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
multinucleate
striated
Voluntary muscle
– 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 _________________
endomysiumperimysium
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
• 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”
Intercalated discs
Nervous system
****** We focus mostly on skeletal muscle here!
Muscle Functions– _______________________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 posturejoints
Generating heat