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Author: admin | 14.04.2015 | Category: One Ear Ringing

In general, ARHL is caused by changes in the inner ear as we age, but genetics, noise exposure, certain medications, smoking, and chronic diseases such as diabetes, kidney disease, and cardiovascular disease can contribute to the progression of ARHL. Tiny hair cells lining the cochlea (a sensory organ inside the inner ear) pick up sound waves and transform them into nerve signals that the brain interprets as sound. The following figure shows the path sound waves travel through the ear drum to the Cochlea, where the hair cells live, work, and play. The next figure illustrates the relationship between the hair cells lining the Cochlea and sound frequency detection. This particular research examined hair cell degeneration in mice with different gene structures, leading to different hearing loss results as the mice aged. Untreated hearing loss can lead to or enhance the effects of serious cognitive disorders and emotional conditions such as dementia, Alzheimer’s disease, and depression, according to a recent study from the National Institute of Aging. Another recent study ( Hearing Loss and Incident Dementia) by the Johns Hopkins School of medicine found a strong link between untreated hearing loss and the development of dementia.
Untreated hearing loss also leads to serious negative lifestyle changes, which often effect family, friends, and others. Mounting evidence of serious consequences resulting from untreated hearing loss underscore why hearing loss should not be considered merely an annoying part of aging, but an important issue for public health. ARHL is progressive and permanent …but you CAN improve your communication …and your quality of life!
Simply put, the louder the sound, the shorter the time before damage occurs… there are no treatments…not medicine, not surgery, not hearing aids…that can restore your hearing once it is damaged by noise. A major role of sensory receptors is to help us learn about the environment around us, or about the state of our internal environment.
Describing sensory function with the term sensation or perception is a deliberate distinction.
Stimuli in the environment activate specialized receptor cells in the peripheral nervous system. Another way that receptors can be classified is based on their location relative to the stimuli. A third classification of receptors is by how the receptor transduces stimuli into membrane potential changes. Receptor cells can be further categorized on the basis of the type of stimuli they transduce. Ask anyone what the senses are, and they are likely to list the five major senses—taste, smell, touch, hearing, and sight. Listing all the different sensory modalities, which can number as many as 17, involves separating the five major senses into more specific categories, or submodalities, of the larger sense. Bitter taste is similar to sweet in that food molecules bind to G protein–coupled receptors. Therefore, the function of bitter taste may primarily be related to stimulating the gag reflex to avoid ingesting poisons.
Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. The axon of an olfactory neuron extends from the basal surface of the epithelium, through an olfactory foramen in the cribriform plate of the ethmoid bone, and into the brain. The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals.
Olfactory System: Anosmia Blunt force trauma to the face, such as that common in many car accidents, can lead to the loss of the olfactory nerve, and subsequently, loss of the sense of smell.
The ability of olfactory neurons to replace themselves decreases with age, leading to age-related anosmia.
Hearing, or audition, is the transduction of sound waves into a neural signal that is made possible by the structures of the ear ([link]). The inner ear is often described as a bony labyrinth, as it is composed of a series of canals embedded within the temporal bone. The oval window is located at the beginning of a fluid-filled tube within the cochlea called the scala vestibuli. A cross-sectional view of the cochlea shows that the scala vestibuli and scala tympani run along both sides of the cochlear duct ([link]). The organs of Corti contain hair cells, which are named for the hair-like stereocilia extending from the cell’s apical surfaces ([link]).
As stated above, a given region of the basilar membrane will only move if the incoming sound is at a specific frequency.
Watch this video to learn more about how the structures of the ear convert sound waves into a neural signal by moving the “hairs,” or stereocilia, of the cochlear duct. Watch this animation to learn more about the inner ear and to see the cochlea unroll, with the base at the back of the image and the apex at the front.
Along with audition, the inner ear is responsible for encoding information about equilibrium, the sense of balance. Somatosensation is considered a general sense, as opposed to the special senses discussed in this section. Two types of somatosensory signals that are transduced by free nerve endings are pain and temperature. Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes.
Movement of the eye within the orbit is accomplished by the contraction of six extraocular muscles that originate from the bones of the orbit and insert into the surface of the eyeball ([link]). The retina is composed of several layers and contains specialized cells for the initial processing of visual stimuli. Note that the photoreceptors in the retina (rods and cones) are located behind the axons, RGCs, bipolar cells, and retinal blood vessels. Light falling on the retina causes chemical changes to pigment molecules in the photoreceptors, ultimately leading to a change in the activity of the RGCs.
At the molecular level, visual stimuli cause changes in the photopigment molecule that lead to changes in membrane potential of the photoreceptor cell.
Opsin pigments are actually transmembrane proteins that contain a cofactor known as retinal.
The shape change of retinal in the photoreceptors initiates visual transduction in the retina. The three types of cone opsins, being sensitive to different wavelengths of light, provide us with color vision.
Watch this video to learn more about a transverse section through the brain that depicts the visual pathway from the eye to the occipital cortex. Once any sensory cell transduces a stimulus into a nerve impulse, that impulse has to travel along axons to reach the CNS.
Generally, spinal nerves contain afferent axons from sensory receptors in the periphery, such as from the skin, mixed with efferent axons travelling to the muscles or other effector organs. Cranial nerves convey specific sensory information from the head and neck directly to the brain.
