5.3: Physiology of the Muscular System: Essential Human Anatomy and Physiology I with Lab- Kassner.p

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BIOD 151Pages5.3: Physiology of the Muscular System!5.3: Physiology of the Muscular System11:35Muscle!ssue is found in three dis!nct types in the body: skeletal, smooth, and cardiac. Skeletal muscle is under voluntary control.Voluntary controlmeans a conscious decision is made to move this type of muscle.Skeletal muscle!ssue allows for conscious movement of the body and limbs. Smoothmuscle and cardiac muscle are underinvoluntary control, meaning contrac!on of this muscle happens without a conscious decision.Smooth muscleisfound within the internal organs of the body, such as the diges!ve tract and blood vessels.Cardiac muscleis only found within the heart. Under themicroscope, skeletal and cardiac muscle appear to bestriatedor striped in appearance, while smooth muscle is free of stria!ons.Figure 5.34 Histological view of the three different types of muscle"ssue:Figure 5.34 Histological view of the three different types of muscle"ssue: Cardiac (top), skeletal (middle), and smooth (bo#om).Figure 5.35 Histology of skeletal muscle"ssue.Figure 5.35 Histology of skeletal muscle"ssue. Note the visible stria"ons (striped appearance).Figure 5.36 Histology of smooth muscle"ssue.Figure 5.36 Histology of smooth muscle"ssue. Note there are not visible stria"ons.Skeletal muscles, which make up over 40% of the body's weight, are a"ached to the skeleton by tendons, made of fibrous connec!ve!ssue.Tendonsconnect muscle to bone, whileligamentsconnect bone!ssue to bone.When muscles contract, they become shorter. Muscles can only pull; they cannot push. Skeletal muscles must work in antagonis!c pairs becausemuscles are only able to pull in the direc!on of their fiber orienta!on. If one muscle of anantagonis!c pairbends the joint and brings the limb towardthe body (theflexor), the other one straightens the joint and extends the limb (theextensor), as shown in the figure below. The following is a review ofac!on terminology (see Module 1) with examples of antagonis!c pairs found within the muscular system:Ac!on Terms -Body MovementFlexion- closing of a joint,“bending”Extension- opening of a joint,“straightening”Antagonis"c pair example:Flexor -biceps brachiiExtensor -triceps brachii
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