Test 2 (muscle organization)

Question 1

Muscle tissues comprise about __of body mass, with skeletal being about __% and cardiac and smooth being __%

Answer 1

half; 30-40, 10

Question 2

characteristics of muscle tissue (4)

Answer 2

contractility, excitability, extensibility, elasticity

Question 3

functions of muscle (9)

Answer 3

focusing eye lens, generating heat, maintaining posture, movement, piloerection, protecting deeper organs, regulating passage of materials through hollow organs, regulating pupil diameter, and stabilizing joints.

Question 4

characteristics of skeletal muscle tissue (3)

Answer 4

long multinucleated cells, striations, voluntary

Question 5

characteristics of cardiac muscle tissue (4)

Answer 5

short branched cells, intercalated discs, striations, involuntary

Question 6

characteristics of smooth muscle tissue (3)

Answer 6

thin tapered cells, no striations, involuntary

Question 7

myo- mys-

Answer 7

muscle

Question 8

sarco-

Answer 8

flesh

Question 9

muscle terminology for muscle fiber

Answer 9

cell

Question 10

skeletal muscles have __ attachments

Answer 10

two or more

Question 11

skeletal muscle functional classification (2)

Answer 11

orgin, insertion

Question 12

skeletal muscle gross anatomy with CT sheaths (3)*

Answer 12

whole muscle, fascicle, muscle fiber

Question 13

skeletal muscle microscopic anatomy (4)

Answer 13

multinucleate, myofibrils, sarcolemma, sarcoplasm

Question 14

sarcolemma classification

Answer 14

t tubules

Question 15

sarcoplasm classification

Answer 15

glycosomes, myoglobin, mitochondria, sarcoplasmic reticulum

Question 16

sarcoplasmic reticulum classification

Answer 16

terminal cisternae

Question 17

myofibril structure

Answer 17

repeated protein structures, striations are aligned
light and dark bands across multiple myofibrils

Question 18

thick myofilament proteins (1)

Answer 18

myosin

Question 19

myosin classifications (3)

Answer 19

head, hinge, tail

Question 20

thin myofilament proteins (3)

Answer 20

actin, tropomyosin, troponin

Question 21

muscle organization

Answer 21

*

Question 22

four main processes of contraction

Answer 22

excitation, coupling, contraction, relaxation

Question 23

sliding filament theory during contraction

Answer 23

myosin heads bind to actin, linked heads automatically pivot 45°, pulling thin filaments.

Question 24

sliding filament theory during relaxation

Answer 24

ends of myosin and actin filaments overlap, tropomyosin covers binding sites on actin.

Question 25

cross bridging

Answer 25

myosin heads bind to actin

Question 26

events of neuromuscular junction excitation (5)

Answer 26

1 nervous impulse signal reaches axon terminal. 2 Ca++ channels open and Ca++ enters the terminal. 3 Vesicles release acetylcholine by exocytosis. 4 acetylcholine diffuses across the synaptic cleft and binds to receptors. 5 receptors initiate a signal (action potential).

Question 27

steps of excitation-contraction coupling (2)

Answer 27

1 Action potential (AP) moves across sarcolemma and connected T tubules. 2 AP opens Ca channels in SR, and Ca diffuses into myofibrils.

Question 28

steps of contraction (3)

Answer 28

1 Ca binds to troponin. 2 Troponin changes shape, moving tropomyosin. 3 Enters cycle

Question 29

contraction cycle continues if (2)

Answer 29

calcium and ATP are present

Question 30

steps of muscle relaxation (8)

Answer 30

1 Neural impulse stops. 2 ACh is decomposed by acetylcholinesterase at motor end plate. 3 Sarcolemma returns to resting state (no AP). 4 Ca is actively pumped back into SR. 5 Decrease in Ca causes Ca to detach from troponin, so troponin moves to resting position. 6 ATP binds to myosin heads and breaks cross bridges. 7 Formation of cross bridges is prevented by tropomyosin blocking binding sites on actin. 8 Sarcomeres lengthen.

Question 31

steps of rigor mortis at death

Answer 31

1 Ca leaks from SR into myofibrils. 2 Tropomyosin shifts and actin-myosin cross bridges form. 3 Cross bridges cannot be broken because there is no ATP.

Question 32

motor unit

Answer 32

one neuron and all the muscle fibers it stimulates; 4+

Question 33

Individual fibers contract __ or __.

Answer 33

all, nothing

Question 34

The number of motor units firing causes variation in __.

Answer 34

force production

Question 35

skeletal muscle fiber types

Answer 35

slow oxidative, fast oxidative, fast glycolyptic

Question 36

slow oxidative skeletal muscle fiber

Answer 36

Small diameter, contracts slowly, resists fatigue, high oxygen demand, lots of myoglobin, mitochondria, and blood capillaries, darker red color.

Question 37

fast oxidative skeletal muscle fiber

Answer 37

Intermediate diameter, contract rapidly, somewhat slow to fatigue, somewhat high oxygen demand.

Question 38

fast oxidative skeletal muscle fiber can __ between types depending on __.

Answer 38

convert; training

Question 39

fast glycolytic skeletal muscle fiber

Answer 39

Large diameter, contracts very rapidly, fatigue quickly, low oxygen demand, few myoglobin, mitochondria, and blood capillaries, lighter white color.

Question 40

smooth muscle lacks

Answer 40

t tubules and myofibrils

Question 41

smooth muscle filaments __ in a net-like pattern, connecting at __.

Answer 41

crisscross; dense bodies

Question 42

smooth muscle contraction is very __ and has a __ duration, making it resistant to __.

Answer 42

slow; prolonged; fatigue

Question 43

__ store and release neurotransmitters like axon terminals.

Answer 43

Varicosities

Question 44

Primary mechanism of smooth muscle excitation

Answer 44

nerve fibers have varicosities that form diffuse junctions

Question 45

other mechanisms of smooth muscle excitation (3)

Answer 45

self-excitatory, hormones, gap junctions