Muscle Worksheet

Question 1

What is the internal organization of a muscle fiber?

Answer 1

> multinucleated with peripheral nuclei
cytoplasm called sarcoplasm
surrounding cell membrane called sarcolemma

Question 2

What is the basic functional unit of a muscle?

Answer 2

sarcomere

Question 3

What is the organization of the myofilaments that contributes to the striations of skeletal muscle including the I band, A band, Z line, H zone, and M line?

Answer 3

> light I band bisected by Z line
between Z lines is sarcomere
center of sarcomere has thick myosin and some thin actin - A band
outside that is thin actin - I band
H zone - consists only of myosin
M line - where adj.myosin filaments are linked, center of sarcomere

Question 4

What is the location of the mitochondria, sarcoplasmic reticulum, and T tubules?

Answer 4

within the sarcolemma

Question 5

What is the location and composition of the epimysium, perimysium, and endomysium?

Answer 5

> epi - surrounds entire muscles; dense irregular CT
peri - surrounds muscle fascicles; dense irregular CT
endo - surrounds muscle fibers; loose irregular CT

Question 6

What is a fascicle?

Answer 6

bundles of muscle fibers

Question 7

What is location of the nuclei in cardiac muscle?

Answer 7

centrally located; may have 1 or 2

Question 8

How are individual cardiac muscle fibers able to function as a synctium?

Answer 8

cells are joined end to end through anchoring cell junctions called intercalated disks; the disks have gap junctions that allow ions to move from cell to cell

Question 9

How does the organization of the sarcomere in cardiac muscle compare to that in skeletal muscle?

Answer 9

similar (A bands, I bands, Z lines, H zones, M lines)

Question 10

What are Purkinje fibers? Where are they located?

Answer 10

part of the conduction system of the heart; beneath endocardium on either side of interventricular septum

Question 11

What is the arrangement of the myofilaments in smooth muscle?

Answer 11

course obliquely throughout the cell in the form of a lattice network that crisscrosses the sarcoplasm

Question 12

What is the attachment point for actin filaments in smooth muscle?

Answer 12

dense bodies (similar to Z disks)

Question 13

What is the location of the nucleus in a smooth muscle cell?

Answer 13

single, central

Question 14

What proteins make up myofilaments?

Answer 14

actin and myosin

Question 15

What kind of muscle has diads of SR and T tubules? What kind has triads?

Answer 15

cardiac

skeletal

Question 16

What are some differences between smooth and striated muscle?

Answer 16

Smooth muscle has actin and myosin but no sarcomere and SR but no T tubules; it can be regulated by innervation, hormones, stretch, and ions via gap junctions