Muscle Structure and Function - Zoology - Lecture Notes, Study notes for Zoology. All India Institute of Medical Sciences


Description: Muscle Structure and Function, Types of Muscle Tissue, Structure of Skeletal Muscle, Hierarchy of Structure, Bundle of Muscle Fibers, Bundles of Contractile Proteins, Sarcomere are some points from this lecture. This lecture is one of lectures on Zoology.
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Mu scle Structure and Function
A. Types of Muscle Tissue
1. skeletal muscle - striated, voluntary
2. cardiac muscle - striated, involuntary
3. smooth muscle - non-striated, involuntary
B. Structure of Skeletal Muscle
1. Hierarchy of structure:
whole muscle
fascicle = bundle of muscle fibers
muscle fiber = cell (multinucleated)
myofibril - subcellular bundles of contractile proteins; striations
myofilaments - thick filaments and thin filaments
sarcomere - structural/functional unit of muscle contraction
- organized array of myofilaments, repeated in series along myofibrils
C. The Sarcomere
A band
I band
Z line (Z disc)
H zone
thick filaments: thin filaments:
myosin actin
D. Sliding Filament Mechanism
1. Changes in the sarcomere during contraction
A band stays the same
I band and H zone become narrower
Z lines move closer together
2. Muscle contraction cycle:
1.cross bridge - myosin head binds to actin
2.power stroke - myosin head rotates and pulls thin filament
3.ATP binding - detaches myosin from actin
4.ATP hydrolysis - energizes myosin head
E. Excitation-Contraction Coupling
muscle action potential - conducted along the sarcolemma (plasma membrane)
sarcoplasmic reticulum
stores calcium ions (Ca2+)
calcium pump (Ca ATPase) in SR membrane
F. Neural Control of Skeletal Muscle
motor neuron
neuromuscular junction
motor unit
muscle spindle stretch receptors
G. Muscle Fiber Types
slow oxidative (red)
fast oxidative-glycolytic (red)
fast glycolytic (white)
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