Muscle Pt. 1 (S.M structure, sliding theory)

Question 1

Striations correspond to the arrangement of ___________________ within the _________

Answer 1

arrangement of thick/thin filaments within the microfibrils create the band pattern

Question 2

the span from one z-disk to the next z-disk represents one _____

Answer 2

sarcomere

Question 3

the dark reigions of skeletal muscle portray?

Answer 3

the overlap of thick/thin filaments

Question 4

a single muscle cell is also referred to as a ________

Answer 4

muscle fiber

Question 5

what is the basic contractile unit of skeletal muscle?

Answer 5

sarcomere

Question 6

where does Ca+ bind to on thin filaments?

Answer 6

troponin complex (TnT C)

Question 7

What does myosin bind to on thin filaments?

Answer 7

on F-actin (the backbone with myosin binding sites on it)

Question 8

What 3 main structures compose the thin(myo)-filaments?

Answer 8

1. Toponin (Ca binding)
2. Topomyosin
3. F-actin (myosin binding)

Question 9

thick filaments consist of a bundle of ____ molecules

Answer 9

myosin

Question 10

Thick filaments are composed of # intertwined ___ chains that each have # of their own __ chains

Answer 10

2 heavey chains with 2 light chains each

Question 11

The _____ head of the thick filament acts as a binding site for ___ &___

Answer 11

myosin site on thick filaments is a binding site for both actin & ATP (also hydrolyzes ATP)

Question 12

What are the name & function of the 2 light chains?

Answer 12

1. Regulatory - controls ATPase activity of myosin
2. Essential - supports myosin head

Question 13

What is the role of Titin (in thick or thin?)?

Answer 13

Titin = thick filaments = stabilizations & elastic recoil of muscle

Question 14

what is the role of nebulin (in thick or thin?)?

Answer 14

thin filaments = controls length of filaments

Question 15

What are the parts of a sarcomere?Their function?

(1 disk) (2 bands) (1 zone) (1 lline)

Answer 15

1. Z disk = attachment site for thin filaments
2. I band = lightest part with only thin filaments (right beside z-disk) (actin only)
3. A band = drak region in middle (thick & thin overlap) (actin & myosin)
4. H-zone = center area of A band with only thick filaments (myosin)
5. M line = attachment point for thick filaments

Question 16

Thin filaments have (actin/myosin) and thick filaments have (actin/myosin)

Answer 16

thin - actin
thick - myosin

Question 17

Where is Ca+ stored within a muscle fiber?

Answer 17

Sarcoplasmic reticulum = the internal release of Ca is what iniates AP? (not the Ca influx)

Question 18

T-tubules are continouation of the ____, indenting inward in skeletal muscle to propogate AP signal inside, and allowing Ca release

Answer 18

continuations of sarcolemma (cell membrane) = AP enters fiber through here

Question 19

What are terminal cisternea?

Answer 19

a specific tubular part of the sarcoplasmic reticulum that is neighbor with T-tubles so when Ca enetrs there, it can store it here. ?

Question 20

glucose is stored as ____- within the sarcoplasm

Answer 20

glycogen (skeletal muscle is storage point for glucose)

Question 21

The sliding filament theory refers to . . .

Answer 21

skeletal muscle contraction happening on a sarcomere level: it results in a sarcomere shortening without actin & myosin changing lengths, due to sliding past eachother.

Question 22

During skeletal muscle contraction, ____ & ___ shorten while ____remains constant

Answer 22

H zone & I band shorten
A band remains constant