anatomy and physiology of sensory system ppt

The most obvious omission from this list is balance. When each of these muscles contract, the eye moves toward the contracting muscle. Comparisons on the chart will refer to this standard measure. The main sensory modalities can be described on the basis of how each is transduced. The extraocular muscles are innervated by three cranial nerves. After a bright flash of light, afterimages are usually seen in negative. Receptors are the cells or structures that detect sensations. Young, James A. The base of each semicircular canal, where it meets with the vestibule, connects to an enlarged region known as the ampulla. Visible light only occupies a small portion of the electromagnetic spectrum. In addition, two separate clusters of hair cells the saccule and utricle are oriented to detect vertical and horizontal movements. Lower frequency waves move the region of the basilar membrane that is near the tip of the cochlea. The posterior cavity is the space behind the lens that extends to the posterior side of the interior eyeball, where the retina is located. The posterior cavity is filled with a more viscous fluid called the vitreous humor. The olfactory receptor neurons are located in a small region within the superior nasal cavity (Figure 14.4). 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. The brain interprets the meaning of the sounds we hear as music, speech, noise, etc. This means that its receptors are not associated with a specialized organ, but are instead spread throughout the body in a variety of organs. There are two types of photoreceptorsrods and coneswhich differ in the shape of their outer segment. Vision is the special sense of sight that is based on the transduction of light stimuli received through the eyes. The stereocilia are tethered together by proteins that open ion channels when the array is bent toward the tallest member of their array, and closed when the array is bent toward the shortest member of their array. List the positions for localization from most to least accurate: Describe any differences in relation to the sensory input required to maintain balance. Pressure, vibration, muscle stretch, and the movement of hair by an external stimulus, are all sensed by mechanoreceptors. Which ear structures are responsible for the amplification and transfer of sound from the external ear to the inner ear? When the stereocilia bend toward the shortest member of their array, the tension on the tethers slackens and the ion channels close. The entry of Na+ into these cells results in the depolarization of the cell membrane and the generation of a receptor potential. The motor nuclei of these cranial nerves connect to the brain stem, which coordinates eye movements. The dynamics of capsaicin binding with this transmembrane ion channel is unusual in that the molecule remains bound for a long time. Also located in the dermis of the skin are lamellated corpuscles, neurons with encapsulated nerve endings that respond to pressure and touch. These cells are located within the vestibule of the inner ear. 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. 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. However, these are not all of the senses. 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. Body parts form a well-organized unitthe human organism. Patterns of olfactory neuron activity can code for complex odors, integrated within the olfactory bulb and temporal cortex. Below, list the micromolar concentrations of mint and circle the one where you can begin to smell the mint. For example, the sensation of heat associated with spicy foods involves capsaicin, the active molecule in hot peppers. Odorants can be detected by some sensitive individuals at concentrations below the micromolar range. These odorant molecules bind to proteins that keep them dissolved in the mucus and help transport them to the olfactory dendrites. Humans consistently recognize certain odorants (e.g. LM 412. The middle ear consists of a space spanned by three small bones called the ossicles. You can locate the blind spot by moving the image below toward your head. As one moves in either direction from this central point of the retina, visual acuity drops significantly. Describe the arrangement of sensory and motor regions in the spinal cord. This article describes the anatomy and physiology of the sensory systems, examining structures associated with vision and hearing, equilibrium and sensation. This explains why some elderly people salt their food more than younger people do. Such stretch receptors can also prevent over-contraction of a muscle. There are four types of papillae, based on their appearance (Figure 14.3): circumvallate, foliate, filiform, and fungiform. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. __________________, ______________________________________________________________________________________________________________________________________________, Color-blindness can be tested with an appropriate Standard Pseudoisochromatic plates (e.g. The eye can focus light images on the retina using the cornea and the lens. 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. Action potentials from ganglion cells, whose axons form the optic nerves, represent patterns of light. A G protein signal transduction system ultimately leads to depolarization of the gustatory cell. 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). Neurotransmitters from the gustatory cells can activate sensory neurons in the facial, glossopharyngeal, and vagus cranial nerves. Dr. Reed discovered that she is a non-taster, which explains why she perceived bitterness differently than other people she knew. The eye itself is a hollow sphere composed of three layers of tissue. Another way that receptors can be classified is based on their location relative to the stimuli. Individuals can map their tongues for taste buds, once sensitivity thresholds have been determined. 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. _______________, Are your eyes exactly the same? The inner ear contains the cochlea and vestibule, which are responsible for audition and equilibrium, respectively. One network of neurons in the retina sends signals to one ganglion cell. Muscles in the iris alter pupil size to vary light entering the eye. 