MUSCLE

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• MUSCLE
• 1. Classification of Muscles
• A. Classification of muscle by location and
  function
• skeletal muscles
• visceral muscles
• cardiac muscle
• B. Classification of muscle by structure
• striated muscle
• skeletal muscles
• cardiac muscle
• smooth muscles
• visceral muscles

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• C. Classification of muscle by mode of action
  and control
• voluntary muscles
• skeletal muscles
• involuntary muscles
• smooth muscles
• cardiac muscle
• 2. Skeletal Muscle
• A. Structure of skeletal muscles
• origin (proximal end)
• muscle belly
• insertion (distal end)

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• Tendons
• antagonistic pairs
• Flexors
• Extensors
• Epimysium
• Perimysium
• Endomysium
• fasciculi

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• B. Cellular and molecular structure of skeletal
  muscle
• muscle fibers
• myofibrils myofilaments (actin and myosin
  filaments)
• sarcomere
• A-band
• I-band
• M-line
• Z-line (Z-disc)
• H-zone

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• myofilaments
• thin filaments (actins)
• tropomyosin (troponin-I, -T and -C)
• thick filaments (myosins)
• cross-bridges
• Accessory protiens Titin and Nebulin
• sarcolemma
• traverse tubules (t-tubules)
• sarcoplasmic reticulum
• terminal cisternae

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• C. Contractile process
• requirements for this process
• the actin and myosin must interact
• Role of tropomyosin and troponin
• the myosin cross-bridges must flex
• the system must be able to convert chemical
  energy to mechanical energy
• Sliding filament theory of contraction
• D. Contraction of muscle
• isometric contraction
• isotonic contraction

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A. In the relaxed state, troponin partially
blocks the myosin-binding sites on actin.
B. Contraction begins when Ca2 binds to
troponin, which uncovers the myosin-binding site
on actin.
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• muscle twitch
• Twitch summation
• length-tension relationship
• E. Nervous control of skeletal muscle
• neuromuscular (myoneural) junction or motor
  end-plate
• Ach secretion by the nerve terminals
• opening of chemical-gated ion channels by Ach
• end-plate potential
• destruction of released Ach by acetylcholinesteras
  e
• Coupling of action potential and Ca release
• Dihydropyridine (DHP) receptors

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Length-tension relationships
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A. Acetylcholine creates an action potential that
moves across the fiber membrane and down the
t-tubules.
B. Ca2 from sarcoplasmic reticulum combines with
troponin uncovering binding sites on actin,
initiating contraction.
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• drugs that affect transmission at the
  neuromuscular junction
• drugs of acetylchloline-like action
• Methacholine
• Carbachol
• nicotine
• drugs that block transmission at the
  neuromuscular junction
• botulinum toxin (presynaptic blockade)
• curare (postsynaptic blockade)
• drugs that inactivate acetylcholinesterase
• Neostigmine
• Physostigmine
• diisopropyl flurophosphate (nerve gas)

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• Skeletal muscle contraction and supply of ATP
• Phosphocreatine
• Glycolysis anaerobic pathway
• Oxidative phosphorylation aerobic metabolism
• Oxygen debt requirement of O2 for conversion of
  lactic acid to pyruvate
• Types of skeletal muscle fibers (Table 12-3)
• White fibers (fast muscle fiber, glycolytic)
• Red fibers (oxidative)
• Fast twitch type
• Slow twitch type

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• Smooth Muscle
• Structure
• No troponin
• Dense bodies as anchor protein
• Actin/myosin ratio 10-121
• Myosin light chains

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• Types of smooth muscle
• Single-unit smooth muscle
• Multi-unit smooth muscle

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• Smooth muscle contraction and relaxation

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• Regulation of contraction in smooth muscle

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Muscle contraction duration
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