EXAM 2 Module 4

Question 1

striated muscles (striped pattern perpendicular to their long axis)

Answer 1

skeletal and cardiac

Question 2

skeletal muscle structures

Answer 2

connective tissue
blood vessels
striated muscle fiber (single muscle cell)
sarcomere between two Z lines

Question 3

thick filament

Answer 3

myosin

Question 4

thin filament

Answer 4

actin

Question 5

muscle contraction:
thick filament cross bridges are composed of ______ proteins

Answer 5

myosin

Question 6

muscle contraction:
myosin proteins contact thin filaments and use the energy of ______ to pull on the thin filaments

Answer 6

ATP

Question 7

muscle contraction:
in the absence of ATP, myosin attaches to _____

Answer 7

actin

Question 8

explains what happens at sarcomere level

Answer 8

sliding-filament mechanism

Question 9

in the sliding filament mechanism at the sarcomere level, the ______ move closer together

Answer 9

Z lines

Question 10

sliding filament mechanism:
- the lengths of the thick filaments (A band) and thin filaments ______ change
- rather, the thin filaments are ________ around the thick filaments
- this does reduce the length of the _____ and ____

Answer 10

do not;
pulled in closer;
H zone; I band

Question 11

cross-bridge cycling in skeletal and cardiac muscle:
- when Ca2+ inside the cell is low, _______ keeps the tropomyosin in a position that blocks cross-bridge binding to the ______
- muscle is ______

Answer 11

troponin; actin;
relaxed

Question 12

cross-bridge cycling in skeletal and cardiac muscle:
- when Ca2+ inside the cell is high, it binds to troponin, which allows ________ to move away from the cross-bridge binding sites
- cross-bridges ______ and muscle is _______

Answer 12

tropomyosin;
form; contracted

Question 13

3 sources of ATP production in muscle (in general order in which they are used during muscle contraction)

Answer 13

1. creatine phosphate
2. oxidative phosphorylation
3. glycolysis

Question 14

synapse where motor neuron AP communicates with muscle fiber to trigger muscle contraction

Answer 14

neuromuscular junction

Question 15

EC coupling in skeletal muscle pathway

Answer 15

AP motor neuron
T tubules
DHP receptors
muscle contraction

Question 16

after ______ flows into the cytoplasm, it binds troponin to allow cross-bridge formation and subsequent muscle contraction

Answer 16

Ca2+

Question 17

EC coupling in cardiac muscle pathway

Answer 17

difference to skeletal muscle is no DHP receptors, instead there are voltage-gated L-type Ca2+ channels

Question 18

muscle type with no striations

Answer 18

smooth muscle

Question 19

smooth muscle structures

Answer 19

thick myosin filaments
thin actin filaments (anchored to plasma membrane or dense bodies)
tropomyosin
NO troponin

Question 20

in smooth muscle, the thick and thin filaments slide past each other, and when the contraction happens, the entire cell ______ and ______

Answer 20

shortens; thickens

Question 21

smooth muscle specialized structures

Answer 21

relaxed spindle-shaped
contracted blob

Question 22

smooth muscles that respond to stimuli as a single unit, cells are connected by gap junctions

Answer 22

single-unit smooth muscles

Question 23

smooth muscles that respond to stimuli independently, fewer gap junctions

Answer 23

multi-unit smooth muscles

Question 24

two things that are lacking in smooth muscle contraction

Answer 24

troponin
sarcomere

Question 25

smooth muscle contraction pathway: 1. increased cytosolic Ca2+ binds and activates _____ 2. active calmodulin activates _______ 3. myosin light-chain kinase ________ smooth muscle myosin 4. _______ can form 5. cross-bridge cycling can occur as long as _______ is phosphorylated

Answer 25

calmodulin; myosin light-chain kinase; phosphorylates; cross-bridges; myosin

Question 26

thick and thin filaments

Answer 26

skeletal, smooth, cardiac

Question 27

sarcomeres - banding pattern

Answer 27

skeletal, cardiac

Question 28

transverse (T) tubules

Answer 28

skeletal, cardiac

Question 29

sarcoplasmic reticulum

Answer 29

high skeletal, low smooth, medium cardiac

Question 30

gap junctions between cells

Answer 30

smooth (more in single-unit, few in multi-unit), cardiac

Question 31

source of activating Ca2+

Answer 31

skeletal: SR smooth: SR and extracellular cardiac: SR and extracellular

Question 32

site of Ca2+ regulation

Answer 32

skeletal: troponin smooth: myosin cardiac: troponin

Question 33

speed of contraction

Answer 33

skeletal: fast-slow smooth: very slow cardiac: slow

Question 34

spontaneous production of action potentials by pacemakers

Answer 34

single-unit smooth, few specialized cardiac

Question 35

tone (low levels of maintained tension in the absence of external stimuli)

Answer 35

single-unit smooth

Question 36

effect of nerve stimulation

Answer 36

skeletal: excitation smooth: excitation or inhibition cardiac: excitation or inhibition

Question 37

physiological effects of hormones on excitability and contraction

Answer 37

smooth, cardiac

Question 38

stretch of cell produces contraction

Answer 38

single-unit smooth

Question 39

once-common viral disease that can destroy motor neurons, leading to paralysis of skeletal muscle

Answer 39

poliomyelitis

Question 40

involuntary tetanic contraction of skeletal muscles

Answer 40

muscle cramps

Question 41

involuntary tetanic contraction of skeletal muscles that occurs when the extracellular Ca2+ concentration decreases to about 40% of its normal value

Answer 41

hypocalcemia tetany

Question 42

common genetic disease, associated with progressive degeneration of skeletal and cardiac muscle fibers, more common in men

Answer 42

muscular dystrophy

Question 43

what causes muscular dystrophy

Answer 43

the absence or defect of one or more proteins that make up the costameres in striated muscle

Question 44

sex-linked recessive disorder caused by a mutation in a gene on the X chromosome that codes for the protein dystrophin

Answer 44

Duchenne muscular dystrophy

Question 45

neuromuscular disorder characterized by muscle fatigue and weakness that progressively worsen as the muscle is used

Answer 45

myasthenia gravis