The senses are olfaction (smell), gustation (taste), somatosensation (sensations associated with the skin and body), audition (hearing), equilibrium (balance), and vision. The cells that transduce sensory stimuli into the electrochemical signals of the nervous system are classified on the basis of structural or functional aspects of the cells. The nerves that convey sensory information from the periphery to the CNS are either spinal nerves, connected to the spinal cord, or cranial nerves, connected to the brain. Answers will vary, but a typical answer might be: I can eat most anything (except mushrooms!), so I don’t think that I’m that sensitive to tastes. The small bones in the middle ear, the ossicles, amplify and transfer sound between the tympanic membrane of the external ear and the oval window of the inner ear. High frequencies activate hair cells toward the base of the cochlea, and low frequencies activate hair cells toward the apex of the cochlea.
The stevia molecule is similar to glucose such that it will bind to the glucose receptor in sweet-sensitive taste buds.
Why does the blind spot from the optic disc in either eye not result in a blind spot in the visual field? The visual field for each eye is projected onto the retina as light is focused by the lens. 4, 1975 the first regular flight #613-614 was inaugurated on the Moscow a€“ Frunze(the former name of Bishkek) air route. A321 plane to the customer - low-cost airlines JetBlue Airways, USA, as it was the first ever built in the United States. The hair cells lining the cochlea have varying sensitivity for detecting sounds of different frequencies.
A scanning electron microscope reveals hair cell damage (hair cells bent over and damaged) due to aging. The risk for these disorders increases with increasing levels of hearing loss; for every 10 decibels of hearing loss, the chance of developing severe cognitive disorders increases by 20 percent.
A study by Johns Hopkins experts, found that older adults with hearing loss are more likely than peers with normal hearing to require hospitalization and suffer from periods of inactivity and depression.
Approximately one third of Americans between 65 and 74 and nearly half of those over 75 have hearing and communication problems.
To enhance your browsing experience, please upgrade to a more current browser such as Firefox, Safari or update to Internet Explorer 9. Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. The pain and temperature receptors in the dermis of the skin are examples of neurons that have free nerve endings. An exteroceptor is a receptor that is located near a stimulus in the external environment, such as the somatosensory receptors that are located in the skin.
Chemical stimuli can be interpreted by a chemoreceptor that interprets chemical stimuli, such as an object’s taste or smell.
A general sense is one that is distributed throughout the body and has receptor cells within the structures of other organs. Modality refers to the way that information is encoded, which is similar to the idea of transduction.
The surface of the tongue, along with the rest of the oral cavity, is lined by a stratified squamous epithelium. When you eat something salty, the salt crystals dissociate into the component ions Na+ and Cl–, which dissolve into the saliva in your mouth. Just as with sodium ions in salty flavors, these hydrogen ions enter the cell and trigger depolarization. However, there are a number of different ways in which this can happen because there are a large diversity of bitter-tasting molecules. Alkaloids are nitrogen containing molecules that are commonly found in bitter-tasting plant products, such as coffee, hops (in beer), tannins (in wine), tea, and aspirin.
Because of this, many bitter foods that are normally ingested are often combined with a sweet component to make them more palatable (cream and sugar in coffee, for example). Like sweet and bitter, it is based on the activation of G protein–coupled receptors by a specific molecule. These neurons are part of the facial and glossopharyngeal cranial nerves, as well as a component within the vagus nerve dedicated to the gag reflex.
Danielle Reed of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, who became interested in science at an early age because of her sensory experiences.
The olfactory receptor neurons are located in a small region within the superior nasal cavity ([link]).
The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe.
Therefore, the olfactory neurons are regularly replaced within the nasal epithelium, after which the axons of the new neurons must find their appropriate connections in the olfactory bulb.
A person with an impaired sense of smell may require additional spice and seasoning levels for food to be tasted.
It has two separate regions, the cochlea and the vestibule, which are responsible for hearing and balance, respectively.
The scala vestibuli extends from the oval window, travelling above the cochlear duct, which is the central cavity of the cochlea that contains the sound-transducing neurons.
The cochlear duct contains several organs of Corti, which tranduce the wave motion of the two scala into neural signals. The stereocilia are an array of microvilli-like structures arranged from tallest to shortest. The basilar membrane is the thin membrane that extends from the central core of the cochlea to the edge.
Because the tectorial membrane only moves where the basilar membrane moves, the hair cells in this region will also only respond to sounds of this specific frequency. Specific wavelengths of sound cause specific regions of the basilar membrane to vibrate, much like the keys of a piano produce sound at different frequencies. A similar mechanoreceptor—a hair cell with stereocilia—senses head position, head movement, and whether our bodies are in motion.
One is oriented in the horizontal plane, whereas the other two are oriented in the vertical plane. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception.
These two modalities use thermoreceptors and nociceptors to transduce temperature and pain stimuli, respectively.
Such low frequency vibrations are sensed by mechanoreceptors called Merkel cells, also known as type I cutaneous mechanoreceptors.
Stretch receptors monitor the stretching of tendons, muscles, and the components of joints. Four of the muscles are arranged at the cardinal points around the eye and are named for those locations. The lateral rectus, which causes abduction of the eye, is innervated by the abducens nerve. The outermost layer is the fibrous tunic, which includes the white sclera and clear cornea. The anterior cavity is the space between the cornea and lens, including the iris and ciliary body.
The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy.
A significant amount of light is absorbed by these structures before the light reaches the photoreceptor cells.
A single unit of light is called a photon, which is described in physics as a packet of energy with properties of both a particle and a wave.
