4-Sensory
what are otholiths? how do otholiths work in us? in fish?
"ear stones"----are: granules of caco3 on top surface of a gelatinous substance (membrane) Because of inertial mass of otholiths, when head changes position, Accel/decelerates, the gelatinous otholith membrane bends hair cells 🔸Like CaCO3, the gravity pushes otholiths down onto ear cells, says its fine, but if you changes position the otholiths change In fish, one calcium carbonate that sits on hair cells; could be a piece of sand that gravity pushes onto cells when in certain position. Tells which way is UP AND WHICH IS DOWN!!
how does lateral line of fishes work? what fish use it? how?
* groupings that are secondary and hooked up to afferent neurons; what happens w hair cells is : 💫Vibrations are picked up from water by hair cells and into the canal, and these mechanorec pick up these vibrations ----So, the info used for movement of water across surface of fish is not even close to how sensitive they are -->Fish use it for: black cave fish, no eyes, use lateral line to navigate; don't bump into objects, can move around well! Compare: still fish feels a water wave (vibrations) ahead of it from attacking fish; the lateral line picks up mvment comig in, can tell the size and direction, so if fish is now moving it is generating vibrations in water ahead of it that bounce off and back of things in the near ahead vicinity, so it can redirect once receives reflections ahead Lateral line is sooooo cool!!! Also, body [position can be picked up, as well as swimming speed This sys evolved into our inner ear sys!!!
What do sensory cells do? What types are there? (what are they based on?)
*Function to convert environmental energy into action potentials, TRANSDUCERS.* Types: - Based on sense - mechanical - light (photoreceptors), including UV - infrared wavelengths - temperature - chemical (taste by binding prot 2 membrane); also monitor oxy in co2 and ph in body - pain (nocioreception) - electrical (platypus, paddlefish, sharks, etc)--->these pick up action potentials in prey's muscles! woah! - magnetic - unknown? - May be interoreceptors or exteroreceptors.
how do hair cells inhibit and excite? also, why is there a benefit to doing this this way?
*Note how AP frequency increases with stimulus direction from left to right (resulting from depolarization), while a stimulus from the opposite direction causes hyperpolarization and decreased AP frequency* 💫The sterocilia: Tip lengths are linked up, so when a sitmulus left to right , there are excitation depolarizaiton changes in sensory cells sensory channels open up along microviill i Interesting is that stimulus In oppostite direction, from right to left (so positive to lower, negative, shown in the first negative in stim movments graph) Some of these hair cells, fire receptor potentials even w/out stimulus; more neurotransmitters ---When stimulus is in opposite direction tho there is inhibitory hyperpolarization affect on postsynaptic cell ***Stim in 1 dir= inc number of action potentials Sitm in opp dir= dec number of action potentials Benefit: cell can understand the direction of things, so don't need as many cells for the same job The input from CNS of efferent cells inputs up or down regulates synapse 💫EFFERENT INPUT UP / DOWN REGULATES THE SYNAPSE
Gustation -depends on ________________ -how many taste buds do we have in epithelium of tongue? -fish? platypus? -many are in raised ________ on tongues ---outer surface of taste buds of fish and platypus each have ________ that does what? -microvilli help SA too -the sensory cells form synapses with dendrites of sensory neurons, so they are _________ sensory cells.
*depends on clusters of chemoreceptor sensory cells called taste buds -10,000 -fish have taste buds on skin; platypus have them on bill -papillae -outer surf of each has a pore that exposes the tips of sensory cells -secondary pic: yellow are the dendrites (from sensory neuron from axon to CNS) that go to the supporting cell that contains a taste bud (the circle) inside at the top is the taste pore with microvilli
in semicircular ducts, the gelatinous cupulae of hair cells are ____________ when changes in head position occur, causing ________.
*pushed one way or another *cause the fluid in the canals to shift
spinal cord processes info: 1) the stretch receptor ______, causing _______ 2) and ____ motor neurons to the __________ causing _____
-1 stimulates motor neurons 2 the stretched muscle, causing it to contract -2 inhibiting motor neurons to the antagonist causing it to relax bec remember: if we have the top muscle in leg being stretched (motor neurons stimulated), then we must relax the lower muscle by dec motor neuron stimulation) all about bringing the muscle length back to setpoint green is inhibitory to lower red
path of sound: from pinnae to how they send singals to the brain!
