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Cell Biology > Muscle > Flashcards

Flashcards in Muscle Deck (53)
1

3 types of muscle

Cardiac, smooth, skeletal

2

Voluntary muscle

Skeletal

3

Involuntary muscle

Cardiac, smooth

4

what are myofilaments made of?

actin, myosin

5

What is the epimysium

Connective tissue that surrounds the entire muscle

6

What is the perimysium

Connective tissue that surrounds the fasicle

7

What is the endomysium

Connective tissue that surrounds each muscle fiber (muscle cell)

8

What is a synctium?

A multinucleated cell that was created through the fusion of unicellular cells

9

Characteristics of skeletal muscle

Each cell has multiple, peripherally located nuclei

Striated

10

How vascularized is skeletal muscle?

Extensive capillary network due to high energy requirement

11

What is a sarcomere?

Single contraction unit (Z dsk to Z disk)

12

What are thin filaments of the sarcomere

Actin

13

What are thick filaments of the sarcomere

Myosin

14

What filament is most abundant in I band?

Actin, troponin, tropomyosin

15

What filament is most abunant in A band?

Myosin and Actin

16

What is the M line?

Where no actin filaments connect with myosin and two myosin filaments cross connect

17

Where are troponin and tropomyosin located?

I band

18

What filament is in the H band?

Myosin only

19

Which bands shorten during contraction?

I and H bands

20

How is troponin and tropomyosin configured?

Tropomyosin is wrapped around actin covering myosin binding sites

Troponin is attached to tropomyosin

21

Is troponin present in smooth muscle?

No

22

What is troponin C

Troponin C binds the calcium to activate movement of tropomyosin

23

How are myosin filaments arranged?

Two heavy chain tails are connected together with cross bridge heads

These heads move back during contraction

24

What 2 structures are important for calcium and muscle contraction?

Sarcoplasmic reticulum and T-tubules

25

What does the sarcoplasmic reticulum do?

Calcium storage

26

What do transverse tubules do?

Cell membrane invaginations that extend between the myofibrils and ensure high calcium inside every cell

27

What are terminal cisternae?

Expansions of sarcoplasmic reticulum

Located adjacent to T-tubules

28

What is a triad?

One T-tubule and its adjacent terminal cisternae

29

What happens at the neuromuscular junction?

ACh causes depolarization which spreads via T-tubules to triad junction to the dihydropyridine receptor activates the ryanodine receptor on the SR

30

What action does myosin have on ATP?

Hydrolyzes ATP

31

What are red muscle fibers?

Aerobic, endurance
Lots of mitochondria
High myoglobin
Slow twitch, sustained contraction

32

What are white muscle fibers

Sprint, anaerobic
Fast twitch

33

What are intermediate fibers?

Hybrid, mostly fast twitch

34

Where are muscle spindles located

Between endomysium and perimysium

35

What do muscle spindles do?

Determine position of body parts and extent of contraction

36

Characteristics of cardiac muscle

Striated
Involuntary
One centrally located nucleus
Intercalated discs

37

What is an intercalated disc?

Electron dense junctional complex with gap junctions, desmosomes, fascia adherens

38

What allows simultaneous contraction in cardiac muscle?

Intercellular junctions, anchors, sarcomeres

39

What is fascia adherens

Similar to Zonula Adherens but not the same (FA not belt-like)

40

How are contraction signals conducted in the heart?

Purkinje fibers and gap junctions

41

What are purkinje fibers?

Modified cardiac myocytes, assist in cardiac contraction

42

Characteristics of smooth muscle

Non-striated
Involuntary
Spindle-shaped cells
One elongated nucleus
Disorganized myofilaments

43

Does smooth muscle have connective tissue?

Yes, but there is little CT separating muscle cells (endomysium)

44

How does smooth muscle contract?

Myosin must be phosphorylated in order to bind to actin

Ca binds to calmodulin which activates light chain kinase

45

How is light chain kinase reglated?

Calmodulin Ca complex

An increase in cytosolic Ca induces calmodulin binding to myosin light chain kinase

46

How is skeletal muscle regenerated?

Satellite cells

47

Characteristics of satellite cells

Spindle-shaped cells with little cytoplasm

Located under the external lamina of muscle cell

Forms myoblasts which differentiate in to muscle fibers

48

What can inhibit muscle cell regeneration?

Damage to external lamina

49

How is muscle repar generally achieved?

Formation of connective scar tissue

50

What is the external lamina?

Surrounds sarcolemma of muscle cells

Secreted by muscle cells

51

Is there cell regeneration in cardiac muscle?

Very little
Transplantation of stem cells can initiate regeneration

52

How does smooth muscle regenerate?

Normal cell division

53

What is the pathological result of a cardiac infarction?

Muscle is replaced with connective scar tissue, not muscle so it loses contractability