anatomy and physiology of sensory system ppt

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. The cranial nerves connect the head and . The taste buds contain specialized gustatory receptor cells that respond to chemical stimuli dissolved in the saliva. The transparent cornea covers the anterior tip of the eye and allows light to enter the eye. When you can no longer read a line accurately with one eye, then this is the acuity for that eye. If you are redistributing all or part of this book in a print format, The standing sound wave generated in the cochlea by the movement of the oval window deflects the basilar membrane on the basis of the frequency of sound. The other tastes result from food molecules binding to a G proteincoupled receptor. Specifically, photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation. The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe. (Micrograph provided by the Regents of University of Michigan Medical School 2012). welcome to Ms. stephens' anatomy and Physiology and Environmental . 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. Salty taste is simply the perception of sodium ions (Na+) in the saliva. The organs of Corti contain hair cells, which are named for the hair-like stereocilia extending from the cells apical surfaces (Figure 14.8). An important distinction to consider is how humans can functionally separate sensation (activation of the different receptors) as compared to perception (the conscious awareness of the sensation). The orbit is surrounded by cranial bones of the skull. Tasting PTC is correlated with the dominant genotype. When it contracts, it laterally rotates the eye, in opposition to the superior oblique. If you answered YES!, then you have the dominant genotype for the PTC gene! Receptors can be classified structurally on the basis of cell type and their position in relation to stimuli they sense. The specific response depends on which molecule is binding to the receptor. The brain interprets the meaning of the sounds we hear as music, speech, noise, etc. 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. We do not perceive the blind spot because the brain interpolates information to fill in the gaps. Perception of the network of interconnected neuron signals is eventually perceived in the occipital cortex. Free Nerve Endings Direct stimulation of sensory neurons the sensory neuron is also the receptor dendrites of sensory neurons 1. citation tool such as, Authors: J. Gordon Betts, Kelly A. Sensation is the activation of sensory receptor cells at the level of the stimulus. The stereocilia of the hair cells extend into a viscous gel called the otolithic membrane (Figure 14.11). In this lab, we will explore the anatomy & physiology used for interpreting the environment both within and outside our bodies. The middle ear consists of a space spanned by three small bones called the ossicles. These two structures bend the lens, allowing it to focus light on the back of the eye. Explain your answer. One bitter taste receptor protein is encoded by the PTC gene, or TAS2R38 (discovered in 2003). Corrective lenses: If you have contacts, keep them in, but if you wear glasses you may want to try the test with and without them to see just how much your corrective lenses improve your vision! The humors are fluids filling the anterior and posterior chambers of the eye. The oval window is located at the beginning of a fluid-filled tube within the cochlea called the scala vestibuli. If you differ, then provide a possible explanation as to why: This lab has been adapted from Rice University and is licensed under a Creative Commons Attribution License License (3.0). 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. The conjunctiva extends over the white areas of the eye (the sclera), connecting the eyelids to the eyeball. The eye is located within the orbit and surrounded by soft tissues that protect and support its function. 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. Nociceptive Pain. When you eat something salty, the salt crystals dissociate into the component ions Na+ and Cl, which dissolve into the saliva in your mouth. Some bitter molecules depolarize gustatory cells, whereas others hyperpolarize gustatory cells. She recognized that her sense of taste was unique compared with other people she knew. Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea. This is actually a reduced eye model, which involves some approximations. This molecule is referred to as 11-cis-retinal. They preferentially absorb light at different wavelengths, shown in the figure below. The neurons can then communicate with other neurons in the nervous system via synapses and networks to coordinate responses. Receptor can refer to specific protein molecules which first interact with the matter or energy, the cell(s) that contains those proteins, or an assembly of cells in the larger organ. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception. 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. Olfactory neurons will undergo adaptation and decrease signals to the brain with constant exposure to a stimulus. Can you label any structures if you use the above diagram as a guide? One network of neurons in the retina sends signals to one ganglion cell. Some thermoreceptors are sensitive to just cold and others to just heat. You can estimate this distance (d, in mm) of your retinal structures by recording the distance when the image disappears (x), and measuring the distance between the cross and circle in the image (d). 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 Figure 14.15). sight, touch, hearing, taste, smell. You will have to identify these structures using both the sheep or cow eye and the models. Other monosaccharides such as fructose, or artificial sweeteners such as aspartame (NutraSweet), saccharine, or sucralose (Splenda) also activate the sweet receptors. __________________, ______________________________________________________________________________________________________________________________________________, Color-blindness can be tested with an appropriate Standard Pseudoisochromatic plates (e.g. 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). The highest concentration of bitter receptors appear to be in the posterior tongue, where a gag reflex could still spit out poisonous food. 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? Mechanoreceptors in the skin, muscles, or the walls of blood vessels are examples of this type. By the end of this section, you will be able to: A major role of sensory receptors is to help us learn about the environment around us, or about the state of our internal environment. Merkel cells are located in the stratum basale of the epidermis. The malleus is attached to the tympanic membrane and articulates with the incus. The odorantprotein complex binds to a receptor protein within the cell membrane of an olfactory dendrite. Like taste, the sense of smell, or olfaction, is also responsive to chemical stimuli. Each of the senses is referred to as a sensory modality. The peripheral nerve provides the pathway for motor, sensory and vegetative axons belonging to the peripheral nervous system. Using the plates are you able to detect the image present for the presented colors? However, these are not all of the senses. 