By comparing the activity of the three different cones, the brain can extract color information from visual stimuli. The first half of the pathway is the projection from the RGCs through the optic nerve to the lateral geniculate nucleus in the thalamus on either side.
In many of the special senses, the axons leaving the sensory receptors have a topographical arrangement, meaning that the location of the sensory receptor relates to the location of the axon in the nerve. For sensations below the neck, the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain.
With the exception of somatosensation, this list represents the special senses, or those systems of the body that are associated with specific organs such as the tongue or eye. The structural classifications are either based on the anatomy of the cell that is interacting with the stimulus (free nerve endings, encapsulated endings, or specialized receptor cell), or where the cell is located relative to the stimulus (interoceptor, exteroceptor, proprioceptor). Spinal nerves have mixed populations of fibers; some are motor fibers and some are sensory.
Danielle Reed of the Monell Chemical Senses Center in Philadelphia, PA, who became interested in science at an early age because of her sensory experiences. My whole family likes eating a variety of foods, so it seems that we all have the same level of sensitivity. What is anchored to this membrane so that they can be activated by movement of the fluids within the cochlea?
The stereocilia of those cells would normally be attached to the tectorial membrane (though they are detached in the micrograph because of processing of the tissue).
The retina contains bipolar cells and the RGCs that finally convert it into action potentials that are sent from the retina to the CNS. The visual information from the right visual field falls on the left side of the retina and vice versa. These and other studies indicate that hearing deficits can lead to social isolation, resulting in physical and mental declines. Receptor cells can be classified into types on the basis of three different criteria: cell type, position, and function. Also located in the dermis of the skin are lamellated corpuscles, neurons with encapsulated nerve endings that respond to pressure and touch. An interoceptor is one that interprets stimuli from internal organs and tissues, such as the receptors that sense the increase in blood pressure in the aorta or carotid sinus.
Some stimuli are ions and macromolecules that affect transmembrane receptor proteins when these chemicals diffuse across the cell membrane.
Mechanoreceptors in the skin, muscles, or the walls of blood vessels are examples of this type. For example, the general sense of touch, which is known as somatosensation, can be separated into light pressure, deep pressure, vibration, itch, pain, temperature, or hair movement.
Research at the turn of the 20th century led to recognition of the fifth taste, umami, during the mid-1980s.
Raised bumps called papillae (singular = papilla) contain the structures for gustatory transduction.
The Na+ concentration becomes high outside the gustatory cells, creating a strong concentration gradient that drives the diffusion of the ion into the cells. A G protein signal transduction system ultimately leads to depolarization of the gustatory cell. Some bitter molecules depolarize gustatory cells, whereas others hyperpolarize gustatory cells. By containing toxic alkaloids, the plant is less susceptible to microbe infection and less attractive to herbivores.
The highest concentration of bitter receptors appear to be in the posterior tongue, where a gag reflex could still spit out poisonous food.

This region is referred to as the olfactory epithelium and contains bipolar sensory neurons. When the frontal lobe of the brain moves relative to the ethmoid bone, the olfactory tract axons may be sheared apart. Anosmia may also be related to some presentations of mild depression, because the loss of enjoyment of food may lead to a general sense of despair.
However, this increased sodium intake can increase blood volume and blood pressure, increasing the risk of cardiovascular diseases in the elderly. Some sources will also refer to this structure as the pinna, though that term is more appropriate for a structure that can be moved, such as the external ear of a cat.
The neural signals from these two regions are relayed to the brain stem through separate fiber bundles. At the uppermost tip of the cochlea, the scala vestibuli curves over the top of the cochlear duct.
The organs of Corti lie on top of the basilar membrane, which is the side of the cochlear duct located between the organs of Corti and the scala tympani. Protein fibers tether adjacent hairs together within each array, such that the array will bend in response to movements of the basilar membrane. Therefore, as the frequency of a sound changes, different hair cells are activated all along the basilar membrane. Based on the animation, where do frequencies—from high to low pitches—cause activity in the hair cells within the cochlear duct?
The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane ([link]). The anterior and posterior vertical canals are oriented at approximately 45 degrees relative to the sagittal plane ([link]). These modalities include pressure, vibration, light touch, tickle, itch, temperature, pain, proprioception, and kinesthesia. For example, have you ever stretched your muscles before or after exercise and noticed that you can only stretch so far before your muscles spasm back to a less stretched state? The bony orbits surround the eyeballs, protecting them and anchoring the soft tissues of the eye ([link]). The sclera accounts for five sixths of the surface of the eye, most of which is not visible, though humans are unique compared with many other species in having so much of the “white of the eye” visible ([link]). The change in membrane potential alters the amount of neurotransmitter that the photoreceptor cells release onto bipolar cells in the outer synaptic layer.
The inner segment contains the nucleus and other common organelles of a cell, whereas the outer segment is a specialized region in which photoreception takes place. The energy of a photon is represented by its wavelength, with each wavelength of visible light corresponding to a particular color. When a photon hits retinal, the long hydrocarbon chain of the molecule is biochemically altered. The G protein changes the membrane potential of the photoreceptor cell, which then releases less neurotransmitter into the outer synaptic layer of the retina. The three color opsins have peak sensitivities of 564 nm, 534 nm, and 420 nm corresponding roughly to the primary colors of red, green, and blue ([link]). For example, a bright blue light that has a wavelength of approximately 450 nm would activate the “red” cones minimally, the “green” cones marginally, and the “blue” cones predominantly.
