Questions and Answers
Which of these are types of muscle tissue? (Select all that apply)
What are the functions of skeletal muscle?
Produce movement, maintain posture, support soft tissues, guard body entrances and exits, maintain body temperature, store nutrients.
What are the layers of connective tissue in skeletal muscle?
Epimysium, Perimysium, Endomysium.
What does the epimysium do?
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What is the function of perimysium?
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What surrounds individual muscle fibers?
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What is a tendon?
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What is an aponeurosis?
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What is the purpose of blood vessels in muscles?
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How do nerves interact with muscle fibers?
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What are myoblasts?
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What is the sarcolemma?
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What is sarcoplasm?
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What are transverse tubules?
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What are myofibrils?
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What are thick filaments made of?
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What are thin filaments primarily composed of?
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What is the sarcoplasmic reticulum?
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What forms a triad in muscle cells?
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Study Notes
Types of Muscle Tissue
- Skeletal muscle tissue: responsible for pulling on bones to facilitate movement.
- Cardiac muscle tissue: specialized for pumping blood throughout the body.
- Smooth muscle tissue: aids in pushing fluids and solids along the digestive tract.
Functions of Skeletal Muscle
- Enables movement: skeletal muscles pull on tendons to move bones.
- Maintains posture: constant muscle tension supports body position.
- Supports soft tissues: provides structure to the abdominal wall and pelvic floor.
- Guards entrances and exits: controls openings of the digestive and urinary tracts.
- Regulates body temperature: generates heat as energy is expended during activity.
- Stores nutrients: contractile proteins can be broken down into amino acids when dietary intake is low.
Layers of Connective Tissue in Skeletal Muscle
- Epimysium: dense layer encloses the entire muscle and connects to deep fascia.
- Perimysium: surrounds fascicles, contains collagen and elastic fibers as well as blood vessels and nerves.
- Endomysium: delicate tissue surrounding individual muscle fibers, interconnects adjacent fibers, and contains capillaries and myosatellite cells.
Tendons and Aponeuroses
- Tendons: collagen fiber bundles that connect skeletal muscle to bone, formed from the fusion of epimysium, perimysium, and endomysium.
- Aponeurosis: broad, sheet-like structure of collagen fibers, serving similar attachment purposes as tendons.
Blood Vessels in Muscles
- Extensive network supplies nutrients and eliminates waste.
- Blood vessels enter through the perimysium and small arterioles supply individual muscle cells via the endomysium.
Nerves in Muscles
- Axons penetrate through connective tissue layers, branching to innervate individual muscle fibers.
- Skeletal muscles are considered voluntary muscles due to conscious control.
Myoblasts
- Embryonic cells that differentiate into muscle fibers or myosatellite cells for regeneration.
- Multiple fused myoblasts form a multinucleated muscle fiber, one nucleus per myoblast.
Sarcolemma and Sarcoplasm
- Sarcolemma: plasma membrane of muscle cells, encloses cytoplasm (sarcoplasm), possesses a characteristic negative membrane potential and conducts electrical impulses.
- Sarcoplasm: cytoplasm within muscle cells, characterized by a more negative potential.
Transverse Tubules
- Conduct action potentials throughout the muscle cell, continuous with the sarcolemma and extending deep into the sarcoplasm.
- Filled with extracellular fluid and essential for conducting electrical impulses.
Myofibrils and Filaments
- Myofibrils: long, cylindrical structures within muscle fibers responsible for contraction; composed of thick (myosin) and thin (actin) filaments.
Thick Filaments
- Comprised of approximately 300 myosin molecules, with a diameter of 10-12 nm and length of 1.6 μm.
- Each myosin molecule features two heads and is also associated with the elastic protein titin.
Thin Filaments
- Made of actin, measuring 5-6 nm in diameter and 1 μm in length.
- Contains F-actin strands, nebulin, troponin, and tropomyosin.
Elastic Myofilaments
- Comprised of titin, providing elasticity and stability to the muscle structure.
Sarcoplasmic Reticulum
- Resembles smooth endoplasmic reticulum, forming a tubular network around myofibrils.
- Functions as a calcium storage site, crucial for muscle contraction.
Terminal Cisternae
- Located alongside t-tubules, they store high concentrations of calcium ions and are involved in calcium transport during muscle contraction.
Triad
- Composed of one t-tubule and two terminal cisternae, facilitating coordinated muscle contraction by linking membrane systems.
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Description
Explore the different types of muscle tissues, including skeletal, cardiac, and smooth muscle. This quiz delves into the various functions of skeletal muscle, such as movement, posture maintenance, and temperature regulation. Test your knowledge on connective tissue layers that support muscle function.
