skeletal muscle

• What is skeletal muscle primarily responsible for?

  Voluntary movement of the body
• How does skeletal muscle contract?

  By receiving electrical messages from neurons via action potentials

  
• What happens if the message from the brain to the skeletal muscle is disrupted?

  The skeletal muscle cannot contract
• What is the neuromuscular junction (NMJ)?

  The last neuron that makes contact with the skeletal muscle
• What is the structure of skeletal muscle fibers?

  Skeletal muscle is made of fibers that receive innervation

  
• What are the three types of muscle tissues?

  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle
• What are the characteristics of skeletal muscle cells?

  Long and cylindrical, striated, with many nuclei
• What is the primary function of cardiac muscle?

  To propel blood into circulation
• What is the primary function of smooth muscle?

  To propel substances or objects along internal passageways
• What is the primary function of skeletal muscle?

  Locomotion and manipulation of the environment
• Where is skeletal muscle located?

  Attached to bones or occasionally to the skin
• What special structures are found inside skeletal muscle fibers?

  Myofibrils, which are fine contractile fibers

  
• What is the sarcolemma?

  The plasmic membrane of muscle cells
• What is the sarcoplasmic reticulum?

  The endoplasmic reticulum of muscle cells
• What are myofilaments composed of?

  Thin filaments (actin) and thick filaments (myosin)

  
• What is the role of T tubules?

  To transmit action potentials through the cell
• What is a sarcomere?

  The main contractile unit of muscle fiber

  
• What gives skeletal and cardiac muscles their striated appearance?

  The overlapping protein filaments within the sarcomere

  
• What are thick filaments primarily composed of?

  Myosin protein

  
• How are thick filaments arranged in the sarcomere?

  In a hexagonal lattice in the center of the sarcomere

  
• What regulates the interaction of thin and thick filaments?

  Troponin and tropomyosin proteins
• What is the role of troponin in muscle contraction?

  To bind tropomyosin to G-actin and regulate contraction
• What happens when calcium binds to troponin?

  It changes shape and exposes bonding sites for contraction
• What is the role of the neuromuscular junction in muscle contraction?

  It allows neuronal signals to interact with skeletal muscle fibers

  
• What is the synaptic cleft?

  The space between the synaptic end bulb and the muscle fiber
• What neurotransmitter is involved in muscle contraction at the NMJ?

  Acetylcholine (ACh)

  
• What happens when ACh is released into the synaptic cleft?

  It binds to receptors on the motor end plate, initiating an action potential
• What is the function of acetylcholinesterase (AChE) in the synaptic cleft?

  To break down ACh and prevent continuous muscle contraction

  
• What is the all-or-none principle in muscle fibers?

  A muscle fiber is either contracted or relaxed
• What factors determine the tension of a single muscle fiber?

  The number of pivoting cross-bridges, resting length, and frequency of stimulation
• What is the length-tension relationship in muscles?

  The relationship between muscle length and the force it can produce

  
• What is the optimal resting sarcomere length for generating tension?

  75% to 130% of optimal length
• What is a motor unit?

  A motor neuron and the muscle fibers it innervates

  
• How does the size of a motor unit affect precision of movement?

  Smaller motor units allow for greater precision
• What is recruitment in muscle contraction?

  Increasing force by recruiting more motor units
• What is summation in muscle contraction?

  The occurrence of additional twitch contractions before complete relaxation

  
• What is tetanus in muscle contraction?

  Maximal force generated without relaxation due to rapid stimuli

  
• What does the length-tension property reflect?

  The importance of thick and thin myofilaments in generating muscle tension

  
• How does muscle length affect the force generated during contraction?

  Muscles generate greater tension when neither too short nor too long

  
• What is the length-tension curve?

  A graph showing the relationship between muscle length and tension generated