This first fiber in the pathway synapses on a thalamic cell that then projects to the visual cortex in the occipital lobe where “seeing,” or visual perception, takes place.
For example, in the retina, axons from RGCs in the fovea are located at the center of the optic nerve, where they are surrounded by axons from the more peripheral RGCs. The dorsal root contains only the axons of sensory neurons, whereas the ventral roots contain only the axons of the motor neurons.
Whereas spinal information is contralateral, cranial nerve systems are mostly ipsilateral, meaning that a cranial nerve on the right side of the head is connected to the right side of the brain. Somatosensation belongs to the general senses, which are those sensory structures that are distributed throughout the body and in the walls of various organs.
Thirdly, the functional classification is based on how the cell transduces the stimulus into a neural signal. The sensory fibers connect to the spinal cord through the dorsal root, which is attached to the dorsal root ganglion. It is important to recognize when popular media and online sources oversimplify complex physiological processes so that misunderstandings are not generated. The optic disc in the right eye is on the medial side of the fovea, which would be the left side of the retina.
Middle frequencies are detected by hair cells at the center of the winding Cochlea, and hair cells at the apex of the Cochlea detect lower tones. The stimulus causes the sensory cell to produce an action potential that is relayed into the central nervous system (CNS), where it is integrated with other sensory information—or sometimes higher cognitive functions—to become a conscious perception of that stimulus.
Receptors can be classified structurally on the basis of cell type and their position in relation to stimuli they sense. The cells in the retina that respond to light stimuli are an example of a specialized receptor, a photoreceptor. Finally, a proprioceptor is a receptor located near a moving part of the body, such as a muscle, that interprets the positions of the tissues as they move. Some stimuli are physical variations in the environment that affect receptor cell membrane potentials. Additionally, pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage, or similar intense stimuli, through a nociceptor. Also, what is referred to simply as touch can be further subdivided into pressure, vibration, stretch, and hair-follicle position, on the basis of the type of mechanoreceptors that perceive these touch sensations. General senses often contribute to the sense of touch, as described above, or to proprioception (body movement) and kinesthesia (body movement), or to a visceral sense, which is most important to autonomic functions. Umami is a Japanese word that means “delicious taste,” and is often translated to mean savory. There are four types of papillae, based on their appearance ([link]): circumvallate, foliate, filiform, and fungiform. The entry of Na+ into these cells results in the depolarization of the cell membrane and the generation of a receptor potential. Increasing hydrogen ion concentrations in the saliva (lowering saliva pH) triggers progressively stronger graded potentials in the gustatory cells.
The sweet taste is the sensitivity of gustatory cells to the presence of glucose dissolved in the saliva. Likewise, some bitter molecules increase G protein activation within the gustatory cells, whereas other bitter molecules decrease G protein activation.
The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. Now, she studies the genetic differences between people and their sensitivities to taste stimuli. Each olfactory sensory neuron has dendrites that extend from the apical surface of the epithelium into the mucus lining the cavity. Some travel to the cerebrum, specifically to the primary olfactory cortex that is located in the inferior and medial areas of the temporal lobe. Professional fighters often experience anosmia because of repeated trauma to face and head. However, these two distinct bundles travel together from the inner ear to the brain stem as the vestibulocochlear nerve. The fluid-filled tube, now called the scala tympani, returns to the base of the cochlea, this time travelling under the cochlear duct.
As the fluid waves move through the scala vestibuli and scala tympani, the basilar membrane moves at a specific spot, depending on the frequency of the waves. The stereocilia extend up from the hair cells to the overlying tectorial membrane, which is attached medially to the organ of Corti.
The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. Which ear structures are responsible for the amplification and transfer of sound from the external ear to the inner ear? Head position is sensed by the utricle and saccule, whereas head movement is sensed by the semicircular canals.
On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths.
The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs.
Deep pressure and vibration is transduced by lamellated (Pacinian) corpuscles, which are receptors with encapsulated endings found deep in the dermis, or subcutaneous tissue. The eyelids, with lashes at their leading edges, help to protect the eye from abrasions by blocking particles that may land on the surface of the eye. All of the other muscles are innervated by the oculomotor nerve, as is the levator palpebrae superioris.
The transparent cornea covers the anterior tip of the eye and allows light to enter the eye. The posterior cavity is the space behind the lens that extends to the posterior side of the interior eyeball, where the retina is located. It is the bipolar cell in the retina that connects a photoreceptor to a retinal ganglion cell (RGC) in the inner synaptic layer. At the fovea, the retina lacks the supporting cells and blood vessels, and only contains photoreceptors. There are two types of photoreceptors—rods and cones—which differ in the shape of their outer segment. Specifically, photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation.
Until the retinal molecule is changed back to the 11-cis-retinal shape, the opsin cannot respond to light energy, which is called bleaching.