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. 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. Nociception is the sensation of potentially damaging stimuli. Strike the fork so it makes a sound and move it to front, back, side, and top of the head at a constant distance, holding it to allow the subject to point out the location. Some structures are quite tough including the lens and sclera (in Latin, sclera means tough!). Which ear structures are responsible for the amplification and transfer of sound from the external ear to the inner ear? The most obvious omission from this list is balance. The stereocilia are an array of microvilli-like structures arranged from tallest to shortest. A particular body part's function depends on its structure. All of our muscles and organs depen. Frequencies as low as 20 Hz are detected by hair cells at the apex, or tip, of the cochlea. 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. Sensory neurons can have either (a) free nerve endings or (b) encapsulated endings. See Full PDF Download PDF Related Papers THE SKELETON BONES AND JOINTS _______________ Right eye? In normal sunlight, rhodopsin will be constantly bleached while the cones are active. Photoreceptors in the eyes, such as rod cells, are examples of (c) specialized receptor cells. You are responsible for identifying these major anatomical structures of the eye: sclera (tough, outer layer), choroid (dark, middle layer), pigmented epithelium, fovea, vitreous humor, aqueous humor, iris, lens, ciliary body, cornea, conjunctiva, optic nerve, blind spot (or optic disc), retina (thin, and pale inner layer). 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. https://openstax.org/books/anatomy-and-physiology-2e/pages/1-introduction, https://openstax.org/books/anatomy-and-physiology-2e/pages/14-1-sensory-perception, Creative Commons Attribution 4.0 International License, Dermis, cornea, tongue, joint capsules, visceral organs, Pain, temperature, mechanical deformation, Epidermaldermal junction, mucosal membranes, Papillary dermis, especially in the fingertips and lips, Deep pressure, high-frequency vibration (around 250 Hz), Wrapped around hair follicles in the dermis, Describe different types of sensory receptors, Describe the structures responsible for the special senses of taste, smell, hearing, balance, and vision, Distinguish how different tastes are transduced, Describe the means of mechanoreception for hearing and balance, List the supporting structures around the eye and describe the structure of the eyeball, Describe the processes of phototransduction. Color vision results from the interaction of 3 sub-types of cone photoreceptors. When the stereocilia bend toward the shortest member of their array, the tension on the tethers slackens and the ion channels close. You can repeat this with your left eye, staring at the circle. 1999-2023, Rice University. 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. The motor nuclei of these cranial nerves connect to the brain stem, which coordinates eye movements. In addition, certain pharmaceuticals, such as antibiotics, can cause anosmia by killing all the olfactory neurons at once. What is the distance between the fovea and optic disk in your left eye? As one moves in either direction from this central point of the retina, visual acuity drops significantly. Structure of Sensory Receptor Sensations can be produced mainly by very simple kinds of receptors or complex sense organs receptors for General Senses are relatively simple A. The tendon inserts obliquely into the superior surface of the eye. Sensory Systems: Anatomy, Physiology and Pathophysiology provides a comprehensive description of how human sensory systems function, with comparisons of the five senses and detailed descriptions of the functions of each of them. If you have missed laboratory or class; complete the makeup work below. 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. It has two separate regions, the cochlea and the vestibule, which are responsible for hearing and balance, respectively. Within the neural tunic is the retina, with three layers of cells and two synaptic layers in between. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla. Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. Some stimuli are physical variations in the environment that affect receptor cell membrane potentials. (c) Axons of the olfactory receptor neurons project through the cribriform plate of the ethmoid bone and synapse with the neurons of the olfactory bulb (tissue source: simian). 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. There are at least 30 different genes coding for bitter taste receptors. The otolithic membrane moves separately from the macula in response to head movements. Repeat while standing with your right or left side closest to the board, and note front-to-back swaying, First with eyes open and then with eyes closed. The perceived sensations correspond to common chemicals: Salty (Na+), Sweet (disaccharides, e.g. The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. Many internal structures are delicate and tear easily such as the retina. LM 412. This condition is known as anosmia. Eyelid. Sound is transduced into neural signals within the cochlear region of the inner ear, which contains the sensory neurons of the spiral ganglia. 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The ability of olfactory neurons to replace themselves decreases with age, leading to age-related anosmia. There is more variability among individuals than accounted for by the original 1942 map (not shown, intentionally). The shape change of retinal in the photoreceptors initiates visual transduction in the retina. Therefore, hair cells at the base of the cochlea are activated only by high frequencies, whereas those at the apex of the cochlea are activated only by low frequencies. Just as with sodium ions in salty flavors, these hydrogen ions enter the cell and trigger depolarization. The hair cell is a mechanoreceptor with an array of stereocilia emerging from its apical surface. 