Skeletal Muscle Contraction & Relaxation

Front 1

What is released when Sarcoplasmic Reticulum (SR) is depolarized?

Back 1

activated Ca2+ VGC, Ca2+ is released into cytosol

Front 2

Troponin C (of sarcomere) binds to Ca2+ =

Back 2

contraction

Front 3

WHere is the location of Ca2+ VGC opening?

Back 3

Terminal cisterns of SR

Front 4

Troponin C changes stereochemistry and cause

Back 4

grip to loosen on Tropomyosin by Troponin T

Front 5

What causes binding sites to be exposed on actin?

Back 5

When Tropomyosin assumes more relaxed lateral position

Front 6

What recognize binding sites?

Back 6

Myosin heads

Front 7

What is used to detach from old bond and make new bond at hot spot?

Back 7

ATP

Front 8

Once ATP on myosin is cleaved, what happens?

Back 8

ATP energy is used to bend myosin head from filament using powerstroke or ratchet movement

Front 9

How many actin filaments are pulled close together?

Back 9

12

= 6 actin filaments on each side, sliding on 1 myosin filament`

Front 10

What represents a muscle contraction?

Back 10

When H zone narrows (overlap increases), and Z lines come closer together)

-

Front 11

Muscle is in a state of contraction when

Back 11

500 myosin heads per myosin filament work with 12 actin filaments times thousands of sarcomeres working together

Front 12

What causes skeletal muscle relaxation?

Back 12

Ca2+ pumped out of muscle by Ca2+/Mg2+ ATPase pump

Front 13

Troponin C tightens grip on

Back 13

Tropomyosin by Troponin T

Front 14

What cause myosin to slide back to resting levels?

Back 14

the repositioning of Tropomyosin over binding sites on actin, prevent any further attachment by myosin heads

Front 15

Powerstroke needs ____ to make new and break old attachments between myosin and actin?

Back 15

ATP and maintain Ca2+/Mg2+ pump action

Front 16

What is defective in muscular dystrophies disorders?

Back 16

protein Dystrophin

Example in Becker's Dystrophy

Front 17

Dystrophin protein is absent in what disease?

Back 17

Duchenne's Dystrophy

Front 18

What is the cause of dystrophy disorders?

Back 18

autoimmune reactions

Front 19

How are muscle cells/fibers classified?

Back 19

4 attributes

1. size

2. color

3. twitch speed

4. type of metabolism

Front 20

What is twitch?

Back 20

the smallest contraction movement that is detected in a given muscle

Front 21

What are the characteristics of Type 1 muscle

Back 21

color = red

size = small

twitch speed = slow

metabolism = oxidative

Front 22

What are the characteristics of Type IIa muscle?

Back 22

color = red

size = medium

twitch speed = fast

metabolism = oxidative

Front 23

What are the characteristics of Type IIb muscle?

Back 23

color = white (pale)

size = large

twitch speed = fast

metabolism = glycolytic

Front 24

Which muscle is predominant in humans?

Back 24

Type I

Front 25

Which muscles are endurance types?

Back 25

Type I and IIa

Front 26

Which muscles are capable of generating large amounts of force in a very short period of time?

Back 26

Type IIb

Front 27

ATP is produced y what processes?

Back 27

glycolysis or

oxidative phosphorylation

Front 28

What percent efficiency is ATP used in the body?

Back 28

40%

Front 29

Skeletal muscles are controlled in groups called

Back 29

motor units

Front 30

what is a motor unit?

Back 30

ratio of number of muscle cells stimulated by a single neuron

Front 31

The larger number of muscle cells under control of a single neuron, the LESS control one has over recruiting varying strength of muscle

Back 31

coarse control

Front 32

What is Fine control?

Back 32

small number of cells being moved by a single neuron = MORE control

Front 33

What are the three types of motor units?

Back 33

1, 2, 3,

Front 34

Type 1

Back 34

motor unit = 2-20-:1

Fine control

ex: eye muscle

Front 35

Type 2

Back 35

motor unit = 160-220-:1

medium control

ex: hands, feet, face muscles

Front 36

Type 3

Back 36

motor unit = 500-2000:1

coarse control

ex: torso/extremities

Front 37

What is relaxation?

Back 37

When Ca2+ no longer flowing from SR, pumped out of system with Ca2+/Mg2+ pump (1:1)

Front 38

Which muscles are striated?

Back 38

skeletal and cardiac

Front 39

Skeletal fiber is known as anatomical syncytium

Back 39

made up of numerous embryonic cells so in mature state they have many small nuclei, but essentially just one.

Front 40

Cardiac muscle has a single

Back 40

nucleus surrounded by a cloud of glycogen

Front 41

What is the purpose of gap junctions in cardiac cell?

Back 41

allow for continuity of sorts between cytoplasm of one cell to next

(Na+ and Ca2+ ions enter cytosol can now drift to adjacent cells as though they were part of same cell)

Front 42

ATP is produced by what processes?

Back 42

Glycolysis

Oxidative Phosphorylation

Front 43

What percent efficiently is ATP used?

Back 43

40%

Front 44

What percent efficiently is ATP used?

Back 44

40%

Front 45

How is creatinemonophosphate (phosphocreatine) made?

Back 45

ATP stored in muscle by transfer of high energy bond with a phosphate to protein creatine

Front 46

What enzyme is used for reaction in making phosphocreatine?

