General Sense Organs of the Body - Research Paper Example

General Sense Organs of the body Sense Organs are ified as general sense organs or special sense organs. General sense organs are specialized with localized receptors in the body that consists of free nerve endings and encapsulated nerve endings. These sensory receptors help the human organism to respond to stimuli. Free nerve endings include epithelial layers while the encapsulated nerve endings include dermal layers, subcutaneous tissue, and skeletal muscles. The eye, ear, nose, and taste buds are all a part of special sense organs. General Sense Organ Receptors of the general sense organs are found in most every part of the body. These receptors detect changes or stimuli and generate impulses. Stimulation of some receptors results to the sensation of heat or cold while stimulation of others gives the sensation of pain or pressure. Sanders and Scanlon (2007) published on their book that the dermis of the skin and the subcutaneous tissue comprise receptors for the sensations of touch, pressure, heat, cold, and pain. They further discussed the receptor for each different sensation. The sensory receptors for pain, heat, and cold are free nerve endings. This refers to the terminal ends of nerve fibers in the skin. They are found in almost every tissue of the body and reach into the lower layers of the epidermis (Kahle & Frotscher, 2003). They react to any intense stimulus. For instance, extreme pressure may be recognized as pain. Likewise, the receptors for touch and pressure are encapsulated nerve endings. They signify that there is a cellular structure around the nerve ending. The Color Atlas and Textbook of Human Anatomy further explained about the encapsulated nerve endings that lie in the papillae of the dermis. They are most densely to be found in the surfaces of the hands and feet. “The purpose of these receptors and sensations is to provide the central nervous system with information about the external environment and its effect on the skin. This information may stimulate responses, such as washing a painful cut finger, scratching an insect bite, or responding to a feeling of cold by putting on a sweater” (Sanders & Scanlon, 2007). Sensation is actually a function of the brain. When receptors detect changes, they generate nerve impulses that are carried to the brain, which interprets the impulses as a particular sensation. Special Sense Organ Special senses are typically associated with the collection of highly specialized and localized sensory receptors. It has extensive neural pathways. The special sense organs are the eye (sight), ear (hearing and balance), nose (smell), and taste buds (taste). On the book Atlas of the Sensory Organs, Csillag (2005) discuss briefly the structure and function of these special sense organs. Our eyes let us see the world around us. Lack of eyesight can deprive a person the joy of living life. The eye is an important organ in the body and is situated in the eyesockets of the skull. There are three primary layers of the eye: the sclera, the choroid, and retina. The sclera is the tough, outermost, white layer that surrounds and protects the eye. Cornea, its front surface, is transparent to let light enter the eye. The choroid coat is the middle layer of the eye that consists of the iris, the colored portion of the eye. The iris has a hole in its center called the pupil. Light enters through the pupil, and the size of the pupil is regulated by the iris. The lens of the eye lies directly behind the pupil and it is held in place by ciliary muscles. It focuses images. The retina is the innermost layer of the eye. It is a thin layer of light sensitive cells at the back of the eye. It contains microscopic structures called rods, which enable us to see in dim light, and cones, which enable us to see color. Aqueous humor and vitreous humor are fluids that fill the hollow inside of the eyeball, thus giving it shape. Interestingly, the human eye can be measured up to a camera which collects, focuses, and transmits light through a lens to create an image of the environment. In a camera, the image is created on film whereas in the eye, the image is created on the retina. The lens of the eye refracts light that enters the eye. On the other hand, the cornea also contributes to focusing light on the retina. Nerve fibers extending back from the retinas nerve cells come together behind the retina to form the optic nerve, a cable of nerve fibers connecting the eye with the brain. The optic nerve transmits messages about what we see from the eye to the brain. Like a camera, the human eye controls the amount of light that enters the eye through the lens under various lighting conditions. The ear is an organ for hearing and equilibrium. It is in charge of collecting sounds, processing them, and sending sound signals to the brain. It also helps keep the balance. The ear is divided into three parts: the external ear, the middle ear, and the internal ear. The external ear is made up of a fleshy flap called the pinna and a curved tube called the ear canal. The middle ear contains three small moveable bones called the malleus, incus, and stapes. The tympanic membrane, or eardrum, separates the middle ear from the external ear canal. The inner ear is further made up of bones and membranes. It is divided into three parts: vestibule, semicircular canals, and cochlea. The sense organ of hearing, called the organ of Corti, lies inside the cochlea. It is stimulated by vibrations that have reached the inner ear from the outside environment. The specialized mechanoreceptors for balance and equilibrium are located in the three semicircular canals