-1.The sound waves arrive at the pinnae which concentrate them and help them travel through the ear canal until the waves reach and hit the tympanic membrane. 2.The tympanic membrane starts vibrating at the same frequency as the sound waves and at this point the sound energy is converted into mechanical energy in the vibrating ear drum. 3.This mechanical energy vibrating at the same frequency is transmitted to the ossicles until it reaches the oval window. 4.At the oval window the mechanical energy is not transformed but it is changed into a pressure wave inside the Cochlea and the fluids within it rather than vibrations. 5.Now that the energy has reached the inner ear, the pressure waves cause the hairs of the organ of corti to bend at the specific frequency which then elicits the last energy transformation. 6.The pressure wave changes and the mechanical energy changes to electrochemical energy because of the *neurotransmitters released by the hair cells which are then relayed through the auditory nerve.* 7.The hair cells create their own action potential which ensures that the signals reach the brain.
what are rod cells?
-A rod cell is a modified neuron. It releases neurotransmitters that influence other neurons. -Rod cells have an outer segment, an inner segment, and a synaptic terminal. --->The inner segment has the nucleus and many mitochondria. --->The outer segment has a stack of discs of plasma membrane densely packed with rhodopsin. The discs function to capture photons.
what is stimulus intensity discrimination?
-The brain determines stimulus intensity by monitoring action potential frequency coming from the particular sensory cells: 1--->Variation in the frequency of APs delivered to the CNS by a given sensory receptor cell. 2--->Variation in the # of receptor cells activated (recruitment of sensory cells). -sensitivity threshold differences in receptors. The sum of #'s 1 & 2 result in the cumulative action potential frequency delivered to the appropriate area of the brain, permitting detection of stimulus intensity.
how do whales hear?
-Whales: sound, such as whale calls, travel great distances in water (hundreds of miles). - declassified military information from submarine monitors - could "hear" waves breaking across seamounts and coasts, whales, etc. for hundreds of miles. - used by whales for distance communication, orientation during migrations, etc.? Their pop densities are not high, so they can use this across hundreds of miles of open ocean! Wow! -picked up in 90's when declassified military info and monitored each other's subs by listening in water for sounds and picked up whale calls and other stuff Could tell waves hitting on a beach 300 miles away, the waves hit and can be picked up, which whales use too, they are migrating so they can tell how to travel offshore w info of waves crashing on beaches as they move along
Vertebrate and cephalopod mollusks eyes and functions of the components
-highly evolved, image forming eyes --transparent cornea in front allows light in --iris inside cornea is pigmented, controlling how much light enters --pupil is where light enters --lens makes fine adjustments in focus on the photosensitive retina at back of eye *note that octopi eyes are very similar but evolved independently--an ex of convergent evolution (developing similar things thru diff species)
the skin is packed w diverse________ that cause sensations. ______of these blanks influences how finely stimulation can be resolved. ---on ur back, 2 stimuli must be farily far apart before resolved, vs on fingers, finer spatial discrimination is possible bec ____________________.
-mechanoreceptors -DENSITY OF THESE tactile MECHANORECEPTORS ---because mechanoreceptors are MUCH MORE DENSE IN FINGER THAN BACK
Hair cells in lateral line of fishes: provide info about: a b these evolved into the hair cells in ______
-moving obj that causes pressure waves in water (object moving toward fish) -stationary obj that reflect the fishes own water wave produces as the fish swims -body position, and swimming speed --in the inner ear of higher vertebrates! The vestibular system consists of bony chambers and fluid-filled canals. (A) Each semicircular duct has a cupula containing stereocilia. When fluid moves against the cupula, the stereocilia bend. (B) In the saccule and utricle, stereocilia are bent by gravitational forces on the otoliths.
olfactory receptor: what is the order of components, starting with the odorant molecules in the nasal cavity up to the olfactory bulb?
-nasal cavity has odorant mol 🔸these odorant mol travel to mucus film 🔹mol then trigger dendrites 🔸dendrites are strips in between the supporting cell 🔹after supporting cell is the basal cell 🔸of course, the dendrites connect to the olfactory receptor cell in between the supporting and basal cell 🔹then connective tissue 🔸bone 🔹the axons of olfactory rec cell travel thru glomeruli within the olfactory bulb
how do fruit flies "taste?"
-▫️Claw and hairs of fruit fly "taste" potential food by placing tips of legs on it. -have primary chemoreceptors on body surface -have receptors for diff chemicals along dendrites
what's the inner ear? what 2 membranes separate its 3 parallel canals?
-▫️The inner ear is a long, tapered, coiled chamber called the cochlea, composed of three parallel canals separated by two membranes, Reissner's membrane and the basilar membrane.
why is loud noise bad for your ears?
-▫️the loud vibrations can cleave off these stereocilia in inner ear, and they don't grow back!▫️
describe the receptor proteins in the microvilli of taste pore: how do the neurotransmitters get released to dendrites? are taste buds replaced? or not? which receptors are ionotrophic and which are metabotrophic?