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. Clinically, pain can be labeled " nociceptive " if it is inferred that the pain is due to ongoing activation of the nociceptive system by tissue injury. Yes or no? Physiology of Sensory system. Once any sensory cell transduces a stimulus into a nerve impulse, that impulse has to travel along axons to reach the CNS. The otolithic membrane moves separately from the macula in response to head movements. Umami is a Japanese word that means delicious taste, and is often translated to mean savory. The neural signals generated in the vestibular ganglion are transmitted through the vestibulocochlear nerve to the brain stem and cerebellum. This video gives an abbreviated overview of the visual system by concentrating on the pathway from the eyes to the occipital lobe. In a darkened room, there is not enough light to activate cone opsins, and vision is entirely dependent on rods. Serial solutions can be applied with cotton swabs to the subject's tongue to test for sensitivity. There are at least 30 different genes coding for bitter taste receptors. Explain your answer. Merkel cells are located in the stratum basale of the epidermis. This molecule is referred to as 11-cis-retinal. Sensory neurons can have either (a) free nerve endings or (b) encapsulated endings. The photoreceptors (rods and cones) change their membrane potential when stimulated by light energy. The molecule that activates this receptor is the amino acid L-glutamate. On top of the otolithic membrane is a layer of calcium carbonate crystals, called otoliths. Also, we may have perceptions that are only present in the brain, even though the sensory organs are silent. The three types of cone opsins, being sensitive to different wavelengths of light, provide us with color vision. then you must include on every physical page the following attribution: If you are redistributing all or part of this book in a digital format, The anterior cavity is the space between the cornea and lens, including the iris and ciliary body. Possible cuts include: To be able to best see the eyes structures, you should work very carefully. If you drag your finger across a textured surface, the skin of your finger will vibrate. Free Nerve Endings Direct stimulation of sensory neurons the sensory neuron is also the receptor dendrites of sensory neurons 1. It is the bipolar cell in the retina that connects a photoreceptor to a retinal ganglion cell (RGC) in the inner synaptic layer. Professional fighters often experience anosmia because of repeated trauma to face and head. The glossopharyngeal nerve connects to taste buds in the posterior two thirds of the tongue. Specifically, photons cause some of the double-bonded carbons within the chain to switch from a cis to a trans conformation. 1999-2023, Rice University. 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 informationor sometimes higher cognitive functionsto become a conscious perception of that stimulus. Most auditory stimuli contain a mixture of sounds at a variety of frequencies and intensities (represented by the amplitude of the sound wave). The group of axons called the olfactory tract connect to the olfactory bulb on the ventral surface of the frontal lobe. The amplified vibration is picked up by the oval window causing pressure waves in the fluid of the scala vestibuli and scala tympani. The cochlea encodes auditory stimuli for frequencies between 20 and 20,000 Hz, which is the range of sound that human ears can detect. Once the gustatory cells are activated by the taste molecules, they release neurotransmitters onto the dendrites of sensory neurons. When the frontal lobe of the brain moves relative to the ethmoid bone, the olfactory tract axons may be sheared apart. The pain and temperature receptors in the dermis of the skin are examples of neurons that have free nerve endings. The tongue is covered with small bumps, called papillae, which contain taste buds that are sensitive to chemicals in ingested food or drink. Smell is the one sensory modality that does not synapse in the thalamus before connecting to the cerebral cortex. The stereocilia are an array of microvilli-like structures arranged from tallest to shortest. 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. Toward the edges of the retina, several photoreceptors converge on RGCs (through the bipolar cells) up to a ratio of 50 to 1. Retinal is a hydrocarbon molecule related to vitamin A. Until the retinal molecule is changed back to the 11-cis-retinal shape, the opsin cannot respond to light energy, which is called bleaching. An individual sensory modality represents the sensation of a specific type of stimulus. The conjunctiva extends over the white areas of the eye (the sclera), connecting the eyelids to the eyeball. vision, taste). Anatomy and Physiology Anatomy is the branch of science that deals with the structure (morphology) of body partsforms and organization. Anatomy and Physiology Environmental Science APES Welcome to Ms. Stephens' Anatomy & Physiology Class Email: [email protected] Class website: Tutorial: Thursday (3:45-4:45) Announcements: The class website contains lesson plans, notes, and study links. 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. Additionally, pain is primarily a chemical sense that interprets the presence of chemicals from tissue damage, or similar intense stimuli, through a nociceptor. The taste buds contain specialized gustatory receptor cells that respond to chemical stimuli dissolved in the saliva. Non-tasters can taste food, but they are not as sensitive to certain tastes, such as bitterness. Find an individual taste bud and draw it in the space provided. Some bitter molecules depolarize gustatory cells, whereas others hyperpolarize gustatory cells. This distinction reveals how sensory deficits can result from damage in brain regions, even though the sensory organ is intact. The semicircular canals are three ring-like extensions of the vestibule. what type of matter or energy they detect and subsequently transduce to produce our perceptions (e.g. 