Muscle -Nbde I

Front 1

Z line to Z line represents?

Back 1

Length of a sarcomere

Front 2

Thick filaments are present in which band of the sarcomere?

Back 2

Thick filaments --> A band (center of sarcomere)

Front 3

Myosin is contained in which filaments of skeletal muscle?

Back 3

Thick filaments --> myosin

Front 4

What does structure of myosin look like?

Back 4

-One par of heavy chains & 2 pairs of light chains
-2 Heads attached to single tail

Front 5

Myosin head binds ? to form cross-bridge?

Back 5

ATP & Actin

Front 6

Thin filaments are present in which bands of the sarcomere?

Back 6

I bands

Front 7

Thin filaments are anchored at?

Back 7

Z lines

Front 8

Which proteins do thin filaments contain?

Back 8

Actin, Tropomyosin & Troponin

Front 9

What is the regulatory protein in skeletal muscle that permits cross-bridge formation by binding Ca?

Back 9

Troponin

Front 10

Troponin is a complex of?

Back 10

Troponin T
Troponin I
Troponin C

Front 11

Tropomyosin attaches to what part of troponin?

Back 11

Troponin T

Front 12

What part of troponin inhibits interaction of actin & myosin?

Back 12

Troponin I

Front 13

Which part of troponin is Ca binding site that allows for interaction of actin & myosin?

Back 13

Troponin C

Front 14

What are T tubules?

Back 14

INvaginations of sarcolemma perpendicular to length of fiber

Front 15

Where are T tubules located in sarcomere of skeletal muscle?

Back 15

Juctions of A & I bands

Front 16

What is the internal tubular structure that is site of Ca storage & release in skeletal muscle?

Back 16

Sarcoplasm reticulum

Front 17

What structure maintains intimate contact with both SR & T tubules?

Back 17

Terminal cisternae

Front 18

Action potential in muscle cell membrane initiat depolarization of?

Back 18

T-tubules

Front 19

Depolarization of T-tubules causes conformational change in which receptor to open Ca release channels in SR?

Back 19

Dihydropyridine

Front 20

When intracellular Ca increases in skeletal muscle cell what does calcium bind?

Back 20

Ca binds troponin C of thin filaments
--> moves tropomyosin out of the way to allow for cross bridge to occur

Front 21

What causes muscle contraction to occur?

Back 21

Ca binds Troponin C --> Allows actin & myosin to bind & contract

Front 22

Rigor occurs when?

Back 22

There is no ATP present --> Myosin stays attached to actin

Front 23

What causes myosin to be released from actin?

Back 23

Binding ATP to myosin

Front 24

What is the power (force-generating) stroke?

Back 24

When ATP bound to myosin is hydrolyzed & myosin attaches to new site on actin

Front 25

What happens when ADP is released from myosin?

Back 25

Myosin returns to rigor state

Front 26

As long as Ca is bound to Troponin C what happens during each cross-bridge cycle?

Back 26

Myosin walks further down actin filament

Front 27

What causes relaxation of skeletal muscle?

Back 27

Ca reaccumulated by sarcoplasmic reticulum Ca-ATPase (SERCA)
-Ca released from troponin C & tropomyosin blocks myosin binding site on actin

Front 28

What is the mechanism of tetanus in skeletal muscle?

Back 28

Single AP --> released of Ca from SR & produces single twitch
-Muscle stimulated repeatedly --> More Ca released from SR --> more cross-bridge cycling --> MUSCLE DOES NOT RELAX

Front 29

What are isometric contractions of skeletal muscle?

Back 29

When muscle length is CONSTANT --> NO shortening

Front 30

What are isotonic contractions?

Back 30

LOAD IS CONSTANT
-Load against which muscle contracts (afterload) is fixed
-Shortening occurs

Front 31

Where are multi-unit smooth muscles present?

Back 31

Iris, cilliary muscle of lens & vas deferens

Front 32

What is the most common type of smooth muscle?

Back 32

Unitary (single-unit) smooth muscle

Front 33

Where is unitary (single-unit) smooth muscle precent?

Back 33

Uterus, GI tract, ureter and bladder

Front 34

Which type of smooth muscle has high degree of electrical couping between cells & permits coordinated contraction?