-▫️▫️▫️Receptor proteins in the microvilli bind specific molecules. This causes the release of neurotransmitters to the dendrites of associated sensory neurons. Taste buds are replaced every few days, but the associated neurons live on. Taste buds can distinguish sweet, salty, sour, bitter, and umami (savory meat) tastes. Saltiness receptors are ionotropic. (fast) Sweetness and bitter receptors are metabotropic (slower) just think: salty fries r fast food, but baked goods and grapefruit take time to do right!
what's the organ of corti? where? function?
-🔸on baislar membrane in inner ear 🔹*CONVERTS pressure waves into ACTION POTENTIALS* in auditory nerve 🔸*contains hair cells whose stereocilia are in contact with the tectorial membrane* (not eardrum that's tympanic membrane remember) 🔹when basilar membranes flexes, the tectorial membrane *is pivoted about hinge pt by THE HAIR CELL STEREOCILIA*
human retina: vision
1 light travels through layers of transparent neurons--ganglion, amacrine, bipolar, horizon. cells 2 and is absorbed by the rods and cones (photoreceptive layer) at back of retina 3 visual info is processed through several layers of neurons 4 and finally reflects backwards, converges on ganglion cells, which send their axons to the brain
mechanoreceptor: examples long list
1st 4 are all releated: ♘Hearing Equilibrium Acceleration *Lateral line (fish)* *Pressure (baroreceptors)* __Modern equilb __Show adaptation if you have bp or something __*Some sensory cell do not adapt, this is good example why* Touch Proprioceptors (body position) __Know where hnd/arm is ___Body get info abou oy __Couldn't walk around without these Vibration __Vibratinos in dark, pick up from your footsteps Stretch recep __Info about muscles SONAR
Is there an advantage for this weird system of detecting light?
AMPLIFIES THE SIGNAL EACH PHOTON can activates HUNDREDS of TRANDUCIN molecules that can then activate MANY PHOSPHODIESTERASE mol. 1 photon can CLOSE HUGE # OF Na+ CHANNELS
what are the 2 causes of deafness? Now, what causes these causes?
CONDUCTION & NERVE DEAFNESS -1) Conduction deafness is loss of FUNCTION of the TYMPANIC membrane or OSSICLES of the middle ear. --->The ossicles STIFFEN with age causing LOSS of ability to hear HIGH FREQ sound (don't conduce as well) -2) Nerve deafness is caused by inner ear or auditory pathway damage, including damage to HAIR cells. --->Loud rock music and other loud noises can cause damage to hair cells. They can actually be sheared off. This damage is cumulative and permanent
how do elephants hear?
Elephants: produce long wavelength "infrasound" calls. Can communicate up to 3 miles. (We cannot hear it.) ▫️▫️▫️Vibrations we cannot hear communicate Seeeing them turn and perk ears, and other biologists see same thing who were miles away as other elephants were heaving their sides
T/F: axons from neurons with the same receptors converge on the same olfactory bulb.
FALSE:--*-IN the olfactory bulb, axons from neurons with the same receptors converge on GLOMERULI. --Complex odorants can activate a unique combination of glomeruli.* (glomeruli are the stars in orange) discriminate smells then bec all this info is processed in brain!
How do ionotrophic and metabotrophic sensory detection compare/contrast?
In ionotropic sensory detection, the receptor protein itself is part of the ion channel and, by changing its conformation, opens or closes the channel pore. In metabotropic sensory detection, the receptor protein is linked to G proteins that activate a cascade of intracellular events that eventually open or close ion channels
what are primary vs secondary sensory cell types?
Primary (1o). Receptors ARE specialized ends (generally dendrites) of sensory neurons. (The sensory cell is also the afferent neuron carrying APs to the CNS.) Secondary (2o). Consist of a separate receptor cell (often an epithelial cell) which synapses with the afferent (sensory) neuron. *In primary receptors, the substrate that reacts to an external influence is embedded in the sensory neuron itself, which is directly (primarily) excited by the stimulus. In secondary receptors, additional specialized (receptive) cells are situated between the acting agent and the sensory neuron. The energy of external stimuli is transformed into nerve impulses in these cells.*
How do Sensory Cell Membrane Receptor Proteins Respond to Stimuli?
Rec proteins in mechanoreceptors are ion channels. The activated receptor proteins of metabotropic chemoreceptors and photoreceptors initiate signal transduction cascades that eventually open or close ion channels.
How does signal transduction work? Describe the steps investigated in crayfish.
Signal transduction in the stretch receptor of a crayfish can be investigated by measuring the membrane potential at different places on the stretch receptor neuron while stretching the muscle innervated by that sensory neuron. 1 stretch muscle is stimulus 2 this stimulus activates opening of ion channels in stretch receptor dendrites 3 resulting depolarization is a receptor potential that spreads to cell body 4 and at axons hillock causes the generation of action potentials 5 the action potentials travel down the axon
How regularly do spinal nerves leave the spinal cord? Each one has ____ root(s), connecting to ???
