Lecture 3

Intercalated discs connect

• smooth muscle cells

• skeletal muscle cells

• cardiac muscle cells

• nerve cells

The area between the axon terminal and the sarcolemma is called

• contracting cleft

• muscular cleft

• synaptic cleft

• sarcoplasmic reticulum

smooth muscle responds to stimuli by

• nerves

• cardiac cells

• hormones

• temperature

calcium

• is released by the T-tubules and binds to troponin

• is released by the SR and binds to tropomyosin

• is released by the SR and binds to actin

• is released by the SR and binds to troponin

Each muscle fiber contains

• one nucleus and hundreds to thousands of myofibrils

• many nuclei and up to 100 myofibrils

• many nuclei and hundreds to thousands of myofibrils

• many nuclei and elastic fibers

Area of the sarcomere that does NOT include myosin filaments

• A band

• M line

• H zone

• I band

The H zone of the sarcomere

• includes both thick and thin filaments

• is found within the A band but includes only which filaments

• includes titin and actin molecules

• all answers are correct

During muscle contraction, the distance between the Z lines of the sarcomere

• does not change

• increases

• decreases

• doubles

Myosin will be able to bind to actin as long as there is availability of

• Sodium

• Magnesium

• Calcium

• Amino acids

Ach is broken down by

• Acetyl-CoA

• Ca+

• Na+

• Acetycholinesterase