Chapter 6 The Muscular System

I.Overview of Muscle Tissues Differ in cell structure,location, and how they are stimulated to contract Smooth and skeletal muscle cells are elongated and called ________________________ Contraction-shortening-depends on 2 types of myofilaments Terms myo-,sarco- and mys- refers to muscle-example-muscular cytoplasm is called ___________________. Muscle fibers sarcoplasm

skeletal muscle attach to skeleton and form smoother contours of body huge,cigar shaped and ______________________ largest of muscle fibers-as much as 30 cm in length __________________________with obvious stripes ___________________since only muscle subject to conscious control Voluntary muscle multinucleate striated

However,subject to involuntary reflexes Tire easily and requires rest Fairly fragile Bound by ___________________________which provides strength and support Connective tissue

Each muscle fiber contained in a declicate connective tissue sheath called ___________________________ _________________________-connective tissue wrapping a bundle of fibers called a _________________   perimysium endomysium fascicle

___________________________= many fascicle bound together w/ this tough coat Epimysia blend into the strong_,cordlike_________ or aponeurose(sheetlike) that connect muscle to bones,cartilages or connective tissue Other functions of tendons-besides movement-are durability and conservation of space epimysium tendons

Smooth Muscle Stomach,bladder,and respiratory passages No striations and is involuntary Mainly in walls of hallow visceral organs such as ____________________________________________________________________________________ Propel substances on a definite tract or pathway Spindle shaped and uninucleate Stomach,bladder,and respiratory passages

Scant endomysium Most often in 2 layers-one running circularily and one running longitudinally-alternately contract or relaxing changing size and shape of organ

Cardiac Muscle Only in heart Forms most of heart walls ________________________but involuntary Cushioned in bundles w/ small amount of endomysium striated

When heart contracts,internal chambers get smaller,forcing blood into arteries leaving heart Branching cells joined by junctions-___________________________________These traits and spiral arrangement of bundles allow heart activity to be closely coordinated,giving steady contraction rate ______________________can shift heart into “high gear” Nervous system Intercalated discs

****** We focus mostly on skeletal muscle here!

Muscle Functions movement posture joints Generating heat _______________________as a result of muscle contraction;quick response to environment Maintaining _____________-maintain erect posture despite gravity Stabilizing ________________-esp. w/ poorly fitting articulating surfaces as in shoulder _________________________________-by –product of muscle activity;ATP used for contractions and ~40% released as heat to mostly maintain normal body temp for at least 40% of body mass movement posture joints Generating heat