Animal muscle is contractile tissue responsible for producing movement. It's the engine driving an organism's interaction with its environment. This intricate process involves the cooperative work of muscle and nerve fibers. Animal muscles are crucial for various functions, from locomotion and digestion to breathing and maintaining posture.
Types and Functions of Animal Muscle
While there are nuances, animal muscle is broadly classified into three types:
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Skeletal Muscle: This is the type of muscle most commonly associated with movement. It's attached to bones and is responsible for voluntary actions like walking, running, and lifting objects. Skeletal muscle cells are long, cylindrical, and multinucleated. Examples include the biceps and triceps. Research into meat science and muscle biology focuses on evaluating meat quality and composition, from live animal to carcass. (Source: University of Arkansas, Meat and Muscle Biology)
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Smooth Muscle: This involuntary muscle type is found in the walls of internal organs like the stomach, intestines, and blood vessels. Smooth muscle controls processes like digestion, blood pressure regulation, and pupil dilation. Its cells are spindle-shaped and have a single nucleus.
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Cardiac Muscle: This specialized muscle forms the heart. Cardiac muscle is responsible for the rhythmic contractions that pump blood throughout the body. Like smooth muscle, it's involuntary; however, its cells are branched and interconnected, allowing for coordinated contractions. Studies show that hepatic expression of malonyl-CoA decarboxylase can reverse muscle insulin resistance in rats fed a high-fat diet. (Source: Nature, Hepatic expression of malonyl-CoA decarboxylase reverses muscle insulin resistance)
Muscle Protein Synthesis and Nutrition
The synthesis of muscle protein is influenced by dietary protein. While animal protein is often considered a more potent stimulator of muscle protein synthesis than plant protein, this isn't always the case, and factors like overall protein intake are critical. A vegetarian diet, for example, can result in lower muscle mass if the protein intake isn't sufficient. (Sources: NCBI, The Role of the Anabolic Properties of Plant- versus Animal-Based Proteins, NCBI, Relationship between animal protein intake and muscle mass index, NCBI, Animal Protein versus Plant Protein in Supporting Lean Mass and Muscle Protein Synthesis)
Muscle Efficiency and Animal Models
The efficiency of animal muscle varies greatly. For example, wildebeest muscles have been shown to be remarkably efficient, at 62.6%, compared to a car engine's ~25% or other animals' muscles around 25%. (Source: RVC, Wildebeest muscles almost three times more efficient than a car engine) Farm animals are often used as models to study muscle development and metabolism, particularly to improve meat quality and reduce production costs. (Source: doi.org, Farm animals for studying muscle development and metabolism)