The absorbance of rhodopsin in the rods is much more sensitive than in the cone opsins; specifically, rods are sensitive to vision in low light conditions, and cones are sensitive to brighter conditions. The relative activation of the three different cones is calculated by the brain, which perceives the color as blue. This video gives an abbreviated overview of the visual system by concentrating on the pathway from the eyes to the occipital lobe. Some of the branches will synapse with local neurons in the dorsal root ganglion, posterior (dorsal) horn, or even the anterior (ventral) horn, at the level of the spinal cord where they enter. Some cranial nerves contain only sensory axons, such as the olfactory, optic, and vestibulocochlear nerves. The special senses are all primarily part of the somatic nervous system in that they are consciously perceived through cerebral processes, though some special senses contribute to autonomic function. Sensory information from the body that is conveyed through spinal nerves will project to the opposite side of the brain to be processed by the cerebral cortex. This video was created by a medical device manufacturer who might be trying to highlight other aspects of the visual system than retinal processing. However, the optic disc in the left eye would be on the right side of that fovea, so the right visual field falls on the side of the retina in the left field where there is no blind spot. ARHL usually begins with high frequency hearing loss (degeneration of the hair cells lining the bottom of the Cochlea) and later affects the lower frequencies at the apex of the Cochlea. They can also be classified functionally on the basis of the transduction of stimuli, or how the mechanical stimulus, light, or chemical changed the cell membrane potential. Physical stimuli, such as pressure and vibration, as well as the sensation of sound and body position (balance), are interpreted through a mechanoreceptor. Other overlooked senses include temperature perception by thermoreceptors and pain perception by nociceptors. A special sense is one that has a specific organ devoted to it, namely the eye, inner ear, tongue, or nose. The general sense that is usually referred to as touch includes chemical sensation in the form of nociception, or pain. Very recent research has suggested that there may also be a sixth taste for fats, or lipids. Within the structure of the papillae are taste buds that contain specialized gustatory receptor cells for the transduction of taste stimuli. For example, orange juice—which contains citric acid—will taste sour because it has a pH value of approximately 3. Other monosaccharides such as fructose, or artificial sweeteners such as aspartame (NutraSweet™), saccharine, or sucralose (Splenda™) also activate the sweet receptors.
The vagus nerve connects to taste buds in the extreme posterior of the tongue, verging on the pharynx, which are more sensitive to noxious stimuli such as bitterness.
In the video, there is a brief image of a person sticking out their tongue, which has been covered with a colored dye.
As airborne molecules are inhaled through the nose, they pass over the olfactory epithelial region and dissolve into the mucus. Others project to structures within the limbic system and hypothalamus, where smells become associated with long-term memory and emotional responses.
In addition, certain pharmaceuticals, such as antibiotics, can cause anosmia by killing all the olfactory neurons at once. Sound is transduced into neural signals within the cochlear region of the inner ear, which contains the sensory neurons of the spiral ganglia. The scala tympani ends at the round window, which is covered by a membrane that contains the fluid within the scala. Higher frequency waves move the region of the basilar membrane that is close to the base of the cochlea. When the pressure waves from the scala move the basilar membrane, the tectorial membrane slides across the stereocilia. The unit of Hertz measures the frequency of sound waves in terms of cycles produced per second. The neural signals generated in the vestibular ganglion are transmitted through the vestibulocochlear nerve to the brain stem and cerebellum. The ampulla contains the hair cells that respond to rotational movement, such as turning the head while saying “no.” The stereocilia of these hair cells extend into the cupula, a membrane that attaches to the top of the ampulla. Many of the somatosensory receptors are located in the skin, but receptors are also found in muscles, tendons, joint capsules, ligaments, and in the walls of visceral organs. Light touch is transduced by the encapsulated endings known as tactile (Meissner) corpuscles. The motor nuclei of these cranial nerves connect to the brain stem, which coordinates eye movements. The middle layer of the eye is the vascular tunic, which is mostly composed of the choroid, ciliary body, and iris.
There, amacrine cells additionally contribute to retinal processing before an action potential is produced by the RGC.
The rod-shaped outer segments of the rod photoreceptor contain a stack of membrane-bound discs that contain the photosensitive pigment rhodopsin. Wavelengths of electromagnetic radiation longer than 720 nm fall into the infrared range, whereas wavelengths shorter than 380 nm fall into the ultraviolet range.
When a large group of photopigments is bleached, the retina will send information as if opposing visual information is being perceived. However, cones cannot react to low-intensity light, and rods do not sense the color of light. The video makes the statement (at 0:45) that “specialized cells in the retina called ganglion cells convert the light rays into electrical signals.” What aspect of retinal processing is simplified by that statement? Other branches will travel a short distance up or down the spine to interact with neurons at other levels of the spinal cord.
Other cranial nerves contain both sensory and motor axons, including the trigeminal, facial, glossopharyngeal, and vagus nerves (however, the vagus nerve is not associated with the somatic nervous system).
The general senses can be divided into somatosensation, which is commonly considered touch, but includes tactile, pressure, vibration, temperature, and pain perception.
Related to chemoreceptors are osmoreceptors and nociceptors for fluid balance and pain reception, respectively.
The cranial nerves can be strictly sensory fibers, such as the olfactory, optic, and vestibulocochlear nerves, or mixed sensory and motor nerves, such as the trigeminal, facial, glossopharyngeal, and vagus nerves. The statement they make is not incorrect, it just bundles together several steps, which makes it sound like RGCs are the transducers, rather than photoreceptors. For humans, the only electromagnetic energy that is perceived by our eyes is visible light. Another physical stimulus that has its own type of receptor is temperature, which is sensed through a thermoreceptor that is either sensitive to temperatures above (heat) or below (cold) normal body temperature. Pressure, vibration, muscle stretch, and the movement of hair by an external stimulus, are all sensed by mechanoreceptors. These receptor cells are sensitive to the chemicals contained within foods that are ingested, and they release neurotransmitters based on the amount of the chemical in the food.
