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Year 1 Cell Biology > Muscle > Flashcards

Flashcards in Muscle Deck (61):
1

What are the components of thin filaments?

1. F-actin2. Troponin3. Tropomyosin

2

Actin, troponin, and tropomyosin are components of what muscle filament?

Thin filament

3

What constitutes thick filaments?

Myosin II

4

What is F-actin made up of?

Two G-actin polymers twisted to form a double stranded helix

5

Two G-actin polymers twisted to form a double stranded helix forms ___________

F-actin

6

What are the components of troponin?

1. TnT2. TnC3. TnI

7

What is the function of TnT?

Troponin subunit that binds to tropomyosin

8

What is the function of TnC?

Troponin subunit that binds calcium

9

What is the function of TnI?

Troponin subunit that binds troponin to actin molecule; inhibits actin-myosin interaction

10

Where does the Tn complex bind to tropomyosin?

Grooves of actin filaments

11

What constitutes a tropomyosin molecule?

1. Two polypeptide chains in an a-helix2. Each a-helix rests on 7 G-actin molecules, covering active site3. Head to tail of tropomyosins form tropomyosin filaments

12

What does trypsin do to myosin molecules?

Breaks them into heavy meromyosin and light meromyosin

13

What is the molecular composition of myosin?

2 heavy chains and 4 light chains

14

What constitutes heavy meromyosin?

1. 4 light chains2. 2 globular chains3. Short twisted tail (a-helix)

15

What constitutes light meromyosin?

The shafts of the heavy chains wrapped around each other

16

What makes up a sarcomere?

Overlapping thick and thin myofilaments

17

Overlapping thick and thin myofilaments make up a _______________

Sarcomere

18

A series of sarcomeres joined end-to-end makes up a _______________

Myofibril

19

What makes up a myofibril?

A series of sarcomeres joined end-to-end

20

What makes up a muscle fiber (muscle cell)?

Many parallel myofibrils

21

Many parallel myofibrils make up a ______________

Muscle fiber (muscle cell)

22

What are the characteristics of the A band?

1. Dark band - thick and thin filaments2. Widest band

23

What are the characteristics of the H band?

1. Thick filaments only2. Bisects the A band

24

What are the characteristics of the I band?

1. Thin filaments only2. Light band3. Made up of portions of adjacent sarcomeres

25

What are the characteristics of the Z disc?

1. Attachment for thin filaments2. Contains a-actinin3. Bisects I band

26

What are the characteristics of the M line?

1. Consists of protein structures lying between thick and thin filaments, holding them together2. Creatine kinase is major protein3. Bisects H band

27

What is the role of a-actinin?

Anchors thin filaments to Z disc

28

What anchors thick filaments to the Z disc?

Titin

29

What is the role of titin?

Anchors thick filaments to Z disc

30

What is the role of myomesin and C protein?

Secures thick filaments at M line

31

What is the role of dystrophin?

Cytoplasmic protein that binds actin filaments to laminin

32

What makes up the sarcolemma?

Cell membrane + external lamina + reticular lamina

33

What is endomysium?

Surrounds muscle fiber, consists of delicate layer of reticular fibers

34

What is a fascicle?

Many muscle fibers bundled together

35

What connective tissue surrounds a fascicle?

Perimysium

36

What is perimysium?

Collagenous connective tissue that surrounds a fascicle

37

What is epimysium?

Deep fascia, surrounds many fascicles

38

What is the term for deep fascia taht surrounds many fascicles?

Epimysium

39

What are T tubules?

Invaginations of sarcolemma which are continuous with extracellular space

40

What is the function of T tubules?

Carry nerve impulses deep into cell

41

What is the terminal cisterna of the sarcoplasmic reticulum?

Stores calcium in its lumen

42

What is the triad located at the A-I junction of the sarcomere?

1 T tubule + 2 terminal cisternae

43

What are satellite cells?

Regenerative cells that lie between the skeletal muscle cell and its external lamina

44

New myoblasts are derived from ___________

Satellite cells

45

What components make up the innervation of skeletal muscle?

1. Motor unit2. Motor end plate

46

What constitutes the motor unit?

A lower motor neuron and all muscle fibers it innervates

47

What constitutes the motor end plate?

1. Axon terminal2. Synaptic cleft3. Muscle cell sarcolemma

48

What is myesthenia gravis?

Autoimmune disease causing muscle weakness

49

What is the cause of myesthenia gravis?

Antibodies attack Ach receptors on sarcolemma of skeletal muscle, forming Ab-receptor complexes

50

What is muscular dystrophy?

Genetic, degenerative disease affecting striated muscles

51

What is the protein affected in Duchenne's muscular dystrophy?

Dystrophin

52

Which muscle type contains a lot of glycogen?

Cardiac muscle

53

What are some characteristics of cardiac muscle?

1. Weakly striated2. Short and branched cells3. Cells contain glycogen, lipid droplets, and lipofuscin4. 1-2 nuclei5. Atrial granules6. Many mitochondria7. Intercalated discs

54

What are atrial granules?

Membrane-bound granules: 1. Contain atrial natriuretic factor and brain natriuretic factor2. Most common in right atrium

55

What are intercalated discs?

Specialized intercellular junctions

56

Are T tubules of the cardiac (ventricular) muscle larger or smaller than in skeletal muscle?

Larger

57

What are Purkinje fibers?

Specialized cardiac muscle cells in the endocardium that act as batteries which relay electrical impulses to cardiac muscle fibers

58

What are some characteristics of smooth muscle?

1. Forms sheets2. No striations3. Mononuclear - nucleus is in center4. Dense bodies - crossing of myofilament bundles5. No T tubules6. Poorly developed SR

59

What are dense bodies?

Criss-crossing of myofilament bundles

60

What is a common component of dense bodies?

a-actinin (similar to Z discs)

61

What are caveolae?

Pinocytotic vesicles that form bubble like structures on inner surface of cell membrane and release calcium into cell for contraction