Muscle Histology

Question 1

Where are nuclei located in skeletal muscle?

Answer 1

At the periphery.

Question 2

What colour are type I fibers?

Answer 2

Red

Question 3

By what portion are sarcomeres formed?

Answer 3

By the portion between two Z disks.

Question 4

Which protein is at the Z disc bound to actin?

Answer 4

Alpha-actinin

Question 5

Which protein alineates the Z discs and connects the myofibrils to the cell organelles?

Answer 5

Desmin

Question 6

Which protein binds thick filaments (myosin) to the Z disc?

Answer 6

Titin

Question 7

Which protein binds actin to the cell membrane?

The cytoskeleton to the ECM.

Answer 7

Dystrophin

Question 8

Which binding protein is elastic and acts as a coil?

Answer 8

Titin

Question 9

Which protein is in charge of mantaining thick filament
cross-linking?

Answer 9

Myomesin

Located at the central part.

Question 10

In what position is the T tubule respecting the myofibrils?

Answer 10

The T tubule is perpendicular (transverse) to the myofibrils.

Question 11

Of what are the triads formed?

Answer 11

Of the T tubule and the terminal cisternae (dilations of the SER) at both sides.

Question 12

Where are the triads located?

Answer 12

In the intersection between I and A bands.

Question 13

What part of the muscle detects the degree of stretching?

Answer 13

The muscle spindle.

Question 14

Where can we find satellite cells?

Answer 14

Inside the same basement membrane than muscle cells (and myofibirls…).

Question 15

Can skeletal muscle divide?

Answer 15

No

But it can regenerate through satellite cells (progenitor cells).

Question 16

Where are the nuclei in cardiac muscle located?

Answer 16

At the center.

Question 17

How many nucleis does a cardiac muscel cell have?

Answer 17

1 or 2 nuclei.

Question 18

True/False

In the cardiac muscle per each fiber there is one cell.

Answer 18

FALSE

One fiber is formed by many different cells.

Branching of the fibers.

Question 19

Does the Sarcoplasmic Reticulum form terminal cisternae in the cardiac muscle?

Answer 19

NO

Question 20

Is the cardiac or the skeletal muscle the one which has wider and less abundant T tubules?

Answer 20

The cardiac muscle.

Question 21

Where do diads appear at the cardiac muscle?

Answer 21

At the Z lines

Question 22

To what are Intercalated discs alligned?

Answer 22

To the Z discs.

Question 23

What is the responsability of the intercalated discs?

Answer 23

To mechanically (transverse, fascia adherens and desmosomes) and electrically (lateral,gap juntions) coupling heart cells.

Question 24

When does contraction in the cardiac muscle initiate?

Answer 24

After the contact of the Purjinke fibers with the Cardiac myocytes.

Question 25

Which is the prinicple difference regarding Calcium between the cardiac and the skeletal muscle?

Answer 25

In the Cardiac Muscle Ca2+ can enter from the Extracellular Region.

Question 26

In the smooth muscle how many cells form a fiber?

Answer 26

1 cell = 1 fiber

Question 27

What contraction is faster the one of the skeletal or smooth muscle?

Answer 27

The one of the skeletal muscle.

Question 28

What is the difference between the nuclei in the smooth muscle and the connective tissue?

Answer 28

Nuclei at the smooth muscle are elongated but more rounded and more euchromatic. (pale)

In fibroblast the nuclei is heterochromatic (darker).

Question 29

Does smooth muscle have T tubules?

Answer 29

NO

Question 30

What structures are distinct of smooth muscle?

Answer 30

It has caveoale at the periphery.

Question 31

Smooth muscle lacks striations,

Does smooth muscle posses fibers?

Answer 31

Yes

Question 32

What protein does smooth muscle don’t have?

Answer 32

Troponin

As the affinity of myosin for actin is VERY LOW.

Question 33

True or False

In the smooth muscle we don’t have an H zone, a space where there are no heads

Answer 33

TRUE

No central bare zone, no bipolar orientation.

Question 34

What structure in smooth muscle stabilize and transmit the contraction, as the Z lines did?

Answer 34

Dense bodies

Question 35

What type of contraction is the one with few nerve endings and cells connected through gap junctions?

The contraction is slower and rhythmic.

Answer 35

Visceral (unitary) contraction.