lecture 8- muscle & nervous tissue

• muscle tissue -> types

  1. skeletal muscle: attaches bones via tendons
  2. cardiac muscle: in the heart
  3. smooth muscle: in the walls of hollow tubes & organs

  
• muscle tissues -> skeletal muscle

  • aka. striated muscle, voluntary muscle (consciously control it)
  • attaches to bone (via tendons)
  • eg. bicep, tricep, quads

  A) striations

  
• muscle tissues -> skeletal muscle

  • Voluntary: under conscious control
  • striated appearance
  • muscle cell = muscle fiber
  • attaches to bone (via tendons), enables movement of skeleton
  • fast and strong contractions
  • multi nuclei per cell, located on edge of cell
  • eg. bicep, tricep, quads

  
• muscle tissues -> cardiac muscle

  • involuntary: contracts unconsciously
  • striated appearance
  • cells are connected by INTERCALATED DISCS in a BRANCHED structure
  • electrical impulse: when heart beats, this impulse is sent throughout the heart, thus contracting it rhythmically.
  • one nuclei, located in the centre

  
• muscle tissues -> smooth muscle

  • involuntary: contracts unconsciously
  • nonstriated appearance
  • fusiform / spindle shaped cells (eye shape)
  • found in: walls of hollow organs, blood vessels, airways etc.
  • function: MOVES substances through hollow organs
  • contraction is SLOW
  • uni nuclei, located in centre

  
• muscle types

  A) skeletal

  B) cardiac

  C) smooth

  
• muscle cell's CYTOSKELETON

  • all muscles have ACTIN and MYOSIN
  • these are arranged into units called sarcomeres, giving a striated appearance
  • this only applies to skeletal and cardiac muscle, not smooth muscle

  A) sarcomere

  B) myosin

  C) actin

  
• muscle tissues -> organisation -> skeletal muscle

  • skeletal muscle fibers = bundles of myofibrils
  • myofibril = multiple sarcomeres
  • sarcomere = actin (thin) and myosin (thick)

  A) myofibril

  B) sarcomere

  C) myosin

  D) actin

  
• muscle tissues -> organisation -> skeletal muscle -> fasicle

  • multiple fascicles = whole muscle
  • fascicles = bundles of muscle fibers (cells)
  • muscle fiber = bundles of myofibrils
  • myofibrils = bundles of sacromeres
  • sacromeres = bundles of thin (actin) filaments and thick (myosin) filaments
• muscle tissues -> skeletal muscle -> connective tissue

  • connective tissue is in between every MUSCLE CELL
  • called endomysium (endo = inner, mys = muscle)
  • connective tissue is in between every FASCICLE
  • called perimysium (peri = around)
  • connective tissue is in between every MUSCLE BELLY
  • called epimysium (epi=over)

  all of the connective tissue has neurovascular supply

  A) endo

  B) peri

  C) epi

  D) myofibril

  
• Skeletal Muscle cell (Muscle fiber)

  • muscle fibers contain many myofibrils, which are arranged into UNITS OF CONTRACTION (sarcomere)
  • Cytoplasm of muscle cells = sarcoplasm
  • Plasma membrane of muscle cell = sarcolemma
  • ER organelle of muscle cell = sarcoplasmic reticulum
• note:

  • in skeletal muscle fibers, the nucleus are PERIPHERALLY located, meaning they sit on the edge of cells, not central
• different types of images of skeletal muscle fibers

  A) endomysium

  B) fibers

  C) mitochondria

  D) nuclei

  
• muscle tissues -> skeletal muscle fibers -> sarcomeres

  • Z-lines: attached to ACTIN, located at the ends of the sarcomeres
  • M lines: attached to MYOSIN, located in the middle of sarcomeres

  A) M

  B) Z

  
• muscle tissues-> skeletal muscle fibers -> sliding filament model

  • sarcomeres must shorten for contraction, BUT the thick and thin filaments DO NOT SHORTEN
  • when sarcomere contracts, actin is pulled in by myosin

  how does it pull?

  • myosin has countless myosin heads which have ATP
  • when ATP hydrolysed, turns to ADP + P, so myosin can bind to actin via CROSS BRIDGE
  • power stroke occurs, when actin's pulled in by myosin
  • myosin then detaches with ATP

  
• muscle tissues -> skeletal muscle fibers -> sarcomeres

  A) A

  B) I

  C)

  D) sarcomere

  
• muscle tissues -> skeletal muscle fibers -> KEY WORDS

  • Sarcolemma: plasma membrane of skeletal muscle cell
  • Sarcoplasmic reticulum: Storage site for calcium
  • Neuromuscular junction: junction. where the nerve tissue meets the muscle fibers
  • Transverse tubules: Extend from sarcolemma to sarcoplasmic reticulum, Extensions of plasma membrane

  A) transverse tubule

  B) sarcoplasmic

  C) sarcolemma

  
• skeletal muscle fiber detailed diagram

  A) sarcoplasmic reticulum

  B) sarcolemma

  C) neuromuscular

  D) transverse

  
• muscle tissues -> cardiac muscle

  • striated - due to sarcomeres
  • branched cells
  • 1 or 2 nuclei, centrally located

  
• muscle tissues -> cardiac muscle -> features

  • Cells are joined together by INTERCALATED DISKS
  • intercalated disks = Adherens-type junctions, Desmosone junctions, Gap junctions
  • abundant MITOCHONDRIA: high aerobic metabolism
  • numerous blood vessels throughout the connective tissue around cardiac muscle cells
• muscle tissues -> smooth muscle -> features

  • located on walls of hollow organs
  • fusiform = eye shape

  A) striations

  B) fusiform