Chapter 11 - Muscular Tissue - Study Guide - Testing Your Comprehension - Page 434: 3

Skeletal muscle is unsuitable for the wall of the urinary bladder due to differences in its structure and function compared to the smooth muscle typically found in the bladder wall. This contrast illustrates the concept of the complementarity of form and function at both the cellular and molecular levels. 1. **Structural Differences:** - **Skeletal Muscle:** Skeletal muscle is composed of long, multinucleated muscle fibers that are striated, meaning they have a striped appearance under a microscope. These muscle fibers are usually attached to bones and are under voluntary control. - **Smooth Muscle:** Smooth muscle, on the other hand, consists of shorter, spindle-shaped cells with a single nucleus. These cells lack striations and appear smooth under a microscope. Smooth muscle is typically found in the walls of hollow organs and is responsible for involuntary, rhythmic contractions. 2. **Functional Differences:** - **Skeletal Muscle Function:** Skeletal muscles are designed for rapid and powerful contractions, making them well-suited for activities such as locomotion and maintaining posture. They contract quickly but can become fatigued relatively quickly, as they rely on anaerobic metabolism for energy production. - **Smooth Muscle Function:** Smooth muscles, like those in the urinary bladder, are designed for sustained contractions without fatigue. They provide the ability to control and maintain pressure within organs like the bladder and blood vessels. Smooth muscle contractions are slow and sustained, allowing for functions like bladder filling and emptying. **Complementarity of Form and Function:** The differences between skeletal muscle and smooth muscle illustrate the concept of complementarity of form and function at both the cellular and molecular levels: - **Cellular Level:** The distinct structural characteristics of skeletal and smooth muscle cells are tailored to their respective functions. Skeletal muscle cells, with their multinucleated, striated appearance, are optimized for powerful and rapid voluntary movements. In contrast, smooth muscle cells, with their single nucleus and lack of striations, are designed for prolonged, involuntary contractions that maintain organ function. - **Molecular Level:** At the molecular level, the proteins involved in muscle contraction differ between skeletal and smooth muscle. For example, the presence of myosin and actin filaments is common to both, but their arrangement and regulatory mechanisms differ. In skeletal muscle, the precise regulation of contractions allows for rapid, voluntary movements, while in smooth muscle, the slower and more sustained contractions are necessary for functions like controlling bladder volume. In summary, the choice of smooth muscle in the wall of the urinary bladder, as opposed to skeletal muscle, demonstrates how the structural and functional characteristics of cells and molecules are intricately matched to the specific requirements of a given organ or tissue, highlighting the principle of complementarity of form and function in biology.

Skeletal muscle is unsuitable for the wall of the urinary bladder due to differences in its structure and function compared to the smooth muscle typically found in the bladder wall. This contrast illustrates the concept of the complementarity of form and function at both the cellular and molecular levels. 1. **Structural Differences:** - **Skeletal Muscle:** Skeletal muscle is composed of long, multinucleated muscle fibers that are striated, meaning they have a striped appearance under a microscope. These muscle fibers are usually attached to bones and are under voluntary control. - **Smooth Muscle:** Smooth muscle, on the other hand, consists of shorter, spindle-shaped cells with a single nucleus. These cells lack striations and appear smooth under a microscope. Smooth muscle is typically found in the walls of hollow organs and is responsible for involuntary, rhythmic contractions. 2. **Functional Differences:** - **Skeletal Muscle Function:** Skeletal muscles are designed for rapid and powerful contractions, making them well-suited for activities such as locomotion and maintaining posture. They contract quickly but can become fatigued relatively quickly, as they rely on anaerobic metabolism for energy production. - **Smooth Muscle Function:** Smooth muscles, like those in the urinary bladder, are designed for sustained contractions without fatigue. They provide the ability to control and maintain pressure within organs like the bladder and blood vessels. Smooth muscle contractions are slow and sustained, allowing for functions like bladder filling and emptying. **Complementarity of Form and Function:** The differences between skeletal muscle and smooth muscle illustrate the concept of complementarity of form and function at both the cellular and molecular levels: - **Cellular Level:** The distinct structural characteristics of skeletal and smooth muscle cells are tailored to their respective functions. Skeletal muscle cells, with their multinucleated, striated appearance, are optimized for powerful and rapid voluntary movements. In contrast, smooth muscle cells, with their single nucleus and lack of striations, are designed for prolonged, involuntary contractions that maintain organ function. - **Molecular Level:** At the molecular level, the proteins involved in muscle contraction differ between skeletal and smooth muscle. For example, the presence of myosin and actin filaments is common to both, but their arrangement and regulatory mechanisms differ. In skeletal muscle, the precise regulation of contractions allows for rapid, voluntary movements, while in smooth muscle, the slower and more sustained contractions are necessary for functions like controlling bladder volume. In summary, the choice of smooth muscle in the wall of the urinary bladder, as opposed to skeletal muscle, demonstrates how the structural and functional characteristics of cells and molecules are intricately matched to the specific requirements of a given organ or tissue, highlighting the principle of complementarity of form and function in biology.