MCQ A.4.3. - BasicPhysiology.org

Created on April 26, 2023 By

wlammers_qzgo0ve6

MCQ A.4.3.

The Sarcomere

1 / 6

It is possible to visualize, under a microscope, the striation pattern of skeletal muscle cells. Which band will increase its width when a skeletal muscle is stretched?

The I-band and the H-zone will increase their widths

The A-band and the H-zone will increase their widths

The A-band and the I-band will increase their widths

The A-band and the Z-Z distance will increase their widths

2 / 6

In the case of rigor mortis, after a few hours, skeletal muscles in the whole body will become stiff. What is the background of that mechanism?

All the calcium ions have diffused from the leaky sarcoplasmic reticulum

All the ATP molecules have appeared in the sarcomeres

All the cross bridges are activated

All the vesicles have been released in the motor end-plates

All the acetylcholine-esterases have been inactivated

3 / 6

The position of a joint determines the length of a skeletal muscle before contraction. In the case of the biceps, what is the optimal angle of the elbow to induce the strongest contraction?

0 degrees

30 degrees

45 degrees

90 degrees

180 degrees

4 / 6

If a skeletal muscle is stretched a lot before a contraction, what will happen?

The contraction will be weak because most of the actin molecules cannot connect to the myosin molecules

The contraction will be strong because most of the actin molecules will now connect to the myosin molecules

The contraction will be weak because the cell will run out of ATP

The contraction will be strong because there is more space available for the calcium ions

5 / 6

In the process of contraction in a skeletal muscle cell, contractions do not last forever but will stop at some point. What is the mechanism that stops a contraction?

Pumping of calcium ions from the intracellular space back into the sarcoplasmic reticulum

Shortage of ATP molecules

Shortage of calcium ions

The myosin molecules bump against the Z-disks

The actin molecules bump against each other

6 / 6

During the contraction of a sarcomere in a skeletal muscle cell, cross bridges play an essential role in connecting the myosin to the actin molecule that require a series of steps. Which step requires energy in the form of ATP?

When the head of the myosin molecule attaches to the actin molecule

When the head of the myosin molecule rotates towards the middle of the sarcomere

When the head of the myosin molecule detaches from the actin molecule

When the head of the myosin molecule rotates away from the middle of the sarcomere

Your score is

The average score is 75%

BasicPhysiology.org

Contents

Info

Translate?

X