The affinity for each of these molecules varies, and some will taste sweeter than glucose because they bind to the G protein–coupled receptor differently.
These odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. This is how certain smells trigger emotional memories, such as the smell of food associated with one’s birthplace. If no axons are in place within the olfactory nerve, then the axons from newly formed olfactory neurons have no guide to lead them to their connections within the olfactory bulb. At the end of the auditory canal is the tympanic membrane, or ear drum, which vibrates after it is struck by sound waves. As vibrations of the ossicles travel through the oval window, the fluid of the scala vestibuli and scala tympani moves in a wave-like motion.
Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea.
Frequencies as low as 20 Hz are detected by hair cells at the apex, or tip, of the cochlea. As the head rotates in a plane parallel to the semicircular canal, the fluid lags, deflecting the cupula in the direction opposite to the head movement.

Mechanical, chemical, or thermal stimuli beyond a set threshold will elicit painful sensations.
The conjunctiva extends over the white areas of the eye (the sclera), connecting the eyelids to the eyeball. The superior oblique originates at the posterior orbit, near the origin of the four rectus muscles. The choroid is a layer of highly vascularized connective tissue that provides a blood supply to the eyeball.
The axons of RGCs, which lie at the innermost layer of the retina, collect at the optic disc and leave the eye as the optic nerve (see [link]). This is because the fovea is where the least amount of incoming light is absorbed by other retinal structures (see [link]). The cone-shaped outer segments of the cone photoreceptor contain their photosensitive pigments in infoldings of the cell membrane.
Light with a wavelength of 380 nm is blue whereas light with a wavelength of 720 nm is dark red.
Before interacting with a photon, retinal’s flexible double-bonded carbons are in the cis conformation. In a darkened room, there is not enough light to activate cone opsins, and vision is entirely dependent on rods. A branch may also turn into the posterior (dorsal) column of the white matter to connect with the brain.
The general senses also include the visceral senses, which are separate from the somatic nervous system function in that they do not normally rise to the level of conscious perception. Mechanoreceptors respond to mechanical stimuli and are the basis for most aspects of somatosensation, as well as being the basis of audition and equilibrium in the inner ear. The cranial nerves are connected to the same side of the brain from which the sensory information originates. A transmembrane protein receptor is a protein in the cell membrane that mediates a physiological change in a neuron, most often through the opening of ion channels or changes in the cell signaling processes. Some other organisms have receptors that humans lack, such as the heat sensors of snakes, the ultraviolet light sensors of bees, or magnetic receptors in migratory birds. Neurotransmitters from the gustatory cells can activate sensory neurons in the facial, glossopharyngeal, and vagus cranial nerves.
The odorant–protein complex binds to a receptor protein within the cell membrane of an olfactory dendrite. Smell is the one sensory modality that does not synapse in the thalamus before connecting to the cerebral cortex. There are temporary causes of anosmia, as well, such as those caused by inflammatory responses related to respiratory infections or allergies. When the stereocilia bend toward the tallest member of their array, tension in the protein tethers opens ion channels in the hair cell membrane.
Frequencies in the higher ranges of 20 KHz are encoded by hair cells at the base of the cochlea, close to the round and oval windows ([link]). Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity.
The semicircular canals contain several ampullae, with some oriented horizontally and others oriented vertically. Stressed or damaged tissues release chemicals that activate receptor proteins in the nociceptors.
These nerve endings detect the movement of hair at the surface of the skin, such as when an insect may be walking along the skin. However, the tendon of the oblique muscles threads through a pulley-like piece of cartilage known as the trochlea.
The choroid is posterior to the ciliary body, a muscular structure that is attached to the lens by zonule fibers. Because these axons pass through the retina, there are no photoreceptors at the very back of the eye, where the optic nerve begins. As one moves in either direction from this central point of the retina, visual acuity drops significantly.
There are three cone photopigments, called opsins, which are each sensitive to a particular wavelength of light.
The photoisomerization is reversed by a series of enzymatic changes so that the retinal responds to more light energy.
Rods are so sensitive to light that a single photon can result in an action potential from a rod’s corresponding RGC.
For the sake of convenience, we will use the terms ventral and dorsal in reference to structures within the spinal cord that are part of these pathways.
Thermoreceptors are sensitive to temperature changes, and photoreceptors are sensitive to light energy. THESE VERY SAME ENFORCEMENT AGENCIES, WHO HAVE SWORN TO PROTECT AND SERVE, OUR COUNTRY, AND CITIZENS ,ARE BUT SOME, OF THE CORRUPT,GREEDY TRAITORS .ENGAGED IN THE TYRANNY AND TORTURE. People fall into two groups known as “tasters” and “non-tasters” based on the density of papillae on their tongue, which also indicates the number of taste buds. These receptors are G protein–coupled, and will produce a graded membrane potential in the olfactory neurons. This intimate connection between the olfactory system and the cerebral cortex is one reason why smell can be a potent trigger of memories and emotion.
The membrane covering the round window will bulge out or pucker in with the movement of the fluid within the scala tympani. This will depolarize the hair cell membrane, triggering nerve impulses that travel down the afferent nerve fibers attached to the hair cells. Most auditory stimuli contain a mixture of sounds at a variety of frequencies and intensities (represented by the amplitude of the sound wave). The moving otolithic membrane, in turn, bends the sterocilia, causing some hair cells to depolarize as others hyperpolarize.
