refractory period notes draft

Submitted by msalvucci on Thu, 11/15/2018 - 12:25

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. 

Ecology Short Essay #2 Part 2 PP

Submitted by sbrownstein on Thu, 11/15/2018 - 11:53

Although ecology is not typically thought of as a subject in the medical field, it can play a role in environmental medicine. This uses environmental science, environmental pathology, and the knowledge of relationships between organisms and the environment to study the individual’s physical, mental and emotional responses to them. Although this may not directly relate to my path in the medical field, it is an important topic that may affect many other branches of the field. Without ecology, we would not be able to study the environmental, or other organisms, effects on human health.

 

Background draft 2

Submitted by curbano on Thu, 11/15/2018 - 10:50

In nearly every living species, temperature influences physiological and biological processes in the body. Spiders are ectothermic organisms, meaning they are unable to regulate their body temperatures relative to their environment. Because of this, changes in temperature can have a large impact on their metabolic rate and overall activity (Barghusen et al). It has been found that even winter active spiders will make less effective webs or no webs at all at temperatures 2° colder than the temperature they are accustomed to. Having a less effective, or no, web greatly reduced feeding, which could be detrimental for spiders (Aitchison 1984). Since web production is a large part of spider activity and survival, we decided to focus our project on how varying temperatures influence web production. Past research has found that spiders in lower temperatures tend to use less spiral silk than spiders in warmer temperatures (Vollrath et al). Our project focuses on how temperature influence the weight of webs.  

Cell cycle

Submitted by curbano on Wed, 11/14/2018 - 23:28

There are many different checkpoints and regulations to help the cell cycle be carried out correctly and successfully. One very important regulation/mechanism used in the cell cycle is cohesion as well as the breaking down of cohesion. If cohesion does not break down properly or at the right time, it can lead to too many or too few chromosomes in a cell, which can be detrimental. I am interested in knowing what is involved with the formation of the contractile ring in animal cells and the phragmoplast in plant cells. How do these two mechanisms differ? I would assume the phragmoplast would have a method in protecting the cell wall during cytokinesis. If the contractile ring/phragmoplast doesn't function properly, then the single cell can't be divided and there would not be two identical daughter cells as the end product. We have lots of different technology and methods in viewing cells and cell processes. These images remind me of some IF imaging that occurs in the genetics lab I work in. The blue staining is most likely DAPI, which is a DNA marker. Markers can be very helpful in identifying certain structures in the cell, different stages in the cell cycle, and many other pieces of information. It is nice to be able to physically see what is happening in these cells because it gives us a better understanding.

 

Results AnCom pt 2

Submitted by cwcasey on Wed, 11/14/2018 - 19:32

While collecting data, intra-personal reliability analysis was conducted as to maintain a high level of accuracy. Similar to the Time budget analysis (Figure 1 and Figure 2) a subset of behaviors was derived from the original list in order to best capture data in as few keystrokes as possible. Between a series of tests, multiple reliability tests were conducted in order to elevate the overall original score of 30 to a high of 50. This means that during the scoring process, we were able to successfully line up the correct timestamp and behavior 32 out of 63 times. When the tests were broken down in order to see the reliability of each behavior; feeding behaviors scored 41, play behaviors scored 44, grooming scored 19, communication scored 21, and locomotive behaviors scored 18.

    Once the reliability scores were assessed, we used the selected behaviors to conduct a time budget analysis (Figure 1). Compared are the proportions of time spent Feeding (53%), Playing (8%), Grooming (16%), Communicating (9%), and Locomoting (13%). Behaviors were analyzed over a 10 minute span and organized in order to gauge which set of behavior is more prevalent over the monitored time span. Such results are indicative of the foals selective behavior when in its homeostatic environment. After the original time budget analysis was conducted, it was important to us to see what the break down of the behaviors were like when the foal was in the presence of its mother, when it was with another foal, and when it was alone (Figure 2). Focusing on the feeding behaviors and communicative behaviors, we observed that feeding took up a larger proportion of time, the foal seldom fed with other foals, and chose to feed more with its mother. Conversely, we observed that the foal primarily decided to communicate with its mother as opposed to other foals or sending signals by itself.

Results AnCom pt 2

Submitted by cwcasey on Wed, 11/14/2018 - 19:31

While collecting data, intra-personal reliability analysis was conducted as to maintain a high level of accuracy. Similar to the Time budget analysis (Figure 1 and Figure 2) a subset of behaviors was derived from the original list in order to best capture data in as few keystrokes as possible. Between a series of tests, multiple reliability tests were conducted in order to elevate the overall original score of 30 to a high of 50. This means that during the scoring process, we were able to successfully line up the correct timestamp and behavior 32 out of 63 times. When the tests were broken down in order to see the reliability of each behavior; feeding behaviors scored 41, play behaviors scored 44, grooming scored 19, communication scored 21, and locomotive behaviors scored 18.

    Once the reliability scores were assessed, we used the selected behaviors to conduct a time budget analysis (Figure 1). Compared are the proportions of time spent Feeding (53%), Playing (8%), Grooming (16%), Communicating (9%), and Locomoting (13%). Behaviors were analyzed over a 10 minute span and organized in order to gauge which set of behavior is more prevalent over the monitored time span. Such results are indicative of the foals selective behavior when in its homeostatic environment. After the original time budget analysis was conducted, it was important to us to see what the break down of the behaviors were like when the foal was in the presence of its mother, when it was with another foal, and when it was alone (Figure 2). Focusing on the feeding behaviors and communicative behaviors, we observed that feeding took up a larger proportion of time, the foal seldom fed with other foals, and chose to feed more with its mother. Conversely, we observed that the foal primarily decided to communicate with its mother as opposed to other foals or sending signals by itself.

results AnCom

Submitted by cwcasey on Wed, 11/14/2018 - 19:30

Upon review of the video information, 62 behaviors were analyzed and categorized into the tables shown above. Such behaviors include the actual feeding of the foal, drinking the mother’s milk, digging for food, and so on. In total, eleven feeding behaviors were observed and categorized (Table 1). In video files three and five, it was observed that the foals were given free range to play and interact with each other. A list of 22 behaviors was composed and arranged denoting said behaviors (Table 2). All the specified behaviors occurred during the interaction between the foal and its partner(s) and so we deemed them to be playful. Afterwards, we established the behaviors associated with the foals grooming themselves. These primarily consist of the foal scratching, nipping, and licking its coat (Table 3). This category contained the least amount of behaviors but was significant in that it displayed a very unique set of behaviors. Communicative behaviors range from mechanical and visual modalities of communication to even a few sporadic vocal cues (Table 4). The foals were effective in getting the attention of their mothers and partners via these communicative behaviors and thus sending the signal they wished to get across. Lastly, Table 5 includes the behaviors associated with miscellaneous locomotion and movement. For example, behaviors like sprinting, non-playful trotting, and indiscriminate head bobbing are included in this table. These behaviors pertain no other use than moving from one location to the other and the ways in which the foal moves upon the initiation of said behaviors. To recap, each of the above tables aims to illustrate the a portion of the overall 62 behaviors within its set category. These categories were drawn from the analysis of the two video files provided and used as an organizational tool to effectively present the collected data.

 

rigor mortis notes draft

Submitted by msalvucci on Wed, 11/14/2018 - 19:01

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. 

notes of thin filaments

Submitted by msalvucci on Wed, 11/14/2018 - 18:45

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

notes draft muscle contraction

Submitted by msalvucci on Wed, 11/14/2018 - 18:43

 

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.

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