Spinal nerves leave the spinal cord at regular intervals; ✰each one has two roots, one connecting it to the DORSAL HORN of the gray matter and the other connecting with the VENTRAL horn.
What are the bones in the middle ear? (3 delicate bones) WHAT DO they do?
The OSSICLES: 🔸malleus, incus, stapes 🔹transfer the vibrations of the eardrum to the OVAL WINDOW THINK: M.I.S. OSS. @ the oval window
how many smells can we discriminate and why?
We have 1,000 diff rec proteins - BUT, Many more odorants can be discriminated than there are olfactory receptors, even though there are ~1,000 receptor types known in humans. One receptor protein type/receptor cell. Similar to taste receptors in that they have specificity (much more specificity than do taste receptors), olfactory receptors are also generalists in the sense that each responds somewhat to a set of different, but similar, odorants. -*-In the olfactory bulb, axons from neurons with the same receptors converge on glomeruli. --Complex odorants can activate a unique combination of glomeruli.*
Focus Mammals and birds focus their eyes by ______________ depending on the eye's distance from the object of focus.
changing the shape of the lens 🔸left: for distant vision ciliary muscles relax and suspensory ligaments pull lens INTO FLATTER SHAPE 🔸right: for near vision, ciliary muscles CONTRACT, causing lens to ROUND UP 🔸the lens of mammal eye focuses an inverted image on the fovea of the retina
the _______ (____ membrane) covers the end of the auditory canal and vibrates in response to pressure waves. on the other side is the fluid-filled middle ear. -pressure on both sides of this ______ bec ____?
💫eardrum, aka tympanic membrane equilibrates because the Eustachian tube allows airflow note: it's auditory canal -->eardrum-->middle ear with fluid
somatosensory cortex
🔳certain regions have more receptors for touch than others 🔳ex: fingers more sensitive than back
how do bats 'see'?
emit hi freq sounds, these hit obj and bounce back, bats' ears pick up the reflected waves can even avoid a string of piano wire in a room
where are tectorial vs basilar membrane? why does basilar membrane flex?
in cochlea: tectorial above basilar membrane below hair cells --->The cochlea is filled with fluid and the upper and lower canals are connected at the distal end. Pressure waves displace the fluid in the upper canal of the cochlea. ---Instead of traveling all the way around the canals, the waves of fluid cross the basilar membrane, causing it to flex. High frequency causes the basilar membrane nearest the oval window to flex. Low frequency causes flexing farther down the membrane.
gray matter white matter
in nervous system, gray matter is tissue rich in neuronal cell bodies; white matter contains axons
understanding higher brain functions in cellular terms: Normal language ability depends on the flow of information among various areas of the__________ cortex. Input from spoken language travels from the ________ to ___________ Input from written language travels from the _______ to the ____________ to ____________.
left cerebral auditory cortex to Wernicke's area visual cortext o angular gyrus to Wernicke's area Using modern methods of functioning brain imaging, it is possible to see the metabolic activity in different brain areas when the brain is using language.
Draw the membrane potential for light off, on, off for A) vertebrates B) invertebrates
light exchange is weird in vertebrates bec light HYPERPOLARIZES VERTEBRATE PHOTORECEPTORS of the cell by closing Na+ channels, vs in invertebrates, the opposite occurs: light DEPOLARIZES the cell with Na+ entering, and at rest, the cell is hyperpolarized (very negative)
if I run forward really fast, what goes on in my inner ears?
my body mvment is forward, so the force of gravity is still pushing otholiths down (they remain on hair cells) but, the hair cells will bend backward because the gelatinous otholith membrane will be pushed backward altho if i tilt head down, otholiths move in same direction
-When muscle needs to be stretched, Like w change of posture, a ____ _______ is made quickly. _______ come in and stimulate contraction or whatever of spindles _or other purposes, like load increases, you stretch muscles, etc. then _____________ are _____! what happens when the load increaseson your arm?
new setpt is asap made Motor neurons come in and stim contraction or whatever of spindles *for other purposes, like load inc, you strech msucle, spindle muscles are activated! When the muscle becomes stretched (relaxed) the stretch receptors are activated, and the CNS responds by increasing APF in the motor neurons to the stretched muscle. Get a cup filled up, your arm doesn't faall with larger stimulus, the muscles are simply stretched a bit, stimulate motor neurons coming back to that position being stretched, and keep the arm there
The ______ direct sound waves down the auditory canal to impinge on the _____ membrane. This membrane mechanically transmits these pressure waves into movements of the _______ in the ____. The _______transmit their movement into pressure waves in the fluid of the ______ at the _____. The _____ is divided into fluid-filled chambers; pressure waves from the ________ cause the membranes between the chambers to flex. (D) Flexing of the _______ bends ______ on hair cells in the _____________.
