Concept Check 27.5 by Diegojose Gomez

Concept check 27.5
1. Explain how muscles work in pairs in moving limbs.
2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.
3. Identify at least 3 organ systems involved in a handshake. Describe WHAT each system contributes to the handshake.
4. Explain how actin and myosin interact as a muscle cell contracts.

1. The muscles are join to the bones by tendons. They are connective tissues. The muscles move oppositly from each other. One muscles contracts the other relaxes.

2. Muscle Fibers: Muscle Cell containing a Nuclei.

Myofibrils:

1. Explain how muscles work in pairs in moving limbs.

Because one muscle move your limb one way and the other muscle move it to the other way because the muscles can only pull and not push. The muscles work in opposite ways for example when one contracts the other one relax

2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.

The skeletal muscle is made up of muscle fibers which contain nuclei and the nuclei contains myofibrils. The unit of muscle fibers are sarcomeres that are made up of myosin (thick) and actin (thin).

3. Identify at least 3 organ systems involved in a handshake. Describe WHAT each system contributes to the handshake.

In the handshake involves first the skeletal system because without it you cannot put your hand in shape so you can shape your hand the way you want, second you use the muscles to move your hand and third the nervous system so you can feel the other person hand.

4. Explain how actin and myosin interact as a muscle cell contracts.

They help in muscle contraction because myosin attaches to actin, then the actin moves to the sarcomere and then the ATP attaches to the myosin and then because of this reaction the myosin and the actin separate. The myosin then would pull the filaments and they would overlap, the sarcomere becomes shorter and that cause the muscle cells to contract

Concept Check 27.5

1.Muscles have the primary objective to work in pair, in order to be able to move the bone freely in all directions, without this pairs the bone could only move in 2 directions.
2.The skeltal muscle have many diffrents parts, some of them are the muscle fibers, inside this we can find nuclei inside them we also find the type of filament.
3.- the skeletal system because of the bones doing the hand shake.-the integumentary system in the skin of our hands.-the nervous system when we make the decision of the handshake
4.first the myosin attaches to the acting filament, and bends.Then the myosinreleases the actin and attaches itself in another part of the acting and keeps pulling it until the actin filament is fully contracted.

Concept Check 27.5 by Micaela Endara

1. Explain how muscles work in pairs in moving limbs.

· As we learn in this reading and in class. A muscle is attached to the skeleton by tendons that are dense connective tissues. But bones are just able to pull and not push. That is why muscles must work in pairs because this way the bone has the ability to move freely and not in only one direction. As one muscle contracts the other relaxes. An example that shows this work of the muscles is in the arm when you are making a movement the triceps contracted, and the biceps relax.

2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.

· The structure that makes up the skeletal muscle is extremely complex, because of the big amount of part that a really small muscle can contain inside. The skeletal muscle is made of bundles of muscle fibers; in each of these fibers we contain a great amount of nuclei. In each of the nuclei they are myofibril that also have repeating units known as sarcomeres. Finally in each of these myofibrils you find to types of filaments one is thick (myosin) and the other thin (actin). Which change the position depending if the muscle is relaxed or contracted.

3. Identify at least 3 organ systems involved in a handshake. Describe WHAT each system contributes to the handshake.

· When a handshake occurs are body usually use many organs systems to help. Some examples of the organs you use are; first you always use the nervous system because the brain is the one in charge of making the decision to handshake, and it send the message along the nerves to make the movement. Also we use a skeletal system because is the one in charge of giving the shape to the 27bones in your hand, and it allows the position in which you change your hand. At last we use the integumentary system, which is the skin, and is in charge of covering and protecting the body of infection, excessive heat or cold and drying out.

4. Explain how actin and myosin interact as a muscle cell contracts.

· Actin and myosin interact as muscle cell contract. First of all the myosin head holds-on to fibers made up of actin that bends. This makes that the actins are pulled together and are put on the center of the sarcomere. After this happens, the myosin head leaves the actin fiber and connect to other parts of the fiber and makes the process of pulling again. When the filament is totally pulled it creates contraction.

Concept Check 27.5
1. Explain how muscles work in pairs in moving limbs.

Muscles are attached to bones by tendons. So as a muscle contracts, it pulls the bone. The muscle then needs to return to its original position, and since it cannot push only pull it needs another muscle to pull it back. That is why muscles need to work in pairs. As one muscle contracts the muscle relaxes and vice versa.

2. Identify the structures that make up a skeletal muscle.

Each skeletal muscle is made up of muscle fibers (long cylindrical muscle cells that contain many nuclei). And each muscle fiber is made up of myofibrils, which when looked under a microscope appear as alternating dark and light stripes. On the other hand, the unit of muscle fibers is sarcomere. Sarcomere is composed of two kinds of filament: thin--- composed of protein actin that have a twisted, ropelike structure; and thick--- composed of protein myosin that have bumplike projections called myosin heads.

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.

When doing a handshake the eyes first see the person and transmit that message to the brain. The brain then decides to initiate the handshake, while other regions of the brain transmit information through the nerves to a series of muscles. The muscles will then move the right bones in order for the handshake to take place. In this case the three organ systems used are the muscular system, the nervous system, and the skeletal system.

4. Explain how actin and myosin interact as a muscle cell contracts.

For each muscle contraction the myosin attaches to the thin filament (actin). Then as the myosin bends, it pulls the actin toward the center of the sarcomere. The ATP (energy storage molecule) then attaches to the myosin causing it to release from the actin. The myosin now free will attach to a spot pulling the thin filament behind it. The filaments will then start to overlap each other. Meanwhile the sarcomere gets shorter. Once the sarcomeres of many muscle fibers shorten, it will cause the muscle to contract.

Concept 27.5 check Alicia Perez

1. Explain how muscles work in pairs in moving limbs.
Muscle are attached to bones by tendons, this way the muscles can move the bone. If there would be only one muscle moving a bone you could only to move that bone once and only in one direction, that is because muscles are only able to pull. Each bone has a pair to be able to make the bone move in the opposite direction. As one of the muscles contracts the other one relaxes and the other way around.

2. Identify the structures that make up a skeletal muscle.
Each muscle is made of bundles with muscle fibers, which are long cells with multiple nuclei. each muscle fiber is formed by various myofibrils, which have alternating dark and light areas. Myofibrils are made of repeating units of sarcomeres, which are the units that contract. Sarcomeres have two types of filaments thick and thin. The thin filaments are made of actin proteins and the thick filaments are made of myosin. Myosin also has myosin heads.

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.
During a handshake you use many of the organ systems. You use muscles to move your hand. You use bones which give your hand the position in which you are holding your hand. You also use your nervous system because you feel the hand of the other person in your skin.

4. Explain how actin and myosin interact as a muscle cell contracts.
Myosin heads attaches to an actin filament and bends, pulling the actin closer to the center of the sarcomere. Then the myosin head releases the actin and attaches itself in another part of the acting and keeps pulling it until the actin filament is fully contracted. This process happens simultaneously in all the myofibrils of the muscle and make the whole muscle contract.

Concept check 27.5

Please read section 27.5 of the online Biology book on muscles. Take notes of the reading in your Health notebook. Post your answers to concept check 27.5 on the blog and provide constructive feedback to three other learners. Constructive feedback not only means you may agree with someone else's answers or ideas but as well how those ideas may open the doors to new learning opportunities.  Due date: Jan. 13, 2011

Concept check 27.5
1. Explain how muscles work in pairs in moving limbs.
2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.
3. Identify at least 3 organ systems involved in a handshake. Describe WHAT each system contributes to the handshake.
4. Explain how actin and myosin interact as a muscle cell contracts.