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The K+ Channel, A New Hope For a Better Understanding
The axons of our neurons are the pathway for the communication that exists in our nervous system. This communication takes the form of an electric signal, also called an action potential. The action potential occurs due to a change in voltage across the membrane of the axon. The change in voltage is achieved by a change in the concentrations of the ions, Na+, Ca+, and K+(1) . The cell starts with a large concentration of potassium ions, K+, inside the cell, and a large concentration of sodium ions, Na+, outside the cell. The action potential propagates down the axon due to openings and closing of different channels allowing changing of the concentrations of the ions(10).
Channels are proteins that span the membrane of the axon. These proteins have a structure so that they can be allow ions to flow through pores that are only open at the appropriate times. Some of the channels are opened and closed by other chemicals, while some are initiated by a change in the membrane potential.
This particular K+ channel, which is greatly studied, is a voltage-gated channel. This means that the channel opens in response to a certain voltage difference that occurs across the membrane. The channel is closed when the cell is at rest. Following inactivation the channel opens via a complicated mechanism, which scientists are still trying to decipher(7)(8). The specific voltage is that which occurs after the Na+ channel has opened and allowed a significant amount of Na+ to be released from the cell. So, the K+ channel is induced to an open state by a depolarization of the membrane potential. The K+ channel opens at the beginning of the repolarization, or after the depolarization has alm...
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6)Reconstructing Voltage Sensor-Pore Interaction from a Fluorescence Scan of a Voltage-Gated K+ Channel
http://serendip.brynmawr.edu/bb/neuro/neuro02/web1/www.neuron.org/cgi/content/reprint/27/3/585
7)Tight Steric Closure at the Intracellular Activation Gate of a Voltage-Gated K+ Channel.
http://serendip.brynmawr.edu/bb/neuro/neuro02/web1/www.neuron.org/cgi/content/full/32/4/649
8)The Polar T1 Interface Is Linked to Conformational. Changes that Open the Voltage-Gated Potassium Channel
http://www.cell.com/content/article/abstract?uid=PIIS009286740000088X
9)Visual of the K+ Channel
http://www.neuron.org/content/article/abstract?uid=PIIS0896627300809046&imageid=GR1
10)Lights, Camera, Action Potential, A site made for children that has great descriptions and visuals of an action potential.
http://faculty.washington.edu/chudler/ap.html
Scientists are stumped as to the development and nature of proteinaceous infectious particles. Neither virus nor bacteria, these prions, are believed to cause transmissible spongiform encephalopathies (TSE), rare diseases said to be 100% fatal, without possessing nucleic acids. Their unhindered growth is thought to be the cause for bovine spongiform encephalopathy (BSE), or Mad Cow Disease, Creutzfeldt-Jakob (CJD), scrapie and other TSE, diseases characterized by the brain microscopically turning into sponge-like matter. There are no cures or effective treatments available today because drawbacks constantly prevent the development of efficient therapy. Studies continue to slowly progress, hoping to find methods to immunize against more prion diseases.
5) Gated channels are used to facilitate the movement of molecules from one side of a membrane to another and are necessary for facilitated diffusion. A gated channel can be open, closed, or in an intermediate state, and are controlled by change in membrane voltage, and differs from active by not requiring additional ATP for movement like active transport. Gated channels are exactly what they sound like, a channel that is controlled by a gate or regulator that will allow the movement of specific molecules in and out of cells. Gated channel facilitated diffusion relies on channel proteins, that form hydrophilic channels which allow the movement water and piggybacking ions through a membrane. An example of a gated channel is the importation of
In examining Washington Irving’s “The Legend of Sleepy Hollow” alongside Tim Burton’s film adaption of the story, titled “Sleepy Hollow,” a number of fascinating similarities and differences emerge. Though elements of the characters and settings of Burton’s film borrow heavily from Irving’s text, the overall structuring of the film is significantly different, and representations of various elements are crucially re-imagined. Tim Burton’s “Sleepy Hollow” was released on November 19, 1999, a few months before the new millennium. Set in 1799, Burton’s film modifies the 1790 date that Irving’s text is set in, showing an acute concern with living out anxieties surrounding millennial change in the ‘safe’ formats of film and of established folk legend. Irving’s tale, written in 1820, also works with antiquity, but in a different manner: it lives out colonial cultural anxieties of Irving’s present, as he seems to be concerned with constructing archetypes of folk and with placing folk culture in the new American literary landscape. Examining the two versions of the tale, then, provides a fascinating peek into the transformation of concerns and values in America from Irving’s nineteenth century landscape to Burton’s twentieth (on the verge of twenty-first) century.
Prion proteins are small infectious particles that are formed by the miss-folding of the protein structure. It is believed the miss-folding of such proteins has been the cause of disease such as Bovine spongiform encephalopathy in cows and Creutzfeldt-Jakob disease in humans. The prion proteins that are known to mankind so far suggest that they affect the brain of the affected individual. “A study1 in the British Medical Journal reveals that 1 in 2,000 people in the United Kingdom might harbour the infectious prion protein that causes variant Creutzfeldt–Jakob disease (vCJD).”(Callaway, 2013). The study therefore shows that a high number of people are at risk and this is a cause for concern as the prion protein which is miss-folded prompts normal proteins present in the brain, to alter their structure so they also become miss folded. The miss folded structure is understood to be very stable and as levels of the protein build up within the infected tissue this results in destruction and eventually death of the cell. The prion protein, PrP is thought to be the cause of all mammalian prion diseases but the structure of the protein is yet to be discovered. The normal cellular form of the prion protein is PrPc, whereas the miss folded scrapie form is PrPSc. PrPc is constructed from 209 amino acids and one disulphide bond and are found on cell membranes. “Several topological forms exist; one cell surface form anchored via glycolipid and two transmembrane forms.”(Hedge et al, 1998). The miss folded form, PrPSc has more Beta sheets however the normal form PrPc has Alpha structure present. “Fourier-transform infrared (FTIR) spectroscopy demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), findings that were c...
