Muscles

Question 1

Epimysium

Answer 1

Superficial collagenous connective tissue layer that covers the muscle and separates it from neighboring structures.

Question 2

Perimysium

Answer 2

The second or middle layer of connective tissue of the muscle. The epimysium folds into the muscle as the perimysium, and divides the muscle fibers into groups called fascicles.

Question 3

Endomysium

Answer 3

The deep layer of connective tissue of the muscles. Connective tissue fivers of the perimysium extend deep into the fascicles as the endomysium, and surround each muscle fiber (cell)

Question 4

Fascicle

Answer 4

Group of muscle fivers

Question 5

Tendon

Answer 5

The connective tissues of the muscle interweave and combine at each ends of the muscle. The tendon and the bone’s periosteum interlace to attach the muscle to the bone.

Question 6

Belly

Answer 6

The center of the muscle

Question 7

Sarcolemma

Answer 7

The cell membrane of the muscle

Question 8

Muscle fiber

Answer 8

Composite of many cells that fused into a single cell during embryonic development

Question 9

Sarcoplasm

Answer 9

Cytoplasm of a muscle fiber

Question 10

Transverse tubule

Answer 10

(T tubules) Connect the sarcolemma to the interior of the muscle fiber. Function is to pass contraction stibuli to deeper regions of the muscle fiber

Question 11

Myofibrils

Answer 11

Proteins that are arranged in thousands of rods inside the muscle fiber. Extends the length of the fiber. Each myofibril consists of several kinds of proteins arranged in about 3000 thin filaments and 1500 thick filaments.

Question 12

Sarcoplasmic reticulum

Answer 12

Surrounds each myofibril. IT is a modified endoplasmic reticulum where calcium ions are stored.

Question 13

Terminal cisternae

Answer 13

Branches of sarcoplasmic reticulum fuse to form large calcium ion storage chambers. Lies adjacent to the transverse tubules.

Question 14

Triad

Answer 14

A “sandwich” consisting of a transverse tubule plus the terminal cisterna on each side of the tubule

Question 15

Thin filaments

Answer 15

Mostly composed of the protein ACTIN; consists of 2 interwined strands of actin.

Question 16

Thick filaments

Answer 16

Composed of the protein MYOSIN; made of approximately 300 subunits of myosin. Each subunit consists of 2 strands: 2 intertwined tail regions and 2 globular heads. Bundles of myosin subunits, with tails parallel to one another and the head projecting outward, constitute thick filaments.

Question 17

Sarcomeres

Answer 17

Repeating patterns of arranged filaments

Question 18

Z line

Answer 18

Where thin filaments are connected to each other on each end of the sarcomere. Each X line is made of a protein called ACTININ

Question 19

I band

Answer 19

Areas near the Z line that contain only thin filaments

Question 20

A band

Answer 20

Area between I bands in a srcomere; containing both thin and thick filaments

Question 21

Zone of overlap

Answer 21

Edges of the A band where the thick and thin filaments bind during muscle contraction

Question 22

H zone

Answer 22

The middle region of the A band and contains only thick filaments

Question 23

M line

Answer 23

A dense line in the center of the A band that attaches the thick filaments

Question 24

Actin

Answer 24

Consists of 4 protein components: G actin, F actin, nebulin, and active sites

Question 25

G actin

Answer 25

Individual spherrical molecules

Question 26

F actin strand

Answer 26

Approximately 300 to 400 G actins twisted together

Question 27

Nebulin

Answer 27

Holds the G actins in position along the F actin strand

Question 28

Active site

Answer 28

On each G actin molecule where myosin molecules in the thick filaments bind during contraction

Question 29

Tropomyosin

Answer 29

Follows the twisted actin strands and blocks active sites to regulate muscle contraction

Question 30

Troponin

Answer 30

Holds tropomyosin in position and has binding sites for calcium ions. Calcium ions cause troponin to change shape and move tropomyosin away from binding sites for contraction

Question 31

Titin

Answer 31

Protein that attaches the thick filament to the Z line on the end of the sarcomere.

Question 32

Myosin

Answer 32

Consists of a head, hinge, and tail. Each head contains a binding site for actin and a region that functions as an ATPase enzyme.