Back 34

UNITARY SMOOTH MUSCLE-- "pacemaker" activity- slow waves (hormones & NT control)
-Multi-unit smooth muscle has no electrical coupling therefore it is highly innervated by autonomics

Front 35

When intracellular Ca levels increase in smooth muscle what occurs?

Back 35

Ca binds Calmodulin (NO TROPONIN)

Front 36

What happens when Ca is bound to Calmodulin in smooth muscle?

Back 36

Ca-Calmodulin binds & activates myosin light-chain kinase

Front 37

What does myosin light-chain kinase do?

Back 37

Myosin light-chain kinase phosphorylates myosin & allows it to bind actin (intiating cross-bridge cycling)

Front 38

The amount of tension in smooth muscle is proportional to?

Back 38

Intracellular Ca

Front 39

troponin C found in which muscle types?

Back 39

Skeletal & cardiac muscle have troponin C (smooth muscle has Calmodulin)

Front 40

Which muscles are striated?

Back 40

Skeletal & cardiac muscles

Front 41

Which muscle type is voluntary?

Back 41

Skeletal

Front 42

One muscle cell is equivalent to?

Back 42

1 muscle cell = 1 muscle fiber

Front 43

What are the 3 connective tissue sheaths found in skeletal muscle?

Back 43

1. Epimysium
2. Perimysium
3. Endomysium

Front 44

What CT sheath surrounds the entire muscle?

Back 44

Epimysium --> entire muscle = Investing fascia

Front 45

Which CT sheath surrounds muscle fascicles?

Back 45

Perimysium

Front 46

Which CT sheath surrounds individual muscle fibers?

Back 46

Endomysium

Front 47

How is a muscle fiber organized?

Back 47

Muscle formed of FASICLES - bundles of FIBERS formed of many MYOFIBRILS which are composed of SARCOMERES made of MYOFILAMENTS (actin & myosin)

Front 48

Why is skeletal muscle considered a multinucleated syncytium?

Back 48

Syncytium formed by fusion of smaller individual muscle cells called myoblasts

Front 49

THe cell membrane in skeletal muscle is known as?

Back 49

Sarcolemma

Front 50

Which type of muscle fibers contain abundant myoglobin & mitochondria & are capable of prolonged contraction but generate less tension?

Back 50

Red- "Slow twitch" muscle fibers

Front 51

WHich type of muscle fibers are larger in size, contain less myoglobin & mitochondria, generate large muscle tension but fatigue rapidly?

Back 51

White- "fast twitch" muscle fibers

Front 52

What provides feedback about changes in muscle length & rate of change in muscle length?

Back 52

Muscle spindles- sensory receptors located among & in parallel w/ muscle fibers

Front 53

What are the 2 types of intrafusal fibers?

Back 53

1. Nuclear bag fibers
2. Nuclear chain fibers

Front 54

Stretching spindle fibers causes?

Back 54

Reflex contraction of muscle to prevent damage

Front 55

Function of golgi tendon organs?

Back 55

Receptors within tendon which detect stretch of tendon causing reflex RELAXATION of muscle

Front 56

what are satellite cells?

Back 56

Stem cells that can differentiate into myoblasts due to injury or other muscle loss
-REGENERATION IS LIMITED

Front 57

Muscle hypertrophy causes what kinds of changes to muscle?

Back 57

-Increase number myofibrils & sarcomeres
-INcrease number of nuclei- sattelite cells proliferate & fuse w/ fibers
-Number of muscle fibers = same

Front 58

Where are the nuclei located in skeletal and cardiac muscle?

Back 58

Skeletal mucsle- peripheral nuclei
Cardiac muscle- central nuclei

Front 59

Which type of muscle fibers can branch?

Back 59

Cardiac muscle fibers can branch - skeletal unbranched

Front 60

A triad consists of?

Back 60

SKELETAL MUSCLE
T-tubule & PAIR of terminal cisternae

Front 61

A diad consists of?

Back 61

CARDIAC MUSCLE
T-tubule & SINGLE terminal cisterna

Front 62

Where is a diad present in a sarcomere of cardiac muscle?

Back 62

Z-line

Front 63

What joins adjacent muscle fibers in cardiac muscle?

Back 63

Intercalated discs

Front 64

Which type of muscle cell contains a single spindle-shaped (fusiform) nucleus?

Back 64

Smooth muscle

Front 65

Smooth muscle fibers are linked by?

Back 65

Gap junctions