Muscle Tissue

Question 1

What are skeletal muscles called?

Answer 1

myocytes or muscle fibers

Question 2

What does groups of muscle fibers form?

Answer 2

fascicles

Question 3

What are muscle fibers separated by?

Answer 3

endomysium

Question 4

What are fascicles separated by?

Answer 4

perimysium

Question 5

what surrounds the entire muscle?

Answer 5

epimysium

Question 6

What is the cytoplasm of myofibers primarily occupied with?

Answer 6

myofibrils

Question 7

Where is the nuclei located in skeletal muscle?

Answer 7

In the periphery

Question 8

What are myofibrils composed of?

Answer 8

thin (actin) and thick (myosin) filaments

Question 9

What is the basic functional unit of a myofibril?

Answer 9

sarcomere

Question 10

What is the group of myofibrils surrounded by?

Answer 10

sarcolemma

Question 11

What are the invaginations of the sarcolemma?

Answer 11

transverse(t)-tubules

Question 12

What are the dilated ends of the sarcoplasmic reticulum that release Ca2+

Answer 12

terminal cisternae

Question 13

anchor site for actin (thin) microfilaments?

Answer 13

Z-line

Question 14

Anchor site for thick myosin filaments?

Answer 14

M-line

Question 15

only contains actin thin filaments?

Answer 15

I-band

Question 16

only contains myosin thick filaments?

Answer 16

H-zone

Question 17

overlap of thick and thin filaments plus the H-zone?

Answer 17

A-band

Question 18

When a muscle cell contracts what occurs with the filaments?

Answer 18

the thin filaments slide past the thick filaments toward the center of the sarcomere bringing Z-lines closer together

Question 19

What are the regulatory proteins found in thin filaments?

Answer 19

tropomyosin and troponin

Question 20

Runs in groove formed by F-actin strands

Answer 20

tropmyosin

Question 21

what does tropomyosin bind to?

Answer 21

to the troponin complex

Question 22

Troponin is a complex composed of what?

Answer 22

3 proteins, troponin I, troponin C, and troponin T

Question 23

What is the role of troponin T?

Answer 23

it binds tropomyosin to the complex

Question 24

What is the role of troponin I?

Answer 24

it inhibits the binding of myosin to actin

Question 25

what is the role of troponin C?

Answer 25

it binds Ca2+ and is only found in striated muscle

Question 26

What is the regulatory protein that permits cross-bridge formation when it binds Ca2+

Answer 26

troponin

Question 27

What carries the depolarization from the sarcolemmal membrane to the cell interior

Answer 27

T-tubules

Question 28

What is the site of Ca2+ storage and release for excitation-contraction coupling?

Answer 28

sarcoplasmic reticulum

Question 29

What does depolarization of of the T tubules cause?

Answer 29

a conformational change in its dihydropyridine receptor (DHPR)

Question 30

what does a conformation change in the DHPR cause?

Answer 30

opens Ca2+ release channels in the nearby sarcoplasmic reticulum

Question 31

What happens when Ca2+ binds to troponin C on the thin filaments?

Answer 31

it causes a conformational change in troponin that moves tropomyosin out of the way

Question 32

When does the cross-bridge cycle begin?

Answer 32

once calcium binds to troponin c and moves tropomyosin out of the way

Question 33

What happens when ATP binds to myosin?

Answer 33

it produces a conformational change in myosin that causes myosin to be released from actin

Question 34

What causes myosin to be displaced toward the plus end of actin?

Answer 34

hydrolysis of ATP to ADP and inorganic phosphate

Question 35

sites of special cell adhesions and low electrical resistance

Answer 35

intercalated discs

Question 36

ribbon- like adhesions found at the ends of terminal sarcomeres and anchored to actin filaments

Answer 36

fascia adherens

Question 37

spot-like adhesions between cells anchored to intermediate filaments of the cell

Answer 37

desmosome

Question 38

small channel-like connections between cells allowing excitation/contraction wave to pass from one cell to the next connected cell

Answer 38

gap junctions

Question 39

How does cardiac muscle contract?

Answer 39

rhythmically without innervation

Question 40

What is the most predominant junction in cardiac muscle?

Answer 40

fascia adherens

Question 41

Which junction transmits contractile forces between cells in cardiac muscle?

Answer 41

fascia adherens

Question 42

What are dense bodies of smooth muscle comprised of?

Answer 42

desmin and vimentin intermediate filaments