if you can distinguish the two
How do we internally sense position and movement of our body parts (somatosensory–mechanoreceptors)
Through the stimulation of stretch receptors in muscles and joints
What are the mechanoreceptors in the muscle?
Muscle spindles
What are the mechanoreceptors/stretch receptors in the muscle?
Muscle spindles
What are muscle spindles?
Stretch receptors within the muscle that detect changes in the length of the muscle Specialized modified muscle cells that have sensory nerves surrounding them and are wrapped around connective tissue
What are muscle spindles?
Stretch receptors within the muscle that detect changes in the length of the muscle Specialized modified muscle cells that have sensory nerves surrounding them and are wrapped around connective tissue
What happens when you’re holding a heavy object?
It stretches your muscle cells which triggers changes in ion channel (ionotropic) –> changes membrane potential –> downstream AP to neurons to brain –> brain sends signal to motor neuron to the muscle, asking the muscle to contract to keep your hand steady
What are the Golgi Tendon organs?
Mechanoreceptors in joints
What are the mechanoreceptors in joints?
Golgi Tendon organs
What does the Golgi Tendon organ do?
Receptors that detect changes in muscle tension
What does the Golgi Tendon organ do?
Receptors that detect changes in muscle tension; inhibits muscle contraction
How does Golgi Tendon organ help with if muscle contraction is too much?
It will send inhibitor signals to the motor neuron to let the muscle relax (keep just the right amount of muscle contractions to hold object steady) Muscle contracts –> signal for Golgi tendon organ (induce changes in membrane potential for downstream AP to brain)
How does Golgi Tendon organ help with if muscle contraction is too much?
It will send inhibitor signals to the motor neuron to let the muscle relax (keep just the right amount of muscle contractions to hold object steady) Muscle contracts –> signal for Golgi tendon organ (induce changes in membrane potential for downstream AP to brain)
What are the similarities between the auditory and vestibular systems?
(sound and equilibrium-maintaining) –Use the same organs (ear) –Use mechanoreceptors called hair cells which live in stereocilia
What are the similarities between the auditory and vestibular systems?
(sound and equilibrium-maintaining) –Use the same organs (ear) –Use mechanoreceptors called hair cells which live in stereocilia
What are the similarities between the auditory and vestibular systems?
(sound and equilibrium-maintaining) –Use the same organs (ear) –Use mechanoreceptors called hair cells which live in stereocilia
What are the mechanoreceptors used in auditory and vestibular systems?
Hair cells
What are stereocilia?
fingerlike extensions of the cell membrane that are on hair cells
What are stereocilia?
fingerlike extensions of the cell membrane that are on hair cells
Where are the mechanosensors on hair cells?
On the stereocilia
What happens when stereocilia moves to the left?
Ion channels open which changes membrane potential –> neurotransmitters trigger AP generation in neurons –> transmits sensory neuron to brain
What happens when stereocilia moves to the right?
Ion channel closes
What ion is involved in hair cells?
Ca2+
What ion is involved in hair cells?
Ca2+
What are sounds?
Pressure waves
What do hair cells do?
Convert pressure waves into changes in resting potentials
What do hair cells do?
Convert pressure waves into changes in resting potentials
What does the pinna do?
Collect sound waves
What does the tympanic membrane do?
Eardrum; converts sound waves to physical forces - vibrations
What does the middle ear do?
Amplifies; as much as 20x amplified
What are the smallest bones in the body?
Ossicles
What are the 3 bones of the ossicles?
Malleus, Incus, Stapes
What are the 3 bones of the ossicles?
Malleus, Incus, Stapes
What does the Malleus do?
“little hammer” directly in contact with the tympanic membrane
What does the Incus do?
“embryo” Malleus knocks on the Incus
What does the Stapes do?
“stirrup” stirs up some liquid inside the inner ear (Incus to Stapes to oval window in inner ear)
What is the oval window and where is it located?
A membrane that causes liquid to move inside; under stapes
What happens during a flight?
There is less air pressure coming into the ear and there is more pressure past the tympanic membrane (which is connected to the throat) –> eardrum pops. You fix this by adjusting your throat pressure
What happens during a flight?
There is less air pressure coming into the ear and there is more pressure past the tympanic membrane (which is connected to the throat) –> eardrum pops. You fix this by adjusting your throat pressure
What does the vestibular nerve connect to?
the semicircular canal of the vestibular system
What does the cochlear nerve connect to?
the cochlea
What is the cochlea for?
hearing
What is the semicircular canal of the vestibular system for?
balance/control
What does the vestibulocochlear do?
joins vestibular and cochlea nerves
What is the oval window and where is it located?
