Nervous Systems And Sensory Organs

Nervous Systems And Sensory Organs You take a needle and prick your finger, your response is probably to get your finger away from the needlepoint quickly and maybe yell ouch. You take the same needle and poke a protist, sponge, cnidarian, or worm with it and they will all probably exhibit a similar response, at least they will all retreat. But how can this be possible? Protists are unicellular organisms that dont have a system to communicate after coming in contact with a stimulus. Similarly, sponges just sit on a rock all day, they also dont have any nervous functions. Cnidarians on the other hand have a nerve net, but how do they coordinate responses without a brain? All of these questions, along with how body plans relate to nervous system evolution, will be answered as this paper explores the evolution of the nervous system and sense organs from protists to the vertebrates. The Protists The classification of protozoans has been changed a lot through time. Cavalier-Smith (1993) came up with what he called the simplest definition of the kingdom Protozoa. They are eukaryotes, other than those that primitively lack mitochondria and peroxisomes, which lack the shared derived characters that define the higher derived kingdoms of Animalia, Fungi, and Plantae (Cavalier-Smith, 1993). Even though protozoans are simple unicellular organisms, they can still respond to many of the same stimuli higher order organisms respond too. Take for example that science class most students have. You put paramecium under a microscope and try to touch them with a probe, or watch their response to the light from the microscope. Most of the time when the anterior membrane of Paramecium is mechanically stimulated the ciliary power stroke reorients so the cell swims backwards, or retreats (Ogura Machemer, 1980). If the posterior membrane is stimulated the cilia beat towards the rear, causing the organism to move forward (Ogura Machemer, 1980). The light from the microscope can affect both the photoreceptors and thermoreceptors of the protists. The unicellular alga Euglena shows two regions of peak sensitivity to light during photokinesis at 465 nm and then again near 630 nm and during phototaxis 490-500 nm (Leys et al., 2002). Euglena is phototactic and its system consists of locomotory flagellum, an eyespot, and a photoreceptor (Gualtieri, 2001). As the organism moves, the eyespot senses the amount of light that reaches it and therefore pushes the Euglena in the direction of more light (Gualtieri, 2001). But moving towards light also means a change in temperature, especially if the light source is close to the organism. Paramecium cells are themo-sensitive and tend to accumulate at temperatures they were cultured at (Toyoda et al., 2009). They become used to their membrane fluidity at this temperature, and small temperatures changes drastically change this fluidity (Toyoda et al., 2001). If the temperatures change too much the Paramecium will retreat away from the heat in order to survive (Hennessey, Saimi, Kung, 1983). Protists also have chemosensory responses to certain odorants and tastes. Rodgers, Markle, and Hennessey (2008) found G-protein coupled receptors in the Paramecium. They tested whether Paramecium and Tetrahymena could respond to the common higher order organisms odorants and tastants (Rodgers, Markle, Hennessey, 2008). If they are affected by the odorants or tastants they will do an avoiding reaction, which can be seen when the organism is leaving an attractant or enters a repellent (Valentine, Yano, Van Houten, 2008). The Tetrahymena was more sensitive and could detect all of the tastants sampled, while Paramecium only detected four or the ten (Rodgers, Markle, Hennessey, 2008). Since Paramecium feed on bacteria Valentine, Yano, and Van Houten (2008) showed that they are attracted to bacterial metabolites such as, folate, acetate, glutamate, cyclic AMP, Biotin, and Ammonium. So an organism without a nervous system or sense organs has the ability to respond to many of the same env ironmental factors that higher order organisms respond too. Poriferia Similar to the protozoans, sponges lack definite body symmetry and also lack nerves and cell junctions, allowing no communication between cells (Leys et al., 2002). Sponges do respond to both light and mechanical stimuli. Recently, some sponges have been found to respond to light by contracting their cilia (Leys et al., 2002). Most larvae, via their cilia, are sensitive to light near 440 nm and again at 600 nm causing them to respond by straightening and bending (Leys et al., 2002). Although sponges lack neurons they are sedimentary feeders and therefore need ways of dealing with excessive particulates in their feeding currents (Tompkins-MacDonald Leys, 2008). Cellular sponges have the ability