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. Therefore, visual acuity, or the sharpness of vision, is greatest at the fovea. There, amacrine cells additionally contribute to retinal processing before an action potential is produced by the RGC. Gustation is the special sense associated with the tongue. Olfactory signals are the only sensory system to send signals directly to the limbic system, which is integral to memory and emotional functions. Very recent research has suggested that there may also be a sixth taste for fats, or lipids. Check with your instructor to determine which way they want you to cut the eye in half. The movement of two canals within a plane results in information about the direction in which the head is moving, and activation of all six canals can give a very precise indication of head movement in three dimensions. As stated above, a given region of the basilar membrane will only move if the incoming sound is at a specific frequency. then you must include on every digital page view the following attribution: Use the information below to generate a citation. Each olfactory sensory neuron has dendrites that extend from the apical surface of the epithelium into the mucus lining the cavity. 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. Professional fighters often experience anosmia because of repeated trauma to face and head. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint. The sphere of the eye can be divided into anterior and posterior chambers. Neurons responding to physical force, temperature, and specific chemicals to warn of (potential) damage. Like sweet and bitter, it is based on the activation of G proteincoupled receptors by a specific molecule. The membrane covering the round window will bulge out or pucker in with the movement of the fluid within the scala tympani. 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 (Figure 14.18). Physical stimuli, such as pressure and vibration, as well as the sensation of sound and body position (balance), are interpreted through a mechanoreceptor. Until recently, only four tastes were recognized: sweet, salty, sour, and bitter. One major group of bitter-tasting molecules are alkaloids. Within the realm of physiology, senses can be classified as either general or specific. The Eustachian (or auditory) tube connects the middle ear cavity to the pharynx (it is an evolutionary descendant of pharyngeal pouches). Specific molecules (odorants) bind to receptor proteins and activate neural electrical signals (action potentials). Measure the distance from the image to your eye. The anterior cavity is the space between the cornea and lens, including the iris and ciliary body. However, the tendon of the oblique muscles threads through a pulley-like piece of cartilage known as the trochlea. LM 812. Describing sensory function with the term sensation or perception is a deliberate distinction. All other colors fall between red and blue at various points along the wavelength scale. Sour flavors are, essentially, the perception of acids in our food. Other overlooked senses include temperature perception by thermoreceptors and pain perception by nociceptors. Specific organs include: In order to investigate and understand sensory processes, we will investigate their anatomical structures (at macro- and microscopic levels) and physiological functions. This complexity allows you to be aware of your surroundings and take appropriate actions. Whereas spinal information is contralateral, cranial nerve systems, with some exceptions, are mostly ipsilateral, meaning that a cranial nerve on the right side of the head is connected to the right side of the brain. 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. In addition, each photoreceptor cell of the fovea is connected to a single RGC. View the University of Michigan WebScope to explore the tissue sample in greater detail. HISTORICAL NOTE: The standard map of taste buds common in many lab manuals has been disproved by subsequent research (J. The innermost layer of the eye is the neural tunic, or retina, which contains the nervous tissue responsible for photoreception. The relative activation of the three different cones is calculated by the brain, which perceives the color as blue. However, at the exact center of the retina is a small area known as the fovea. The central integration may then lead to a motor response. Young, James A. OpenStax is part of Rice University, which is a 501(c)(3) nonprofit. mucous membrane that lines the anterior surface of the eye and the posterior surface of the eyelid. Prefrontal Constraints In Volleyball Each component of the motor control system is extremely dependent on the sensory The Somatosensory System Balance & Movement (The Vestibular System): C: Romberg Testing Involves Maintaining Balance: source@https://libguides.daltonstate.edu/PrinciplesofBiology/labmanual, Visible light (Electromagnetic Radiation), Multilayered nervous sheet within the eye with muscles and lenses for focusing, Flexible hair cells that release signal molecules based on waves in fluid started by the motion of the, A layer of neurons at the top of the nasal cavity, Clusters of epithelial cells that release signals to neurons if specific chemicals are present (e.g. However, there are a number of different ways in which this can happen because there are a large diversity of bitter-tasting molecules. Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. Humans have five special senses: olfaction (smell), gustation (taste), equilibrium (balance and body position), vision, and hearing. In many sensory organs, additional cells and tissues will contribute to the process of signal transduction. 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. 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. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Muscles in the iris alter pupil size to vary light entering the eye. Sucrose and NaCl are common tests for sweet and salty. The focused image is directed toward the fovea (or fovea centralis), which contains the highest density of photoreceptor neurons. LM 800. Individuals can map their tongues for taste buds, once sensitivity thresholds have been determined. Overlaying the ciliary body, and visible in the anterior eye, is the iristhe colored part of the eye. 1_Digital Dots Adobe Photoshop Image Microsoft Photo Editor 3.0 Photo Sensory Overview Classification of Sensory System by Structural Complexity Sensory Receptors - Overview Sensory Transduction Complexity Range of Receptors 4 Types of . b. Merkel disks - attached to nerve endings of the epidermis. Our mission is to improve educational access and learning for everyone. Temperature receptors are stimulated when local temperatures differ from body temperature. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs. From there, the axons split to travel to several brain regions. 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. Some stimuli are ions and macromolecules that affect transmembrane receptor proteins when these chemicals diffuse across the cell membrane. 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 (Figure 14.15).

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