Inhibitory Or Excitatory Potential Changes :: Biology Biological Papers

Inhibitory Or Excitatory Potential Changes Graded potentials can be either hyperpolarizations (inhibitory) or depolarizations (excitatory). Inhibitory postsynaptic potential, also referred to as IPSP, is the temporary hyperpolarization of a membrane. An inhibitory postsynaptic potential occurs when synaptic input selectively opens the gates for potassium ions to exit the cell (carrying a positive charge with them) or for the chloride ions to enter the cell (carrying a negative charge with them). Inhibition is not just the absence of excitation, it is an active brake that is able to suppress the excitatory responses from occurring (Kalat, 2004). Excitatory postsynaptic potential, also known as EPSP, is a graded depolarization. As a result of sodium ions enter the cell, excitatory postsynaptic potential occurs. As a result of the synaptic activation, the sodium gates open, allowing an increase in the flow of sodium ions crossing the membrane. Excitatory postsynaptic potential is a subthreshold event that decays over space and time, meaning its magnitude decreases as it travels along the membrane (Kalat, 2004). Lithium has both inhibitory and excitatory features. Evidence has shown that lithium alters sodium transportation (http://www.mentalhealth.com). In the extracelluar fluid lithium may replace sodium. During the process of depolarization lithium has an extremely rapid intracellular influx. Although, it is not effectively removed by the sodium-potassium pump. According to Kalat (2004) the sodium-potassium pump, "[is] a protein complex that repeatedly transports three sodium ions out of the cell while drawing two potassium ions into the cell" (p. 41). As a result, it prevents the cellular reentry of potassium. This interferes with the electrolyte distribution across the neuronal membrane, resulting in a decrease in the membrane potential, changes in conduction and neuronal excitability. As measured by cortical evoked potential, for humans lithium alters the excitability of the central nervous system (http://www.mentalhealth.com). Lithium enhances the uptake of norepinephrine and serotonin into the synaptosomes, thus reducing their action. Lithium also reduces the release of norepinephrine from synaptic vesicles and inhibits production of cAMP. "Lithium inhibits the synthesis of cAMP by the adenylyl cyclase in many brain regions, including the cerebral cortex, caudate, and hippocampus, but not the brain stem or cerebellum" (Feldman, Meyer & Quenzer, 1997). "The inhibitory action of lithium on NE-sensitive adenylyl cyclase is a consistent finding, but lithium clearly has distinctive effects on the adenylyl cyclase that is coupled with receptors