to close the openings to their incurrent canals, constrict the size of their intake canals, and even carry out a series of slow contractions that expel unwanted material (Tompkins-MacDonald Leys, 2008). The syncytial tissues of glass sponges allow action potentials initiated at single or mult iple sites to propagate through the entire animal, stopping the feeding current (Tompkins-MacDonald Leys, 2008). When Tompkins-MacDonald and Leys (2008) tested this response they found that by probing the interal body wall, allowing light to touch the outer body wall, or by knocking on the outer body wall pumping was stopped. This shows that a sponge, although not having an nerves or cell junctions can still respond to its environment. Cnidaria and Ctenophora Cnidaria and Ctenophora are the most basally branching lineages with specialized sense organs. The Cnidaria are radially symmetrical and have a nerve net where the sensor and ganglionic neurons and their processes are interspersed among the epithelial cells of both layers (Watanabe, Fujisawa, Holstein, 2009). Sensory structures that form part of epidermis are found in all animal phyla. Cnidarian neurons do not cluster to form a central nervous system or ganglia, which is why the nerve net is considered the simplest nervous system (Sarnat Netsky, 2002). In cnidarians sensory structures consist of naked sensory neurons whose dendrite is formed by a modified cilium (Jacobs et al., 2007). Sensilla are individual sensory neurons, or small groupings of sensory neurons, that typically function in one of the following; light detection, mechanoreception, and chemoreception (Jacobs et al., 2007). Photoreception and chemoreception involve G protein-coupled receptors (GPCRs) and membrane ion c hannels, similar to what was observed in the protists (Jacobs et al., 2007). Jacobs et al. (2007) believes that sense organs and kidneys in bilterians may have evolved from groupings of choanocytes in sponges. Cnidarian sense organs are usually associated with the free swimming form that resembles a jellyfish (Jacobs et al., 2007). Neural regionalization is most evident in the medusozoans that have rhopalia , an eye system with lenses (Watanabe, Fujisawa, Holstein, 2009). Other cnidarians contain simple eyes. A statocyst is a dense array of mechanosensory cells that serve as a touch plate (Jacob et al., 2007). In most cnidarians the rhopalia, sense organ, alternate with tentacles, appendages, similar to how vertebrates have organs associated with appendages (Jacobs et al., 2007). Photoreceptors responsible for contractions in Hydra in response to blue light at 470 nm, are consistent in spectral location and shape with a rhodopsin-based photoreceptive system (Leys et al., 2002). One of the newest findings deal with coral larvae and their exterior cilia being able to detect and respond to underwater sound fields (Vermeij et al., 2010). Vermeij et al. (2010) setup six chambers directed towards underwater speakers playing day and night reef sounds. Free-swimming coral larvae moved predominately towards the speakers independent of chamber orientation (Vermeij et al., 2010). This study was done because fish larvae used it as well. Platyhelminthes The flatworms have true bilateral symmetry (Reuter Gustafsson, 1995). Some flatworms have a nerve net like Cnidarians. Others have a central nervous system that consists of anterior ganglia, the brain, and one or several pairs of longitudinal nerve cords that are connected in a ladder-like configuration (Reuter Gustafsson, 1995). The peripheral nervous system is just a meshwork of nerves that are interconnected to the central nervous system (Reuter Gustafsson, 1995). Platyhelminthes has eyes, a light sensing organ, on the dorsal side of the body composed of two cell types: pigment cells and photoreceptor cells (Inoue et al., 2004). The pigment cells form an eye-cup while the visual neurons are located outside the eye-cup (Inoue et al., 2004). The eyes do not allow Planarians to see distinct images, but allows them to be repulsed by bright light, a condition known as negative phototrophism (Hyde, 2003). Not only does the head bear a pair of eyes, but a also a pair of ear-like lobes called auricles. Auricles have nothing to do with hearing; instead they are involved in mechanoreception, chemoreception, and pressure reception (Hyde, 2003). Nematodes Caenorhabditis elegans (C. elegans) has been established as a genetic and genomic model organism (Zhang, 2008). C. elegans does not have a visual or auditory system so it depends on chemosensation to detect bacteria to feed on (Zhang, 2008). C. elegans has exactly 302 neurons, 32 of which are chemosensory because they have ciliated endings that are directly exposed to their external environment (Troemel et al., 1995). Free-living nematodes use amphids and phasmids