MUSCLE PHYSIOLOGY

Question 1

• Myosin only
• Light in color
• Thick filament

Answer 1

H zone

Question 2

• Actin only
• Dark in color
• Thin filaments only on myofibril

Answer 2

I band

Question 3

• Holds the thick filaments together
• Myosin linked with accessory proteins

Answer 3

M line

Question 4

Anchors thin filaments and ties all myofibrils together (regular banding)

Answer 4

Z line (disc)

Question 5

• Actin and myosin overlap
• Has both thick and thin filaments (dark bands) on myofibril

Answer 5

A band

Question 6

• The invagination of sacrolemma that forms a permeability barrier between cytosol and extracellular space
• Extension of sarcolemma within the sarcoplasm

Answer 6

T tubules

Question 7

Smallest functional contractile unit of muscle

Answer 7

Sarcomeres

Question 8

• Striated muscle organelles comprised of sarcomeres that are aligned in series
• Creates contraction

Answer 8

Myofibrils

Question 9

A protein that converts chemical energy in the form of ATP to mechanical energy, thus generating force and movement.

Answer 9

Myosin molecule

Question 10

What makes a filament thick?

Answer 10

Myosin

Question 11

Thin myofilaments

Answer 11

Actin, Troponin, and Tropomyosin

Question 12

Troponin that binds calcium

Answer 12

Troponin - C

Question 13

Inhibits the ATPase activity of the actomyosin cross-bridge and effectively blocks the myosin-binding site on actin subunits

Answer 13

Troponin I

Question 14

Rod shape molecule, two strands of tropomyosin molecules run diametrically opposed along actin filaments

Answer 14

Tropomyosin

Question 15

Interacts with tropomyosin and anchors troponin to actin

Answer 15

Troponin - T

Question 16

Stabilize the sarcolemma and, hence, prevent contraction-induced injury (rupture)

Answer 16

DGC - Dystrophin Glycoprotein Complex

Question 17

Connects actin to the glycoproteins of the extracellular domain of the sarcolemma

Answer 17

Dystrophin

Question 18

Stabilizes myosin

Answer 18

Titin

Question 19

• Helps in the alignment of actin
• Encloses actin

Answer 19

Nebulin

Question 20

Anchors Z disk to sarcolemma

Answer 20

Desmin

Question 21

• Myofilament with binding sites for myosin head (contains G-Actin)
• Anchored by Z-Discs
• Regulatory proteins of troponin & tropomyosin
• Troponin holds thin filament in place, and tropomyosin blocks active binding sites on actin

Answer 21

Actin (thin filaments)

Question 22

Activation of the force-generating sites within muscle fibers—the cross-bridges

Answer 22

Muscle contraction

Question 23

Motor neuron and
the skeletal muscle fibers it innervates

Answer 23

Motor unit

Question 24

Comprise various tightly controlled, complex circuits throughout the body that allow for both voluntary and involuntary movements through the innervation of effector muscles and glands

Answer 24

Motor neurons

Question 25

- Where nerves and muscle fibers meet—is an essential synapse for muscle contraction and movement - Point of contact between a motor neuron and a skeletal muscle cell

Answer 25

Neuromuscular Junction

Question 26

Conversion of electrical signal to chemical signal cycle

Answer 26

Somatic Nervous System

Question 27

Temporary depolarization of postsynaptic membrane caused by the flow of positively charged ions into the postsynaptic cell as a result of opening of ligand-sensitive channels

Answer 27

Excitatory Postsynaptic Potentials (EPSP)

Question 28

- Where nicotinic receptors are found - The end of a motor neuron that stores acetylcholine

Answer 28

Motor End-Plate

Question 29

RMP: -90 mV Duration: 2.5 ms

Answer 29

Muscle action potential

Question 30

RMP: -70 mV Duration: 1-2 ms

Answer 30

Nerve action potential

Question 31

- Occurs when myosin head does not dissociate from actin - Stiffness of the body that sets in several hours after death

Answer 31

Rigor mortis

Question 32

Where does the cycle stop when ATP is exhausted?

