Thick and Thin Filaments

[engineeredout]

Just to clarify a point for me, when talking about skeletal muscle, thick and thin filaments do NOT contract during a muscular contraction, however in a smooth muscle contraction, they DO contract, causing the intermediate filaments to pull the dense bodies closer together shrinking the smooth muscle cell.


... right?

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[TieuBachHo]

I think both skeletal and smooth muscles contract during muscular contraction, voluntary and involuntary respectively. The sliding of thin and thick filaments (not the shortening of the thick and thin filaments) causes the shortening of sarcomere (contraction).

 

[Magus]

Skeletal muscle and smooth muscle contraction involve the sliding filament model, however there are some differences. Smooth muscle involves calcium phosphorylation of myosin (rather than binding to troponin, which is not present in smooth muscle) and creating a Ca+2-calmodulin complex. Both do contract, however smooth muscle generally tends to have constant muscle tone (intuitive since smooth muscle is constantly needed to pump blood in vessels whereas skeletal muscle is voluntary).

http://en.wikipedia.org/wiki/Muscle_contraction

 

[Vihsadas]

The biggest "trick" question you'll get on this subject would be something like:


With regards to thin and thick filament length during a muscle contraction, which of the following is true?

A) The thick filaments contract and the thin filaments do not
B) The thin filaments contract and the thick filaments do not
C) Both the thick and thin filaments contract
D) Neither the thick or thin filaments contract

 

[engineeredout]

The biggest "trick" question you'll get on this subject would be something like:


With regards to thin and thick filament length during a muscle contraction, which of the following is true?

A) The thick filaments contract and the thin filaments do not
B) The thin filaments contract and the thick filaments do not
C) Both the thick and thin filaments contract
D) Neither the thick or thin filaments contract

YES. Thats the question from EK that really confused me. I still don't really get it.

 

[Neurokiran]

The biggest "trick" question you'll get on this subject would be something like:


With regards to thin and thick filament length during a muscle contraction, which of the following is true?

A) The thick filaments contract and the thin filaments do not
B) The thin filaments contract and the thick filaments do not
C) Both the thick and thin filaments contract
D) Neither the thick or thin filaments contract

So what's the Correct Answer.
I would go for "D" as it's slides over each other.
In Addition,if you read the Sliding Theory,it says that
Only I band get short during contraction.
So Please tell the correct answer.
Thanks.

 

[engineeredout]

So what's the Correct Answer.
I would go for "D" as it's slides over each other.
In Addition,if you read the Sliding Theory,it says that
Only I band get short during contraction.
So Please tell the correct answer.
Thanks.

Doesn't the H band get shorter too?

 

[Neurokiran]

Doesn't the H band get shorter too?

Yes! You are Right.But,
It doesn't get Shorter,it just disappear becoz
the Contraction of the I band.

 

[Vihsadas]

Exactly. Neither the thick, nor the thick filaments actually "contract" or get shorter. They simply slide over one another, increasing their level of overlap. The net effect is that the entire myofibril contracts, and thus the entire muscle...but not the filaments themselves!

 

[YA7ES]

The BANDS get shorter, but not the filaments themselves. The only band that doesn't get shorter during contraction is A band, the I and H do get shorter.

In order for these bands to get shorter the filaments slide over one another, instead of contracting.