Muscle Tissue

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  • Topic: Muscle, Muscle contraction, Skeletal muscle
  • Pages : 13 (2159 words )
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  • Published : August 13, 2010
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Muscle Tissue

Introduction
* Motion
* Results from alternating contraction (shortening) and relaxation of muscles * Skeletal system
* Provides leverage and a supportive framework for this movement * Myology – study of muscles

Muscle Tissue
* Alternating contraction and relaxation of cells
* Chemical energy changed into mechanical energy

Types of Muscle Tissue
* Skeletal muscle – primarily attached to bones
* Striated and voluntary
* Cardiac muscle – forms the wall of the heart
* Striated and involuntary
* Smooth (visceral) muscle – located in viscera
* Non-striated and involuntary
Striated “striped”

Skeletal Muscle
* Attaches to bone, skin, or fascia
* Striated with light and dark bands
* Voluntary control of contraction and relaxation

Cardiac Muscle
* Striated in appearance
* Involuntary control
* Auto-rhythmic because of built in pacemaker

Smooth Muscle
* In walls of hollow organs blood vessels and GI
* Nonstriated in appearance
* Involuntary

Functions of Muscle Tissue
* Producing body movements
* Stabilizing body positions
* Regulation organ volumes
* Bands of smooth muscle called sphincters

Functions of Muscle Tissue
* Movement of substances within the body
* Blood, lymph, urine, air, flood and fluids, sperm
* Production of heat
* Involuntary contractions of skeletal muscle (shivering) * Excitability
* Respond to chemicals released from nerve cells

Properties of Muscle Tissue
* Conductivity
* Ability to propagate electrical signals over membrane * Contractility
* Ability to shorten and generate force
* Extensibility
* Ability to be stretched without damaging the tissue
* Elasticity
* Ability to return to original shape after being stretched

Skeletal Muscle Tissue
Each skeletal muscle,
is a separate organ,
composed of cells,
called “Fibers”

Muscle Cell = Muscle Fiber

Skeletal Muscle
* Connective tissue components:
* Endomysium – seperates individual muscle cells (fibers) * Perimysium – surrounds bundles (fasicles) of 10-100 muscle cells (fibers) * Epimysium – surrounds the whole muscle
These connective tissue layers extend beyond the muscle belly to form the tendon)

Tendons and Aponeuroses
* Extensions of connective tissue beyond muscle cells that attach muscle to bone or other muscle * Tendon
* Cord of dense connective tissue that attaches a muscle to the periosteum of a bone * Aponeurosis
* A tendon that extends as a broad, flat layer

Nerve and Blood Supply
* Each skeletal muscle is supplied by:
* Artery
* Veins
* Nerve
* Each motor neuron supplies multiple muscle cells
* Each muscle cell is supplied by 1 motor neuron terminal branch

Anatomy of the Skeletal Muscle Cell
* Sarcolemma cell membrane
* Sarcoplasm cytoplasm
* Sarcoplasmic reticulum modified ER
* T-tubules and myofibris aid in contraction

Transverse Tubules
* T (transverse) tubules
* Invaginations of the sarcolemma into the center of the cell * Filled with extracellular fluid
* Carry muscle action potentials down cell

Myofibris
* Muscle fibers are composed of threadlike structures called “Myofibrils” * Each myofibril is encircled by SR (sarcoplasmic reticulum) * Sarcoplasmic reticulum – stores calcium ions

Myofilaments
* Myofilaments
* Found within each myofibril
* Types:
* Thick
* Thin
* Function and Composition
* Contractile proteins of muscle

Sarcoplasmic Reticulum
* System of tubular sacs to smooth ER in non-muscle cells * Stores Ca+2 in a relaxed muscle
* The release of Ca+2 trigger muscle contraction

Filaments and the Oarcomere
* Thick & Thin Filaments overlap each...
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