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