Anatomy and Physiology - Muscle Tissue - Quick Guides

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Study GuideAnatomy and Physiology–Muscle Tissue1.Quiz: Types of Muscles1. QuestionWhich of the following muscles typically operate under voluntary control?Answer Choices• cardiac• skeletal• smoothCorrect AnswerskeletalWhy This Is CorrectSkeletal musclesarevoluntary, meaning you control them consciously.Example: walking, lifting, writing.2. QuestionWhich muscles can cause blood vessels to dilate or constrict depending on external conditions?Answer Choices• cardiac• skeletal• smooth

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Study GuideCorrect AnswersmoothWhy This Is CorrectSmooth musclelines blood vessels and can automatically controlvasodilation(widening) andvasoconstriction(narrowing).This helps regulate blood pressure and blood flow.3. QuestionWhich of the following muscles do NOT consist of striations?Answer Choices• cardiac• skeletal• smoothCorrect AnswersmoothWhy This Is CorrectSmooth muscleisnon-striated, meaning it does not have the striped appearance seen in skeletaland cardiac muscles.Cardiac and skeletal muscles are bothstriated.2.Connective Tissue Associated with Muscle TissueAskeletal muscleis made up of many muscle cells calledmuscle fibers. These fibers are groupedtogether and wrapped in layers ofconnective tissue.

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Study GuideThese connective tissue layers help the muscle stay organized, strong, and able to contract efficiently.2.1Connective Tissue Layers Around Skeletal Muscle1. EndomysiumTheendomysiumis the connective tissue layer that surrounds:each individual muscle fiber (muscle cell)Think of it like the thin wrapping around a single thread.2. PerimysiumTheperimysiumsurrounds a group of muscle fibers.It wraps muscle fibers into a bundle called afascicle.So:•muscle fibers + perimysium =fascicle3. EpimysiumTheepimysiumis the outer connective tissue layer.It surroundsall fascicles togetherto form theentire muscle.This is like the outer cover holding the whole muscle together.Tendons and Aponeuroses4. TendonAtendonis a strong, cord-like extension of the three muscle coverings:•endomysium•perimysium•epimysium

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Study GuideIt extends beyond the muscle and connects:•muscle toboneor•muscle toanother muscle5. AponeurosisAnaponeurosisis similar to a tendon, but instead of being cord-like, it is:flat and broadIt performs the same job as a tendon—connecting muscles to bones or other muscles.Fascia (Connective Tissue Sheets)6. FasciaFasciais a general term for asheet or layer of connective tissue.7. Deep FasciaThedeep fasciais located deeper in the body.It surrounds theepimysiumand also encloses or lines structures nearby such as:•blood vessels•nerves•body wall structures8. Superficial FasciaThesuperficial fasciais the layer locatedjust under the skin.It is also called:•hypodermis•subcutaneous layerThe superficial fascia merges with deep fascia in areas where skin surfaces meet.

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Study Guide3.Quiz: Connective Tissue Associated with Muscle Tissue1. QuestionThe __________ surrounds the entire muscle. The __________ surrounds groups of muscle fibers.The __________ surrounds individual muscle fibers.Answer Choices• endomysium; epimysium; perimysium• epimysium; perimysium; endomysium• perimysium; epimysium; endomysiumCorrect Answerepimysium; perimysium; endomysiumWhy This Is CorrectMuscles are wrapped in 3 layers of connective tissue:•Epimysium= surrounds theentire muscle•Perimysium= surroundsbundles of muscle fibers(fascicles)•Endomysium= surroundseach individual muscle fiberA good way to remember:EPI = Entire muscle2. QuestionA tendon is an extension of which of the following?Answer Choices• endomysium and epimysium• endomysium and perimysium• endomysium, epimysium, and perimysium

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Study GuideCorrect Answerendomysium, epimysium, and perimysiumWhy This Is CorrectAtendonforms when all three connective tissue layerscome together and mergeat the end of amuscle.This creates a strong attachment that connectsmuscle to bone.4.Structure of Skeletal MuscleAskeletal muscle fiberis a singlemuscle cell, but it is very different from most other cells in thebody. It has special names for its parts and a unique internal structure that helps it contract.4.1Special Terms in a Muscle Fiber1. SarcolemmaThesarcolemmais theplasma membraneof a muscle cell.It is deeply folded inward to formtransverse tubules (T tubules or T tubes).These T tubules go deep into the cell and help signals spread quickly throughout the muscle fiber.2. SarcoplasmThesarcoplasmis thecytoplasmof the muscle cell.Inside the sarcoplasm there is a special calcium-storing structure called thesarcoplasmic reticulum.The sarcoplasmic reticulum is thespecialized endoplasmic reticulumof muscle cells, and itstorescalcium, which is important for muscle contraction.3. Nuclei in Skeletal MuscleSkeletal (striated) muscle cells aremultinucleated, meaning:

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Study Guideeach muscle fiber hasmany nucleiThese nuclei are located along theouter edge (periphery)of the cell.They form small swellings that can often be seen through the sarcolemma.4. MyofibrilsMost of the inside of the muscle fiber is filled with long structures calledmyofibrils.Myofibrils are the structures that actually help the muscle contract.4.2Filaments Inside MyofibrilsEach myofibril is built usingtwo main types of filaments.Figure 1.Two types of filaments

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Study Guide1. Thin Filaments (Actin)Thin filaments are mainly made of the proteinactin.Key features:•actin formstwo strands•arranged in adouble helix•along the actin are two important proteins:otroponinotropomyosinTroponin and tropomyosin help control contraction by covering specialbinding siteson actin.2. Thick Filaments (Myosin)Thick filaments are made from groups of the proteinmyosin.Key features:•myosin forms protrudingheads•each myosin filament has a head at one end•in a thick filament, many myosin molecules are arranged so there areprotruding heads atmany positions, on both ends of the filament4.3Sarcomeres and Muscle StriationsInside a myofibril:•actin and myosin filaments are arrangedparallel•they lieside by side•they overlap in a repeating patternThis overlap creates the light and dark band pattern that makes skeletal muscle lookstriated(striped).

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Study GuideSarcomere (The Functional Unit)The repeating unit of the pattern is called asarcomere.•Each sarcomere is separated by a boundary called theZ disc (Z line)•Actin (thin filaments)are attached to theZ disc•Myosin (thick filaments)lie between the actin filamentsImportant:Myosin filaments “float” between actin filaments and arenot attached to the Z disc.5.Quiz: Structure of Skeletal Muscle1. QuestionMuscle cells store calcium ions needed for contraction in an organelle called __________.Answer Choices• fascia• sarcolemma• sarcoplasmic reticulumCorrect Answersarcoplasmic reticulumWhy This Is CorrectThesarcoplasmic reticulum (SR)is a specialized organelle in muscle cells thatstores calciumions (Ca²⁺).When contraction begins, the SR releases calcium so the muscle can contract.

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Study Guide2. QuestionMyosin cross-bridges are extensions of __________.Answer Choices• actin• myosin• troponinCorrect AnswermyosinWhy This Is CorrectThecross-bridgesare the “heads” sticking out frommyosin (thick filaments).They attach to actin and pull it during muscle contraction.3. QuestionThe membrane around a muscle cell is called a __________.Answer Choices• sarcoplasm• sarcolemma• sarcomereCorrect AnswersarcolemmaWhy This Is CorrectThesarcolemmais thecell membraneof a muscle fiber.It surrounds the muscle cell and helps carry electrical signals that start contraction.

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