as sensory structures to seek food and avoid harmful situations, while parasitic nematodes use amphids to actively or passively see a host (Srinivasan, Durak, Sternberg, 2008). Amphids are either enclosed in the amphid sheath or exposed to the environment (Zhang, 2008). Ascaris lumbricoides (A. lumbricoides), a larger nematode, contains 298 neurons (Srinivasan, Durak, Sternberg, 2008). Each group of neurons reacts to certain stimuli. For example, some respond to salt (ASE chemosensory neurons), others respond to volatile al dehydes, ketones, and alcohols (AWC olfactory neurons), and yet others respond to chemical, mechanical, and osmotic stimuli (ASH neurons) (Srinivasan, Durak, Sternberg, 2008; Troemel et al., 1995). Mollusks, Annelids, and Arthropods There are three different nervous systems seen in mollusks alone. Bivalves tend to have no cephalization, while slowing moving mollusks have some cephalization, primary to connect senses and motor information while moving through the environment (Gregory, 2006). The cephalopods require complex sense organs and so they are highly cephalized Gregory, 2006). The cephalopods are known for their well-developed eye, that functions almost exactly like the human eye, which is why they such good eye sight (Oceanic Research Group, 2007). Annelids and Arthropods have repeating segments and an anterior brain. Each segment contains its own ganglion, which controls the muscles of that segment (Gregory, 2006). The nerve cord of both phylum runs directly through all of the segments (Gregory, 2006). These two were grouped together because they are very similar in function for being two different phyla. Vertebrates Amphioxous, part of the phylum chordata, are only capable of a few reflexive responses. They do not have the ability to recognize tactile stimuli, so all stimuli are interpreted as a threat and the organism curls away in defense (Sarnat Netsky, 2002). This reaction demonstrates how neurons that feel the stimuli on one side of the body are transmitted and affect motor neurons on the other side of the body (Sarnat Netsky, 2002). The neuron that served this function was known as the decussating interneuron (Sarnat Netsky, 2002). This is the underlying groundwork of the vertebrate nervous systems. Vertebrates have bilateral symmetry, complex sense organs and complex behaviors, requiring a very cephalized, complex nervous system. Vertebrates consist of two nervous systems, the Central and Peripheral. The central nervous system (CNS) contains the brain and spinal cord, while the peripheral nervous system (PNS) is composed of the nerves running through the body. The CNS has been conservative in its evolution, especially when looking at the senses of the vertebrates (Hodos Butler, 1997). The receptor types are either monopolar or pseudomonopolar neurons, each consist of parallel pathways connecting the receptors to the primary central neurons, which are located inside the sense organs where the stimuli is processed (Hodos Butler, 1997). Nerves are bundles of neurons, without cells bodies (Gregory, 2006). Most nerves contain both sensory and motor abilities (Gregory, 2006). There are both cranial and spinal nerves. There are multiple cranial nerves in all vertebrates, with humans having 12, and they are responsible for both sensory and motor information (Brown, 2003). The nerves are numbered using roman numerals from 1 to 12 (Brown, 2003). Brown (2003) described all of the following cranial nerves. Cranial nerve I is the olfactory nerve and it carries the sense of smell to the olfactory bulb of the brain. Cranial nerve II is the optic nerve and it carries visual information to the brain. Cranial nerve III is the oculomotor nerve and it provides motor ability to the four-extrinisic eye muscles, muscles of the upper eyelid, and intrinsic eye muscles. Cranial nerve IV is the trochlear nerve and it gives motor ability to the superior oblique eye muscle. Cranial nerve V is the trigeminal nerve and it provides sensory info rmation from the face, forehead, nasal cavity, tongue, gums and teeth. Cranial nerve VI is the abducens nerve gives motor ability to the lateral rectus muscle of the extrinisic eye. VII is the Facial nerve that provides humans with facial expressions. VIII is the vestibulocochlear nerve and it innervates the hair cell receptors of the inner ear. IX or the glossopharyngeal nerve moves the pharynx, soft palate, and posterior region of the tongue. X is the vagus nerve, it is the longest nerve, and provides sense transports from the ear to the taste buds to the throat. Cranial nerve XI is the spinal accessory nerve and it is involved in swallowing and powering muscle movement for the upper shoulders, head, and neck. Lastly, XII is the hypoglossal nerve and it moves the muscles of the tongue (Brown, 2003). As you can