Genetic and Autoimmune Causes with Focus on Affected Proteins

### **Muscle Diseases: Muscles and Their Types** Muscles are specialized tissues that perform critical functions in the body, including movement, posture, and organ function. There are three main types of muscles, each with distinct roles: - **Skeletal Muscle**: These muscles are attached to the bones of the skeleton and are responsible for voluntary movements like walking, running, and maintaining posture. They generate force to support body movements and posture, helping to keep the body erect or seated. - **Cardiac Muscle**: Found exclusively in the heart, cardiac muscles work involuntarily to pump blood throughout the body. Their rhythmic contractions are vital for maintaining a constant blood flow. - **Smooth Muscle (Visceral Muscle)**: These muscles line the walls of internal organs, such as the digestive tract and blood vessels. Smooth muscles facilitate involuntary movements, including the propulsion of food through the digestive system and the regulation of blood flow in vessels. --- ### **Functions of Muscles** Muscles perform several essential functions that are vital to the body’s overall operation: #### **1. Movement and Locomotion** Skeletal muscles are the primary drivers of body movement. Through contraction, they generate the force needed to move bones, allowing for activities like walking, running, and jumping. They also play a key role in maintaining **posture**, supporting the body in both standing and seated positions. #### **2. Respiration** Muscles are essential for the process of breathing. The **diaphragm**, a skeletal muscle, contracts and relaxes to enable air movement in and out of the lungs. Additionally, smooth muscle in the respiratory tract assists with regulating airways. #### **3. Heat Production** Muscle activity contributes to heat generation in the body. During contraction, muscles produce heat, which helps regulate body temperature, especially in cold environments. #### **4. Communication** Muscles are involved in various forms of communication, such as speaking, writing, and body language. **Facial muscles** allow for expressions, while skeletal muscles in the hands enable writing and other gestures. #### **5. Blood Circulation** Cardiac muscles pump blood through the heart and the circulatory system. Smooth muscles in blood vessel walls control the diameter of the vessels, regulating blood pressure and flow. --- ### **Properties of Muscles** Muscles have specific properties that enable them to perform their various functions: #### **1. Contractility** This refers to a muscle's ability to **contract** or shorten forcefully. For example, when you flex your elbow, the **biceps** muscle in the front of your arm contracts, pulling the forearm upward. Muscles can only pull; they do not push. #### **2. Excitability** Muscles respond to stimuli, such as signals from motor nerves or hormones. For example, the hormone **epinephrine**, released during stress, can stimulate muscles to respond more actively. This property also includes **autorythmicity**, which refers to the self-generated rhythm in cardiac muscle contractions. #### **3. Extensibility** Muscles have the ability to stretch beyond their normal length. This is essential in allowing the muscle to relax after contraction or spasm. Lack of extensibility can lead to muscle **spasticity**, a condition where the muscle remains in a contracted state. #### **4. Elasticity** Elasticity is the ability of a muscle to **recoil** back to its original shape after being stretched. This property is crucial, especially in skeletal muscles, ensuring they return to their resting position after stretching or contraction. Here’s a well-organized and visually appealing version of your notes, presented in a clear article format: ### Muscle Types and Their Functions Muscles are essential components of the human body, performing a variety of critical functions. There are three primary types of muscles: **visceral (smooth), cardiac,** and **skeletal muscles.** Each type has distinct characteristics and plays a unique role in the body's overall function. **Visceral Muscle (Smooth Muscle)**Visceral muscle, also known as smooth muscle, lines various organs, including blood vessels, ducts, glands, and the digestive tract. These muscle cells have a unique spindle shape with a central nucleus and lack the striations characteristic of other muscle types, giving them a smooth appearance. As involuntary muscles, they are controlled by signals from the brain and the autonomic nervous system. The primary role of visceral muscle is to facilitate the movement of substances through the ducts of glands and within the digestive system. **Cardiac Muscle**Cardiac muscle is found exclusively in the heart, where it functions to pump blood throughout the body. It is also involuntary and possesses the unique ability of auto-rhythmicity, allowing it to generate its own rhythmic contractions without external stimuli. Cardiac muscle