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. The C-shaped curves of the auricle direct sound waves toward the auditory canal. The sphere of the eye can be divided into anterior and posterior chambers. These receptors are G proteincoupled, and will produce a graded membrane potential in the olfactory neurons. The frequency of the fluid waves match the frequencies of the sound waves (Figure 14.6). The tube is normally closed but will pop open when the muscles of the pharynx contract during swallowing or yawning. Now, she studies the genetic differences between people and their sensitivities to taste stimuli. 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. Like sweet and bitter, it is based on the activation of G proteincoupled receptors by a specific molecule. consent of Rice University. They alter the lens to aid focusing. Sensory (olfactory) neurons are present at the top of the nasal cavity, extending their axons into the cranium. Distinguish between anatomy and physiology, and identify several branches of each Describe the structure of the body, from simplest to most complex, in terms of the six levels of organization Identify the functional characteristics of human life Identify the four requirements for human survival 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. A significant amount of light is absorbed by these structures before the light reaches the photoreceptor cells. The focused image is directed toward the fovea (or fovea centralis), which contains the highest density of photoreceptor neurons. There are several ways to slice through an eye. Other monosaccharides such as fructose, or artificial sweeteners such as aspartame (NutraSweet), saccharine, or sucralose (Splenda) also activate the sweet receptors. The essential component is neurons, the major functional cells in nervous tissue. The specific response depends on which molecule is binding to the receptor. Opsin pigments are actually transmembrane proteins that contain a cofactor known as retinal. Balance & Movement (The Vestibular System): C: Romberg Testing Involves Maintaining Balance: source@, 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. b. Merkel disks - attached to nerve endings of the epidermis. The eye is located within the orbit and surrounded by soft tissues that protect and support its function. The choroid is posterior to the ciliary body, a muscular structure that is attached to the lens by suspensory ligaments, or zonule fibers. 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. (Micrograph provided by the Regents of University of Michigan Medical School 2012), (a) The olfactory system begins in the peripheral structures of the nasal cavity. Have the subject stand and stare straight ahead for 2 minutes, and note the range of movement. This is how Dr. Reed is able to visualize and count papillae on the surface of the tongue. Four of the muscles are arranged at the cardinal points around the eye and are named for those locations. Mechanical, chemical, or thermal stimuli beyond a set threshold will elicit painful sensations. The first two tastes (salty and sour) are triggered by the cations Na+ and H+. Tasting PTC is correlated with the dominant genotype. This is because the fovea is where the least amount of incoming light is absorbed by other retinal structures (see Figure 14.15). At the fovea, the retina lacks the supporting cells and blood vessels, and only contains photoreceptors. Activation of retinal and the opsin proteins result in activation of a G protein. The visual stimulus in the middle of the field of view falls on the fovea and is in the sharpest focus. The opsins are sensitive to limited wavelengths of light. Stand there and cover one eye without squinting. Therefore, the function of bitter taste may primarily be related to stimulating the gag reflex to avoid ingesting poisons. The eyes are located within either orbit in the skull. However, there are a number of different ways in which this can happen because there are a large diversity of bitter-tasting molecules. Stimuli are of three general types. 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. Proprioceptors - near junction General Sense Organs between tendons and muscles. 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. covers outer layer of eye- closes to protect the eye and allow for sleep and rest. Such low frequency vibrations are sensed by mechanoreceptors called Merkel cells, also known as type I cutaneous mechanoreceptors. This will depolarize the hair cell membrane, triggering nerve impulses that travel down the afferent nerve fibers attached to the hair cells. The taste known as umami is often referred to as the savory taste. 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. The cone-shaped outer segments of the cone photoreceptor contain their photosensitive pigments in infoldings of the cell membrane. Ask anyone what the senses are, and they are likely to list the five major sensestaste, smell, touch, hearing, and sight. Rhodopsin, the photopigment in rods, is most sensitive to light at a wavelength of 498 nm. However, at the exact center of the retina is a small area known as the fovea. The unit of Hertz measures the frequency of sound waves in terms of cycles produced per second. This presentation introduces basic knowledge of cellular structure and function, and the organisation of the body as a whole, and then builds on this to develop a more detailed knowledge of the fine anatomy and physiology of the systems involved in energy metabolism. For example, when the superior rectus contracts, the eye rotates to look up. This bends the stereocilia either toward or away from the tallest member of each array. 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. The humors are fluids filling the anterior and posterior chambers of the eye. Other species and artificial technologies can detect other parts of this energy spectrum. When a photon hits retinal, the long hydrocarbon chain of the molecule is biochemically altered. The inner ear is often described as a bony labyrinth, as it is composed of a series of canals embedded within the temporal bone. Each of the hair cell clusters has a small collection of dense connective tissue attached to the hair cell membrane extensions (stereocilia) to add mass to the system. 