Muscles

• The study of muscles is called myology
• Total muscles in the human body: 639
• Smallest muscle: stapes (in the ear)
• Broadest muscle: gluteus maximus (in the hip)
• Longest muscle: Sartorius
• Well, we see different types of movements in both humans and other living beings.

TYPES OF MOVEMENT IN HUMANS:

• Protoplasmic movement
  • pseudopodia in amoeba, and macrophage, WBC in humans
  • cilia in the paramecium, respiratory tract, ependymal cell, fallopian tube, and collecting duct in humans.
  • flagella in euglena, sperm tail in humans.
• Muscular Movement
  • muscles: excitability, contractibility, extensibility, elasticity
  • coordinated work by muscle, bone, and nerve

CLASSIFICATION OF MUSCLES:

• SKELETAL MUSCLES:
  • Voluntary
  • connected with skeleton
  • found in bundles
  • striated
  • unbranched (muscle cell)
  • multinucleated
• SMOOTH MUSCLES
  • involuntary
  • connected to visceral organs
  • not found in bundles
  • unbranched
  • unstriated
  • uninucleated
• CARDIAC MUSCLES
  • in heart
  • involuntary
  • branched
  • striated
  • uninucleated
  • muscles connected to each other in the intercalated disc

MUSCLE

• Muscle cells are surrounded by a plasma membrane called sarcolemma.
• The cytoplasm which acts as the main arena of activities is called sarcoplasm.
• cell organelles include the nucleus, mitochondria, er
• cytoplasmic inclusions: glycogen, lipid, myoglobin, creatine phosphate, enzymes, ATPase, creatine phosphate kinase.
• Skeletal muscle layer (epimysium)
• Muscle fascicle layer (perimysium)
• Muscle fiber layer (endomysium)

COMPOSITION OF MUSCLE FIBER:

• Water (75%)
• Other (25%)
  • protein (20%)
  • force-generating: actin, myosin
  • regulating: troponin, tropomyosin
  • structural: actinine
  • other (5%) ions like Na+, K+, HCO3-

MYOFIBRIL:

• Z line is attached to sarcolemma by costomere.
• M line consists of myosin rod.
• Actin is attached to sarcolemma by dystrophin.