Final

Question 1

What are t-tubules?

Answer 1

Transverse tubules that are extensions of the sarcolemma

Question 2

What can be found on the sarcolemma?

Answer 2

motor end plate (has ligand gated channels), voltage gated NA+ and K+ channels, nuclei,

Question 3

WHat do t-tubules contain? How does this explain their function?

Answer 3

contain voltage gated channals and voltage sensitive receptors. the ap from sarcolemma propogates to the t-tubles, and triggers receptors that Ultimately leads to release of Ca2+ from internal storage

Question 4

WHAT IS THE sarcolemma?

Answer 4

the cell wall of a muscle cell/fibre

Question 5

What is the role of the sarcolemma?

Answer 5

To receive action potentials through motor end plate.

Question 6

WHat does the motor end plate contain?

Answer 6

Neuromusclar juction. This junction has ligand-gated channels.

Question 7

What is the terminal cisternae of the sarcoplasmic reticulum?

Answer 7

It is where Ca+ is stored. It releases the Ca+ for contraction when receptors on transverse tubules receive the action potential

Question 8

What is the sarcoplasm?

Answer 8

the cytoplasm of the muscle fiber/cell

Question 9

What does the sarcoplasm contain?

Answer 9

sarcoplasmic retoiculum (terminal cisternae), mitochondria, myoglobin, glycogen granuses, myofibrils

Question 10

WHat type of proteins are found in sarcomeres?

Answer 10

contractile, regulatory, and stabilizing

Question 11

Which proteins are stabilizing?

Answer 11

Titin (thick), Z-line and M-line

Question 12

WHat type of proteins are regulatory? Which myofilament are they associated with?

Answer 12

troponin and tropomyosin. thin

Question 13

What type of proteins are contractile?

Answer 13

Myosin (thick) and actin(thin)

Question 14

How are myoglobin and glycogen granules used for energy? How do they influence appearance?

Answer 14

Myoglobin stores O2 which is needed for ATP production in the mitochondria. Glycogen granules stores energy in the form of many glucose molecules. Myoglobin provides red pigment. If a molecule is white, it means it doesn’t have much myoglobin and relays on glycogen for glycolysis

Question 15

What is titin?

Answer 15

runs through the core of the thick filament and attaches it to the Z-line

Question 16

Describe the structure of thick filaments and myosin

Answer 16

myosin = tail, hinge, head
thick filaments have many individual myosin molecules clustered together

Question 17

What contains binding sites for myosin heads?

Answer 17

globin (G) actin molecules

Question 18

Describe the structure of filamentous (F) actin

Answer 18

Individual g-actins are like beads that come together to form a string.
Filamentous actin is the string of actins coming together and intertwining

Question 19

What covers actin active sites for myosin heads when muscle is at rest?

Answer 19

Tropomyosin covers the active sites on actin

Question 20

What holds tropomyosin in place?

Answer 20

troponin

Question 21

Describe the A-band

Answer 21

It is the entire length of the myosin(thick filament). Includes the actin that overlaps

Question 22

Describe the I band

Answer 22

Length of thin filement that do not overlap with the myosin. a z-line (disc) will be in the middle

Question 23

How are thick filaments anchored and stabilized?

Answer 23

They are anchored by proteins in the middle (M-line). Titin extends through the thick filaments to attach to the end of the sarcomere(Z-line)

Question 24

Where do thin filaments attach?

Answer 24

They attach to the z-line proteins

Question 25

What is the zone of overlap?

Answer 25

The area were thick and thin filaments overlap

Question 26

WHat is the H-band?

Answer 26

Length of the thick filament that does not overlap with thin filaments

Question 27

What is another name for titin?

Answer 27

Elastic Filaments

Question 28

Describe the sliding filament mechanism of contraction.

Answer 28

As the muscle contracts, the A band doesn’t change in length. INstead, the actin/thin filaments slide across the thick filaments as moves toward the m-Line . Titin gets compressed. This means the Z-line is pulled toward the middle by the actin. Ultimately, the zone of overlap increase, I band decrease, and H zone decreases