5.3 Physiology of the Muscular System Part 3

Question 1

What are the striations of myofibrils formed by?

Answer 1

protein myofilaments within contractile units known as sarcomeres

Question 2

What does a sarcomere contain?

Answer 2

two types of protein myofilaments konwn as actin and myosin

Question 3

What is myosin?

Answer 3

thick filament

Question 4

What is actin?

Answer 4

thin filaments

Question 5

What causes muscles to shorten?

Answer 5

movement of actin filaments in relation to myosin filaments

Question 6

What are the Z lines of a sarcomere?

Answer 6

connect parallel bands of thin filaments

Question 7

What are the M lines of a sarcomere?

Answer 7

hold the thick filaments together

Question 8

What is the I band of the sarcomere?

Answer 8

light band, only contains thin filaments

Question 9

What is the A band of the sarcomere?

Answer 9

dark band; contains thick and thin filaments

Question 10

When a muscle contracts what happens to the Z and M lines?

Answer 10

Z lines move closer together towards the center of the sarcomere (M line)

Question 11

Where does a nerve meet a muscle?

Answer 11

neuromuscular junction

Question 12

What is acetylcholine?

Answer 12

neurotransmitter

Question 13

Once a nerve impulse reaches a muscle fiber what occurs?

Answer 13

acetylcholine is released from the motor nerve ending and binds to receptors on the muscle cell opening sodium channels

Question 14

What is the sarcoplasm?

Answer 14

cytoplasm of a muscle cell

Question 15

What does the influx of sodium ions into the sarcoplasm cause?

Answer 15

an action potential

Question 16

What is the sarcolemma?

Answer 16

cell membrane of a muscle fiber

Question 17

Where does an action potential occur?

Answer 17

sarcolemma

Question 18

What does an action potential cause in a muscle fiber?

Answer 18

calcium ions to be released from the sarcoplasmic reticulum

Question 19

What is the sarcoplasmic reticulum?

Answer 19

specialized type of smooth ER found within striated muscle tissue

Question 20

What does the release of calcium ions in the muscle fiber cause?

Answer 20

portions of the myosin filaments called cross bridges will bend backward and attach to actin filaments