see the ability for control of all of these senses and movements makes for a very complex nervous, something that was never seen in earlier organisms. The spinal nerves are connected directly to the spinal cord by two roots, the dorsal (strictly sensory) and ventral (strictly motor) (Gregory, 2006). All of the above are seen in the PNS, which is then subdivided into the Somatic and Autonomic Nervous System. The Somatic Nervous System is the voluntary system, including all of the nerves that serve the skeletal muscles and exterior sense organs (Gregory, 2006). Reflexes are also seen in this nervous system. Just like in the lower organisms, vertebrates respond to stimuli. Except vertebrates have a much more complex stimulus-reflex system. Remember how a Paramecium came in contact with a stimulus and retreated until adaptation occurred? Vertebrates have the ability to think about coming in contact with a stimulus, they dont have to come in contact with everything they see because they have the somatic nervous system (Gregory, 2006). The other subdivision is the autonomic nervous system that is responsible for actions without conscious control; examples are heart beating and smooth muscle actions (Gregory, 2006). Everything in the PNS needs a place to send its information too and that is why there is the central nervous system. In the more primitive animals the brain, or ganglia, was there to simply send out reflexes to external stimuli (Gregory, 2006). The vertebrates have evolved a very complex brain because they have the ability to respond to reflexes, hold memory, learn, and think (Gregory, 2006). The brain has three divisions, the hindbrain, midbrain, and forebrain. The important portion when talking about senses is the midbrain because it receives sensory information and sends it to the forebrain to be processed (Gregory, 2006). In fishes and amphibians it is geared towards reflexes associated with visual input (Gregory, 2006). The cerebrum in reptiles, birds, and mammals receives sensory information and coordinates motor responses (Gregory, 2006). There are four lobes the frontal (motor functions), parietal (sensory receptors from skin), occipital (vision), and temporal (hearing and sm elling) (Gregory, 2006). Similar to decussating interneuron in Amphixous, vertebrates have the corpus callosum that contains neurons that cross from one side of the brain to the other, allowing communication between both sides (Gregory, 2006). Conclusion Bioluminescence is when luciferase catalyzes the oxidation of luciferin to excited oxyluciferin that then relaxes to produce a visible photon (Akilesh, 2000). The most common colors for bioluminescence are blue and green, although red and violet can be seen as well (Akilesh, 2000). Bioluminescence was developed in order to protect the organism. For example dinoflagellates flash their light during night or dark cycles to distract predators and reveal their predator to higher predators (Akilesh, 2000). Another example is the cookie-cutter shark, whose belly lights up, and is covered during the day by another organ. When the shark swims up in the waters its neck does not have the bioluminescence and so it appears to be a small fish and when bigger predators get close it attacks (Akilesh, 2000). Bioluminescence is seen more in aquatic organisms, probably because it is more beneficial to them in the mercy waters. This paper talked about the different phylum from protists all the way to vertebrates. Protists being unicellular and having no nervous system still had the ability to respond to many different kinds of environmental stimuli. Sponges have no symmetry and they are also able to respond to environmental stimuli, although usually larvae respond to more. Cnidarians have radial symmetry and therefore a corresponding nerve net, which helps them respond to environmental stimuli. Platelyhelminthes are the first to have bilateral symmetry and to go along with that their nervous system extends the length of its body, with centralization in the head, or anterior end. They also have to ganglia at the end of each nerve cord and the nerve cords are connected to allow both sides of the body to move together. The mollusks have a wide range of diversity in their nervous systems, ranging from nerve nets to highly cephalized cephalopods. The segmentation of annelids and arthropods allows each segment to be controlled individually but the nerve cord still runs through each segment. The vertebrates have the most evolved nervous system. This is because they have the ability to respond to stimuli, hold memory, learn, and think. This means that we dont have to come in contact with everything in the environment to understand it. The more complex a body plan becomes the more complex the corresponding nervous system becomes as well. A simple body plan