Prions are pathogens, and cause infections, like viruses. Prions cause many neurodegenerative diseases, but are made up of harmless proteins found in mammals and birds. The proteins are not in their normal form though, and once they enter the human brain, can cause severe brain infections. One thing that makes them different from viruses, is the lack of nucleic acids, which means they have no genetic code. Once in the brain, they make normal proteins turn into abnormal ones, which then multiply, causing severe infection. Soon, holes appear in the brain that can only be treated by incineration. An example of a disease caused by a prion would be the Mad Cow Disease, or the human equivalent Creutzfeldt–Jakob disease. Prions are very dangerous. While some people can confuse prions and viruses, there are some ways to tell the difference.
In their inactive state neurons have a negative potential, called the resting membrane potential. Action potentials changes the transmembrane potential from negative to positive. Action potentials are carried along axons, and are the basis for "information transportation" from one cell in the nervous system to another. Other types of electrical signals are possible, but we'll focus on action potentials. These electrical signals arise from ion fluxes produced by nerve cell membranes that are selectively permeable to different ions.
The brain is part of the central nervous system, which consists of neurons and glia. Neurons which are the excitable nerve cells of the nervous system that conduct electrical impulses, or signals, that serve as communication between the brain, sensory receptors, muscles, and spinal cord. In order to achieve rapid communication over a long distance, neurons have developed a special ability for sending electrical signals, called action potentials, along axons. The way in which the cell body of a neuron communicates with its own terminals via the axon is called conduction. In order for conduction to occur, an action potential which is an electrical signal that occurs in a neuron due to ions moving across the neuronal membrane which results in depolarization of a neuron, is to be generated near the cell body area of the axon. Wh...
According to Hegel, our self-consciousness arises from recognizing another individual and being recognized by that individual. Hegel concedes that such self-consciousness makes us dependent on the one who we are both recognizing and being recognized by. In order to break free of this dependency, the equals must struggle for death; whoever is more afraid of death will be unwilling to give up his life and will therefore become dependent on the other. Marx takes this concept and applies it to labor under the system of capitalism, where people are forced to either be employers or employees.
Normal functioning sodium channels play a fundamental role in physiology. Sodium channels transmit depolarizing impulses promptly
The neuron has two important structures called the dendrite and axon, also called nerve fibers. The dendrites are like tentacles that sprout from the cell and the axon is one long extension of the cell. The dendrites receive signals from other neurons, while the axon sends impulses to other neurons. Axons can extend to more than a meter long. Average sized neurons have hundreds of dendrites; therefore it can receive thousands of signals simultaneously from other neurons. The neuron sends impulses by connection the axon to the dendrites of another nerve cell. The synapse is a gap between the axon and the adjacent neuron, which is where data is transmitted from one neuron to another. The neuron is negatively charged and it bathes in fluids that contain positively charged potassium and sodium ions. The membrane of the neuron holds negatively charged protein molecules. The neuron has pores called ion channels to allow sodium ions to pass into the membrane, but prevent the protein molecules from escaping (potassium ions can freely pass through the membrane since the ion channels mostly restrict sodium ions). When a neuron is stimulated (not at rest), the pores open and the sodium ions rush in because of its attraction to the negatively charged protein molecules, which makes the cell positively charged. As a result, potential energy is released and the neurons send electrical impulses through the axon until the impulse reaches the synapse of any neurons near it.
“American society and as more Americans have experience with adoption, there is also more attention focused on those involved in adoption- the adopted person, the birth parents, and the adoptive parents” (Child welfare Information gateway, 2016). Seeing that more and more Americans are adopting it is important to look at how a child’s emotional development can be impacted by adoption. The first is the development of their identity. Research as shown heat identity is difficult for anyone, however being adopted can have an added impact on one’s identity. The adopted child can began to ask questions like, “why was I placed for adoption? what is my place?, who do I look like?, do I have any siblings that could relate to me?” (Child welfare Information gateway, 2013). The adoptive child who then becomes an adult has gone through five stages according to article by the child welfare. The first is they do not acknowledge any adoption issues, the second ...
Neurons dispatch signals to other cells through thin fibers called axons, that cause chemicals acknowledged as neurotransmitters to be released at junctions identified as synapses. A synapse gives a command to the cell and the entire communication process typically takes only a fraction of a millisecond.
...g adopted, almost every theory of children development predicts problems for adoptees. In 1960, the archives of general psychology published a report by M. D. Schecter which started found that 13.3 percent of the children he had treated for psychiatric disorders over a five-year period, were adopted. Dr. Schecter’s data was therefore used to suggest that something about the adoptive situation left an adopted child with a 100-times greater chance of running into psychological problems in his life than did a non-adopted child (Lasnik 102). Statistics show that children over the age of 5 who are adopted run even a higher risk of mental and emotional problems (Luther Online).
Poverty is prevalent throughout the world around us. We watch television and see famous people begging us to sponsor a child for only ten dollars a month. We think in our own minds that ten dollars is only pocket change, but to those children and their families, that ten dollars is a large portion of their annual income. We see images of starving children in far away countries, and our hearts go out to them. But we really do not know the implications of poverty, why it exists, or even what we can do to help combat this giant problem in our world.
Colleges and universities need to be structured so that they prepare students for specific career roles, as well as give them a level of appreciation for the world in which they live. Brewer’s succe...