Muscle

Question 1

What are the types of muscle?

Answer 1

1. Striated
2. Smooth muscle
3. Contractile filaments

Question 2

Skeletal muscle is ____

Answer 2

Voluntary

Question 3

Cardiac muscle is ____

Answer 3

Involuntary

Question 4

Smooth muscle is ____

Answer 4

Involuntary

Question 5

Under contractile filaments

Answer 5

Actin and Myosin

Question 6

CONNECTIVE TISSUE INVESTMENTS:

Answer 6

Epimysium
Perimysium
Endomysium

Question 7

CONNECTIVE TISSUE INVESTMENTS:

surrounds entire muscle

Answer 7

Epimysium

Question 8

CONNECTIVE TISSUE INVESTMENTS:

surrounds muscle bundles or fascicles (small bundles)

Answer 8

Perimysium

Question 9

CONNECTIVE TISSUE INVESTMENTS:

surrounds individual muscle cells

Answer 9

Endomysium

Question 10

CONNECTIVE TISSUE INVESTMENTS:

Reticular fibers and external lamina

Answer 10

Endomysium

Question 11

Long, cylindrical, multinucleated

Answer 11

SKELETAL MUSCLE CELLS

Question 12

Sarcoplasm, sarcolemma with T (transverse) tubules

Answer 12

SKELETAL MUSCLE CELLS

Question 13

MYOFIBRILS structure has:

Answer 13

• Thick filaments (myosin)
• Thin filaments (actin)
• Dark A bands, light I bands (bisected by Z disks)
• DESMIN (with plectin) glues Z disks together

Question 14

CROSS-STRIATIONS

Answer 14

TABLE 8.2
A-bands
I-bands
H-bands
M lines
Z disks (lines)

Question 15

CROSS-STRIATIONS:

Anisotropic; stain dark; thin and thick filaments

Answer 15

A-bands

Question 16

CROSS-STRIATIONS:

Isotropic; light stain; thin filaments

Answer 16

I-bands

Question 17

CROSS-STRIATIONS:

Light regions transecting A bands; thick filaments

Answer 17

H-bands

Question 18

CROSS-STRIATIONS:

Narrow dark regions at center of H bands; cross-bridges

Answer 18

M lines

Question 19

CROSS-STRIATIONS:

Dense regions bisecting I-band

Answer 19

Z disks (lines)

Question 20

Z to Z

Answer 20

SARCOMERE

Question 21

Functional unit of contraction

Answer 21

SARCOMERE

Question 22

Dilated terminal cisternae that encircle myofibrils at the junction of each A and I band

Answer 22

Sarcoplasmic reticulum

Question 23

Regulates muscle contraction by calcium sequestration (relax) and release (contract)

Answer 23

Sarcoplasmic reticulum

Question 24

Central T tubule flanked by 2 terminal cisternae of SR

Answer 24

Triads

Question 25

Help provide uniform contraction

Answer 25

Triads

Question 26

Under sarcomere

Answer 26

Sarcoplasmic reticulum Triads

Question 27

MOLECULAR ORGANIZATION: THIN FILAMENTS

Answer 27

F-actin Tropomyosin Troponin

Question 28

double helix arrangement

Answer 28

F-actin

Question 29

has an active site for interacting with myosin

Answer 29

F-actin

Question 30

In the grooves of the F-actin helix

Answer 30

Tropomyosin

Question 31

Troponin: bind to tropomyosin

Answer 31

TnT

Question 32

Troponin: 4 binding sites for calcium

Answer 32

Tnc

Question 33

Troponin: binds to actin, inhibiting myosin-actin interaction

Answer 33

TnI

Question 34

MOLECULAR ORGANIZATION: THICK FILAMENTS

Answer 34

Myosin II

Question 35

2 identical heavy chains and 2 pairs of light chains

Answer 35

Myosin II

Question 36

Double-headed golf club

Answer 36

Myosin II

Question 37

Globular heads (S1 fragments) have ATPase activity but require interaction with actin to release ADP and Pi.

Answer 37

Myosin II

Question 38

During contraction, thick and thin filaments do not shorten but increase their overlap

Answer 38

Huxley’s Sliding-Filament Model

Question 39

Thin filaments slide past thick filaments and penetrate more deeply into the A band, which remains constant in length

Answer 39

Huxley’s Sliding-Filament Model

Question 40

I and H bands shorten as Z disks are drawn closer together

Answer 40

Huxley’s Sliding-Filament Model

Question 41

INITIATION AND REGULATION OF CONTRACTION

Answer 41

Depolarization + calcium release 🡪 actin-myosin binding 🡪 muscle contraction

Question 42

INITIATION AND REGULATION OF CONTRACTION: ______ depolarized at MNJ

Answer 42

Sarcolemma

Question 43

INITIATION AND REGULATION OF CONTRACTION: ______ convey depolarization to myofibrils (voltage-sensitive dihydropyridine (DHP) receptors)

Answer 43

T tubules

Question 44

INITIATION AND REGULATION OF CONTRACTION: ______ released to cytosol at A-I junction via ________ of SR terminal cisternae opened by activated DHP receptors

Answer 44

Ca 2+, Ca2+ release channels (junctional feet, ryanodine receptors)

Question 45

INITIATION AND REGULATION OF CONTRACTION: Sufficient Ca2+ 🡪 continued contraction cycle

Answer 45

Ca2+

Question 46

Resting state 🡪 myosin-binding sites on actin are partially covered by tropomyosin. TnI is also bound to actin.

Answer 46

Activation of actin by Ca2+

Question 47

Ca2+ + TnC 🡪 break TnI-actin bond; tropomyosin shifts position and uncovers myosin-binding sites (active state)

Answer 47

Activation of actin by Ca2+

Question 48

Calcium concentration in the cytosol is reduced enough that TnC loses its bound Ca2+

Answer 48

Relaxation

Question 49

Relaxation: SR calcium pump binds Ca2+ to the SR inner membrane with ______

Answer 49

calsequestrin

Question 50

Motor unit is consists of:

Answer 50

neuron muscle cell it innervates