pinnae tympanic ossicles middle ear ossicles cochlea oval window ossicles basilar membrane stereocilia organ of corti
the ________ of a snake allow it to see really well in the dark--it sees infrared light.
pit organs monitors infrared radiation (heat)
How does the transduction of stimulus energy into depolarization work?
stimulus (mechanical, chem, light, ...) on rec endings; spike initiating zone has graded receptor potential (electrical) = all or none impulses (electrical); CNS gets graded synaptic potential (electrical) then all or none impulses and onto another graded synaptic potential of course, bigger gradient = bigger electron potential = stronger stimulus
what kinds of visual systems do invertebrates have?
▫️ - photosensitive cups that detect light, but do not form images. ▫️ - vertebrate type eyes in cephalopod mollusks. ▫️ - compound eyes of arthropods
What do stretch receptors do? by what? What are stretch receptors in skeletal muscle tissues called? ---->they are modified muscle fibers that are ______ in the center w extensions of ________________. How does the CNS keep contraction /muscle tone?
▫️WHAT: Stretch receptors provide an animal with information about the position of its limbs and the stresses on its muscles and joints. BY: They feed information continuously to the CNS. ----called muscle spindles. -----are innervated in the center with extensions of sensory neurons. -------The CNS uses information from muscle spindles to maintain a certain level of contraction or muscle tone.
how do insects see compared to us?
▫️a bee perceives what we see as an even, bright yellow flower as a stronger pattern in with wider areas of nectar, using ultraviolet light as guide 4 nectar
if cross mechanoreceptors from tongue with touch, the ________________
▫️brain discriminates by receptors: so, when neural inputs are crossed, you could have a sensation of taste when scratch arm bec of crossing touch and taste receptors. --when surgeoun probed around, the patient had sensation of seomthing bec probe sent of action potentials
when a rod cell absorbs photons, its membrane potential __________________
▫️changes IN PROPORTION to the STRENGTH of light stimulus ▫️▫️In outer segment is lots of cell membrane that stacks up on itself, light enters and changes polarity in cell: *The plasma membrane of a rod cell hyperpolarizes—becomes more negative—in response to a flash of light. Rod cells do not fire action potentials, but in response to the absorption of light energy, the neuron experiences a change in membrane potential*
nocturnal animals' vision
▫️get eye shine which is light that bounces off reflector glare and bounces the light photons so a second chance for photorecp cells to pick up photons it didn't get on way thru, although some of these still don't get thru; adaptations that helps them see at night in the dark! Cool beans! Many animals have a tissue layer called the tapetum lucidum in the back of the eye that reflects light back through the retina, increasing the amount of light available for it to capture, but reducing the sharpness of the focus of the image. This is found in many nocturnal animals and some deep sea animals, and is the cause of eyeshine. Humans, and monkeys, lack a tapetum lucidum
as we inc the intensity of stimulus, the sensory cells ___________________
▫️get higher frequency action potentials until maxes out ▫️of course, the freq of AP depends on the stimulus intensity but also on the receptor --->for example, remember the graph with Freq of AP on y and log stimulus intensity on x axis? ---->receptor 1--which began and maxed out at a lower x axis value than 2, 2 lower than 3, etc.--is more sensitive and also, a low stimulus still evokes a reaction. so, although 2 is less than 1, 2 can discriminate at the higher intensities that 1 couldn't (bec it would already be maxed out) (the curves were log (stimulus intensity) on x axis btw---chg in concavity from up to down)
what's cool about the star-faced mole?
▫️its think projections on face map right onto brain! ▫️meaning, its projections match up, are differently shaped and sized, depending on function. ▫️so, the skinny proj corresponds to the skinny region in the brain
How does photosensitivity work? range of abilities? -evolution?
▫️sensitivity to light ▫️ranges from ability to orient to sun to the ability to see ▫️evolution has conserved molecules used for photosensitivity across entire range of animal species; = family of pigments called *rhodopsins*
describe the membrane potential if your eyes: are flashed w light vs are in the dark
▫️▫️▫️Lights are off, monitoring inside the cell, might expect low resting potential; we see -35 resting potential then w flash of light instead of a depolarization we actually get a hyperpolarization and inside gets more NEGATIVE!!! compared to outside! Stronger the light = greater the hyperpolarization , kinda goofy IF DARK: resting potential, is more positive in dark than in light, depolarized IN DARK!!!!
