John Park (wisejsm@yahoo.com)
Monday, April 4, 2011
Bones and their protector
Starting in page 126, Shubin talks about the bones and the cartilage, and how these joint tissues protect our bones from grinding against each other. He also mentions that the cartilage tissues can even withstand our entire body mass' weight. Discuss the strength of the cartilage tissues, how they are able to withstand such pressure. Also, discuss about those who have arthritis, and how those people with arthritis weakens the cartilage tissues so much that their bones start to grind against each other.
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According to Shubin, there are two proteins that are made to create the strength of a bone: Hydroxyapatite and collagen. Hydroxyapatite is a very hard structure that has strength when compressed and is less strong when its twisted or bent. Collagen, on the other hand, is a rope like structure that has its strength from being pulled and loses it when its compressed. A healthy combination of the two proteins gives bones the strong feel.
ReplyDeleteCartilage is very different compared to bone because its more of a tissue in between joints; it can bend unlike bone. This is an important feature of cartilage because it can "bend and smush as forces are applied to it" (126). The way it works is proteoglycan complex gives cartilage strength when squeezed or compressed. This gives it a very pliant feature and the way it reverts back to its normal state is through the re-absorption of water. The proteoglycan complex "loves to attach to water" (126). These molecules are then surrounded by a large amount of collagen that gives it resistance to tension, giving it a very strong build.
Cartilage is found on the very ends of bones to prevent the grinding of separate bones. This is a thin layer that if damaged, takes a while to repair/divide. This is due to the fact that there is a limited blood flow to that area and its highly dependent on the diffusion of materials between the collagen cells in that area. This disease is called Osteoarthritis and the treatment involves the replacement of the bone with a Stainless Steel alloy (cobalt chromoly) and High Molecular Weight Polyethylene (HMWPE). If this isn't treated properly, the patient would go through a great deal of pain and their bones will slowly grind against each other until it renders useless.
Sources:
Your Inner Fish
Campbell
http://en.wikipedia.org/wiki/Cartilage
Nikhil Pereira (nikhil.pereira3@gmail.com)
Cartilage is a type of connective tissue—that is, tissue which helps to hold together and support other tissues of the body. Some other examples of connective tissue are blood and bone. As Nikhil described, the hydroxyapatite allows for cartilage to maintain some solidity, yet the collagenous tissue fibers of cartilage allow it to be able to be strong, yet flexible—this makes cartilage the perfect candidate to act as cushion between bones because it has some resistance to bending, and thus its degree of flexibility is able to help better protect our joints from wear and tear damage. These fibers are “embedded in a rubber y matrix made of a protein-carbohydrate complex called chondroitin sulfate” (Campbell & Reece 857), which, along with collagen, is secreted by cells called the chondrocytes. The molecule known as the proteoglycan complex that Nikhil discussed also adds to the strength of cartilaginous tissues because it allows for the cartilage to be “squeezed or compressed” (Shubin 126). To expand on this idea, this complex is shaped like a large brush, with many little branches that have an affinity to swell up with water—this “gelatin” is then wrapped with “collagen ropes” (Shubin 127), creating the tissue know as cartilage which is both able to be padded support and resist some forms of tension. Think of the difference between applying much pressure on a wooden board, and applying the same amount of pressure on a rubber board—eventually, the wooden board will snap in half and break, but the rubber board will instead be able to bend and bounce back to its original shape. This is similar to how cartilage works; the cartilage protects the bones (which, like the wooden board, break more easily) by surrounding the bones in its collagenous, somewhat flexible, yet strong substance.
ReplyDeleteThe arthritis that John and Nikhil refer to, osteoarthritis, is the most common form of arthritis (http://www.nlm.nih.gov/medlineplus/osteoarthritis.html), which typically comes with old age. This is because with old age, “water content of the cartilage increases, and the protein makeup of cartilage degenerates” which causes degeneration of the cartilage by “flaking or forming tiny crevasses” (http://www.medicinenet.com/osteoarthritis/article.htm). Over time, as the cartilage cushion in between bones of the joints is steadily worn down, the cartilage is irritated and inflamed, which leads to joint pain and sometimes swelling at the site of wear. In more severe cases, if the cartilage is lost altogether, then there is dangerous friction between the bones—there is no longer that cushion that allows for more flexibility and prevents the bones from rubbing together. This ultimately leads to “pain and limitation of joint mobility” as well as stimulation of “new bone outgrowths (spurs, also referred to as osteophytes)” (http://www.medicinenet.com/osteoarthritis/article.htm) that form around inflamed areas of the joints. If you are familiar with anyone who has arthritis, you may sometimes see that the knuckles of their hands are very knobby or may seem to be sticking out—this is because the joints in our hands are used very frequently, and thus more susceptible to arthritis as the joints are continually worn down with usage as the cartilage also deteriorates. Some other commonly affected areas of the body are the feet, spine, hips, and knees—other commonly used body parts.
(continued...)
ReplyDeleteIn addition to the solutions that Nikhil offers to treat this disease, there are also some other less intrusive treatments, though they are more long-term. Simple factors of lifestyle, such as diet and exercise, are especially important to the treatment of arthritis. Often being overweight can contribute to being more prone to a form of arthritis, since there is more stress put on the bones, and thus adjusting one’s diet may help to decrease the severity of the disease. In addition, moderate exercise can also help relieve the symptoms of arthritis, though moderate is the key word here—too rigorous exercise may further aggravate the joints. One example of beneficial exercise is swimming, since it “allows patients to exercise with minimal impact stress to the joints” (http://www.medicinenet.com/osteoarthritis/page4.htm) since they are underwater. This movement allows for maintaining joint mobility and keeping the joints from “freezing up.”