doesnt have the room to house a huge brain, and therefore simple or no nervous systems are seen. Literature Cited Akilesh, S. (2000). Bioluminescence: Natures Bright Idea. Retrieved from: dujs.dartmouth.edu/2000S/06-Biolumen.pdf Brown, W. (2003). Cranial Nerves. Retrieved from http://www.pitt.edu/~anat/Neuro/CranialNerves/CN.htm Cavalier-Smith, T. (1993). Kingdom Protozoa and Its 18 Phyla. Microbiological Reviews, 57(4), 953-994 Gregory, M. (2006) The Nervous System: Organization, Overview of Nervous System in the Animal Kingdom [PDF document] Retrieved from Lecture Notes Online Web site: http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/bio%20102/bio%20102%20lectures/nervous%20system/nervous1.htm Gualtieri, P. (2001). Morphology of photoreceptor systems in microalgae. Micron, 411-426 Hennessey, T.M., Saimi, Y., and Kung, C. (1983). A heat-induced depolarization of Paramecium and its relationship to thermal avoidance behavior. J. Comp. Physiol., 153, 39-46 Hodos, W. and Butler, A.B. (1997). Evolution of Sensory Pathways in Vertebrates. Brain Behav Evol, 50, 189-197 Hyde, K. (2003). Chapter 6: The Flatworms. An Inside View of Animals: Zoology, 3rd ed., 121. Inoue, T., Kumanoto, H., Okamoto, K., Umesono, Y., Sakai, M., Alvarado, A.S., and Agata, K. (2004). Morphological and Functional Recovery of the Planarian Photosensing System during Head Regeneration. Zoological Science, 21, 275-283. Jacobs, D.K., Nakanishi, N., Yuan, D., Camara, A., Nichols, S.A., and Hartenstein, V. (2007). Evolution of sensory structures in basal metazoa. Integrative and Comparative Biology, 47(5), 712-723 Leys, S.P, Cronin, T.W., Degnan, B.M., and Marshall, J.N. (2002). Spectral sensitivity in a sponge larva. J Comp Physiol A, 188, 199-202 Oceanic Reasearch Group. (2007). The Wonders of the sea: The snail and its relatives. Retrieved from http://www.oceanicresearch.org/education/wonders/mollusk.html Ogura, A., and Machemer, H. (1980). Distribution of Mechanoreceptor Channels in the Paramecium surface membrane. J. Comp. Physiol., 135, 233-242 Reuter, M., and Gustafsson, M.K.S. (1995). The flatworm nervous system: Pattern and phylogeny. The Nervous System of Invertebrates: An evolutionary and comparative approach. Pg.25-59. Rodgers, L.F., Markle, K.L, and Hennessey, T.M. (2008). Responses of the Ciliates Tetrahymena and Paramecium to Vertebrate Odorants and Tastants. J. Eukaryot. Mircobiol., 55(1), 27-33. Sarnat, H.B., and Netsky, M.G. (2002). When Does a Ganglion Become a Brain? Evolutionary Origin of the Central Nervous System. Seminars in Pediatric Neurology, 9(4), 240-253 Srinivasan, J., Durak, O., and Strenberg, P.W. (2008). Evolution of a polymodal sensory response network. BMC Biology, 6(52), 1-15 Thompkins-MacDonald, G.J., and Leys, S.P. (2008). Glass sponges arrest pumping in response to sediment: implications for the physiology of the hexactinellid conduction system. Mar Biol,154,973-984 Toyoda, T., Hiramatsu, Y., Sasaki, T., Nakaoka, Y. (2009). Thermo-sensitive response based on the membrane fluidity adaptation in Paramecium multimicronucleatum. The Journal of Experimental Biology, 212, 2767-2772 Troemel, E.R., Chou, J.H., Dwyer, N.D., Colbert, H.A., and Bargmann, C.I. (1995). Divergent Seven transmembrane receptors are candidate chemosensory receptors in C. elegans. Cell, 83, 207-218 Valentine, M., Yano, J., and Van Houten, J.L. (2008). Chemosensory Transduction in Paramecium. Jpn. J. Protozool., 41(1) Vermeij, M.J.A., Marhaver, K.L., Huijbers, C.M., Nagelkerken, I., Simpson, S.D. (2010). Coral Larvae move towards reef sounds. PLoS One, 5(5) Watanabe, H., Fujisawa, T., and Holstein, T.W. (2009). Cnidarians and the evolutionary origin of the nervous system. Develop. Growth Differ., 51, 167-183 Zhang, Y. (2008). Neuronal mechanisms of Caenorhabditis elegans and pathogenic bacteria interactions. Current Opinion in Microbiology, 11, 257-261

Reading Books Essay

Reading a book is one of the best forms of entertainment a person can have. Books can take you places to a time and lifestyle that you will never visit or experience. I remember the old show called â€Å"Reading Rainbow† and it lyrics were gave a very interesting take on books they went like this: â€Å"I can twice as high take a look, it’s in a book A Reading Rainbow, I can go anywhere, Friends to know and ways to grow, Reading Rainbow, I can be anything take a look it’s in a book.