lecture 5

• What is the primary function of muscle tissue?

  Convert chemical energy into mechanical energy
• How many types of muscle tissue are there?

  Three types
• What are the three types of muscle tissue?

  Skeletal, cardiac, and smooth
• What is the characteristic of skeletal muscle cells?

  They are long and contain several nuclei
• What is the appearance of skeletal muscle cells?

  They have a striated banding pattern
• What type of control do skeletal muscles have?

  Voluntary control
• Where is smooth muscle found?

  In walls of blood vessels and hollow organs
• How does smooth muscle contract?

  By relaxing and contracting to squeeze substances
• What is the shape of smooth muscle cells?

  Spindle-shaped
• What is the control type of smooth muscle?

  Involuntary control
• What is unique about cardiac muscle cells?

  They contain intercalated discs
• Where is cardiac muscle found?

  In the walls of the heart
• What type of control do cardiac muscles have?

  Involuntary control
• What is the function of cardiac muscle?

  Pumping blood around the body
• What are the four characteristics of muscle tissue?

  Excitable, contractile, extensible, elastic
• What is the role of muscle contraction in the body?

  Responsible for movement and generating heat
• What surrounds and supports skeletal muscle?

  Connective tissue
• What are myofibrils?

  Rod-like structures in muscle fibers
• What do myofibrils contain?

  Sarcomeres, the contractile elements
• What causes muscle cells to contract?

  Intracellular calcium (Ca$^{2+}$)
• What is the sliding filament model?

  Filaments slide to cause muscle contraction
• What are the two types of filaments in a sarcomere?

  Thick (myosin) and thin (actin)
• What is excitation-contraction coupling?

  Process linking action potential to muscle contraction
• What happens at the neuromuscular junction?

  Release of acetylcholine (ACh) occurs
• What is the synaptic cleft?

  The gap between neuron and muscle
• What is the end plate potential (EPP)?

  Depolarization event in muscle fiber
• What causes the release of Ca$^{2+}$ ions?


  Action potential in muscle fiber
• What is the role of Ca$^{2+}$ in muscle contraction?


  Allows thick and thin filaments to slide
• What happens to ACh after muscle contraction?

  It is degraded in the synaptic cleft
• What is the organization of smooth muscle?

  Two sheets: longitudinal and circular layers
• How does smooth muscle contraction differ from skeletal muscle?

  Contraction is slow and synchronized
• What is unique about cardiac muscle contraction?

  It contracts as a unit due to intercalated discs
• What is the primary energy source for cardiac muscle?

  Aerobic respiration
• What is the most common muscular dystrophy?

  Duchenne’s muscular dystrophy
• What is the cause of most human muscle disorders?

  Genetic abnormalities
• What is the purpose of somatic cell reprogramming in muscle engineering?

  To generate any cell type for muscle restoration
• What are the key differences between skeletal and cardiac muscle?

  • Skeletal muscle: voluntary, multi-nucleated, striated
  • Cardiac muscle: involuntary, single or double nuclei, striated, interconnected
• What are the characteristics of muscle tissue?

  1. Excitable: responds to stimuli
  2. Contractile: shortens upon stimulation
  3. Extensible: can be stretched
  4. Elastic: returns to resting length
• What are the steps of muscle contraction induced by the brain?

  1. AP generated in the brain
  2. AP travels to spinal cord and motor neurons
  3. Motor neuron fires AP to axon terminal
  4. ACh released at neuromuscular junction
  5. EPP occurs in muscle fiber
  6. AP propagates throughout muscle fiber
  7. Ca$^{2+}$ released, causing contraction
  8. ACh degraded, signal terminated
• What are the types of muscle contraction regulation?

  • Regulated by nerves
  • Regulated by hormones
  • Regulated by local chemical changes (e.g., pH)