Excitation-Contraction Coupling: How Muscles Turn Electrical Signals Into Movement

Excitation-Contraction Coupling: How Muscles Turn Electrical Signals Into Movement

Question 1. excitation contraction coupling.
Answer:

Excitation Contraction Coupling Definition:

• excitation of muscle fiber causes development of action potential which through sequence of events produces muscular contraction.
• These both are coupled by Ca2+
• The process by which depolarization of the muscle fiber initiates contraction is called excitation contraction coupling.

Excitation Contraction Coupling  Stages:

Question 2. Sliding theory/ratchet/walk along theory.
Answer:

The process by which the shortening of the contractile elements in the muscle is brought about is the sliding of actin filament over the myosin filament.

Events:

• Thus, myosin head move back and forth and bring all the actin filament towards the center of sarcomere.
• This forms actomyosin complex which cause muscular contraction.

Question 3. Myasthenia Gravis.
Answer:

Myasthenia Gravis Definition:

• It is a neuromuscular diseases characterized by grave weakness of the muscle.

Myasthenia Gravis Cause:

• It is autoimmune disease
• Caused due to formation of circulating antibodies against nicotinic acetycholine receptors.

Myasthenia Gravis Symptoms:

• Muscles mostly involved are: facial extraocular, swallowing and chewing muscles.
• Rapid onset of fatigue.
• Slow and weak muscular contraction.
• Marked generalised weakness of muscles.
• In severe condition.
  1. Paralysis of muscles.
  2. Death due to paralysis of respiratory muscles.