During the absolute refractory period, there are no action potentials occurring in the cell. This is due to the voltage gates sodium channels being inactivated. This occurs in the time frame directly after the depolarization. Following the absolute refractory period is the relative refractory period. During this refractory period, the voltage gated sodium channels are closed, however, the voltage gated potassium channels are open. This means that an action potential will most likely not occur unless there is a huge stimulus that causes a rush of positive potassium into the cell. These refractory periods are different when muscle twitches or tetanus occurs. Following a contraction, calcium is typically pumped away from the cell when the repolarization occurs. However, in a muscle twitch, action potentials happen quickly after one another and stops the calcium from being pumped away from the cell. This means that the left over calcium adds to the following contraction, leading to more force. In muscle tetanus, these contractions continue because the fast flow of action potentials causes the calcium to be pumped into the cell as fast as it is pumped out of the cell.
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Rigor mortis is the chemical change in one’s body after death characterized by the stiffness and rigidity of the limbs. Rigor mortis is caused by the lack of ATP in the body after the organs shut down. ATP is needed for muscle contraction as it binds to myosin and allows myosin to pull the thin filaments of the muscle closer to the sarcomere. However, once the ATP is used up, the contracted muscles cannot relax because ATP is required for the myosin to release from the actin binding site and reset itself. Therefore, when the ATP runs out, the muscles stay in a contracted state causing stiffness. Rigor mortis is the third stage of death and can last up to eighteen hours. However, the rigor goes away after some time because the proteins completely denature. The proteins denature because the calcium is eventually pumped away from the troponin binding sites, allowing them to cover up the actin binding sites. Once the actin binding sites are covered up, the myosin can detach and relax the muscle.
Once calcium floods the cell, it attaches to troponin. Troponin, a regulatory protein on the thin filament, changes shape when bound to calcium. This shape conformation causes the tropomyosin protein to shift away from the actin binding site on the thin filament strands. The binding sites of actin must be exposed for contraction to occur. ATP bound-myosin on the thick filament can then bind itself to the actin binding site and pull the thin filament towards the center of the sarcomere. Following this movement, another ATP binds to myosin, and myosin uses the ATP to release from the actin and cock itself. The myosin gets ready to bind another actin if and when it is exposed. This process creates the contraction of a skeletal muscle
At the neuromuscular junction, an axon terminal releases acetylcholine into the synapse where they then bind to acetylcholine receptors. The binding of the acetylcholine causes a graded potential or depolarization of the muscle. Once the voltage threshold is met, the voltage gated ion channels open and allow sodium to rush into the cell. This rush of sodium causes a depolarization, and an electric current flows down the plasma membrane of the cell. The electric current passes through the t-tubules of the sarcoplasmic reticulum. The t-tubule surrounds the sarcoplasmic reticulum and once depolarized, it opens calcium channels on the sarcoplasmic reticulum. The free calcium floods the area around the thick and thin filaments and causes a muscle contraction.
While reading the scientific posters, I noticed three positive and negative characteristics of a poster that authors should pay attention to when creating posters. Firstly, researchers should avoid overlapping textboxes or images on the poster in order to keep the text easy to read. Positioning the text incorrectly makes it difficult to read and is distracting to the reader. Instead of overlapping sections, the text boxes and images should flow in an organized order. I noticed a few posters that had text boxes scattered randomly on the poster. These authors should have created distinct margins for each text box and visual on the poster. Having distinct rows and columns makes the poster easier to follow.
Similarly, another common mistake to avoid on posters is having too much text. Including text boxes on a poster is necessary in moderation; however, long blocks of text can be boring to look at and make the reader uninterested. Rather than writing long paragraphs of text, the author should add images or graphs to break up the text. Visuals can make the research easier to understand and give flow to the poster while still adding valuable information. Additionally, the text boxes should be limited in length so that the reader can easily follow the author’s work.
Lastly, authors should avoid creating a poster with only black and white text and visuals. The first impression of a poster is very important in telling whether a reader will be interested in the poster or not. That being said, a dull poster does not catch the eye of the reader. A poster with colors and visuals make it interesting to look at and creates a fascinating first impression. Colors are important because they can be used to highlight different paragraphs or characteristics on a poster. This type of color coding is a useful tool in highlighting areas of a poster to help with organization. It is also important to note that while colors are important, neon colors and confusing patterns should be avoided as this can be distracting. A balance of visuals and color can enhance the poster; this tactic could be as simple as making the background of the poster a light color.