FOR SECONDARY SENSORY CELLS(remember, 2 pieces): A __________ receptor potential is genererated and electronically spread to synapse of the sensory cell. the distance is ____? What depends on the size of the receptor potential?
▫️💥graded, because amplitude depends on stimulus intensity 💥short 💥the amount of neurotransmitter to be released depends on the SIZE of the GRADED RECEPTOR POTENTIAL
Hair cells have evolved for many uses in the acoustico-lateralis sensory system of vertebrates
♘Lateral line --Otoliths: gravity perception --Semi-circular canals: acceleration, gravity --Organ of Corti: auditory
if a muscle contraction is TOO forceful, the ______ sends signals to the CNS that ______________________________________________ and so the muscle ____. THIS does what, why is it gooood?
♘THE GOLGI TENDON ORGAN, a stretch receptor in the tendons and ligaments -signals: inhibit motor neurons =muscle relaxes --->prevents muscle/tendon damage by limiting the force of contracting muscles when excessive force could Injure CONNECTIVE TISSUE
The spinal cord does ____? what?
✰ conducts information between the brain and organs of the body ✰integrates information coming from the peripheral nervous system ✰and issues motor commands. ✰
why don't animals notice stimuli that is constant, like us not feeling the chair under us? what is this phenomenon called? how does it occur? why doesn't it always happen, then? what is the example of smell?
✰Some sensory cells respond less (*produce fewer action potentials per unit time) when stimulation is held constant and/or repeated, a phenomenon called adaptation.* ---The ability of animals to ignore continuous stimuli while remaining sensitive to changing stimuli is sometimes due to sensory cell adaptation. ---Some sensory cells (baroreceptors, pressure receptors in the vascular system) do not adapt. ---there is no adaptation if the stimulus is turned off and the ap freq dec ---there is adapt IF THE STIMULUS INTENSITY IF CONSTANT/Repeated AND yet WE DON'T NOTICE IT BEC OF A CHANGE IN SENSORY CELLS (so smell isn't an adapt bec no change in the cells, only a hange in brain where brain stops paying attention)
hair cells are what kind of receptors? each hair cell has a set of ______ and longer _____. when ^these 2 are bent in one direction, the _______ becomes negative, other direction become positive. ^this allows _____ of the stimulus in just 1 sensory cell when membrane potential becomes more positive, hair cell ____ a ____ to the sensory neuron associated w it and sensory neuron sends AP to CNS.
✰mechanoreceptors ✰set of stereocilia (microvilli) ✰longer kinocilium ✰receptor potential ✰allows detection of direction of the stimulus -releases a neurotransmitter
mechanoreceptors: what r they? what do they work in? how do they work, as in how do they create ap?
⭐️Mechanoreceptors are cells that are sensitive to mechanical forces. -They are involved in many sensory systems, including skin sensations, hearing, and sensing blood pressure. --Physical distortion of a mechanoreceptor's plasma membrane CAUSE ion channels to OPEN, which leads to the generation of GRADED receptor potentials. If threshold is reached then action potentials result. -->The action potential frequency is related to the strength of the stimulus.
how are so many different tastes discriminated? where are the neurons for salt and sour located?
⭐️Only five different basic types of receptor cells. However, in one sense the receptors are generalists, responding to many different chemicals at least a bit. But, they respond most strongly to just one. The brain integrates AP information from many receptors to provide an overall sense. ---Taste receptors were exposed to 4 different tastes and the APs resulting were recorded. Note that all receptors responded at least a little to all 4, but maximally to just one. most salt-sensitive neurons in nerves that innervate outer 2/3 tongue, vs the sour-sensitive innervate the inner 1/3
why is the star nosed mole cool
⭐️it has no eyes and lives in tunnels, so the mechanoreceptors of nose guide it perfectly!
the skin feels many sensations
⭐️ruffini ending: touch, pressure merkel's discs: touch meissner's corpuscle: sensitive touch free nerve endings: pain, itch, temp nerves run across the skin dermis sweat gland runs perpendicular pacinian corpuscle: pressure ⭐️
How are APs interpreted by the brain as light, mechanical, etc.?