† Those lyrics are so true. Reading a book you can read about how life was in the 1700’s up until our generation today. I could be a detective who solves a famous mystery or I could be the killer trying to get away. I can learn to speak another language. There are so many things and topics in reading a book that can change your appearance, your political viewpoints, and change your attitude. Some say that books might become obsolete because movies are made from these books and you can watch the movies in two hours. Watching the movies a person feels that you can get the plot and conclusion of the book in two hours. This is true but for example if it is true life story the movie are going to change some parts of the books to make it more enjoyable, whereas the book is going to give you every detail the author wants you to have. Books gives people a conversation piece just like a movie but the only difference is books can join the world. Movies can’t be seen in some countries but a book can be read. So like the Reading Rainbow says â€Å"take a look it’s in a book†. So in conclusion reading a book is the best form of entertainment. Stephanie C. Williams November 20, 2010

Cultural Artifact Essay †Blue Jeans Essay

Blue jeans in the last thirty years have attained such world wide popularity that they have come to be considered an American icon. However jeans have not always been held in high stead, but rather have had a troubled history including its beginnings within the working class movement, being considered unsavory by religious leaders and also seen as a rebellious statement about ‘western decadence’. According to the University of Toronto, no other garment has served as an example of status ambivalence and ambiguity than blue jeans in the history of fashion. Throughout this essay I will discuss how jeans have become such a common treasured and even expensive item crossing over class, gender, age, regional, and national lines as reflected by the many changing political views and acceptance from various social classes over the past 50 years. History of Blue Jeans According to the University of Toronto, blue jeans were originally created for the California coal miners in the mid-nineteenth century by the Morris Levi Strauss, a Bavarian immigrant who relocated to New York in 1847. Mr Strauss’ fate and the history of clothing changed forever when in 1872 he received an offer from Jacob Davis, a tailor from Reno Nevada. Mr. Davis, in order to improve the durability of the pants that he made for his clients, had been adding metal rivets to the highly stressed seams. The idea was successful and he wished to patent it, but due to financial constraints required a partner and hence Levi became the financial backer and partner. In 1873, the new partners received a patent for â€Å"an improvement in Fastening Pocket-Openings†, and thus the history of blue jeans as we know them began. Blue jeans were originally called â€Å"waist overalls† by Levi Strauss and Co and in the 1920’s these were the most widely used worker’s pants in America. The name of these trousers changed to â€Å"jeans† in the 1960’s when Levi Strauss and Co. recognized that this was what the product was being called by the young, hip teenage boys. The history of â€Å"waist overalls† continues as the history of blue jeans. â€Å"Jeans† is now generally understood to refer to pants made out of a specific type of fabric called â€Å"denim† (Fashion Encyclopedia). Blue Jeans through the decades The popularity of blue jeans spread among working people, such as farmers and the ranchers of the American West. According to the Encyclopedia of Fashion, in the 1930’s jeans became so popular among cowboys that Wrangler formed just to make denim work clothing for those who rode the range. Jeans have tended to follow along in popularity with popular culture as evident with the popular Western films which found adventure and romance in the adventures of the cowboys who rode horses, shot bad guys, and wore blue jeans. Those who wished to imitate the casual, rugged look of the cowboys they saw in films began to wear jeans as casual wear (Fashion Encyclopedia). This effect is not hard to understand, as even today fashion trends are greatly influenced by what highly publicized celebrities choose to wear. During World War II blue jeans became part of the official uniform of the Navy and Coast Guard, and became even more popular when worn as off-duty leisure clothing by many other soldiers. In his book, â€Å"Jeans: A Cultural History of an American Icon†, James Sullivan states that the rise of the popularity of jeans after the WWII can greatly be attributed to the influence of the film and music industry, during the 1950s many young people began to wear jeans when they saw them on rebellious young American film stars such as Marlon Brando and James Dean. By 1950, Levi’s began selling nationally and other brands started emerging, such as Lee Coopers and each with its own particular fit (Sullivan 287). According to the University of Toronto, in the 1960’s and 1970’s jeans were embraced by the nonconformist hippie youth movement, and the history of blue jeans even gets linked to the downfall of communism. Behind the iron curtain, jeans became a symbol of â€Å"western decadence† and