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Study Guide for Muscle Tissue, Study Guides, Projects, Research of Anatomy

Study Guide for Types of Muscle Tissue

Typology: Study Guides, Projects, Research

2021/2022

Available from 08/05/2023

tarika-arjune
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Anatomy: Thursday October 6, 2022
Types of Muscle Tissue:
Skeletal Muscle:
Functions of skeletal muscle:
o Producing movement
o Maintaining posture and body position
o Supporting soft tissues
o Guarding body entrances and exits
o Maintaining body temperature
o Storing nutrients
Skeletal muscles contain:
o Skeletal muscle tissue (primarily)
o Connective tissues
o Blood vessels
o Nerves
Collagen fibers of epimysium, perimysium, and endomysium come together: At ends of
muscles to form:
o A tendon (bundle)
o Or aponeurosis (sheet)
To attach skeletal muscles to bones
Bundle within a Bundle (organization of muscle) & connective tissue wrappings
Skeletal muscles have three layers of connective tissue:
o Epimysium: [epi= above] a connective tissue wrapping around the bundle of bundles.
Layer of collagen fibers that surrounds the muscle
o Perimysium: Surrounds muscle fiber bundles (fascicles).
o Endomysium: Surrounds individual muscle cells (muscle fibers)
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Anatomy: Thursday October 6, 2022

Types of Muscle Tissue:

Skeletal Muscle:

Functions of skeletal muscle: o Producing movement o Maintaining posture and body position o Supporting soft tissues o Guarding body entrances and exits o Maintaining body temperature o Storing nutrients Skeletal muscles contain: o Skeletal muscle tissue (primarily) o Connective tissues o Blood vessels o Nerves Collagen fibers of epimysium, perimysium, and endomysium come together: At ends of muscles to form: o A tendon (bundle) o Or aponeurosis (sheet) To attach skeletal muscles to bones Bundle within a Bundle (organization of muscle) & connective tissue wrappings Skeletal muscles have three layers of connective tissue: o Epimysium: [epi= above] a connective tissue wrapping around the bundle of bundles. Layer of collagen fibers that surrounds the muscle o Perimysium: Surrounds muscle fiber bundles (fascicles ). o Endomysium: Surrounds individual muscle cells ( muscle fibers)

Cells called myoblasts, which have one nucleus each, fuse together to form long cylindrical multinucleated cell called a muscle fiber, with its nuclei located at the periphery, and this is surrounded by a sheath of connective tissue called the endomysium. Inside each muscle fiber (muscle cell) are many myofibrils, and these contain myofilaments, which are themselves organized into units called sarcomeres. These are the contractile machinery which actively shorten, and are therefore responsible for skeletal muscle contraction. It is also these sarcomeres that gives skeletal muscle a straited or stripe appearance, and they are the smallest functional unit in the muscle. These myofilaments within are two types, thinner actin filaments and thicker myosin filaments, and the sliding of these filaments past one another is what produces contraction. Each muscle fiber is arranged into a bundle of muscle cells called a fascicle, which is surrounded by a layer of fibrous connective tissue called the perimysium, and multiple muscle fascicles will in turn group together to form an even larger structure surrounded by a layer of dense irregular connective tissue called the epimysium. This group of fascicles along with blood vessels, nerves, and all the tissue comprise an entire skeletal muscle, and these will span joints and attach to bones at least two places. Type of Skeletal muscle:

  • Myoblasts: During development, groups of embryonic cells called myoblasts fuse to form individual skeletal muscle fibers.
  • Muscle fibers: muscle fiber are enormous compared to other cells, Contain hundreds of nuclei ( multinucleate ), develop by fusion of embryonic cells (myoblasts ), Also known as striated muscle cells due to striations, and consist of myofibrils.
  • Myofibrils: Myofibrils are made of bundles of protein filaments called myofilaments { think (composed of primarily myosin ) & thin (composed of primarily actin )}. Responsible for muscle contraction
  • Myofilament: this is referring to a protein fiber like (Actin & myosin) which are involved in muscle cell contraction.
  • Fascicle: each fascicle is a bundle of muscle fibers. Fascicles are covered by a layer of connective tissue called perimysium. Organelles / structures in skeletal muscle Terminology: o Sarcoplasm : it is the cytoplasm of muscle. o Sarcolemma : it is the plasma membrane of muscle or muscle fiber.

Histology of muscle

  • It is Striated
  • Skeletal muscle is Multinucleated : meaning they have multiple nuclei. Structure of the sarcomere ( it is the functional units of the skeletal muscle)
  • Sarcomere : a section of myofibril between two Z lines where muscle contraction physically occurs. A band = thick fibers (anisotropic-dark ) purple in the figure. This band contains myosin. o M line: in the center of A band, Proteins stabilize positions of thick filaments o H band: on either side of M line, has thick filaments but no think filaments. o Zone overlap: dark region, where thick and thin filaments overlap. I band โ†’ thin fibers (isotropic lighter because they are thinner. This band contains actin, troponin and tropomyosin o Z lines/ discs/ bands โ†’ attachment point of thin fibers. The zigzag lines o Contain thin filaments but no thick filaments o Titin: Elastic protein, Extends from tips of thick filaments to the Z line, Keeps filaments in proper alignment, Aids in restoring resting sarcomere length.

NMJ : neuromuscular junction

  • It is a gap junction
  • Motor end plate is the proximal portion of muscle at the NMJ
  • Motor neuron is a neuron that controls muscle
  • Synaptic left is the space Found in the chicken: White fibers = glycolytic (glycogen) โ†’ fast fibers โ†’ pale (chicken breast)

Red fibers = oxidative (myoglobin) โ†’ slow fibers โ†’ dark (chicken legs)

Cardiac Muscle:

  • It is straited like skeletal muscle
  • Found only in the heart
  • It has many mitochondria
  • Are small
  • It has gap junctions known as intercalated discs
  • Nuclei surrounded by glycogen ( glycogen does not pick up the stain it looks white)
  • Interdigitating folds

Smooth Muscle

  • Does not have striation
  • Is also called visceral muscle
  • 2 or 3 layers, depending on where it's on the body. If two layers longitudinal layer and circular. If three layers extra layer would be the oblique layer.
  • Long, slender, spindle-shaped cells
  • Single, central nucleus (No T tubules, myofibrils, or sarcomeres)