Relating back to our previous unit on embryo formation, vertebrate embryos (such as our own) often have cartilage, though it is often replaced by bone as we mature. The different connective tissues serve different functions in our bodies—in some cases, we may need the hard, mineralized structure of bone to keep us standing upright and able to be sturdy, but in other cases we need the softer structure of cartilage, or the fibrous tissue of tendons (Campbell & Reece 857). It all depends on what purpose the tissue must serve, but without one or the other, our functioning would suffer—we can’t have bodies only made of bone, or bodies only made of cartilage; both our necessary to work together and give us maximum mobility without damaging ourselves.
Sources:
Your Inner Fish
Campbell & Reece
http://www.medicinenet.com/osteoarthritis/article.htm
http://www.nlm.nih.gov/medlineplus/osteoarthritis.html
Kathy Li, kathy2132@gmail.com
In addition to what Kathy was saying, there are many reasons why/how organisms get arthritis. One of these ways are genetics. Although it hasn't been statistically proven to be cause arthritis, its likely that variation is one of the causes of it. As Kathy said before, age and weight also takes a major role in arthritis. The reason why obesity is one of the problems causing arthritis is because weight adds more pressure at the points where cartilage. This in turn, forces the two joints to rub against each other harder. More friction occurs. This occurs mostly on the lower part of the body including your hips, knees, and ankle. Other reasons why arthritis occurs are previous injury
ReplyDeletejoint damage, occupational hazards, and illness or infection. Injury to the joints can cause arthritis because there can be an abnormality in the shape of the cartilage. This would cause the bones to rub against each other in an uncomfortable pattern. An example of this would be "a tibial plateau fracture, where the broken area of bone enters the cartilage of the knee joint." Occupational hazards are very similar because it deals with adding too much weight throughout most of your day. These are primarily high demand jobs such as assembly line workers and heavy construction.
Illness or infection can also be another way one gets arthritis. "People who experience a joint infection (septic joint), multiple episodes of gout, or other medical conditions, can develop arthritis of the joint." There are more than one way to get arthritis and there are multiple ways of treating it, just as Kathy said above.
http://orthopedics.about.com/od/arthritis/f/arthritiscauses.htm
Nikhil Pereira(nikhil.pereira3@gmail.com)
Expanding on what Nikhil mentioned about how arthritis is caused by illness and infection, one specific case of this can be seen in another form of arthritis other than osteoarthritis, and that is rheumatoid arthritis. Unlike osteoarthritis, which usually is caused simply by aging, as the cartilage degenerates and flakes, rheumatoid arthritis is an autoimmune disease-- this means that this type of arthritis results from "your immune system attacking your body's own tissues" (http://www.nlm.nih.gov/medlineplus/rheumatoidarthritis.html). Though the exact cause of rheumatoid arthritis is unknown (it is an active area of research), the result of the disease is the same—inflammation of joints and often other parts of the body, such as the eyes and lungs, showing how this disease, because it affects your immune system, can prove to be highly dangerous if it spreads throughout the body—this is why it is known as a systemic disease.
ReplyDeleteThe onset of rheumatoid arthritis involves the immune cells, called “lymphocytes, [to be] activated and chemical messengers (cytokines, such as tumor necrosis factor/TNF, interleukin-1/IL-1, and interleukin-6/IL-6)“ to be expressed in the inflamed area (http://www.medicinenet.com/rheumatoid_arthritis/page2.htm#2whatcausera). This correlates with the inflammatory response, which involves the release of cytokines at the injury site, ultimately causing the increased permeability and dilation of nearby blood vessels, which causes more blood flow to the damaged site (Campbell & Reece 935), bringing macrophages as well as platelets to rid of the foreign invader and repair the tissue. The inflammation we see (red, swollen) will eventually fade as the tissue is repaired and returned to normal. However, with the case of rheumatoid arthritis, the lymphocytes are constantly activated, creating an inflammation that won’t go away for a long period of time, unlike the repairing action of the inflammatory response. Similar to other autoimmune diseases, such as AIDS, rheumatoid arthritis can have a latent period; in these remissions, “symptoms of the disease disappear, and people generally feel well [, but] the disease [can become] active again (relapse)” (http://www.medicinenet.com/rheumatoid_arthritis/page2.htm#2whatcausera).
Though there is no main cause for rheumatoid arthritis currently, there are certain factors that can influence the onset of this disease. The factors are very similar to any form of arthritis, or other common diseases (such as heart disease)—the first factor is that rheumatoid arthritis may be due to heredity—rheumatoid arthritis may be genetically inherited and passed on through generations. Another aspect of the disease includes healthy life habits—smoking, for example, causes an increase in the chances of getting rheumatoid arthritis. Currently, there is no cure for this form of arthritis, though there are several treatments that attempt to decrease the pain and inflammation resulting from the disease. There are two types of treatments—one is “first-line”, meaning drugs that are anti-inflammatory; the second type is “second-line,” made up of slower-acting drugs that promote “disease remission and prevent progressive joint destruction, but they are not anti-inflammatory agents.” Through the cooperation between the slow-acting and fast-acting drugs, rheumatoid arthritis symptoms can be reduced, though, sadly, they still can’t be eliminated, and will end up (most likely) being passed on to the next generation.
Sources:
Campbell & Reece
http://www.nlm.nih.gov/medlineplus/rheumatoidarthritis.html
http://www.medicinenet.com/rheumatoid_arthritis/page2.htm#2whatcausera
Kathy Li, kathy2132@gmail.com