Accepting Ones Heritage in Everyday Use

Accepting Ones Heritage in Everyday Use Ember Eslinger February 24, 2010 English219-M Essay 1 Individuals’ identities are formed and moulded by how he or she chooses to accept and preserve their culture. One might believe that it is important to have the chance to pass down the stories of their past and the significance of their family treasures. Another opinion one might have in saving one’s heritage may be simply possessing family heirlooms. This paper focuses on the importance of experiencing people’s heritage and being proud of it; despite hardships and stereotypes.In the short story â€Å"Everyday Use† by Alice Walker it is evident that the antagonist is interested in preserving her heritage for the wrong reasons. Common sense seems to dictate that Mama is more sympathetic towards Maggie because they have more in common and share the respect for their heritage. Some critics believe that Mama possibly favours Maggie when it comes to the admiration and respect of their heritage. Even though Dee claims she’s become more knowledgeable about her African-American culture, Mama doesn’t believe that her heart is in it.It’s almost as if she has shed her identity to satisfy this mistaken image that’s imbedded in her head of what being true to her African-American culture is all about. When Mama realizes the only reason Dee came home was to claim their family’s old quilts so she could hang them on the wall, Mama becomes resentful and disappointed towards her for not valuing the sentimentality behind her family’s heirlooms. Having the quilts hang on the wall of her house for everyone to see is essentially a reminder of her superior social and economic status.Mama believes Dee is ignorant and naive towards her own inheritance. By conforming to the white Americans view of the African-American traditions she’s cheating herself out of both cultures. She’s both and neither at the same time. Although Walker does not directly state, Dee’s character seems ashamed of how Mama and Maggie live their lives. The short story supports the fact that Mama puts her foot down when Dee tries to take the quilts even though they were promised to Maggie.When Maggie tries to willingly allow Dee to take the quilts Mama steps in and insists Dee take some of the other ones. Some might believe Mama is unfair when it comes to her daughters, when really she’s handling the situation as her mother and grandmother would have handled it, supporting her idea of preserving heritage. Maggie, the younger of the two daughters, is covered in scars from when their old house went up in flames. The scars symbolize the almost uncomfortable state in which Maggie lives. Although she is content with what she has, she will probably never have more.Her quiet, withdrawn character helps readers see the contrast between the two sisters. Similarly their complete opposite views of their heritage. Dee h as a superficial idea of her heritage and prefers appearance over substance; how things appear on the outside, rather than the in depth meaning. Maggie on the other hand has respect for and is very aware of where she came from. Evidence from the text supports the idea that Maggie knew a great deal more than Dee about the significance of many family heirlooms.Like Mama, Maggie is able to take pride in the practical aspects of her nature and their lack of education does not prevent them from appreciating their heritage and those who came before them. Maggie values the importance of experiencing her heritage rather than putting in on display. She’s an utilitarian whose everyday use of the quilts remind her of her family ties and especially of her Grandma Dee. Because Mama and Maggie share not only cultural beliefs but also physical attributes Walker makes it clear that Mama is able to better relate with Maggie over Dee.Along with accusing Mama of not understanding her own herita ge, Dee furiously states that â€Å"‘Maggie can’t appreciate these quilts! She’d probably be backward enough to put them to everyday use. ’† (Walker 253) Unfortunately for Dee, Mama sides with Maggie in hope that she would use them. Earlier in the story, Dee tries to prove her knowledge about the quilts but she only states how they were made from pieces of dresses her Grandma used to wear, nothing about either Grandpas clothing scraps.She finished her argument with what she thought was a strong statement about how they were all stitched by hand by her Grandma Dee, when in fact Mama and Big Dee also helped create the works of art. To Mama the quilts have a deeper meaning. When she moves up to touch the quilts, she is reaching out to touch the people whom the quilts represent. Mama is more willing to pass down the quilts to Maggie because she believes Maggie is able to make the same connection as she does to the quilts.Mama and Maggie are able share t he belief that the true meaning behind every family heirloom comes from the memories in which that item has made, so even when the object is no more, the memories are still able to live on through one’s bequest. In this short story, Walker indirectly focuses on the fact that Maggie is following in Mama’s footsteps and that it is very likely that she will lead the same lifestyle as Mama has. If one is able to take the time to recognize the recollections of the past through family heirlooms, he or she will more likely be able to understand and value their heritage.In conclusion this paper goes in depth about being true to ones heritage, furthermore, being true to oneself. When it comes to the topic of heritage, most of us will willingly agree that it takes more than knowledge of one’s grandparents’ names and a couple of old quilts to show ones passion and sentiment. In this case, Dee seems content with how she has decided to accept and portray her own herit age whereas most people, including Mama and Maggie, are on the opposite side of the spectrum since they believe it is more important to view your heritage as your entire lives experiences.When it is said that Mama is more sympathetic towards Maggie it is merely stating With that said, to actually have the personal satisfaction of being part of one’s heritage, they first need to accept their own purities and faults. Once you are able to do so, recognizing oneself as a part of one’s heritage should surge naturally.Works Cited Walker, Alice. â€Å"Everyday Use. † Making Arguments about Literature: A Compact Guide and Anthology. Ed. John Schilb and John Clifford. Boston: Bedford/St. Martin’s. 2005. 247-253.

Is Gender Identity the Result of Biology - 946 Words

Human beings are born sexual. They develop a strong sense of being male and female, the human behaviour of being a man or a woman is called gender identity. The characteristics of being a man or a woman involve biological, psychological, and sociological factors. People from all cultures have acted in relationships in different ways that are influenced by their cultural traditions and laws about sex. Human sexuality and how males and females act within the relationship can be considered as physically influenced by biology, for example hormones, brain centres, networks of nerves, and sex organs all shape the character of the male and female. However there are various arguments to this. hjwatson24, please do not redistribute this paper.†¦show more content†¦They state that hormones are linked to the activity of the brain, which can influence the nervous system, which can in turn influence behaviour, personality and emotions. This has been tested through animal experimentation. Some studies showed a link between testerone levels in human males and aggression. Others showed how castrated male rats tend to fight less, while female rats given extra hormones are more aggressive in life than those who have not been given them. This has been criticised by Ruth Bleier (1984), who states that there are numerous flaws in animal experiments, because it would be dangerous to assume that humans behave exactly like animals, furthermore the experiments that were carried out where under un-natural circumstances (laboratory conditions). Anne Oakly agrees with this argument and backs up the criticism of the hormonal explanations by referring to a study she carried out consisting of a boy who underwent an operation at seven months so that she took on the appearance of a girl. At seventeen months old her name was changed from a boy to a girl and later she was dressed in girls clothes. Afterwards her mother commented on how feminine she had become. This strongly suggests that it is environmental influences that have changed her behaviour and not biological matters, because no changes to hormones in the brain were made. ThereShow MoreRelatedGender And Sex Are Kindred, But They re Not1418 Words   |  6 Pages Most people believe gender and sex are kindred, but they’re not. There is a difference between gender and sex. According to OpenStax, â€Å"Sex is how society classifies a person’s genetic and biological anatomy. Gender is how an individual views their identity, regardless of sex. Sex is biological in nature and determines one s biological destiny. Gender, on the other hand, helps define one s role within society†. 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