individuality and as such were highly sought. Jeans had become extremely popular, but were still mainly worn by working people or the young. In the 1980’s through to the 1990’s jeans were no longer seen as rebellious or a source of individuality, but they were transformed as the term ‘designer jeans’ was discovered. Many designers such as Jordache and Calvin Klein came on board to create expensive jeans and some jeans even reached haute couture status (Fashion Encyclopedia). In the new millennium denim is seen on designer catwalks and there are now hundreds of styles, types and labels available and of various price ranges. Changing Popularity According to Peter Beagle in his book â€Å"American Denim: A New Folk Art†, the popularity of jeans can be attributed to the fact that jeans can be seen to embrace the American democratic values of independence, freedom and equality. Some Americans even consider jeans to be the national uniform. Blue jeans have evolved from a garment associated exclusively with hard work to one associated with leisure. What began as work clothes has transformed into one of the â€Å"hottest† items available on the consumer market today. What was once apparel associated with low culture has undergone a reversal in status. Blue jeans were the first to accomplish a rather revolutionary cultural achievement bringing upper class status to a lower class garment. Conclusion At one point or another throughout history, blue jeans have been the uniform of many groups and are considered the one garment of clothing that has remained hip for over a century and has survived everything from World War II to the eighties. For half a century blue jeans have helped define every youth movement, and every effort of older generations to deny the passing of youth. Fifty years ago America invented the concept of teenager, and it is probably no coincidence that the enduring character of blue jeans, claiming independence and the right to self-expression, can be traced to the same time. Jeans were once seen as clothing for minority groups such as workers, hippies or rebellious youth, but are now embraced by the dominant American culture as a whole. Works Cited â€Å"Material Culture†. Utoronto. ca. University of Toronto Department of History, University of Toronto, n. d. Web â€Å"European Culture 19th Century – Blue Jeans†. Fashionencyclopedia. com. Fashion Encyclopedia, Advameg, June 2010. Web. â€Å"Modern World 1980 – 2003, Designer Jeans†. Fashionencyclopedia. com. Fashion Encyclopedia, Advameg, June 2010. Web. Sullivan, James. Jeans: A Cultural History of an American Icon. New York: Penguin, 2007. Print. George, Diana and Trimbur, John. Reading Culture: Contexts for critical reading and writing. New York: Longman, 2007. Print. Beagle, Peter. American Denim: A New Folk Art. New York: Harry N. Abrams, 1975. Print.

The Marketing Opportunities and Threats Posed by the Growing Importance of Socially Conscious Consumer Free Essay Example, 5500 words

Basically setting of prices is an effective and critical stage for every management. It involves many factors to be considered to set the final price of the product. From the sales point of view, the manager has to set a competitive price through which they can earn more profit. The ratio of sales increases and they can compete well in the market. Whereas accountants are reviewing the prices to effectively reduce the cost in order to have high-profit margins. All these factors are considered to set the prices. From my point of view, the accountant's point is valid. the prices are set in such a way to earn maximum profit. Whereas I totally agree with the sales manager s point of view, is to set competitive prices to excel in the market. The sales managers can play a drastic role in price setting. The prices of the products are such which brings high yield and simultaneously gets high sales from the market. The price setting process also considers the point on which the consumer has t o pay indirectly the sales tax. We will write a custom essay sample on The Marketing Opportunities and Threats Posed by the Growing Importance of Socially Conscious Consumer or any topic specifically for you Only $17.96 $11.86/page There are many factors which can gain bad publicity for the company. It could be because of some dissatisfied employees, or customers, due to some accidents or some mishap at the factory area. It could be anything which costs heavily to the company. The competitors takes advantage of such incidents and the financial effect are adverse in such cases. The share price of many companies in such situations falls rapidly. Whatever the case may be which results in bad publicity. The key is how to handle the situation. Most of the companies avoid having public dealing or meeting which creates a negative impression in such a situation.