and the vestibule. Various researches show that the ear plays a part in the distribution of tension and relaxation. In the regulating circuit of the movement processes, the brain gives the order to the muscles to move and when they are carrying out these orders, the muscles are controlled by the organ of balance in the ear. In this way our ear also determines our body’s tension profile – that is the distribution of the different states of tension and relaxation in the different parts of our body. Taste sensation is a form of chemical sense, specialized for the detection of compounds dissolved in the saliva (Csillag, 2005). Taste is produced by the stimulation by various substances of the taste buds on the mucous membrane of the tongue. The book Atlas of Sensory Organs reveals some facts about the sense of taste. It acknowledged that the taste is just one specific type of visceral sensation that is particularly relevant to food ingestion. Taste signals trigger a host of behavioral and autonomic responses, appetitive or aversive, most of which are visceral reflexes (salivation, gastrointestinal activation, swallowing, gagging, vomiting), or patterns of involuntary locomotor activity (orofacial movements, disgust responses). When eating something, the saliva in the mouth helps break down the food. This causes the receptor cells located in the tastes buds to send messages through sensory nerves to the brain. The brain then informs what flavors you are being tasted. We are quite familiar of the taste receptors like sweet, sour, salty and bitter. Taste buds play an important part in helping man enjoy the many flavors of food. Identifying tastes is the brains way of telling about whats going into the mouth. Once the brain sort out the nerve impulses, it recognized the taste as a good or dangerous one, which then gives its instructions whether to eat or not. Humans breathe through the nose and smell through the nose. The sense of smell and that of taste work closely as one.  Any food has a smell and a taste and the tongue and the nose come together to give the flavor of a particular food. The sense of smell actually helps to recognize tastes. Specialized receptor cells of the olfactory epithelium detect smells. It lies in the mucosa of the upper part of the nasal cavity. Olfactory sensation belongs to the chemical senses, in particular for the detection of volatile molecules that are traveling freely in the atmosphere. These receptors are stimulated by odor-causing chemicals in the environment. Olfactory nerve picks up the scents from the air being breathe and translate them into nerve impulses or messages that are then sent to the brain. The role of smell is as important to our well-being and to our life as any other part of our body and is equally important as all other senses. The process of recognition of a place is accomplished by our sense of smell. Smell call to mind emotions such as fear, contentment, even sexuality. It can also influence mood, physical well-being, memory, emotions and sexual desire. That is why we feel at ease with soothing, familiar smells, get turned on sexually with sensual perfume smells, and get upset and uneasy with foul or harsh smells. The eyes, the ears, the nose, the taste buds, and the skin constantly receive sensory stimulation from our surroundings, which they then convert into electrical impulses in their sensory cells and pass on to the brain. They provide information about the outside world. Thus, in our brain, no pictures, no sound, no smells, no taste and no touch are encountered, just electrical impulses which only become our sensory experiences through diverse processing steps taking place in our brain. In this way, our brain receives a constant flow of bioelectrical energy from our sensory organs, without which it is unable to function correctly. Whether the organisms are big or small, they have to know the changes in their surroundings. This is essential for their survival. There are so many mechanisms for this. Fishes and crabs have separate receptors to receive different stimuli. Crickets receive sound waves through pores in its legs. Though the snakes lack external ear it has certain parts in the ear which can recognize sound waves. Researches on human sensory organs acknowledged that sharpness definitely starts with the senses. The eyes, ears, and other sensory organs constantly send information to the brain. The brain, in turn, uses this information to construct experiences and memories. We would not know of anything if it were not for our sense organs. We would not even know of ourselves. We would not walk, find out anything, do anything, eat, drink, or live. Through various research conducted, we knew a lot as to how our body parts function and what it do for us. We are sensitive to the world around us. We can feel when it is cold or warm. We can identify where we are and what is around us. We can recognize people and identify their voices. If fact we are receiving stimuli from the external world every second, awake or asleep, and we have the capability of interpreting these stimuli to derive useful information from them. The sense of sight, hearing, touch, smell, and taste provide us with the sensation of the external world. We already know we have a special organ associated with each sense. What we sometimes don’t know is to take care of them. Sanders, T., & Scanlon, V. (2007). Essentials of Anatomy and Physiology (5th ed.). Philadelphia: F. A. Davis Company. Csillag, A. (2005). Atlas of Sensory Organs. New Jersey: Humana Press. Kahle, W. & Frotscher, M. (2003). Color Atlas of Human Anatomy: Nervous System and Sensory Organs (Vol. 3). New York: Thieme. Read More