A membrane that causes liquid to move inside; under stapes connected to the vestibular system (semicircular canal)
What does the vestibulocochlear do?
joins vestibular and cochlea nerves
What does the vestibulocochlear nerve do?
joins vestibular and cochlea nerves
what is the cochlea?
a tapered and coiled chamber composed of three parallel canals
what are the three canals in the cochlea?
vestibular canal, cochlear canal, and tympanic canal
what are the three canals in the cochlea?
vestibular canal, cochlear canal, and tympanic canal
what is the order of the three canals in the cochlea when you unwrap them?
vestibular –> cochlear in the middle –> tympanic Vestibular connects to tympanic
what is the order of the three canals in the cochlea when you unwrap them?
vestibular –> cochlear in the middle –> tympanic Vestibular connects to tympanic (any movement in vestibular will become movement in the tympanic canal)
what is significant about the cochlear canal?
It has the most important sensory part of the ear here–hair cells
What happens when movement comes to the tympanic canal?
It will flex the Basilar membrane
What is significant about the Basilar membrane
It flexes: on top of this membrane is where hair cells are located
What does the Organ of Corti do?
Transduces pressure waves into action potentials
Where is the Organ of Corti?
on top of the Basilar membrane; has hair cells, stereocilia, and tectorial membrane
What is significant about the Basilar membrane?
It flexes–> puts pressure on hair cells–> membrane potential changes –> AP –> sensory: on top of this membrane is where hair cells are located
Where is the Organ of Corti?
on top of the Basilar membrane; has hair cells, stereocilia, and tectorial membrane
How do you sense pressure waves in the inner ear?
Vibrations from tympanic membrane –> transmits vibrations into liquid at the stapes –> goes through oval window to vestibular canal as liquid movement –> Basilar membrane in the cochlear canal flexes and hair cells move (perceive as different types of sounds) –> goes to tympanic canal –> exits round window
Where is and what is the round window?
On the tympanic canal; another membrane to release pressure
How do you sense pressure waves in the inner ear?
Vibrations from tympanic membrane –> transmits vibrations into liquid at the stapes –> goes through oval window to vestibular canal as liquid movement –> Basilar membrane in the cochlear canal flexes and hair cells move (perceive as different types of sounds) –> goes to tympanic canal –> exits round window to release pressure
Where is and what is the round window?
On the tympanic canal; another membrane to release pressure
What is conduction deafness?
Loss of function of tympanic membrane and/or the middle ear (ossicles) More outer Can fix to a certain degree, doesn’t transfer sound properly
What is conduction deafness?
Loss of function of tympanic membrane and/or the middle ear (ossicles) More outer Can fix to a certain degree, doesn’t transfer sound properly
What is conduction deafness?
Loss of function of tympanic membrane and/or the middle ear (ossicles) More outer Can fix to a certain degree, doesn’t transfer sound properly
What is nerve deafness?
Damage to hair cells or auditory nerve pathways Permanent Damage to the inner ear
What is a common cause of nerve deafness?
Damaged hair cells in the organ of Corti by loud sounds. Cumulative and irreversible damage
What is a common cause of nerve deafness?
Damaged hair cells in the organ of Corti by loud sounds. Cumulative and irreversible damage
What makes up the vestibular system?
3 semicircular canals at angles to each other and 2 chambers
What do hair cells do for the vestibular system?
Sense position and orientation of head
What do hair cells do for the vestibular system?
Sense position and orientation of head
What are the utricle and saccule?
2 bony little chambers filled with liquid in the vestibular system
What are the two chambers in the vestibular system?
Utricle and saccule
What are the utricle and saccule?
2 bony little chambers filled with liquid in the vestibular system; both have hair cells but look different from the semicircular canals
What are the two chambers in the vestibular system?
Utricle and saccule
What and where is the cupula?
Jelly-like structure with hair cells and stereocilia in the vestibular system; at the end of one of the semicircular ducts
What happens in the vestibular system to allow ion channels to open and close in the chambers?
the bending of stereocilia from liquid and the body moving in opposite directions
What is vertigo?
A problem with the vestibular system –> world is spinning in front of you
What are otoliths and where are they located in what system?
Ear stones (calcium carbonate); on top of stereocilia in the utricle and saccule of the vestibular system Direction of body movement –> Force of gravity weighs down on the otoliths Stereocilia move
What are otoliths and where are they located in what system?
Ear stones (calcium carbonate); on top of stereocilia in the utricle and saccule of the vestibular system Direction of body movement –> Force of gravity weighs down on the otoliths Stereocilia move
What is the organ of the visual system?
Eye
What does the visual system do?
Generates detailed images of the visual world
What does the eye focus?
It focuses inverted images on a surface that is sensitive to light, like cameras
What does the ciliary muscle do in what system?
Contracts to allow the lens to round out (bend light in different ways) in the visual system
What is the iris in what system?
Color pigment, controls size of pupil based on light coming in
What does the pupil do?
