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Ch 6 The Muscular System Notes Lisa Peck
Muscular System: consists of skeletal muscles and their connective tissue attachments
organ- skeletal muscle
consists of hundreds of muscle fibers (cells) bound tog. by connective tissue
cell- muscle fibers- elongated cells
largest (compared to smooth muscle)
primary function is contraction: ability to shorten dep. on myofilaments
muscle prefixes “myo” - muscle
“mys” - muscle
“sarco” - flesh
3 Muscle Types (p 178-181)
1. Skeletal Muscle- skeletal, striated, & voluntary
referred to as the human body’s “muscular system”
location: attach to bones or indirectly to other connective tissues or cartilage
attach via tendons or aponeuroses
exception: some facial muscles attach to soft tissues (oth. muscles or skin)
function: create movement of bones or facial skin via contractions
contraction 1. regulation: voluntary
subject to conscious control via nervous system
only muscle type that is voluntary
2. speed: rapidly w/ great force
tire easily
must rest after activity
3. no rhythmic contractions
morphology: single cell
elongated cylindrical shape
myofiber (cell):
sarcolemma- muscle cell membrane
myofibrils- contractile organelles found in cytoplasm of muscle cells
long tube-like
have light and dark bands along length
many aligned perfectly w/ in sarcolemma
giving a striated appearance to cell
multinucleated- nuclei and cytoplasm pushed to edge of sarcolemma by
numerous myofibrils
sarcoplasmic reticulum- ER of cell
stores calcium (for contraction)
striated- banded appearance due to alignment of bands on myofibrils
myofibril bands created by arrangement of myofilaments within myofibril
myofilaments- filaments composing the myofibrils
two types: actin & myosin
,Skeletal Muscle 2
connective tissue coverings of skeletal muscle
endomysium- thin connective tissue covering muscle cell (fiber)
perimysium- coarser fibrous membrane covering bundles of muscle fibers
creating a fascicle- bundle of muscle fibers bound tog. by connective tissue
epimysium- tough fibrous connective tissue surrounding many fascicles
creating a skeletal muscle
outer covering of entire skeletal muscle
blend into strong, cordlike tendons or into sheetlike aponeurosis
tendon- cord of dense fibrous tissue attaching a muscle to a bone
aponeuroses- fibrous or membranous sheet connecting a muscle & the part it moves
fascia- layers of fibrous tissue covering and separating muscles
tendon f’ns: 1. provide durability & conserve space
2. tough collagenic fibers, can cross rough bony projections (would tear muscle)
3. have small size, therefore more tendons than fleshy muscles can passover a joint
,3 types of muscle cells: 3
Skeletal Cardiac Smooth
Smooth Muscle- visceral, nonstriated, & involuntary
location: walls of hollow visceral organs
stomach, urinary bladder, respiratory passages
function: create movement of substances through a tract or pathway
contraction 1. regulation: involuntary
control via nervous system
endocrine system (hormones)
chemicals
mechanical stretching
2. speed: very slow & sustained
does not tire easily
3. rhythmic contractions in some
morphology: single cell
fusiform shape (spindle shaped)
nonstriated
uninucleated
arranged in sheets or layers
1. runs circularly
2. runs longitudinally
-layers alternatively contract & relax
-changing shape & size of organ
-moving substances through tract
, Cardiac Muscle- cardiac, striated, & involuntary 4
location: walls of the heart
function: force movement of blood through heart chambers to arteries
contraction 1. regulation: involuntary
control via heart “pacemaker” (for rhythmic contraction)
nervous system (for increased # of contractions for short period)
endocrine system (hormones)
2. speed: slow
does not tire easily
3. rhythmic contractions
morphology: branching chains of cells
striated
uninucleated
fibers cushioned with soft connective tissue
fibers arranged in spiral or figure 8 shaped bundles
enables heart activity to be closely coordinated
branching cells joined by intercalated discs
Muscle Functions (pp 181-182)
1. producing movement- result of contraction
skeletal muscles: enable quick response to changes in environment
enable expression of emotions (facial & neck muscles)
smooth muscles: force substances to move thru visceral tracts
cardiac muscles: circulate blood & maintain blood pressure
2. maintaining posture- via skeletal muscles
overcoming gravity effects while sitting or standing
3. stabilizing joints- pull of skeletal muscles on bones
tendons important in reinforcing & stabilizing joints too
4. generating heat- by-product of muscle activity
75% of ATP energy creates heat (only 25% used to contract muscle)