🎲-APs produced by various sensory systems are essentially the same whether they are initiated by light or chemical or mechanical, etc. stimuli. ----therefore, how do APs evoke a specific feeling or response? 🎲*sensation depends on the specific area of the brain innervated. The sensory pathways are discrete from sensory cell to CNS.* No matter where a sensory path is stimulated along it's course, the sensation felt is referred to the location of the receptor. - amputees, phantom limb. ⭐️⭐️⭐️--->this means that even if sensory path along the upper arm is stimulated, if the receptor was located where a hand once was, then the sensation is interpreted as a sensation of the hand. ⭐️=Phantom limb: ex: nerves are still firing and there in thumb even after taken off; action potentials go right to the brain in that region the specific area that action potentials send to in brain are key!
pheromones give examples
🎲extremely sensitive detection of these chemicals by chemoreceptors 🎲Female silkworm moths , Bombyx mori, release a pheromone called bombykol from glands at the tip of the abdomen, and males have receptors for bombykol on their antennae. *A single molecule of the pheromone can stimulate a perceivable action potential.* When 200 chemoreceptor cells or more per second are activated, the male flies upwind in search of the female, following a concentration gradient to the female. Note that, unlike the dog that is tracking in 2- dimensions, the moth has a much more difficult job as it tracks in 3-dimensions. MUCH HARDER!
chemoreceptors: detect chemical stimuli what do they detect? examples of importance (in animals)?
💥Internal and external --Taste and smell ---pH, PCO2, PO2, glucose, etc. Examples of the important role of chemoreceptors in animals. - great sensitivity, dog, etc. (Powerful, can smell what was there and tell which direction the rabbit went bec he can tell diff in conc of bunny smell within just 4 feet! Almost any dog can do this) - pheromones, silkmoth (Bombyx mori)
FOR PRIMARY SENSORY CELLS(remember, specialized ends, one piece) Small receptor potentials are __________ spread to the ________________________, where, if depolarization reaches threshold, an AP is generated. --the AP is then propagated where? ---the amplitude of the receptor potential is dependent on the ____________. it's "_____"
💥Small receptor potentials are *electronically spread (not self-generated) to the spike initiating zone* where, if the depolarization reaches threshold (generator potential), an action potential is generated. 💥"The AP is then propagated to the CNS. 💥The amplitude of the receptor potential is *dependent on the stimulus intensity. It is "graded"* -lose some charge over travel
olfaction also depends on __________ their sensors are ______ sensors located where? how do chemicals send messages?
💥chemoreceptors In vertebrates, olfactory sensors (1o) are neurons embedded in a layer of epithelial cells at the top of the nasal cavity. The axons of these sensors project to the olfactory bulb of the brain. The dendrites end in olfactory hairs at the surface of the nasal epithelium. Molecules from the environment diffuse through nasal mucus to reach the surface of the olfactory hairs. Chem enter nostrils, diss in nasal passages' wet mucose later, picked up by sensroy lter by bindng to rec of dendrites, make rec potneials, and message sent to
pressure waves in inner ear: low medium high pitch
💫*Pressure waves of different frequencies flex the basilar membrane at different locations. Information about sound frequency is specified by which hair cells are activated.* 💫low pitch: pressure waves travel FAR down vestibular canal and flex basilar membrane, activating ap in low-freq sensors 400Hz 💫medium pitch: pressure waves travel PARTLY DOWN upper canal before flexing basilar membrane and act MID FREQ SENSORS 3000 Hz 💫high pitch: pressure waves travel SHORT distance b4 flexing basilar membrane and act HIGH FREQ sensors 22,000Hz
what kinds of eyes do arthropods have? what do they consist of? how do they work?
💫COMPOUND EYES Arthropods have compound eyes consisting of many optical units called ommatidia. ---Each ommatidium has a lens that directs light onto photoreceptor cells (retinula cells). ---RETINULA cells have microvilli with rhodopsin, and their axons communicate with the nervous system. --Each ommatidium gives a slightly different view, resulting in broken-up images. ---The number of ommatidia in an eye varies, from a few in certain ants to 10,000 in dragonflies.
lateral line canal of fish: what is it exactly?
💫Lines along sid eof fish are laterla line Some have extensions of this onto head but idea is the same *Line is a series of holes that go thru the scales of the fish and there's link w canal under surface of fish; the hair cells along lateral lines💫
Positron emission tomography PET
💫What part of brain lights up when you do diff things Tell us what part of brain is MOST active when you are doing/concentration gand what metabolic act is going on to support the activity! Points out that lots of metabolism goes on to support brain, it is NOT basal, lots of O and CO2 given off to support when you are focused!!! 💫a: passively viewing words b listening to words c speaking workds d generating words
what are the 2 vertebrate photoreceptors?
