Muscle Tissue.ppt

8/22/2019 Muscle Tissue.ppt

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Muscle Tissue


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Characteristics of Muscle:

1. Excitability ability to respond to stimuli

2. Contractility ability to shorten forcefully

3. Extensibility ability to stretch

4. Elasticity ability to resume resting length aftercontraction

5. Tonicity- ability to maintain a steady partial

contraction


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Functions of Muscle:

1. Produce movement

Locomotion/manipulation (skeletal)

Blood pressure (cardiac)

Propulsion ( smooth)

2. Maintain posture or body position

3. Support soft tissues (abdominal muscles)

4. Guard entrance/exit (lips, anus)

5. Store nutrients


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Skeletal muscles are not ripped apart as they exert force because

thousands of their fibers are bundled together by connective tissue, which

provides strength and support to the muscle as a whole.

Each muscle fiber is enclosed in a delicate connective tissue sheath called

an endomysium

Several sheathed muscles are then wrapped by a coarser fibrousmembrane called a perimysium to form a bundle of fibers called a fascicle

Many fascicles are bound together by an even tougher overcoat of

connective tissue called an epimysium, which covers the entire muscle

The epimysia blend into the strong, cordlike tendons, or into sheetlike

aponeuroses which attach muscles indirectly to bones, cartilages, or CT

coverings of each other


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The entire muscle is surrounded by an external connective

tissue wrapping called the epimysium

Skeletal muscle is made up offascicles which are bundles

of individual muscle cells Each fascicle is surrounded by a connective tissue called

perimysium

Each individual muscle fiber inside the fasciculus is

enveloped by a thin fibrous cT capsule called endomysiumEpimysium

fascicle

Perimysium


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FascicleMuscle cell

Endomysium

Perimysium

epimysium


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Muscle fiber (cell)- functional unit of muscle

Sarcolemma- cell membrane of muscle cell

Sarcoplasm- cytoplasm of the muscle fiber

Transverse Tubules- network of passageways through fiber- continuous with outside of cell

Sarcoplasmic Reticulum- specialized endoplasmic reticulum- contain calcium ions (Ca++) [40,000x] compared to cytoplasm


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Terminal cisternae

- sac like region of SR

- reservoir of calcium ions

Myofibrils

- cylindrical structures containingcontractile fibers

Triad

- 3 unit group consisting of 1 T tubule

lying between 2 adjacent terminalcisternae

The interconnecting tubules and sacs of theSR surround each and every myofibril asthe sleeve of a loosely crocheted sweater

surrounds your arm

The major role of this elaborate system is tostore calcium and to release it on demandwhen muscle fiber is stimulated tocontract


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Myofibrils

- contractile elements of the skeletal muscle

Sarcomere

- basic structural and functional unit of skeletal muscleA band

- dark central region in the sarcomere

- made up of overlapping myosin and actin myofilament

I band- light band in the sarcomere

- made up of actin myofilament

H zone

- light zone at the center of the sarcomere

M line

- dark staining band

Z disk

- network of protein fibers forming an attachment site for actin

myofilament


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Types of Muscle Tissue:1.Smooth Muscle

2. Skeletal Muscle

3. Cardiac Muscle


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Muscle Tissue

Tissue with cells having fibers specialized for contraction. Skeletal Muscle (Striated, voluntary)

Parallel elongated cells (fibers)

multinucleated and each cell is the length of the muscle

attached to the skeleton Smooth Muscle (Visceral, involuntary)

Cells are long and tapered (spindle)

Organized into sheets of muscle

Centrally located nucleus Cardiac Muscle

Intercalated discs

Branched

Striated


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* Skeletal Muscle 1000X

striations acrossmuscle fiber

nucleus

long parallel fibers


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Skeletal Muscle

Attached to the bones

and cartilages

voluntary muscle; nervous

system consciously controls

the contraction

striated due to alternate light

and dark bands

Multinucleated, peripheral


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Smooth Muscle 400X

intestinal wall


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Smooth muscle

involuntary, contract in

response to stimulation of

ANS

spindle shaped

mono-nucleated, central

arranged in parallel pattern

forming sheets


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* Smooth Muscle (teased) 400X

spindle shape cell

nucleus


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* Cardiac Muscle 1000X

intercalated disc

striations

short branching cells; intercalated discs at cell junctions

nucleus


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Cardiac Muscle found in the heart and in the roots of

large blood vessels arising from the

heartStriated but apparently branched

mononucleated

Specialized to contract automatically

and rhythmically

most characteristic feature:

intercalated discs

intercalated discs (specialized cell

junctions that allow fibers to interlock

for greater strength during contraction ;

also provide ionic continuity

betweencent cells


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Cardiac muscle

Muscle Tissue.ppt

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