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. Describing sensory function with the term sensation or perception is a deliberate distinction. Specific locations along the length of the duct encode specific frequencies, or pitches. Also, taste is often integrated as a perception with olfactory sensory input. Want to cite, share, or modify this book? All other colors fall between red and blue at various points along the wavelength scale. A sound wave causes the tympanic membrane to vibrate. The dorsal root contains only the axons of sensory neurons, whereas the ventral roots contain only the axons of the motor neurons. This process is called photoisomerization. There are temporary causes of anosmia, as well, such as those caused by inflammatory responses related to respiratory infections or allergies. The human sensory system is highly evolved and processes thousands of incoming messages simultaneously. Somatosensation is the group of sensory modalities that are associated with touch, proprioception, and interoception. Outer ear - from pinna (or auricle) to tympanum (also known as tympaninc membrane or eardrum). Until recently, only four tastes were recognized: sweet, salty, sour, and bitter. Receptor cells can be classified into types on the basis of three different criteria: cell type, position, and function. All of the other muscles are innervated by the oculomotor nerve, as is the levator palpebrae superioris. This is how certain smells trigger emotional memories, such as the smell of food associated with ones birthplace. Temperature receptors are stimulated when local temperatures differ from body temperature. 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). 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. A general sense is one that is distributed throughout the body and has receptor cells within the structures of other organs. Tilting the head causes the otolithic membrane to slide over the macula in the direction of gravity. Movements generate electrical signals in hair cells, which signal sensory neurons with released chemical neurotransmitters. What is anchored to this membrane so that they can be activated by movement of the fluids within the cochlea? Have your partner stand near the chart and tell you which line to read starting from the top. If you answered YES!, then you have the dominant genotype for the PTC gene! The sensory receptors detect the surroundings, like temperature changes and the central nervous system controls our body. Use a microscope to explore the cellular aspect of a taste bud. Salty taste is simply the perception of sodium ions (Na+) in the saliva. sucrose), Bitter (various, common test is Ca2+), sour (H+), and umami (glutamate). Prefrontal Constraints In Volleyball Each component of the motor control system is extremely dependent on the sensory The Somatosensory System Without moving your eyes off that word, notice that words at the beginning or end of the paragraph are not in focus. The afferences to the peri 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). Stimuli from varying sources, and of different types, are received and changed into the electrochemical signals of the nervous system. 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. Rotational movement of the head is encoded by the hair cells in the base of the semicircular canals. Many internal structures are delicate and tear easily such as the retina. The optic disk, the sight where ganglion cell axons exit the eye, does not contain photoreceptors. Bulbous corpuscles are also present in joint capsules, where they measure stretch in the components of the skeletal system within the joint. 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. 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. The nasal epithelium, including the olfactory cells, can be harmed by airborne toxic chemicals. We do not perceive the blind spot because the brain interpolates information to fill in the gaps. Some thermoreceptors are sensitive to just cold and others to just heat. are not subject to the Creative Commons license and may not be reproduced without the prior and express written 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. 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 the spinal nerve nears the spinal cord, it splits into dorsal and ventral roots. The complexity of the pressure waves is determined by the changes in amplitude and frequency of the sound waves entering the ear. Neurons responding to physical force, temperature, and specific chemicals to warn of (potential) damage. In many sensory organs, additional cells and tissues will contribute to the process of signal transduction. Middle ear - contains 3 ossicles, anchored between tympanum & oval window. Possible Specimens & Models for examination: (sheep or cow) eyeballs for dissection, microscope slides of the retina, and models of eyes. In this lab, we will explore the anatomy & physiology used for interpreting the environment both within and outside our bodies. A special sense is one that has a specific organ devoted to it, namely the eye, inner ear, tongue, or nose. When the stereocilia bend toward the tallest member of their array, tension in the protein tethers opens ion channels in the hair cell membrane. Sucrose and NaCl are common tests for sweet and salty. Using the plates are you able to detect the image present for the presented colors? HISTORICAL NOTE: The standard map of taste buds common in many lab manuals has been disproved by subsequent research (J. At the end of the auditory canal is the tympanic membrane, or ear drum, which vibrates after it is struck by sound waves. Sensory System f Sensory Organs (Receptors) Monitor the internal and external environment Transmit signals from periphery to CNS for processing Critical for homeostasis f Types of Sensory Receptors Functional Types Based on modality (type of environmental change they sense) 1. Resources Notes: Chapter 2: Tissues | Presentation Slides Inner ear Cochlea, which contains the hair cells (receptors) within the Organ of Corti. In other words, in a dark room, everything appears as a shade of gray. All of our muscles and organs depen. Golgi tendon organs similarly transduce the stretch levels of tendons. Write your acuity here: ____________________. honda rancher neutral switch location, pga tour putting stats from 3 feet, is lisa desjardins ill,

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