Sliding Filament Theory in Muscle Contraction

Sliding Filament Theory

• Myosin filaments use energy from ATP to "walk" along actin filaments with their cross bridges.
• This pulls actin filaments closer together, shortening the sarcomere.
• When all sarcomeres in a muscle fiber shorten, the fiber contracts.

Muscle Contraction Process

• A message travels from the nervous system to the muscular system, triggering chemical reactions.
• The chemical reactions lead to muscle fibers reorganizing themselves to shorten the muscle.
• When the nervous system signal is no longer present, the chemical process reverses, and the muscle fibers rearrange again, and the muscle relaxes.

Functions of the Muscular System

• Maintain Posture: Muscles help keep the human frame in the correct position.
• Movement: Muscles contract to result in various activities such as walking, eating, running, etc.
• Blood Circulation: Muscles in the heart ensure proper flow of blood to various portions of the body.
• Respiration: The diaphragm muscle relaxes, pushing air from the lungs.
• Digestion: Smooth muscles in the stomach and intestines ensure proper digestion.
• Regulation of Temperature: The muscular system is also accountable for maintaining stable body temperature.

Types of Muscle Tissue

• Skeletal muscles: voluntary muscles that we use to move our arms and legs.
• Smooth muscle: found in organs such as the stomach and intestines and is involuntary.
• Cardiac muscle: found in the heart and is also involuntary.

Functions of different types of muscles

• Skeletal muscles: move our arms and legs.
• Smooth muscle: pushes food through the digestive system.
• Cardiac muscle: pumps blood around the body.

Muscle Disorders

• Myopathy: a disease that affects the muscles that connect to your bones (skeletal muscles).
• Muscular dystrophy: an inherited disorder that causes muscle weakness and atrophy.
• Types of Muscular Dystrophy:
  • Duchenne: affects boys, typically manifests in early childhood.
  • Becker: similar to Duchenne, but typically has a later onset and milder progression.

Specific Muscles

• Erector spinae: a set of muscles that straighten and rotate the back.
• Biceps: found in the front of the upper arm, helps control the motion of both the shoulder and elbow joints.
• Triceps: muscles in the back of the upper arm, helps stabilize the shoulder joint and allow the elbow joint to be straightened.
• Deltoids: known as the shoulder muscles, used on all sides of body lifting motions.
• Obliques: the muscle group on the sides of the abdominals.

Takotsubo Cardiomyopathy (Broken Heart Syndrome)

• Temporary and reversible condition characterized by sudden and severe weakening of the heart muscle, often triggered by severe emotional or physical stress.
• Symptoms: shortness of breath, fatigue, swelling, chest pain or discomfort, palpitations, dizziness or fainting, and more.
• Causes: genetic factors, viral infections, alcohol abuse, hypertension, coronary artery disease, and more.
• Treatment: medications, lifestyle modifications, device therapy, surgical procedures, and regular monitoring and follow-up.