Lastly, researchers should avoid creating a poster with only black and white text or visuals. A dull black and white poster does not catch the eye of the reader while a poster with colors and visuals make it interesting to look at. Additionally, colors are important because they can be used to highlight different paragraphs or characteristics on a poster. This color coding is a useful tool in highlighting areas of a poster that are particularly important and help with organization. It is also important to note that while colors are important, neon colors and confusing patterns should be avoided as this can be distracting. A balance of visuals and color can enhance the poster; this tactic could be as simple as making the background of the poster a light color. This is why researchers should try to add more vibrant visuals and colors. Some posters observed on the website did not catch my attention because they were bland.
After observing three different scientific posters, I noticed three mistakes that one should avoid and three positive factors that one should follow when making posters. The first factor that negatively affected the poster is overlapping the text boxes on the poster. I noticed in one poster example that the text boxes for each specific paragraph or topic were overlapping rather than having distinct separating lines. This made it difficult to read all of the text as well as distracting to the reader. Mixing the sections on a poster should be avoided; instead, the sections should have distinct margins. A factor to include in a research poster is to have distinct sections for each text box, graph, or image in the poster. Having distinct rows and columns makes the poster more organized and easier to follow. Another mistake to avoid when making a scientific poster is making long paragraphs of text. While having text on the poster is necessary, long blocks of text can be boring to look at. Instead, one should add more images or graphs to break up the text; images and graphs can make the research easier to understand.
Other factors that affect drug use are personality and the type of drug. Personality and mood have an effect on drug use as people with a lack of hope, direction, or self-esteem are more likely to abuse drugs in the future. Individuals with a lack of hope for the future have a higher chance of taking drugs because they feel their life is at a standstill. For example, many people in prison or veterans have a lack of hope for the future which can cause a deep depression. These qualities make individuals turn to drugs to help them feel better. Additionally, young kids with a lack of direction or aspirations for what they want to do in life may be more likely to use drugs because it can make them feel better temporarily. This is similar for individuals with low self-esteem; these individuals believe that the drug makes them more outgoing and talkative rather than being an introvert. The type of drug has a huge effect on drug use as some drugs are more addictive than others. Addictiveness is correlated to the type of drug because the highs felt on each drug can be varying in intensity and duration. Research has indicated that drugs with an extremely intense high are more addictive. Research also shows that drugs that induce a shorter duration of the high are highly addictive compared to drugs that induce a long high. This is because it is more likely for a human to become addicted to “chasing a high” that comes in short, intense bursts.
Whether or not someone will be a drug user in the future is not known for certain, but there are several factors that can influence drug use in teens. Drug use in teenage years make it more likely that the individual will use drugs in adult years as well. The factors including friends, biology, culture, personality, and type of drug may increase the likelihood of someone using drugs or possibly abusing drugs. Firstly, friends have a huge effect on drug use. If a teenager hangs around friends that are using or abusing drugs, it is more likely that they will join to try to fit in or find something in common with this group of people. The biological make up can also have an effect on drug use as children of drug abusers have a higher chance of becoming an addict later in life; there is a research depicting that there is a genetic predisposition to addiction. This is also seen in research on identical twins. It is likely that both twins have the same genetic predisposition as well as likely hood to become addicts. The culture in which someone lives has a huge effect on drug use. For example, the rate of alcoholism across Europe is very small compared to other countries because it is normal for alcohol to be introduced at a young age in Europe. There is little taboo about alcohol, therefore, the young drinking ages make it less likely for alcoholism to be a big problem; it is normal to drink wine at dinner as a teenager. On the other hand, there is a high rate of alcoholism amongst Amish kids that break away from their roots as they are steered away from it their whole life and then have the opportunity to try what they want when they leave their community and culture.
Examples of stimulants include caffeine, cocaine, and amphetamines. These drugs turn on the flight response of the sympathetic nervous system; this makes sense as coffee is typically used to wake people up and make them more alert. One may notice that when they get nervous their stomach hurts. This is due to the effect on the digestive system that stimulants have. They turn off the sympathetic nervous system which can decrease appetite. These drugs are very addictive, and harmful drugs like cocaine can have detrimental effects on the brain. Some research has proven that one in five people who try cocaine become addicted to it. As for hallucinogens, these include examples of THC and LSD. These drugs typically distort perceptions and increase sensitivity to colors, sounds, tastes and smells. They can also evoke vivid images which is understood as the hallucinating aspect of the drug. They drugs can be used for medicinal reasons; for example, THC can aide chemotherapy patients in curbing nausea and increasing appetite. It can also aide in reducing chronic pain for patients which some health conditions. Some bad side effects of these drugs include a decrease in motor control, as well as a false sense of euphoria. This can make these drugs highly addictive as they help the body to relax. Additionally, research on hallucinogens has proven that THC can cause a decrease in fertility for men.