MUSCLE TISSUE HISTO

1. movement of the body

2. responsible for changes in size and shape in internal organs

function of muscle tissue

muscle tissue

aggregates specialized, elongated cells which primary role is CONTRACTION

thin filaments

composed primarily of the protein Actin

F-actin (Fibrous) and G-actin (Globular)

under the thin filaments

striated muscle

cells exhibit cross- striations at the light microscope

skeletal muscle

attached to bone and is responsible for movement of the axial and appendicular skeleton and for maintenance of body position and posture.

Visceral striated muscle

is structurally identical with skeletal muscle but is resteed to ue son ussues namely, tongue, onarynx, lumodr vant of dia shraym and upper part of esophagus. These muscles play roles in speech, breathing and swallowing.

cardiac muscle

is a type of striated muscle found in the wall of the heart and in the base of the large veins that empty into the heart.

Smooth muscle

the cells do not exhibit cross-striations (eg. Viscera,

Vascular System, Arrector pili muscles of the skin and Intrinsic muscles of the Eye)

skeletal muscle

strong, quick discontinuous voluntary contraction

composed of large, elongated, multinuc/eated fibers.

cardiac muscle

Strong, quick continuous involuntary contraction

composed of Irregular branched cells bound together longitudinally by intercalated disks.

smooth muscle

weak, slow involuntary contraction

is an agglomerate of fusiform cells.

Syncytium

Each muscle cell, more commonly called a muscle fiber, is actually a multinucleated…

Myoblasts

Each muscle fiber is formed during development by the fusion of small, individual muscle cells called

polygonal shape with a diameter of 10-100 um

In cross-section, the mature multinucleated muscle fiber reveals a..

Sarcolemma

The nuclei of a Skeletal Muscle fiber are located in the cytoplasm beneath the plasma membrane, also called…

Endomysium

Is the delicate layer of reticular fibers that immediately surrounds individual muscle fibers.

Perimysium

thicker, connective tissue layer that surrounds a group of fibers to form a bundle or fascicle.

the sheath of dense connective tissue that surrounds a collection of fascicles that constitute the muscle.

Myoglobin

oxygen-binding protein that closely resembles hemoglobin (in Erythrocytes) and occurs in varying amounts in muscle fibers.

It also provides muscle metabolic reactions.

Myofibril

Structural and functional subunit of the muscle fibers

fascicles

Skeletal Muscles are composed

Myofilament

• Individual filamentous polymers of Myosin Il and Actin and its associated proteins (thin filaments).

• Actual contractile elements of Striated Muscle.

Sacroplasmic Reticulum

The bundles of myofilaments that make up the myofibril are surrounded by a well-developed Smooth ER

A Band (Anisotropic Band)

bisected by the H band which in turn is bisected by a narrow dense line called M line.

I-Band or Isotropic Band

bisected by the Z-line.

Sacromere

• The functional unit of the myofibril is the ….the segment of the myofibril between the two adjacent Z lines.

Tropomyosin

- Il forms filaments that run in the groove between the F-actin molecules in the thin filament.

Troponin

consists of a complex of three globular subunits.

Troponin C

the smallest subunit; Its binds with Ca

Troponin T

binds to Tropomyosin, anchoring the Troponin complex

Troponin I

binds to Actin, thus inhibiting Actin-Myosin interaction.

Contraction Cycle

Shortening of a muscle involves ______ that move the thin filaments along the thick filament.

Attachment

is the initial stage of the contraction cycle, in which the Myosin head is tightly bound to the Actin molecule of the Thin filament.

Rigor Configuration

an arrangement under the stage 1 attachment of contraction cycle

RELEASE

In this stage of the cycle, ATP binds to the myosin head and induces conformational changes of the actin-binding site.

actin, tropomyosin and Troponin

3 major protein components

BENDING

hydrolysis in ATP (breakdown of ATP will go into ADP phosphate

FORCE GENERATION

the release of inorganic phosphate; loss of ADP and inorganic phosphate

REATTACHMENT

The Myosin head is again tightly bound to a new Actin molecule of the Thin filament (Rigor Configuration), and the cycle can repeat.

Transverse Tubular System

T SYSTEM, consists of numerous tubular invaginations of the plasma membrane; each one is called a T Tubule.

Triad

the complex of T Tubule and the 2 adjacent

Terminal Cisternae.

Myosin head

binds the actin and ATP breaks down to ADP

Thin Filaments

contains F-actin, Troponin and Tropomyosin

this is the I band

Thick filaments

Contains only Myosin II

Triad

The complex of T tubule and the 2 adjacent terminal cisternae

terminal cisterna

Sarcoplasmic Reticulum forms a slightly more regular ring-like channel called

Terminal cisterna

Serves as a reservoir for Ca