By comparing the relative movements of both the horizontal and vertical ampullae, the vestibular system can detect the direction of most head movements within three-dimensional (3-D) space. For example, the sensation of heat associated with spicy foods involves capsaicin, the active molecule in hot peppers. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint.
Tears produced by this gland flow through the lacrimal duct to the medial corner of the eye, where the tears flow over the conjunctiva, washing away foreign particles. This creates a “blind spot” in the retina, and a corresponding blind spot in our visual field. A photon interacting with the molecule causes the flexible double-bonded carbons to change to the trans- conformation, forming all-trans-retinal, which has a straight hydrocarbon chain ([link]). If you think that you can see colors in the dark, it is most likely because your brain knows what color something is and is relying on that memory. People fall into two large groups known as “tasters” and “non-tasters” on the basis of the density of papillae on their tongue, which also indicates the number of taste buds. Non-tasters can taste food, but they are not as sensitive to certain tastes, such as bitterness.
The three ossicles are the malleus, incus, and stapes, which are Latin names that roughly translate to hammer, anvil, and stirrup.
When the stereocilia bend toward the shortest member of their array, the tension on the tethers slackens and the ion channels close. The hair cells along the length of the cochlear duct, which are each sensitive to a particular frequency, allow the cochlea to separate auditory stimuli by frequency, just as a prism separates visible light into its component colors. The exact position of the head is interpreted by the brain based on the pattern of hair-cell depolarization. Capsaicin molecules bind to a transmembrane ion channel in nociceptors that is sensitive to temperatures above 37°C.
Bulbous corpuscles are also known as Ruffini corpuscles, or type II cutaneous mechanoreceptors. The types of nerve endings, their locations, and the stimuli they transduce are presented in [link]. The angle of the tendon through the trochlea means that contraction of the superior oblique rotates the eye medially. Overlaying the ciliary body, and visible in the anterior eye, is the iris—the colored part of the eye. Therefore, this RGC does not have to integrate inputs from multiple photoreceptors, which reduces the accuracy of visual transduction. The pigments in human eyes are specialized in perceiving three different primary colors: red, green, and blue. Typically, spinal nerve systems that connect to the brain are contralateral, in that the right side of the body is connected to the left side of the brain and the left side of the body to the right side of the brain.
Other transmembrane proteins, which are not accurately called receptors, are sensitive to mechanical or thermal changes. When no sound is present, and the stereocilia are standing straight, a small amount of tension still exists on the tethers, keeping the membrane potential of the hair cell slightly depolarized. The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. The inferior oblique muscle originates from the floor of the orbit and inserts into the inferolateral surface of the eye. The iris is a smooth muscle that opens or closes the pupil, which is the hole at the center of the eye that allows light to enter. Toward the edges of the retina, several photoreceptors converge on RGCs (through the bipolar cells) up to a ratio of 50 to 1. Physical changes in these proteins increase ion flow across the membrane, and can generate an action potential or a graded potential in the sensory neurons.
Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew.
Because of this, it will decrease the ability of other stimuli to elicit pain sensations through the activated nociceptor. The iris constricts the pupil in response to bright light and dilates the pupil in response to dim light. The difference in visual acuity between the fovea and peripheral retina is easily evidenced by looking directly at a word in the middle of this paragraph.
The stapes is then attached to the inner ear, where the sound waves will be transduced into a neural signal.
For this reason, capsaicin can be used as a topical analgesic, such as in products such as Icy Hot™. Rotation of the eye by the two oblique muscles is necessary because the eye is not perfectly aligned on the sagittal plane. The innermost layer of the eye is the neural tunic, or retina, which contains the nervous tissue responsible for photoreception. The visual stimulus in the middle of the field of view falls on the fovea and is in the sharpest focus. The middle ear is connected to the pharynx through the Eustachian tube, which helps equilibrate air pressure across the tympanic membrane.
When the eye looks up or down, the eye must also rotate slightly to compensate for the superior rectus pulling at approximately a 20-degree angle, rather than straight up. Without moving your eyes off that word, notice that words at the beginning or end of the paragraph are not in focus. The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning.
The same is true for the inferior rectus, which is compensated by contraction of the inferior oblique. The images in your peripheral vision are focused by the peripheral retina, and have vague, blurry edges and words that are not as clearly identified.
A seventh muscle in the orbit is the levator palpebrae superioris, which is responsible for elevating and retracting the upper eyelid, a movement that usually occurs in concert with elevation of the eye by the superior rectus (see [link]).
As a result, a large part of the neural function of the eyes is concerned with moving the eyes and head so that important visual stimuli are centered on the fovea. The school district has moved to a biometric identification program, saying students will no longer have to use an ID card to buy lunch.A  BIOMETRICS TO TRACK YOUR KIDS!!!!!i»?i»?A TARGETED INDIVIDUALS, THE GREEDY CRIMINALS ARE NOW CONDONING THEIR TECH! Paul Weindling, history of medicine professor at Oxford Brookes University, describes his search for the lost victims of Nazi experiments.
The chairman of the board at ESL a€” then proprietor of the desert wasteland in Nevada known as a€?Area 51a€? a€” was William Perry, who would be appointed secretary of defense several years later.
EUCACH.ORG PanelIn a 2-hour wide-ranging Panel with Alfred Lambremont Webre on the Transhumanist Agenda, Magnus Olsson, Dr.
