Muscular System

• Movement

• Maintain posture

• Produce heat

• Role in organ function, blood circulation

Muscular system functions

• Where: attached to bones

• Characteristics: multinucleated, striated, long/cylindrical shape

• Control: Voluntary

• Action: movement at jts, stimulated by nervous system

Skeletal muscle

• Where: walls of heart

• Characteristics: branching, intercalated discs, 1 nucleus, lightly striated

• Control: involuntary

• Action: pumps blood out of the heart, self-excitatory (influenced by nervous system and hormones)

Cardiac muscle

• Where: walls of hollow organs, vessels, resp passages

• Characteristics: tapered at each end (spindle), branching, nonstriated

• Control: involuntary

• Action: peristalsis

Smooth (visceral) muscle

atrophy

Decrease in size (wasting) of muscle

muscular dystrophy (MD)

Genetic disease where muscles waste away or atrophy

myalgia

painful muscle

• Antinuclear antibody (ANA)

• Autoimmune profile

• Cold agglutinin titer

• Creatine

• Creatine kinase (CK)

• Electromyography

• Lactate dehydrogenase (LD/LDH)

• Lactic acid

• Myoglobin

• Tissue biopsy or culture

Tests for muscular system disorders

Autoimmune connective tissue disease - antibodies accidentally target normal proteins —> inflammation that leads to jt/tissue damage

Antinuclear antibody (ANA)

Immune system attacks RBCs when cold, associated with rheumatoid arthritis

Cold agglutinin titer

Waste produce from muscle breakdown - rhabdomyolysis

Creatine test

Enzyme in muscle tissue (elevated levels indicate muscle damage)

Creatine kinase (CK)

Measures electrical activity of the muscles/nerves

Electromyography

• Enzyme in muscles - damaged tissue w/ LDH, cells release the enzyme into the bloodstream (high levels = sign of damage)

• Used to track muscular dystrophy

Lactate dehydrogenase (LD/LDH)

Byproduct of muscle metabolism - accumulates when O2 is low

Lactic acid test

Protein in muscle tissue that stores oxygen, elevated levels - muscle damage

Myoglobin test