Muscles part 2

A flat, thin structure made of dense connective tissue that serves to attach a muscle to a bone (or to another muscle) is a(n) aponeurosis. tendon. perimysium. myolemma. superficial fascia.

• superficial fascia

• myolemma

• perimysium

• tendon

• aponeurosis

A power stroke involves an actin molecule pulling a myosin molecule toward the M-line. a thin filament shortening in length and thereby shortening the sarcomere. a myosin head pulling a thin filament toward the center of the sarcomere. a thick filament pushing an actin filament towards the nearest Z-line.

• a myosin head pulling a thin filament toward the center of the sarcomere

• a thin filament shortening in length and thereby shortening the sarcomere

• an actin molecule pulling a myosin molecule toward the M-line

• a thick filament pushing an actin filament towards the nearest Z-line

For relaxation to occur, calcium leaves the sarcoplasmic reticulum, and troponin binds calcium and blocks the binding sites on actin. calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive. cytosolic calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin. extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin.

• calcium enters the myofibril, it detaches from myosin, and the binding sites on myosin become inactive

• calcium leaves the sarcoplasmic reticulum, and troponin binds calcium and blocks the binding sites on actin

• cytosolic calcium levels fall, calcium is removed from troponin, and tropomyosin blocks binding sites on actin

• extracellular calcium levels fall, calcium is pumped into the myofibril, and tropomyosin slides away from actin

Tags

NGSS.HS-LS1-3

Oxidative fibers are red and fatigue-resistant. red and fatigable. white and fatigue-resistant. white and fatigable.

• white and fatigue-resistant

• red and fatigable

• red and fatigue-resistant

• white and fatigable

Tags

NGSS.HS-LS2-3

Which may occur as a result of muscle atrophy? Reduction in muscle size. Fibers become weaker. Muscle loses tone. Fibers waste away and die. All of the choices are correct.

• All of the choices are correct

• Fibers waste away and die

• Muscle loses tone

• Fibers become weaker

• Reduction in muscle size

Lifting weights will cause muscles to enlarge. This is primarily due to an increase in the number of muscle cells. an increase in the size of muscle cells.

• an increase in the size of muscle cells

• an increase in the number of muscle cells

The type of muscle fibers that are striated, form Y-shaped branches, and are joined by intercalated discs are skeletal. cardiac. smooth. voluntary. skeletal and voluntary.

• voluntary

• smooth

• cardiac

• skeletal and voluntary

• skeletal