Chapter 9 Muscle Tissue

Question 1

Muscle Tissue Terminologies

Answer 1

• Makes nearly half of the bodies mass (not terminology)
• Myo, Mys, and Sarco are all prefixes for muscle
  
  • Sarcoplasm) Muscle cell cytoplasm
  • Sarcolemma) Plasma membrane of muscle cells.

Question 2

Skeletal Muscle

Answer 2

• Has Elongated Muscle Fibers
• Voluntary Muscle
• Contract rapidly but tire easily
• Very adaptable; can exert diffrent levels of force
• Require nervous System Stimulation
• KEY WORDS) Skeletal, Striated, Voluntary

Question 3

Cardiac Muscle

Answer 3

• Found only in the walls of the heart. (Makes up bulk of the heart)
• Contacts at a steady rate due to the “pacemaker” of the heart
• KEY WORDS) Cardiac, Striated, Involuntary

Question 4

Smooth Muscle

Answer 4

• Lines hollow organs
  
  • Forces fluide and other substances through body channels
• KEY TERMS) Visceral, Nontriated, Involuntray

Question 5

Characteristice of Muscle Tissue (Four)

Answer 5

• Excitability (Responsivness) Ability to recive/respond to stimuli
• Contractibility) Ability to shorten forcefully
• Extensibility) ability to Stretch
• Elasticicity) Ability to recoil and resume its resting length.

Question 6

Muscle Funtions (four)

Answer 6

• Produce Movment
  
  • Of bones (skeletal)
  • Blood in heart (cardiac)
  • Other Bodily substances (smooth)
• Mantain Body Posture and Position
• Stabilize Joints
• Generate Heat as they Contract.

Question 7

Skeletal Muscles (Nerves and Blood Supply)

Answer 7

• Each Muscle receives one nerve, artery, and one or more viens
  
  • If the mucle is consciously controlled there is one nerve for each fiber to control activity.

Question 8

Connective Tissue Sheaths (Skeletal Muscle)

Answer 8

• Support and Reinforce whole muscle
• Three types
  
  • Epimysium (outside the Muscle)
    
    • Dense irregular CT
    • Surrounds enteire muscle; may blend with fascia
  • Perimysium (around the muscle)
    
    • Surrounds group of muscle fiber called a Fasicle
  • Endomysium
    
    • Fine areolar connective tissue
    • Surrounds each muscle fiber.

Question 9

Attachements (Skeletal Muscle)

Answer 9

• Based on Movment
  
  • Insertion) attached to the movable bone
    
    • Pulls on
  • Origin) attached to immovable (less) movable bone
    
    • Pulls toward
• Based on Connection
  
  • Direct (fleshy) epimysium fused to periostium or perichondirum
  • Indirect) CT extends beyond muscle as a tendon or aponerosis which anchor the muscle to CT of bone or cartlidge.

Question 10

Sarcolemma

Answer 10

Plasma Membrane

Question 11

Sarcoplasm

Answer 11

• Cytoplasm
  
  • contains Glycosomes (glycogen Storage)
  • Contains Myogloboin (oxygen Storage)

Question 12

Myofibrils

Answer 12

• There are hundreds of myofibrils in a single muscle cell.
  
  • Run parallel to the cell lenght
• Makes 80% of a muscle cell volume

Question 13

Striations

Answer 13

• Series of stripes formed from repeating series of Dark A bands and light I Bands along each Myofibril.
• A Bands) Dark Regions
  
  • H Zone) Lighter region in the middle of the A band where filaments do not overlap
  • M Line) Line of Protien which bisects H zone vertically.
• I bands) Lighter Regions
  
  • Z Disc Line) Sheet of protiens in the middle of I band.

Question 14

Sacromere

Answer 14

• Smallest Functional Unit of a Muscle Fiber
  
  • Area between each Z discs.
  • Consits of an A band with half and I band on each side

Question 15

Myofilaments

Answer 15

• Actin Myofiliment) Thin filament
  
  • Extend across I beand and partway into the A band
  • Connected to Z Discs
• Myosin Myofilaments) Thick Filaments
  
  • Extend entire length of A band
  • Connected at the M Line

Question 16

Compisition of Myofilaments

Answer 16

• Thick Filaments) Made of myosin that has
  
  • Two heavy chains (forms myosin tail)
  • Four Light chains (forms myosin head)
    
    • Two light chains form one head of myosin
  • During contraction heads link with acitin to combine the filaments togehter
  • Each thick filament contians about 300 myosin molecules
• Thin Filaments) Made of Acitin
  
  • Acitin is made of G acitin subunits which combine to make fibrous F acitin
    
    • Two F Acitin twist together to make thin filament
  • Tropomyosin) Covers binding sites of Acitin when not in use
    
    • When moved contraction can begin
  • Troponin) Moves Tropomyosin to expose acitin binding sited.
    
    • Also binds calcium ions
• Elastic Filaments) Holds filaments in place
  
  • Made of titin
• Dystrophin) Links thun filaments to sacrolema.

Question 17

Duchenne Muscular Dystrophy (DMD)

Answer 17

• Caused by deffective Dystrophin gene
• Common in Males
  
  • Appears as clumsineess from ages 2-7
  • Progresses to whole body; people with DMD can live into their thirites at the latest.

Question 18

Sarcoplamic Reticulium

Answer 18

• Network of Smooth ER surrounding each myofibril.
  
  • Run along myofibril
• Stores and Releases Ca2+

Question 19

T Tubules

Answer 19

• At each A band-I band junction, the sarcolemma of the muscle cell protrudes deep into the cell interior, forming an elongated tube called the T Tubule.

Question 20

Sliding Filament Model of Contraction

Answer 20

• Contraction) Activation of cross bridges (myofilaments) to generate force
• Sliding model
  
  • States that thin filaments slide past thick filaments to shorten
  • Actuall filaments themselves do not change length.
  • Myosin heads bind to acitin which cause slifing
• During Contraction
  
  • Z discs are pulled toward the M line
  • I bands shorten
  • Z discs become closer
  • H zones disappear
  • A bands move closer (lenghth dosent change)