the muscular system. structure and function of muscle tissue muscle type skeletalcardiacsmooth...
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The Muscular System
Structure and Function of Muscle Tissue
Muscle type
Skeletal Cardiac Smooth
Striated?
Voluntary?
Location?
Regenerate
Function?
Structure and Function of Muscle Tissue
Muscle type
Skeletal Cardiac Smooth
Striated?
Voluntary?
Location? Throughout
Body
Heart Digestive tract, etc.
Regenerate Limited No Yes
Function? Movement Movement Movement
Functions of muscle tissue important for Homeostasis
MovementStabilizes bodyRegulates organ
volumeProduces heatMovement of food,
urine, blood
Layers of deep dense CT that surrounds muscle SG pg 108
Epimysium – entire muscle
Perimysium – bundle of muscle fibers
Endomysium – individual fibers
Muscle MicroanatomyA band – darkest color – most dense
thick and thin filaments overlapH band - medium color – medium density
thick filaments onlyI band – lightest color – least dense
thin filaments only
Z disc – separate one sarcomere from another
M line – dark middle of sarcomereMyofibrils – 1 – 2 micrometers in diameterSarcomere – contractile unitSarcolemma – plasma membrane of muscle
fiberSarcoplasm – cytoplasm of muscle fiber
Sarcoplasmic reticulum – fluid-filled sacs around each myofibril
During the contraction phase – thin filaments move towards M line
Ach (acetylcholine) released at neuromuscular junction
Muscle Ultrastructure Muscle fiber Myofibrils Filaments
Basics of Muscle Contraction SG pg 110
Animation of Muscle Contraction
Isometric exercises – exercise with an immovable resistant object
Contraction with NO movement
Isotonic exercises (aerobic exercise) – exercise with movement
Contraction with movement
Skeletal muscles cooperate!Muscles can only pull or contract – so most
body movements are the result of muscles acting together or against each other.
Prime moversAntagonistsSynergists Fixators
Origin – end of muscle attached to immovable bone
Insertion – end of muscle attached to movable bone
Naming MusclesAction
Direction of Fibers
Location
Number of Origins
Points of attachment of origin and insertion
Size or Shape
ANATOMY STUDY WEBSITE
ANATOMY ARCADE GAMES
Muscles that move the Head and Neck
Muscles that move the Trunk
Posterior
Pelvis, Hip, and Thigh
Lower Leg
Atrophy – shrinking of muscle tissue from lack of use
Hypertrophy – enlargement of existing muscle cells
Hyperplasia – increase in the number of muscle fibers
Muscles and Aging
Beginning at around 30 years, slow, progressive loss of skeletal muscle tissue
Replaced by fibrous CT and adipose tissue
Decrease in muscle strength
Slower muscle reflexes
Loss of flexibility
Common Muscle disordersMyasthenia gravis –
Autoimmune disorder that causes chronic, progressive damage of the neuromuscular junction
Muscles of face and neck
1 in 10,000 peopleMostly women
Muscular DystrophyA group of inherited
muscle-destroying disorders that target specific muscle groups
Cause is the lack of a protein muscle fibers
No cureEx. Duchenne’s MD
FibromyalgiaPainful,
nonarticular rheumatic condition
more common in women
Affects fibrous CT of muscles, tendons, and ligaments
Abnormal contractionsSpasm
Sudden involuntary contraction of a single muscle in a large group of muscles
CrampPainful spasmodic
contractionInadequate blood flow,
overuse, dehydration, injury
Holding a position for a long time
Low potassium level
Tremor Rhythmic, involuntary,
purposeless contraction Quivering or shaking
motionFasciculation
Twitching often seen in MS
Fibrillation Spontaneous
contraction only seen by electromyography
Tic – spasmodic twitching of a muscle normally under voluntary control
Muscle cramps Not enough
CalciumLack of oxygen
Muscle strainTearing of a
muscleBleeding within
muscle and severe pain
Treat with RICERestIceCompressionElevation
Causes of muscle fatigueMuscle fatigue –
when a muscle is unable to contract even when it is still being stimulated
Oxygen depletion/debt from prolonged muscle activity
Lactic acid buildupATP depletion
Oxygen DebtO2 debt, which
occurs after vigorous muscle activity, must always be “paid back”
This “pay back” begins when a person breathes rapidly and deeply after activity – this continues until the muscles have enough O2 to get rid of the lactic acid buildup