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Block 2; Week 1 > Histo Muscle > Flashcards

Histo Muscle Flashcards

1
Q

What are the 3 major types of muscle?

A

Skeletal, Cardiac, Smooth

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2
Q

What germ layer does all muscle come from? What is the one exception to this rule?

A

mesoderm

iris comes from the ectoderm

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3
Q

Describe the fibers of skeletal muscle.

A

have peripherally located nuclei…are multinucleated; elongated, striated

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4
Q

Describe the contraction of skeletal muscle.

A

strong, quick, discontinuous, involuntary

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5
Q

Describe the fibers of cardiac muscle.

A

They are striated, mono nucleated or sometimes binucleated, & there are intercalated discs that allow it to act like a synctium…the fibers are branched

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6
Q

Describe the contraction of cardiac muscle.

A

strong, quick, continuous, voluntary

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7
Q

Describe smooth muscle fibers.

A

an agglomeration of cells whose density depends on the amt of surrounding CT…no striations…centrally located cells.

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8
Q

Describe the contraction of smooth muscle. What is it like in a relaxed state? In a contracted state?

A

weak, slow, involuntary
Relaxed State: elongated
Contracted State: all crunched up

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9
Q

What do all types of muscle contain? What are these an example of?

A

Actin & myosin. Microfilaments.

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10
Q

What is the structural organization of skeletal muscle?

A

Sacomeres–>Myofibrils–>muscle fiber=muscle cell–>fascicle–>muscle

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11
Q

How does skeletal muscle develop?

A

primitive mesenchymal cells of the mesoderm–>myoblasts–>myotubes–>muscle fiber=muscle cell

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12
Q

What are the 3 layers that cover muscle cells/muscle fibers?

A

Sarcolemma
Basal Lamina
Endomysium (CT)

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13
Q

What covers fascicles?

A

perimysium

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14
Q

What covers the entire muscle?

A

epimysium

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15
Q

What are the 3 layers of the CT sheath around skeletal muscle? What are its functions? What produces it?

A

Endomysium, Perimysium, Epimysium
connects muscle cells that don’t reach the entire length
necessary to transmit forces from one end to the other
allows for blood vessels & nerves to travel w/ the muscle
fibroblasts make it.

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16
Q

What are satellite cells? Where are they found?

A

stem cells capable of regeneration

found b/w the sarcolemma & the basal lamina

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17
Q

What makes the Z disc? M line?

A

Z disc: cross-linking actin; M-line: myosin tails

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18
Q

Explain the structure of a sarcomere.

A

Z disc, I band, A band, H zone, M line, H zone, rest of A band, I band, Z disc

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19
Q

What are the I band, A band, & H band composed of?

A

I band: only actin; H band: only myosin; A band: myosin & actin & just myosin…essentially the entire length of myosin filaments

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20
Q

What is the relationship of the I band & A band to polarized light?

A

I band has actin thin filaments & is isotropic to polarized light–light pass thru–light in color
A band has thick myosin filaments & is anisotropic to polarized light–light doesn’t pass thru as much–dark in color.

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21
Q

What is the AI junction?

A

It is located b/w the A band & I band…it is an invagination of sarcolemma into muscle cells. Allows proper amt. of Ca++ to get into muscle for uniform contraction.

22
Q

What happens to the sarcomere during contraction according to the sliding filament theory?

A

Z discs move closer together
I band & H band get smaller b/c they are pure actin & myosin & w/ contraction there is more overlap.
A band stays the same.

23
Q

What are 2 important elements to keep in mind concerning skeletal muscle contraction?

A

Triggered by calcium.

All or none.

24
Q

At what age does the number of muscle fibers stop increasing? Keep in mind w/ pitching baseball!

A

14 years of age…about puberty

25
Q

How can you get stronger skeletal muscles?

A

Increasing thickness–hypertrophy thru repeated exercise
Increasing CT
Increasing Number of Cells–hyperplasia thru excessive exercise; suppression of myostatin; stimulation of satellite cells
NOT the length of muscle cells

26
Q

What is myostatin?

A

cytokine produced by skeletal muscle; suppresses skeletal muscle growth

27
Q

What else is the epicardium called?

A

Visceral layer of the serous pericardium

28
Q

What are the layers of the heart (outside–inside) starting with the epicardium on the outside?

A

Epicardium
Myocardium
Subendocardial Space
Endocardium

29
Q

What are cardiomyocytes derived from?

A

Mesoderm

30
Q

Where are Purkinje fibers found? What are they? What do they do?

A

Subendocardial space
modified cardiomyocytes
propagate contraction down to the apex of the ventricle–blood squeezes out of the pulmonary trunk & aorta

31
Q

What are the 3 types of cardiocytes in the myocardium?

A

Contractile Cardiocytes–contract & pump blood into circulation
Myoendocrine cardiocytes–produces ANP
nodal cardiocytes–responsible for rhythmic contraction–in SA & AV nodes.

32
Q

Where are purkinje fibers found?

A

after the AV node, under the endocardium, lining the interventricular septum

33
Q

How can Purkinje fibers be distinguished from cardiocytes?

A

Location
Purkinje are larger
Purkinje stain lighter b/c of the high glycogen content

34
Q

What is found in the subendocardial CT layer?

A

collagen & elastic fibers made from fibroblasts

blood vessels, nerves, Purkinje fibers

35
Q

What are the 2 main parts of the intercalated discs & what is found their?

A

Transverse (vertical): fascia adherens & desmosomes

Longitudinal (horizontal): gap jcns

36
Q

How can you differentiate smooth muscle from CT?

A

There are a ton of nuclei in smooth muscle.

37
Q

What is the exact location of the SA node?

A

SVC RA jcn

38
Q

What is the exact location of the AV node?

A

under the endocardium that covers the intertribal & inter ventricular septa.

39
Q

What is located inside of a dense body?

A

plaque
plasma membrane thickening
some microfilaments

40
Q

Which types of muscle require calcium?

A

skeletal, cardiac, & smooth muscle!!

41
Q

What takes up the calcium? What binds it?

A

Caveolae assist in taking up calcium.

Calmodulin bind the calcium

42
Q

What do smooth muscle cells look like in the relaxed state & the contracted state?

A

Relaxed: cigar, longitudinal
Contracted: all crunched up

43
Q

What is the outside of smooth muscle like?

A

external basal lamina w/ gap jcns

44
Q

What is the contraction of smooth muscle like?

A

weak, slow, involuntary

45
Q

What is the nucleus situation of smooth muscle?

A

mononucleated. Centrally located nuclei.

46
Q

Which types of muscle have T-tubules?

A

T tubules are found in skeletal & cardiac muscle.

47
Q

Which types of muscle have gap jcns?

A

Cardiac & Smooth

48
Q

What binds calcium in each type of muscle?

A

Smooth muscle uses calmodulin.

Skeletal & cardiac muscle uses troponin C.

49
Q

Which types of muscle can undergo mitosis?

A

Only smooth muscle cells.

50
Q

Cardiac & smooth muscle don’t have epimysium…what is their CT sheath situation?

A

They just have CT sheaths & endomysium.

Block 2; Week 1 (9 decks)

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