Muscle Tissue

1
Muscle Tissue

• Chapter 11

2
Muscle Tissue

• Types and characteristics of muscular tissue
• ______________________________________
• Nerve-Muscle relationship
• Behavior of skeletal muscle fibers/whole muscles
• ______________________________________
• ______________________________________

3
Introduction to Muscle

• Movement is a characteristic of living things
• ______________________________________
  ______________________________________
• Types of muscle
• ______________________________________
• Physiology of skeletal muscle

4
Characteristics of Muscle

• _____________________ (excitability)
• chemical signals, stretch and electrical changes
  across the plasma membrane
• _____________________
• local electrical change triggers a wave of
  excitation that travels along the muscle fiber
• ____________________________________
• Extensibility -- capable of being stretched
• ____________________________________
  ____________________________________

5
Skeletal Muscle

• _________________________ attached to bones
• ______________________ as long as 30 cm
• Exhibits alternating light and dark transverse
  bands or striations
• reflects overlapping arrangement of internal
  contractile proteins

6
Muscle Fibers

• ________________________
• ______________________ has tunnel-like infoldings
  or transverse (T) tubules that penetrate the cell
• carry electric current to cell interior

7

• ________________ is filled with
• ______________ (bundles of myofilaments)
• glycogen (stored energy) and myoglobin (oxygen)
• ______________________________ smooth ER
• network around each myofibril
• dilated end-sacs (terminal ___________) store
  calcium

8
____________________

• Made of 200 to 500 ___________________
• entwined polypeptides (golf clubs)
• In bundles with heads directed outward around
  the bundled tails

9
Thin Filaments

• Two strands __________________
• Has a myosin binding site
• Groove holds _______________________
• each blocking 6 or 7 active sites of G actins
• _______________ (calcium-binding) on each
  tropomyosin molecule

10
Regulatory and Contractile Proteins

• Myosin and actin are __________________________
• ______________________________ regulatory
  proteins
• switch that starts and stops shortening of muscle
  cell
• contraction activated by release of calcium into
  sarcoplasm and its binding to troponin,
• troponin moves tropomyosin off the actin active
  sites

11
Overlap of Thick and Thin Filaments
12
Striations Organization of Filaments

• ________________ ? unit of contraction gives
  striated appearance
• ________________ (regions) alternate with lighter
  I bands
• anisotrophic (A) and isotropic (I) stand for the
  way these regions affect polarized light
• __________________________________________
• lighter, central H band area contains no thin
  filaments
• __________________________________________
• bisected by ___________ protein anchoring elastic
  and thin filaments
• from one Z disc (Z line) to the next is a
  sarcomere

13
Relaxed and Contracted Sarcomeres

• ________________________________________
  ________________________________________
• pulling Z discs closer together
• pulls on sarcolemma
• Notice neither thick nor thin filaments change
  length during shortening
• Their overlap changes as sarcomeres shorten

14
Motor Units

• ___________________________________
  ___________________________________
• throughout the muscle
• when contract together causes weak contraction
  over wide area
• provides ability to sustain long-term contraction
  as motor units take turns resting
  (_____________________)
• ________________________
• small motor units contain as few as 20 muscle
  fibers per nerve fiber
• eye muscles
• ________________________
• gastrocnemius muscle has 1000 fibers per nerve
  fiber

15
Neuromuscular Junctions (Synapse)

• Connection between nerve fiber and muscle cell
• __________________________________ stimulates
  muscle cell
• Components of synapse (NMJ)
• synaptic knob is swollen end of nerve fiber
  (contains ACh)
• junction region of sarcolemma
• contains acetylcholinesterase (breaks down Ach)
• __________________ ?gap between nerve and muscle
  cells

16
Neuromuscular Toxins

• ________________ (cholinesterase inhibitors)
• bind to acetylcholinesterase and prevent it from
  degrading ACh
• spastic paralysis and possible suffocation
• ___________________________________
  ___________________________________
• blocks glycine release in the spinal cord and
  causes overstimulation of the muscles
• _____________________ (limp muscles) due to
  curare that competes with ACh
• respiratory arrest

17
Electrically Excitable Cells

• _____________________________________
• resting membrane potential due to Na outside of
  cell and K and other anions inside of cell
• ________________________________________
  ________________________________________
• Stimulation opens ion gates in membrane
• ion gates open (Na rushes into cell and K
  rushes out of cell)
• quick up-and-down voltage shift action
  potential
• spreads over cell surface as nerve signal

18
Muscle Contraction and Relaxation

• Four actions involved in this process
• _______________ nerve action potentials lead to
  action potentials in muscle fiber
• excitation-contraction coupling action
  potentials on the sarcolemma activate
  myofilaments
• ________________ shortening of muscle fiber
• ________________ return to resting length