Chapter 9

Question 1

Parallel arrangement of muscle fibers?

Answer 1

fasciculi run parallel to the long axis of the muscle and extend the entire length of the muscle, origin to insertion

example: sartorius

Question 2

Convergent arrangement of muscle fibers?

Answer 2

origin of the muscle is wide and the fasciculus converge toward the tendon of insertion

triangular of fan shaped, extend from origin to insertion

example: pec major

Question 3

Pennate arrangement?

Answer 3

fasciculi and fibers attach obliquely to tendon that runs the entire length of muscle (uni, bi, multi), fibers are short

Question 4

T/F

Skeletal muscle cells have one nucleus.

Answer 4

False

many

Question 5

Sarcolemma?

Answer 5

skeletal muscle cell membrane

Question 6

Satellite cells?

Answer 6

precursor cells that have on nucleus and function to facilitate repair and growth of damaged skeletal muscle following injury

-most repair and growth is found in nuclei

Question 7

Appearance of striations originate in ______.

Answer 7

Myofibrils

Question 8

Sarcoplasm?

Answer 8

cytoplasm of muscle cell that contain mitochondria

Question 9

What is the cross sectional area of one myofibril?

Answer 9

1-2 micrometers squared

Question 10

Sarcomere?

Answer 10

• segment of myofibril between two adjacent z lines

- basic contractile unit of skeletal muscle

Question 11

Z lines?

Answer 11

• at the end of sarcomere

- alpha actinin proteins arranged in a zigzag pattern that are the attachment sites for actin filaments

Question 12

protein that overlaps the central ends of the actin?

Answer 12

myosin filaments

Question 13

A band?

Answer 13

• dark band
• anisotropic
• full length of myosin

Question 14

I band?

Answer 14

• light band
• isotropic
• space between ends of myosin in two consecutive sarcomeres

Question 15

Two contractile proteins in sarcomere?

Answer 15

Actin

Myosin

Question 16

Two regulatory proteins in sarcomere?

Answer 16

Troponin
Tropomyosin

-control interaction of actin and myosin

Question 17

5 structural proteins in sarcomere?

Answer 17

Desmin
Nebulin
Titin
M line proteins (myomesin)
Myosin binding C proteins

Question 18

G-actin?

Answer 18

• globular actin
• polymerize to form long strands, filaments
• has active sites to attach myosin heads

Question 19

F-actin?

Answer 19

• filament actin

- two strands twist together

Question 20

Thin filament?

Answer 20

actin filament

Question 21

Tropomyosin?

Answer 21

protein filament that wraps around the double strand of F-actin, blocking the active sites on the G-actin

Question 22

Troponin?

Answer 22

protein that is attached to the tropomyosin about every 7th actin

Question 23

What are the three subunits of troponin? Functions?

Answer 23

C- binds Ca 2+
T- anchors troponin complex to tropomyosin
I - binds to actin and holds the troponin-tropomyosin complex in place

Question 24

Myosin function?

Answer 24

ATP dependent motor protein responsible for motility of actin

Question 25

What makes up Myosin?

Answer 25

-one pair myosin heavy chains intertwined to form a long coiled tail, a neck region, and a pair of tadpole like heads

Question 26

What is found in the head region of myosin?

Answer 26

two pairs of myosin light chains

Question 27

Thick filament?

Answer 27

myosin

Question 28

Function of neck and head region of myosin?

Answer 28

retain motor functions of myosin filament, forming cross bridges between thick and thin filaments

Question 29

Central bare zone?

Answer 29

central region of myosin filament where the tails of all myosin meet and there are no heads (H zone)

Question 30

What two things bind to myosin?

Answer 30

F-actin filament | ATP

Question 31

What breaks down ATP in myosin?

Answer 31

Myosin ATPase (enzyme)

Question 32

What results when ATP is broken down?

Answer 32

ATP --> ADP + Pi + heat + energy

Question 33

Desmin?

Answer 33

- links Z lines of adjacent myofibrils together keeping sarcomeres aligned - links outer myofibril and costameres to sarcolemma - transmits force of contraction to exterior of muscle fiber

Question 34

Nebulin?

Answer 34

- intertwined with actin filament and anchors actin to the Z line - molecular ruler- determines length of actin

Question 35

Titin?

Answer 35

- largest protein in skeletal muscle - attach Z line and M line - contribute to elasticity of fiber, limit range of motion of sarcomere

Question 36

M line proteins?

Answer 36

holds myosin in vertical alignment

Question 37

Myosin binding C proteins?

Answer 37

hold the ends of adjacent myosin filaments in vertical alignment

Question 38

Sarcoplasmic reticulum function?

Answer 38

- storage, release, and reuptake of Ca 2+ during the contractile process - divided into terminal cisternae and longitudinal tubules

Question 39

Longitudinal tubules?

Answer 39

- run parallel to fiber | - responsible for reuptake of Ca 2+ following excitation of fiber

Question 40

Terminal cisternae?

Answer 40

responsible for storage and release of Ca 2+ when muscle fiber is depolarized

Question 41

Triad?

Answer 41

one T-tubule and two adjacent cisternae

Question 42

T-tubules?

Answer 42

- perpendicular to muscle fiber - carry wave of depolarization from sarcolemma to interior of cell where it initiates sequence of events to contract muscle