midterm lab quiz

• function of muscle tissue


  Characterized by the ability to contract or move upon stimulation [body movement] Composed of cells that optimize the universal cell property of contractility.
• 3 types of muscle tissue

  skeletal muscle cardiac muscle smooth muscle
• striated/voluntary muscle - other name for skeletal muscle
• myocardium - other name for cardiac muscle
• visceral muscle - other name for smooth muscle
• single multinucleated cells - fibers of skeletal muscle
• aligned cells in branching arrangement - fibers in cardiac muscle
• single small, closely packed fusiform cell - fibers of smooth muscle
• peripheral adjacent to sarcolemma - location of nuclei of skeletal muscle
• central - location of nuclei of cardiac muscle
• central at widest part of cell - location of nuclei of smooth muscle
• voluntary movement - key function of skeletal muscle
• automatic/involuntary pumping of blood - key function of cardiac muscle
• involuntary movement - key function of smooth muscle
• present - striation of skeletal muscle
• present - striation of cardiac muscle
• absent - striation of smooth muscle
• cylindrical 10-100um diameter many cm long - cell/fiber shape & size of skeletal muscle
• cylindrical 10-20um diameter 50-100um long - cell/fiber shape & size of cardiac muscle
• fusiform 0.2-10um diameter 50-200um length - cell/fiber shape & size of smooth muscle
• well organized sarcomere SR and transverse tubule system - special structural function of skeletal muscle
• intercalated disk joining cell with many adherent and gab junction - special structural function of cardiac muscle
• gab junction caveolae dense bodies - special structural function of smooth muscle
• skeletal muscle tongue diaphragm eyes and upper esophagus - major location of skeletal muscle
• heart - major location of cardiac muscle
• blood vessel digestive respiratory tract uterus bladder - major location of smooth muscle
• Alpha Actinin – supports and connects Z discs to the thin filaments
• Titin – binds Z discs to the thick filament; largest protein in our body, with some elastic properties
• MECHANISM OF CONTRACTION

  1. Nerve impulse triggers release of Acetyl Choline [neurotransmitter] from the synaptic knob into the synaptic cleft. ACh binds to ACh receptors in the motor end plate of the neuromuscular junction, initiating a muscle impulse in the sarcolemma of the muscle fiber.
  2. As the muscle impulse spreads quickly from the sarcolemma along T tubules, calcium ions are released from terminal cisternae into the sarcoplasm
• MECHANISM OF CONTRACTION

  3. Calcium ions bind to troponin. Troponin changes shape, moving tropomyosin on the actin to expose active sites on actin molecules of thin filaments. Myosin heads of thick filaments attach to exposed active sites to form cross-bridges.

  4. Myosin heads pivot, moving thin filaments toward the sarcomere center. ATP binds myosin heads and is broken down into ADP and P. Myosin heads detach from thin filaments and return to their prepivot position. The sarcomere shortens and the muscle Contracts
• MECHANISM OF CONTRACTION

  5. When the impulse stops, calcium ions are actively transported into the sarcoplasmic reticulum
• Troponin has 3 subunits:

  • TnT – attaches to the tropomyosin
  • TnI – regulates actin myosin interaction
  • TnC – binds calcium
• LABEL:

  A) stratum corneum

  B) stratum lucidum

  C) stratum granulosum

  D) stratum spinosum

  E) stratum basale

  F) epidermis

  G) dermis

  H) hypodermis

  I) meissner corpuscle

  J) pacinian corpuscle

  K) hair shaft

  L) dermal papilla

  M) arrector pili muscle

  N) sebaceous oil gland

  O) merocrine sweat gland

  
• enumerate cell of epidermis:

  • KERATINOCYTES
  • MELANOCYTES
  • LANGERHANS CELLS
  • MERKEL CELLS
• KERATINOCYTES


  Primary Cells located at Epidermis Originate in the deepest layer of the epidermis, the stratum basale and move up to the final barrier layer of the skin, the stratum corneum.
• MELANOCYTES


  Located at basal epidermis. Neural Crest Derived. Synthesize dark melanin pigment in melanosomes. Organelle where melanin pigment is synthesized
• MELANOCYTES


  Protect nuclear DNA from UV damage
• Eumelanin – brown or black pigment; found in hair follicles
• Pheomelanin – red hair
• LANGERHANS CELLS


  APC (Antigen Presenting Cells) 2-8% of cells in epidermis Located at spinous layer [stratum spinosum] of epidermis Bind, process and present antigens to T-lymphocytes