• Describe the basic structure of skeletal
• Understanding the steps of skeletal muscle contraction
• List & describe the types of skeletal muscle fibers
Skeletal attached to bones, move axial & appendicular skeleton
muscle
Striated
Visceral tongue, pharynx, part of diaphragm, part of esophagus
Cardiac
Smooth
Muscle cell cytoplasm = sarcoplasm
Smooth ER = sarcoplasmic reticulum (SR)
Cell membrane = sarcolemma
muscle
epimysium
fascicle
perimysium
Muscle fiber endomysium
(Myocyte)
Muscle fiber
(Myocyte)
Myofibril
Myofilamint
A: anisotropic
I: isotropic
Z: German Zwischen, between
I band A band
Accessory proteins
• Structural proteins regulate the spacing, attachment & alignment of myofilaments
• Tinin 2500 KD
• Tropomodulin
• Desmin
• Myomysin
• Dystrophin it links actin to the sarcolemma & endomysium
Duchenne muscular dystrophy DMD
• X-linked recessive genetic disorder: abnormally low dystrophin in myofiber
• Progressive muscular weakness
Normal
DMD
Stretched sarcomere
Resting sarcomere
Contracted sarcomere
Rigor mortis (stiffness of death!)
• Death
calcium released from sarcoplasmic R
mitochondrial hydrolysis
No more ATP
Muscle stiffness
S: Slow (type I)
I: Intermediate (type IIa)
F: Fast (type IIb)
Geoffrey Kipsang Kamworor
Usian Bolt
Muscle cramps
fast-contracting fibers
Anaerobic glycogenosis
Accumulation of lactic acid
Oxygen deficit
Ischemic pain (cramps)
Top 3 causes of death
in the USA?
Intercalated disc
• Fascia adherens (adhering j)
• Macula adherents (desmosome)
• Gap junctions
Muscle response to load (skeletal muscle)
Muscle response to load (cardiac muscle to increased blood
pressure i.e. hypertension))
Cardiac Muscle injury & repair
Cardiac markers (enzymes)
Troponin I (TnI)
Troponin T (TnT)
Skeletal
Cardiac
Smooth