Answer 32

State C

Question 33

The consequence of severely lowered calcium levels

Answer 33

Hypocalcemic tetany

Question 34

Space between a nerve (axon) terminal and motor end-plate (gap between cells) – ACh diffuses across

Answer 34

Synaptic Cleft

Question 35

Neurotransmitter that binds at a motor end plate to trigger depolarization

Answer 35

Acetylcholine (ACh)

Question 36

A source of ATP that uses stored ATP in seconds and can generate it for about 15 seconds

Answer 36

Creatinine Phosphate

Question 37

- A source of ATP that is used for lower demand of ATP delivery with O2 used - 2 ATP from glycolysis + pyruvate sent to mitochondria makes = 36 ATP - Hours of sustained activity

Answer 37

Cellular respiration

Question 38

A sustained muscular contraction resulting from a rapid series of nerve impulses when cholinesterase doesn't break down ACh caused by bacteria found in dirt and manure

Answer 38

Tetanus

Question 39

- Temporary lack of O2 in the muscle due to exertion - Lack of O2 caused by Lactic Acid to build up in muscle tissue leads to muscle soreness

Answer 39

Oxygen debt

Question 40

Sustained involuntary contraction of a muscle

Answer 40

Muscle cramp

Question 41

Inability of muscle to maintain its strength of contraction or tension; may be related to insufficient O2, depletion of glycogen, and/or lactic acid buildup

Answer 41

Muscle fatigue

Question 42

A neuron's reaction of either firing (with a full-strength response) or not firing.

Answer 42

All-or-none response

Question 43

The minimal strength required to cause a contraction

Answer 43

Threshold stimulus

Question 44

Tiny pouches or sacs in the axons that contain chemicals called neurotransmitters.

Answer 44

Synaptic vesicles

Question 45

Organelle of the muscle fiber that stores calcium

Answer 45

Sarcoplasmic reticulum

Question 46

Cytoplasm of a muscle cell

Answer 46

Sarcoplasm

Question 47

Enzyme that degrades Ach immediately after depolarization (neuron stops sending a signal for contraction) for precise contraction control

Answer 47

Cholinesterase (ACh-ase)

Question 48

Mainly areolar connective tissue around each fiber

Answer 48

Endomysium

Question 49

- Dense irregular connective tissue surrounding fascicles - Grain of muscle and allows precise movement

Answer 49

Perimysium

Question 50

A band or sheet of fibrous connective tissue that covers, supports, and separates muscle

Answer 50

Fascia

Question 51

Bundle of muscle fibers

Answer 51

Fasicle

Question 52

Outermost layer of dense irregular connective tissue that separates muscle from organs and allows independent movement

Answer 52

Epimysium

Question 53

- Specialized muscle tissue found only in the heart - Striated and involuntary - Intercalated discs

Answer 53

Cardiac muscle tissue

Question 54

- Involuntary muscle tissue - Not striated - Found in intestines

Answer 54

Smooth muscle tissue

Question 55

Striated and voluntary

Answer 55

Skeletal muscle tissue

Question 56

- Theory that actin filaments are pulled closer by myosin, causing Z-Discs to also move closer - I-Bands shrink and A-Bands stay the same - At full contraction action and myosin overlap completely

Answer 56

Sliding Filament Theory

Question 57

Myosin filament with heads that bind to actin by reaching up and ratcheting forward (about 300/filament)

Answer 57

Myosin (thick filaments)

Question 58

Loss of muscle mass due to lack of use or aging

Answer 58

Atrophy

Question 59

Increase in size of skeletal muscle through a growth in size of its component cells (increase in myofibrils & connective tissue)

Answer 59

Hypertrophy

Question 60

Anchoring point that does not move with contraction

Answer 60

Origin

Question 61

Muscle attachment site that moves toward the origin

Answer 61

Insertion