MS1, Block 2, Smooth Muscle

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MS1, Block 2, Smooth Muscle
2010-10-31 22:31:33
Smooth Muscle Muscle microanatomy

Smooth Muscle IS from Garrett
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  1. shape diameter and length of smooth mm
    small spindle shaped cells, 2-10 Micrometers in diameter, 20-600 micrometers in length
  2. do smooth mm have banding pattern?
  3. Sarcoplasmic reticulum of smooth mm
    Not well developed
  4. does smooth mm have transverse tubules?
  5. thick and thin filaments of smooth mm are made of
    actin, myosin, tropomysin + calmodulin
  6. ratio of thick and thin filaments of smooth mm
  7. Dense bodies on Smooth mm
    similar to Z-lines of skeletal mm
  8. Dense bands of smooth mm
    attach actin to membrane
  9. link dense bands to dense bodies and cytoskeleton network
    intermediate filaments
  10. attachments b/t cells
    intermediate junction
  11. low resistance electrical pathways b/w cells
    gap junctions
  12. from autonomic nervous system
    innervation of smooth mm
  13. twitches of smooth mm are ___ than skeletal mm (phasic)
  14. smooth mm does not _____
  15. dephosphorylates myosin so that it detaches from actin
  16. major sources of calcium for contraction (4)
    • voltage-gated Ca channels
    • receptor mediated
    • stretch-activated
    • store-operated
  17. T or F, Smooth mm has a neuromuscular junction
  18. synapse b/w autonomic nerves and smooth mm is called
    neuroeffector junction
  19. Allows smooth mm to contract in concert with other cells
    gap junctions (single unit smooth mm or unitary smooth mm)
  20. Length-tension relationship of smooth mm is ____ then skeletal
    broader (allows for variations in organ volume)
  21. tension of smooth mm as compared to skeletal mm is _____,
    Velocity of smooth mm as compared to skeletal mm is _____,
    Reasons for this are (3 B)
    • the same,
    • 10 to 100 times slower
    • (B) ATPase for myosin is slower,
    • Ca comes from extracellular sources,
    • cross bridge cycle depends on the degree of phosphorylation of the myosin (greater % phosphorylated myosin=faster velocity of contraction
  22. depolarization causes the generation of an action potential. The tension generated is due to the entry of Ca through the voltage-gated Ca channels
    Stimulus -induced action potentials
  23. oscillations in the resting membrane potential bring the membrane to threshold and generate an action potential. The tension generated is due to the entry of Ca through the voltage-gated Ca channels.
    Slow wave/ pacemaker depolarization
  24. There are changes in the membrane potential with no action potentials. the tension in the mm is dependent on the membrane potential.
    Graded potentials
  25. Contraction w/out changes in membrane potential. Receptor activation leads to increase inositol triphosphate (IP3) and release of Ca from SR
    Pharmacomechanical coupling
  26. Agents that produce pharmacomechanical coupling (3)
    • Neurotransmitters
    • Hormones
    • Paracrines and autocrines