Ch 6 The Muscular System Notes Lisa Peck
Muscular System: consists of skeletal muscles and their connective tissue attachments
organ- skeletal muscle
consists of hundreds of muscle fibers (cells) bound tog. by connective tissue
cell- muscle fibers- elongated cells
largest (compared to smooth muscle)
primary function is contraction: ability to shorten dep. on myofilaments
muscle prefixes “myo” - muscle
“mys” - muscle
“sarco” - flesh
3 Muscle Types (p 178-181)
1. Skeletal Muscle- skeletal, striated, & voluntary
referred to as the human body’s “muscular system”
location: attach to bones or indirectly to other connective tissues or cartilage
attach via tendons or aponeuroses
exception: some facial muscles attach to soft tissues (oth. muscles or skin)
function: create movement of bones or facial skin via contractions
contraction 1. regulation: voluntary
subject to conscious control via nervous system
only muscle type that is voluntary
2. speed: rapidly w/ great force
tire easily
must rest after activity
3. no rhythmic contractions
morphology: single cell
elongated cylindrical shape
myofiber (cell):
sarcolemma- muscle cell membrane
myofibrils- contractile organelles found in cytoplasm of muscle cells
long tube-like
have light and dark bands along length
many aligned perfectly w/ in sarcolemma
giving a striated appearance to cell
multinucleated- nuclei and cytoplasm pushed to edge of sarcolemma by
numerous myofibrils
sarcoplasmic reticulum- ER of cell
stores calcium (for contraction)
striated- banded appearance due to alignment of bands on myofibrils
myofibril bands created by arrangement of myofilaments within myofibril
myofilaments- filaments composing the myofibrils
two types: actin & myosin
,Skeletal Muscle 2
connective tissue coverings of skeletal muscle
endomysium- thin connective tissue covering muscle cell (fiber)
perimysium- coarser fibrous membrane covering bundles of muscle fibers
creating a fascicle- bundle of muscle fibers bound tog. by connective tissue
epimysium- tough fibrous connective tissue surrounding many fascicles
creating a skeletal muscle
outer covering of entire skeletal muscle
blend into strong, cordlike tendons or into sheetlike aponeurosis
tendon- cord of dense fibrous tissue attaching a muscle to a bone
aponeuroses- fibrous or membranous sheet connecting a muscle & the part it moves
fascia- layers of fibrous tissue covering and separating muscles
tendon f’ns: 1. provide durability & conserve space
2. tough collagenic fibers, can cross rough bony projections (would tear muscle)
3. have small size, therefore more tendons than fleshy muscles can passover a joint
,3 types of muscle cells: 3
Skeletal Cardiac Smooth
Smooth Muscle- visceral, nonstriated, & involuntary
location: walls of hollow visceral organs
stomach, urinary bladder, respiratory passages
function: create movement of substances through a tract or pathway
contraction 1. regulation: involuntary
control via nervous system
endocrine system (hormones)
chemicals
mechanical stretching
2. speed: very slow & sustained
does not tire easily
3. rhythmic contractions in some
morphology: single cell
fusiform shape (spindle shaped)
nonstriated
uninucleated
arranged in sheets or layers
1. runs circularly
2. runs longitudinally
-layers alternatively contract & relax
-changing shape & size of organ
-moving substances through tract
, Cardiac Muscle- cardiac, striated, & involuntary 4
location: walls of the heart
function: force movement of blood through heart chambers to arteries
contraction 1. regulation: involuntary
control via heart “pacemaker” (for rhythmic contraction)
nervous system (for increased # of contractions for short period)
endocrine system (hormones)
2. speed: slow
does not tire easily
3. rhythmic contractions
morphology: branching chains of cells
striated
uninucleated
fibers cushioned with soft connective tissue
fibers arranged in spiral or figure 8 shaped bundles
enables heart activity to be closely coordinated
branching cells joined by intercalated discs
Muscle Functions (pp 181-182)
1. producing movement- result of contraction
skeletal muscles: enable quick response to changes in environment
enable expression of emotions (facial & neck muscles)
smooth muscles: force substances to move thru visceral tracts
cardiac muscles: circulate blood & maintain blood pressure
2. maintaining posture- via skeletal muscles
overcoming gravity effects while sitting or standing
3. stabilizing joints- pull of skeletal muscles on bones
tendons important in reinforcing & stabilizing joints too
4. generating heat- by-product of muscle activity
75% of ATP energy creates heat (only 25% used to contract muscle)
