Muscular System

Nicole Graham

Function Of The Muscular System

The function of the muscular system is to produce voluntary movement, circulate blood, and move food through the digestive system.

3 Types Of Muscular Tissue

Cardiac

  • Cardiac Muscle is found in the heart
  • Cardiac Muscle is striated like skeletal muscle but differs in the plasma membrane of the cardiac muscle causes the muscle to beat even when away from the heart
  • The action potentials of cardiac and skeletal muscle also differs
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Smooth

  • Smooth Muscle is involuntary
  • It is found in organs and enables functions such as digestion and respiration
  • Smooth muscle is not striated
  • Smooth muscle has less myosin and does not generate as much tension as the skeletal muscle
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Skeletal

  • Skeletal Muscle is voluntary
  • These muscles are attached to bones and are responsible for their movement
  • Skeletal muscle consists of long fibers and is striated due to the repeating patterns of the myofilaments that make up the fibers
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Sarcomere

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How Skeletal Muscle Contracts

An action potential travels along a motor neuron toward a skeletal muscle. Their point of connection is called a neuromuscular junction. At the junction, acetylcholine vesicles are released. Acetylcholine binds to its receptor on the sarcolemme causing Na+ influx into the muscle fiber, generating an action potential within the muscle fiber. The action potential travels through the T-tubules, allowing calcium channels to open and release calcium into the cytoplasm. Calcium ions activate the actin-myosin binding sites and cross-bridges for between the actin and the myosin heads. An ATP is hydrolyzed to provide energy for flexing the myosin heads. Flexion brings the actin filaments closer to the middle of the sarcomere. The overall length of the sarcomere is shorter; contracted. In order for relaxation to occur, ATP must be used to pump calcium back into the sarcoplasmic reticulum.

Major Disorders In The Muscular System

Myopathy:

  • A disease that causes the skeletal or voluntary muscles to become weak or wasted
  • Symptoms/Signs: Aching, cramping, pain, stiffness, tenderness, and tightness
  • Prevalence: 14%
  • Treatment Options: Drug therapy for muscular dystrophies, inflammatory myopathies, and avoiding situations that work the muscles too hard


Tendonitis:

  • The inflammation or irritation of the tendons
  • Symptoms/Signs: Pain, tenderness, and mild swelling
  • Prevalence: 1.1 of 100,000 individuals
  • Treatment Options: Pain relievers, corticosteriods, platelet-rich plasma, a boot, and surgery