Muscle Contraction Assignment PDF

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Summary

This document goes over questions related to muscle contractions with displayed figures, definitions, and statements....

Description

1- Describe the structure and location of the thick filaments (horizontal). - The thick filaments are located in A band region (center area of sarcomere) and are straight and long (and thick) 2- Describe the structure and location of the thin filaments (horizontal). - Attached to the Z disc and look like thin lines around both sides of the sarcomere and thick filaments 3- How many sarcomeres are pictured above? 3 4- Based on your observations of the location of thick and thin filaments, describe each of the following: a) A band - has all of the thick filaments along with a small portion of thin filaments b) I band - include thin filaments up until the point where the thin and thick filaments align c) H zone - includes no thin filaments, only part of the thick filaments before its shown directly above the thin filament d) Z disc - the end (corner) of the thin filament e) M line - center of sarcomere and middle of the thick filaments 5- Using complete grammatically correct sentences, describe how the H zone differs from the A band. - The H zone is only including the thick filament while the A band includes all of the thick filament with parts of the thin filament right where they meet. (Thick above thin)

6- How many sarcomeres do you think are in a muscle cell found in your quadriceps? 4 7- Do you think you would have more or fewer sarcomeres in an eye muscle? - More because our eyes are constantly moving and blinking (this can be contracting)

QUESTIONS: 8. In Figures 1 and 2 above, identify the A-bands, I-bands, and H-zones and use your observations to complete the comparisons below. Structure Length in Relaxed Length in Contracted Did the length change Sarcomere Sarcomere betn. Figs. 1&2? Y/N

Thick filament - when relaxed the thick filament is stretched out and longer than if it was contracted. It looks like when there is a contracting that the thick filament gets thicker as well. Thin filament - when relaxed they are spread out and not completely aligned with the thick filament, only a small portion is over/under the thick filament directly. Once it contracts, the thin filament gets shorter and seems to squish in towards the thick filament. A band - in relaxation the A band only has a small portion of the thin filament included and all of the thick filament. When it contracts, it seems to cover more thin filament over/under the thick filament but the length itself does not seem to change too much. I band - lengthens and covers more of the thick filament when contraction occurs. When it is related it included a lot of thin filament and only the ends of the thick filament H zone - this shortens when it contracts (gets smaller) and is stretched when its relaxed Sarcomere - shrinks when it contracts because it is being pulled into the center, when it is relaxed it grows and appears longer 9. After reviewing the table in Question 8, describe what happens to thick and thin filaments when muscles contract: -

Thin filament shrinks inward while thick filament looks thicker and slightly longer. Thin filament seems to be covering more thick filament.

10. Examine the diagram in Model 2. Why is there a limit to the amount of shortening that can occur in a sarcomere during muscle contraction? -

There is a limit because if it shortens too much then there will be many overlaps and no space for muscles to go back to relaxation. It can cause the sarcomeres to attach in the wrong areas and could possibly cause damage, making it harder to get back to relaxation....