Musculoskeletal Systems and Locomotion

Question 1

an external skeleton made primarily of chitin that surrounds and protects most of the body

Answer 1

exoskeleton

Question 2

an internal hard skeleton covered by soft tissue; present in echinoderms and vertebrates

Answer 2

endoskeleton

Question 3

the junction where two or more bones of an endoskeleton come together

Answer 3

joint

Question 4

a type of muscle tissue found only in hearts in which physical and electrical connections between individual cells enable many of the cells to contract simultaneously

Answer 4

cardiac muscle

Question 5

a type of muscle tissue that surrounds and forms part of the lining and hollow organs and tubes in animal bodies; not under conscious control

Answer 5

smooth muscle

Question 6

a type of muscle tissue that is attached by tendons to bones in vertebrates and to the exoskeleton in invertebrates

Answer 6

skeletal muscle

Question 7

individual cell within a muscle

Answer 7

muscle fibers

Question 8

a muscle that bends a limb at a joint

Answer 8

flexors

Question 9

a muscle that straightens a limb at a joint

Answer 9

extensors

Question 10

two or muscles that produce oppositely directed movements at a joint

Answer 10

antagonists

Question 11

one complete unit of the repeating patterns of thick and thin filaments within a myofibril

Answer 11

sacromere

Question 12

a section of the repeating pattern in a myofibril composed almost entirely of the motor protein myosin

Answer 12

thick filaments

Question 13

a motor protein found abundantly in muscle cells and also in other cell types

Answer 13

myosin

Question 14

a section of the repeating pattern in a myofibril that contains the cytoskeleton protein actin as well as two other proteins-troponin and tropomysoin-that play important roles in regulating contraction

Answer 14

thin filaments

Question 15

a cytoskeletal protein, found in the thin filaments of myofibrils

Answer 15

actin

Question 16

the part of the sacromere in muscle fibers that is formed by thick filaments

Answer 16

A band

Question 17

a network of proteins to which thin filaments are attached at the boundary of a sacromere

Answer 17

Z line

Question 18

the component of a sacromere that lies between the A bands of two adjacent sacromeres

Answer 18

I band

Question 19

the narrow region at the center of an A band of a sacromere

Answer 19

H zone

Question 20

the central part of the H zone in a sacromere, which links the central regions of adjacent thick filaments

Answer 20

M line

Question 21

a region of myosin molecules that extends from the surface of each thick filament toward a thin filament in skeletal muscle

Answer 21

cross-bridges

Question 22

the process by which a muscle fiber shortens during muscle contractions

Answer 22

sliding filament mechanisms

Question 23

during muscle contraction, the sequence of events that occurs between the time when a cross-bridge binds to a thin filament and when it is set to repeat the process

Answer 23

cross-bridge cycle

Question 24

a rod shaped protein that plays an important role in regulating muscle cell contraction

Answer 24

tropomyosin

Question 25

a small globular-shaped protein that plays an important role in regulating muscle contraction through its ability to bind Ca2+

Answer 25

troponin

Question 26

the sequence of events by which an action potential in the plasma membrane of a muscle fiber leads to a cross-bridge activity

Answer 26

excitation-contraction coupling

Question 27

a specialized form of endoplasmic reticulum in a muscle fiber that is the source of the increase in cytosolic calcium involved muscle contraction

Answer 27

sarcoplasmic reticulum

Question 28

invaginations of the plasma membrane of skeletal muscle fibers that open to the extracellular fluid and conduct action potentials from the outer surface of the fibers to the myofibrils

Answer 28

transverse tubules (T-tubules)

Question 29

the contact point between an axon terminal of a motor neuron and a skeletal or cardiac muscle fiber

Answer 29

neuromuscular junction

Question 30

the region of the plasma membrane of a skeletal muscle fiber that lies beneath an axon terminal at the neuromuscular junction

Answer 30

motor end plate

Question 31

an enzyme located on membranes of postsynaptic cells that respond to the neurotransmitter acetylcholine, such as in muscle fibers in a neuromuscular junction; breaks down excess acetylcholine released into the synaptic cleft

Answer 31

acetylcholinesterase

Question 32

a skeletal muscle fiber containing myosin with low ATPase activity

Answer 32

slow fibers

Question 33

a skeletal muscle fiber containing myosin with higher ATPase activity

Answer 33

fast fibers

Question 34

a skeletal muscle fiber that contains numerous mitochondria and has a high capacity for oxidative phosphorylation

Answer 34

oxidative fibers

Question 35

a skeletal muscle fiber that has relatively few mitochondria but possesses a high concentration of glycolytic enzymes and a large store of glycogen

Answer 35

glycolytic fibers

Question 36

a reduction in size of structure, such as a muscle

Answer 36

atrophy

Question 37

a condition in children characterized by bone deformations due to inadequate mineral intake or malabsorption in the small intestine

Answer 37

rickets

Question 38

a disease in which the minerals or the organic components of bone are reduced

Answer 38

osteoporosis

Question 39

a group of diseases associated with progressive degeneration of skeletal and cardiac muscle fibers

Answer 39

muscular dystrophy

Question 40

an inherited X-linked recessive disorder of humans causing muscle weakness and muscle degeneration

Answer 40

Duchenne muscular dystrophy