ch. 11

Question 1

what are the three types of muscular tissue

Answer 1

skeletal
cardiac
smooth

Question 2

what are the functions of the muscle

Answer 2

excitability (repsonsiveness)

conductivity

contractility (shortens when stimulating)

extensibility (stretched between contractions)

elasticity

Question 3

what is skeletal muscle

Answer 3

voluntary, striated muscle usually attached to bones

Question 4

striations

Answer 4

alternating light and dark transverse bands

results from arrangement of internal contractile proteins

only cardiac and skeletal muscle have

Question 5

what does voluntarymean

Answer 5

usually subject to conscious control

Question 6

what is a muscle fiber

Answer 6

muscle cell as long as 30 cm

Question 7

what are the connective tissues of the skeletal muscle

Answer 7

ednomysium: connective tissue around muscle cell
perimysium: connective tissue around muscle fasicle
epimysium: connective tissue surrounding entire muscle

Question 8

tendons

Answer 8

attachments between muscle and bone matrix

continous with collagen fibers of tendons and with connective tissue of bone matrix

Question 9

collagen

Answer 9

extensible and elastic

stretches slightly under tension and recoils upon release

resists excessive stretching = no muscle injury

returns muscle to resting length

contributes to power output and muscle efficeny

Question 10

sarcolemma

Answer 10

plasma membrane of muscle fiber

conducts electrical signal that travels to nerves

Question 11

sarcoplasm

Answer 11

cytoplasm of the muscle fiber

very specific organelles and inclusions

Question 12

myofibrils

Answer 12

long protein cords occupying most of the sarcoplasm

muscle fibers that give organized straitions

Question 13

glycogen

Answer 13

granules that provide instant energy to muscle

carbohydrate stores for energy for exercise

Question 14

myoglobin

Answer 14

red pigment protein

provides some o2 for muscle activity

stores O2

O2 is required for muscle to contract/endurance

Question 15

multiple nuclei

Answer 15

flattened nuclei pressed against the inside of the sarcolemma

Question 16

myo blasts

Answer 16

stem cells that fused to form each muscle fiber early in development

have centrioles in kids byt replaced by cytoskeleton as adults

Question 17

satellite cells

Answer 17

unspecialized myoblasts remaining between the muscle fiber and endomysium

play a role in regeneration of damaged skeletal muscle tissue (injury)

muscle doesnt usually multiply, cytoskeleton gets bigger as muscle
fibers = stressed
this increases strength with no new cells

have centroles

Question 18

mitochondria

Answer 18

packed into spaces between myofibrils

Question 19

sarcoplasmic reticulum

Answer 19

smooth er that forms a network around each myofibril

specialized to store and release calcium

stimulated by electrical signals to bind and activate contraction

Question 20

terminal cisterns

Answer 20

dilated end-sacs of SR which cross the muscle fiber from one side to the other

Question 21

T tubules

Answer 21

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

Question 22

triad

Answer 22

a T tubule and two terminal cisterns `associated with it

Question 23

Thick filament

Answer 23

made of several hundred myosin molecules

Two chains intertwined to form a shaft-like tail

Double globular head

Bare zone with no heads in the middle (H band)

Question 24

what are the two types of myofilaments

Answer 24

thick filaments and thin filaments

made by free ribosomes organizes them within the cytoskeleton = striations

Question 25

Thin filaments

Answer 25

fibrous actin

two intertwined strands

String of globular (G) actin subunits each with an active site that can bind to head of myosin molecule

contain tropomyosin molecules and troponin

Question 26

what is tropomyosin and troponin

Answer 26

Regulatory proteins:

tropomyosin
Each blocking six or seven active sites on G actin subunits

troponin
small, calcium-binding protein on each tropomyosin molecule

Question 27

titin

Answer 27

keeps organized stretches during contraction

unstretches when no contraction and pulls apart myosin and actin

Question 28

explain the process of tropomyosin and troponin

Answer 28

act like a switch that determines when fiber can and cant contract

contraction activated by release of calcium into sarcoplasm and its binding to troponin

troponin changes shape and moves tropomyosin off the active sit on actin

Question 29

elastic filaments

Answer 29

includes titin: huge springy protein

run through core of thin filament and anchor it to z disk and m line

help stabilize and position the thick filament

prevent overstretching and provide recoil

dystrophin too

Question 30

dystrophin

Answer 30

protein

link actin in outermost myofilaments to membrane proteins that link to endomysium

transfer forces muscle contraction to connective tissue ultimaletly leading to tendon

Genetic defects in dystrophin produce disabling disease muscular dystrophy

Question 31

what are striations

Answer 31

alternating A bands (dark) and I bands (light)

Question 32

a band

Answer 32

dark (anisotropic band)

darkest part is where thick filament overlaps thin filament

contains Hband (thick filament only) = darker contraction and m band (middle of H band)

Question 33

I band

Answer 33

light (isotropic)

contains actin and titin

no zone overlap

the way the bands reflect polarized light

contains z disc (anchorage for thin and elastic filaments)

Question 34

sacromere

Answer 34

segment from z disc to z disc

the functional contractile unit of muscle fiber

when muscle contracts= each sacromere shortens

(z discs pulled together as thick/thin filaments slide past eachother, they do not shorten just overlap)

dystophin and linking proteins also pull on extracellular proteins during shortening