Health Blog!

Health Blog!

Welcome students to our class blog. We will be using this space for class discussions to examine, evaluate, and share knowledge. Discussions provide opportunities for students to think critically on the topics we will be learning about in Health class. Concepts, assignments, and readings will be used as the basis for our discussions to create a positive learning community in which students are willing to share their ideas and to accept constructive criticism form their peers.







Wednesday, January 12, 2011

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.

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1 comment:

  1. Mica EndaraJanuary 12, 2011 at 4:25 PM

    Kyla! I have read you information and I have two important thing to comment about. The first one is about question number three, I think you made a incredible work taking about the organ systems that are used while handshaking the part I liked the most was the one of the brain and how it transmits information through the nerves. But my second comment is that I think that you need a little more of explanation in the structure of the skeletal system you may include a little more of information as what is a muscle fiber or a sarcomere, and even what is a myosin.

    Muscle Fiber: single, long cylindrical muscle cell containing many nuclei
    Sarcomere: unit of contraction in a muscle fiber
    Myosin:thick filament in a muscle fiber; has bump-like projections

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