💫cones provide sharpest vision; fovea only has cone cells respond to different wvlengths of light for color vision need 3 kinds of cone cells 2 see color; insects cannot see red bec lack a rhodopsin cone cell 💫rods more sensitive to light THINK: CONES =SHARP ^, CONES HAVE COLOR (ICE CREAM) ___ ROD: HE IS A LIGHT to many people
describe the workings of hair cells' mechanoreceptors in doing work (#workworkworkworkwork)
🔸*hair cells DEPOLARIZE K+ CHANNELS ONLY IN THE INNER EAR* 🔹 1 stereocilia project into space w fluid HIGH in K+ and low in Na (opp of usual btw); so when K channels open, K enters and depolarizes cell(also unusual, since Na usually enters to depolarize) 2 ion channels open when stereocilia are bent in 1 direction 3 and ion channels close when bent in opposite direction 4 membrane depolar. OPENS VOLTAGE-GATED Ca channels, CAUSING NEUROTRANSMITTER RELEASE from hair cell to the sensory neurons! :))) 🔹summary: mechanoreceptors of hair cells (on stereocilia) bend, open K+ channels= depolar cells, open Ca2+ channels =release neurotransmitter
How do your ears detect motion and gravity? Why would you get dizzy from spinning?
🔸Fluid is whipping thru canals where hair cells sit, as fluid moves by hair cells it deflects the hair cells and everything works -when you whip and nay nay, your ear cells detect your spinning and gravity, you get dizzy bec your fluid continues to move and so brain doesn't know Which way you are moving!!! 🔹🔸🔹
light absorption: give the detailed steps :)
🔸In dark, channel is open, get -35 mV across membrane bec Na+ comes in, hyperpol the cell -shine light, change cis to trans retinal, an intermediate changes opsin confirmation, which act tranducin g protein cascade --to trade GTP for GDP, which activates phosphodiesterase to hydrolyze cGmp to Gmp, causing Na+ channels to close = hyperpolarization so w light there is less cyclic gmp and MORE GMP, so the channel then closes, less Na+ comes in, so recall that the cell becomes more negative w hyeprpolarizaiton as less Na+ enters ---invertebrate cell works oppositely and representative of how we would expect Typical 2nd messenger cascade, one can close thousands (in vertebrates) 🔸*The absorption of light by rhodopsin initiates a signaling cascade that hyperpolarizes the rod cell. (A) In the dark, Na+ channels in the plasma membrane of the rod cell's outer segment are held open by cGMP, allowing positive charges to enter the cell (upper right of panel). When the rod cell is stimulated by light, it activates transducin (lower portion of panel). (B) Transducin activates a molecule of phosphodiesterase (PDE). (C) Activated PDE catalyzes the breakdown of cGMP to GMP. The depletion of cGMP results in closure of the Na+ channels and hyper-polarization of the cell.*
what collect vibrations from the air? The middle air is filled with fluid: T/F Where is the auditory info deciphered?
🔸Pinna collects vibrations into the air and into auditory canal, leading 2 middle ear FALSE! the middle ear should be air filled unless bad cold and clogged w infeciton/ache the three bones in membrane connecting to inner is where auditory info is deciphered
Rhodopsin: -significance -makeup -HOW IS LIGHT DETECTED?
🔸Rhodopsin molecules can absorb photons of light and undergo shape changes. --Rhodopsin consists of a protein called OPSIN and a light-absorbing group, 11-cis-RETINAL. The retinal group is in the CENTER of the opsin, and the entire complex is within the plasma membrane of a photoreceptor cell. When 11-cis-retinal absorbs a photon, it changes to all-TRANS-retinal, which passes through several unstable intermediates. One of these changes the conformation of the OPSIN and ACT a G-protein CASCADE---> This change SIGNALS detection of light. 🔸G proteins are so-called because they bind the guanine nucleotides GDP and GTP
When a vertebrate rod cell is in the dark, it has a _______ resting potential. ____ ions can continually enter the outer segment. When light flashes on the rod cell, the outer segment becomes more _______. When light is absorbed by ________, it becomes photoexcited and activates a G protein called _______. The activated transducin activates a _________, which converts _____to ____. _______ keeps ligand-gated sodium channels open; in light, GMP levels rise and channels close.
🔸depolarized Na+ 🔸hyperpolarized (negative) rhodopsin transducin phosphodiesterase 🔸cGMP---->GMP cGMP so when we convert to GMP (bec of light), the ligand-gated Na+ channels close and we get a hyperpolarization of the cell
what is the oval window? where is it? what does it do?
🔸spot right behind the stapes 🔹behind oval window is fluid filled inner ear 🔸mvments of oval window cause pressure changes in inner ear🔹
what is a spinal reflex?
🔸🔹 =The conversion of afferent to efferent information in the spinal cord without participation of the brain is called a spinal reflex. The simplest spinal reflex involves only two neurons and one synapse; it is called a monosynaptic reflex, such as the knee-jerk reflex. can cut cord 2 brain and still get these!___get good look at pic: __so when you hit muscle spindle, this activates + feedback to brain, telling it to stretch the other antagonistic muscle, as well as firing negative feedback that dampens the inhibition of antagonistic muscle (so it comes to rest again)