Henning Witte, and Melanie Vritschan, three experts from the European Coalition Against Covert Harassment, revealed recent technological advances in human robotization and nano implant technologies, and an acceleration of what Melanie Vritschan characterized as a a€?global enslavement programa€?.Shift from electromagnetic to scalar wavesThese technologies have now shifted from electromagnetic wave to scalar waves and use super quantum computers in the quantum cloud to control a€?pipesa€? a reference to the brains of humans that have been taken over via DNA, via implants that can be breathed can breach the blood-brain barrier and then controlled via scalar waved on a super-grid. Eventually, such 'subvocal speech' systems could be used in spacesuits, in noisy places like airport towers to capture air-traffic controller commands, or even in traditional voice-recognition programs to increase accuracy, according to NASA scientists."What is analyzed is silent, or sub auditory, speech, such as when a person silently reads or talks to himself," said Chuck Jorgensen, a scientist whose team is developing silent, subvocal speech recognition at NASA Ames Research Center in California's Silicon Valley. We numbered the columns and rows, and we could identify each letter with a pair of single-digit numbers," Jorgensen said. People in noisy conditions could use the system when privacy is needed, such as during telephone conversations on buses or trains, according to scientists."An expanded muscle-control system could help injured astronauts control machines. If an astronaut is suffering from muscle weakness due to a long stint in microgravity, the astronaut could send signals to software that would assist with landings on Mars or the Earth, for example," Jorgensen explained. These are processed to remove noise, and then we process them to see useful parts of the signals to show one word from another," Jorgensen said.After the signals are amplified, computer software 'reads' the signals to recognize each word and sound. Our Research and Development Division has been in contact with the Federal Bureau of Prisons, the California Department of Corrections, the Texas Department of Public Safety, and the Massachusetts Department of Correction to run limited trials of the 2020 neural chip implant. We have established representatives of our interests in both management and institutional level positions within these departments. Federal regulations do not yet permit testing of implants on prisoners, but we have entered nto contractual agreements with privatized health care professionals and specified correctional personnel to do limited testing of our products. We need, however, to expand our testing to research how effective the 2020 neural chip implant performs in those identified as the most aggressive in our society. In California, several prisoners were identified as members of the security threat group, EME, or Mexican Mafia.
They were brought to the health services unit at Pelican Bay and tranquilized with advanced sedatives developed by our Cambridge,Massachussetts laboratories.
The results of implants on 8 prisoners yielded the following results: a€?Implants served as surveillance monitoring device for threat group activity. However, during that period substantial data was gathered by our research and development team which suggests that the implants exceed expected results.
One of the major concerns of Security and the R & D team was that the test subject would discover the chemial imbalance during the initial adjustment period and the test would have to be scurbbed.
However, due to advanced technological developments in the sedatives administered, the 48 hour adjustment period can be attributed t prescription medication given to the test subjects after the implant procedure. One of the concerns raised by R & D was the cause of the bleeding and how to eliminate that problem. Unexplained bleeding might cause the subject to inquire further about his "routine" visit to the infirmary or health care facility.
Security officials now know several strategies employed by the EME that facilitate the transmission of illegal drugs and weapons into their correctional facilities. One intelligence officier remarked that while they cannot use the informaiton that have in a court of law that they now know who to watch and what outside "connections" they have. The prison at Soledad is now considering transferring three subjects to Vacaville wher we have ongoing implant reserach. Our technicians have promised that they can do three 2020 neural chip implants in less than an hour. Soledad officials hope to collect information from the trio to bring a 14 month investigation into drug trafficking by correctional officers to a close.
Essentially, the implants make the unsuspecting prisoner a walking-talking recorder of every event he comes into contact with. There are only five intelligence officers and the Commisoner of Corrections who actually know the full scope of the implant testing.
In Massachusetts, the Department of Corrections has already entered into high level discussion about releasing certain offenders to the community with the 2020 neural chip implants. Our people are not altogether against the idea, however, attorneys for Intelli-Connection have advised against implant technology outside strick control settings.
While we have a strong lobby in the Congress and various state legislatures favoring our product, we must proceed with the utmost caution on uncontrolled use of the 2020 neural chip.
If the chip were discovered in use not authorized by law and the procedure traced to us we could not endure for long the resulting publicity and liability payments.
Massachusetts officials have developed an intelligence branch from their Fugitive Task Force Squad that would do limited test runs under tight controls with the pre-release subjects. Correctons officials have dubbed these poetnetial test subjects "the insurance group." (the name derives from the concept that the 2020 implant insures compliance with the law and allows officials to detect misconduct or violations without question) A retired police detective from Charlestown, Massachusetts, now with the intelligence unit has asked us to consider using the 2020 neural chip on hard core felons suspected of bank and armored car robbery.
He stated, "Charlestown would never be the same, we'd finally know what was happening before they knew what was happening." We will continue to explore community uses of the 2020 chip, but our company rep will be attached to all law enforcement operations with an extraction crrew that can be on-site in 2 hours from anywhere at anytime.
We have an Intelli-Connection discussion group who is meeting with the Director of Security at Florence, Colorado's federal super maximum security unit. The initial discussions with the Director have been promising and we hope to have an R & D unit at this important facilitly within the next six months. Napolitano insisted that the department was not planning on engaging in any form of ideological profiling. I will tell him face-to-face that we honor veterans at DHS and employ thousands across the department, up to and including the Deputy Secretary," Ms.
Steve Buyer of Indiana, the ranking Republican on the House Committee on Veterans' Affairs, called it "inconceivable" that the Obama administration would categorize veterans as a potential threat.

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