1001NSC Lecture Notes - Lecture 5: Astrocytoma, Endoplasmic Reticulum, Perimysium
20 Jun 2018
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The Muscular System
Myology: the study of muscles
Kinesiology: the study of movement of body parts
Properties of Muscle Tissue:
Excitability: respond to chemicals released from nerve cells
Conductivity: ability to propane electrical signals over membrane
Contractility ability to shorten and generate force
Extensibility: ability to be stretched without damaging the tissue
Elasticity: ability to return to original shape after being stretched
Muscle tissue:
1. Cardiac: striated, involuntary control
2. Smooth: non-striated, involuntary control
3. Skeletal: striated, voluntary control
Structure of skeletal muscle
Tendons join muscle to bone
Muscle - Fascicle - Muscle fibre (cell) - Myo-fibrils - sarcomeres (microfilaments)
Muscle Wrappings:
Epimysium: outside wrapping
Perimysium: wrapped around fascicles
Endomysium: muscle fibres wrapped in this
Fusion of myoblasts in muscle fibres:
Every mature muscle cell develops from 100 myoblasts that fuse together in the foetus
Mature muscle cells cannot divide
Each muscle cell consists of:
Sarcolemma: cell membrane
Many mitochondria
Transverse tubules (extension of sarcolemma)
Sarcoplasmic reticulum: special endoplasmic reticulum closely associated with T tubules
stores intracellular Ca2+ ions, vital for muscle contraction
Proteins of muscle:
Myofibrils: are built of theres kinds of protein
Contractile proteins (myosin and actin)
regulatory protein (switch contractions on or off: troponin and tropomyosin)
Structural proteins (which provide correct alignment, elasticity and extensibility: titin,
dystrophin and others)
Muscular dystrophies:
Inherited, muscle-destroying diseases
Sarcolemma tears during muscle contraction
Muscle fibre dies
Degenration of muscle fibres
Muscle eventually replaced by fibrous connective and fat tissues
Appears by age 5
Thin filaments are composed of:
Actin: two twisted strings of bead-like actin sub-units
Tropomyosin: two ribbons around the actin
Troponin: composed of three protein sub-units
pg30
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Document Summary
Kinesiology: the study of movement of body parts. Excitability: respond to chemicals released from nerve cells. Conductivity: ability to propane electrical signals over membrane. Extensibility: ability to be stretched without damaging the tissue. Elasticity: ability to return to original shape after being stretched. Muscle tissue: cardiac: striated, involuntary control, smooth: non-striated, involuntary control, skeletal: striated, voluntary control. Muscle - fascicle - muscle bre (cell) - myo- brils - sarcomeres (micro laments) Every mature muscle cell develops from 100 myoblasts that fuse together in the foetus. Sarcoplasmic reticulum: special endoplasmic reticulum closely associated with t tubules stores intracellular ca2+ ions, vital for muscle contraction. Myo brils: are built of theres kinds of protein. Contractile proteins (myosin and actin) regulatory protein (switch contractions on or off: troponin and tropomyosin) Structural proteins (which provide correct alignment, elasticity and extensibility: titin, dystrophin and others) Muscle eventually replaced by brous connective and fat tissues. Actin: two twisted strings of bead-like actin sub-units.