Allows light to go through and get detected Smaller if there’s too much light (allows control not to damage sensory cells) and bigger if there’s too little light so you can see
What does the lens do?
Forms type of image in back of eye
What does the lens do?
Forms type of image in back of eye on fovea –Flattens out to allow light to bend less if objects are far away –Bunches up to allow light to bend more if objects are close
What is and what is on the fovea?
a bump on the retina; the most concentrated sensory cells; lens forms an image on the fovea
What does the optic nerve do?
Transmits signals to the brain
What is myopia?
Nearsighted (lens does not flatten out enough to see things – doesn’t reach the retina)
What is hyperopia?
Farsighted (lens flattens out too much and goes past the retina–doesn’t reach the fovea)
What is hyperopia?
Farsighted (lens flattens out too much and goes past the retina–doesn’t reach the fovea)
What is the difference between receptors and receptor cells?
Receptors are proteins sitting on the inside or on membrane of a cell (aka receptor protein) Receptor cells are cells that receptors are sitting on or are inside of
What is the difference between receptors and receptor cells?
Receptors are proteins sitting on the inside or on membrane of a cell (aka receptor protein) Receptor cells are cells that receptors are sitting on or are inside of
Where are the sensory cells in the visual system?
On the retina
Where are the sensory cells in the visual system?
On the retina
What are photoreceptor cells of the retina?
Metabotropic sensory cells that transform light into action potentials
What are the two photoreceptor cells of the retina?
Rod and cone cells
What are the two photoreceptor cells of the retina?
Rod and cone cells
What are rod cells?
highly light-sensitive and perceive shades of gray in dim light; night-time animals have more of this
What are cone cells?
function at high light levels and are responsible for color vision humans have more of this
What does fovea have a high density of?
Cone cells
What does fovea have a high density of?
Cone cells
What does light change?
the conformation of photoreceptor Rhodopsin
What is the photoreceptor of the eye?
Rhodopsin
What is Rhodopsin made of?
Opsin (protein) + 11-cis-retinal (light absorbing group)
What is opsin?
The protein part of Rhodopsin
What is 11-cis-retinal?
the light absorbing group of Rhodopsin; covalently bound to protein (opsin)
What is 11-cis-retinal?
the light absorbing group of Rhodopsin; covalently bound to protein (opsin)
What is 11-cis-retinal?
the light absorbing group of Rhodopsin; covalently bound to protein (opsin)
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin) –> activates secondary messenger –> ion channel closes/opens
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin: GTP to GDP) –> activates secondary messenger –> ion channel closes/opens
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin: GTP to GDP–GDP released, GTP stays stuck on transducin) –> activates secondary messenger –> ion channel closes/opens
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin: GTP to GDP–GDP released, GTP stays stuck on transducin) –> activates secondary messenger –> ion channel closes/opens
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin: GTP to GDP–GDP released, GTP stays stuck on transducin) –> activates secondary messenger –> ion channel closes/opens
What does light absorption do to the sodium channels? (Rod cells)
Closes them
What does light absorption do to the sodium channels? (Rod cells)
Closes them
What happens in darkness with rod cells?
The sodium channel is open. GTP forms GDP and cGMP is next to the sodium channel.
How does the conformation of Rhodopsin change with light?
11-cis-retinal becomes All-trans-retinal when absorbing light –> Change in rhodopsin –> Change in G protein (transducin: GTP binds to G protein, transducin) –> activates secondary messenger –> ion channel closes/opens
What happens in darkness with rod cells?
The sodium channel is open. GTP forms GDP and cGMP is next to the sodium channel.
What happens in light with rod cells?
The sodium channel closes. GTP binds to transducin, transducin attaches to secondary messenger, cGMP pulls down from Na+ channel and forms GMP.
What happens in light with rod cells?
The sodium channel closes. GTP binds to transducin, transducin attaches to secondary messenger, cGMP pulls down from Na+ channel and forms GMP.
When light flashes, what happens to the membrane potential? What happens in the darkness?
Hyperpolarization: makes it more negative because ion channels close Depolarization
How many different cone cells are there?
3
What do the different cone cells do?
Detect different wavelengths (color perception–what we detect as color is a combination of all the different cone cells)
What is the test for color blindness?
Ishihara Test
What is color blindness?
When a person doesn’t have one or more types of cone cells and cannot detect certain colors.
What is color blindness?
When a person doesn’t have one or more types of cone cells and cannot detect certain colors.
What do rod and cone cells release when they detect light and color?
Neurotransmitters to additional layers of neuronal cells that generates action potential sent to the optic nerve
Why do people see different colors?
May have different number of cone cells Brain adaptation–how we respond
Why do people see different colors?
May have different number of cone cells Brain adaptation–how we respond
What type of signal can go through the membrane?
Nonpolar signal
What type of signal can’t go through the membrane?
Polar signal
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