Isotonic Contraction and the Effect of Load on Skeletal Muscles
Lab #3: Isotonic contraction and the effect of load on skeletal muscles
Abstract The job of the motor nervous system is to control certain elements in muscles simultaneously to ultimately produce movement. Movement of the body is the result of specialized cells directly associated with skeletal muscle. Skeletal muscles are voluntary muscle and must contract before movement can occur. We know the muscle team moving the arm is formed at the biceps and triceps. Biceps can bend the elbow, but by itself can not extend the arm. Biceps contract and triceps relax to flex the elbow. When the elbow is straightened, the reverse takes place; the biceps relax and triceps contract. However, what happens during skeletal muscle contraction? For instance, what happens to the muscles in the leg when one lifts weights? We used two variables, muscle length and resistance; to explore how skeletal muscle speed and contraction is affected during an isotonic contraction when these variables are manipulated. We found if resistance is too light skeletal muscle contracts with ease and at a faster rate. However, if the resistance is heavy muscle contraction has a much slower rate. These findings give good insight into safety precautions, maintenance, and medical diagnoses’ of our body. For instance when lifting weights, or determining underlining causes of a heart condition.
Introduction
The muscular system has more than 600 muscles (cardiac, skeletal and smooth muscle) throughout the human body. Contraction of these muscles is generated by specialized muscle cells. Skeletal muscles are voluntary and move the body by pulling on the bones, for instance, when throwing a ball or walking. This involves a series of steps in which bones are moved at the joint by a complex electrochemical and mechanical process of contraction and relaxation of skeletal muscles (Kendal et al., 2000). First, skeletal muscle fibers communicate with the nervous system at the neuromuscular
Abstract The job of the motor nervous system is to control certain elements in muscles simultaneously to ultimately produce movement. Movement of the body is the result of specialized cells directly associated with skeletal muscle. Skeletal muscles are voluntary muscle and must contract before movement can occur. We know the muscle team moving the arm is formed at the biceps and triceps. Biceps can bend the elbow, but by itself can not extend the arm. Biceps contract and triceps relax to flex the elbow. When the elbow is straightened, the reverse takes place; the biceps relax and triceps contract. However, what happens during skeletal muscle contraction? For instance, what happens to the muscles in the leg when one lifts weights? We used two variables, muscle length and resistance; to explore how skeletal muscle speed and contraction is affected during an isotonic contraction when these variables are manipulated. We found if resistance is too light skeletal muscle contracts with ease and at a faster rate. However, if the resistance is heavy muscle contraction has a much slower rate. These findings give good insight into safety precautions, maintenance, and medical diagnoses’ of our body. For instance when lifting weights, or determining underlining causes of a heart condition.
Introduction
The muscular system has more than 600 muscles (cardiac, skeletal and smooth muscle) throughout the human body. Contraction of these muscles is generated by specialized muscle cells. Skeletal muscles are voluntary and move the body by pulling on the bones, for instance, when throwing a ball or walking. This involves a series of steps in which bones are moved at the joint by a complex electrochemical and mechanical process of contraction and relaxation of skeletal muscles (Kendal et al., 2000). First, skeletal muscle fibers communicate with the nervous system at the neuromuscular
References: Kandel, ER., Schwartz, JH., and Jessell, TM (2000). The Motor Unit and Muscle Action, Principles of Neural Science (chp. 34, 4th edition, pp. 675-683). New York: McGraw-Hill. Marieb, E. and Mitchell, S. (2009). Investigating the Effect of Load on Skeletal Muscle. Laboratory Manual: Human Anatomy & Physiology, (Exercise 26, 9th edition, pp. 419-420). New York: Pearson Education Inc. Martini, F., Nath, J. and Bartholomew, E. (2012). Muscle Tissue. Fundamentals of Anatomy & Physiology, (chp. 10, 9th edition, pp. 290-305). New York: Pearson Education Inc. ----------------------- [pic] (Figure 1) Skeletal muscle response to a single stimulus [pic] (Figure 2) Relationship between resistance and initial velocity of shortening