Back 46

CreatinePhosphoKinase (CPK)

Front 47

What happens when phosphorylcreatine decays into creatine as waste?

Back 47

Creatine is removed from muscle and into blood then into urine by Kidneys

Front 48

What happens when phosphorylcreatine decays into creatine as waste?

Back 48

Creatine is removed from muscle and into blood then into urine by Kidneys

Front 49

What is the normal blood level range of creatinine in the body?

Back 49

0.6-1.5 mg/dl

Suggest normal kidney or muscle

Hint 49

Higher levels in kidney/muscle damage, pregnancy, growing children, post IM injections and large adults

Front 50

Motor Units?

Back 50

The groups that skeletal muscles are controlled in

Front 51

Which muscle types have striations?

Back 51

Cardiac and Skeletal

Front 52

Which muscle types have striations?

Back 52

Cardiac and Skeletal

Front 53

Does cardiac muscle go into Tetany?

Back 53

No

Front 54

Which muscle types have striations?

Back 54

Cardiac and Skeletal

Front 55

Does cardiac muscle go into Tetany?

Back 55

No

Front 56

What is the benefit of gap junctions in smooth and cardiac muscles?

Back 56

Able to stimulate action potentials: migrate easily and set off another action potential - depolarization wave

Hint 56

Sodium and calcium ions can drift to adjacent cells

- laws of diffusion

Promote depolarization

Cardiac muscle - intercalated discs

Smooth muscles - branchings

Front 57

What is the difference between propagating action potential down cardiac muscles and skeletal muscles?

Back 57

Cardiac muscles membrane is wider, different in morphology, action potential takes a long time - relative refractory could be reached and by that time muscle cells already in relaxation phrase

Front 58

Why do Cardiac muscles show evidence of spontaneous depolarization?

Back 58

Because cardiac muscle have slow sodium gated channels that open upon hyper polarization - why heart (pacemaker) cells

AKA funny channels

Front 59

Why are skeletal muscles not automatic?

Back 59

Because their action potential more or less mimic neuronal AP except for excitation contraction coupling that follows in muscle

Front 60

Why is the action potential wide in cardiac muscle ?

Back 60

Because Ca2+ stays longer in cytosol than in skeletal muscle

Hint 60

This increase refractory period which prevents a significant summation of contractions

Cardiac muscle stimulation do not tetanize like skeletal muscle (but known to shred)

Front 61

Troponin T interact with

Back 61

Tropomyosin

Front 62

Troponin T interact with

Back 62

Tropomyosin

Front 63

Troponin C interact with

Back 63

Ca2+

Front 64

Troponin T interact with

Back 64

Tropomyosin

Front 65

Troponin C interact with

Back 65

Ca2+

Front 66

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 66

Catalized ATP

Front 67

Troponin T interact with

Back 67

Tropomyosin

Front 68

Troponin C interact with

Back 68

Ca2+

Front 69

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 69

Catalized ATP

Front 70

What is A band?

Back 70

Middle area in sarcomere where thick and thin filaments are found

Front 71

Troponin T interact with

Back 71

Tropomyosin

Front 72

Troponin C interact with

Back 72

Ca2+

Front 73

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 73

Catalized ATP

Front 74

What is A band?

Back 74

Middle area in sarcomere where thick and thin filaments are found

Front 75

What is I band?

Back 75

Contains thin filaments because it's lighter in color

Front 76

Troponin T interact with

Back 76

Tropomyosin

Front 77

Troponin C interact with

Back 77

Ca2+

Front 78

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 78

Catalized ATP

Front 79

What is A band?

Back 79

Middle area in sarcomere where thick and thin filaments are found

Front 80

What is I band?

Back 80

Contains thin filaments because it's lighter in color

Front 81

What are Z discs?

Back 81

Separate one sarcomere from the next

Front 82

Troponin T interact with

Back 82

Tropomyosin

Front 83

Troponin C interact with

Back 83

Ca2+

Front 84

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 84

Catalized ATP

Front 85

What is A band?

Back 85

Middle area in sarcomere where thick and thin filaments are found

Front 86

What is I band?

Back 86

Contains thin filaments because it's lighter in color

Front 87

What are Z discs?

Back 87

Separate one sarcomere from the next

Front 88

What is H zone?

Back 88

Area of only thick filaments

Front 89

Troponin T interact with

Back 89

Tropomyosin

Front 90

Troponin C interact with

Back 90

Ca2+

Front 91

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 91

Catalized ATP

Front 92

What is A band?

Back 92

Middle area in sarcomere where thick and thin filaments are found

Front 93

What is I band?

Back 93

Contains thin filaments because it's lighter in color

Front 94

What are Z discs?

Back 94

Separate one sarcomere from the next

Front 95

What is H zone?

Back 95

Area of only thick filaments

Front 96

What is M line?

Back 96

Supporting proteins that hold thick filaments together in H zone

Front 97

Troponin T interact with

Back 97

Tropomyosin

Front 98

Troponin C interact with

Back 98

Ca2+

Front 99

What cause mechanical movement of myosin head? (Ratchet style or power stroke )

Back 99

Catalized ATP

Front 100

What is A band?

Back 100

Middle area in sarcomere where thick and thin filaments are found

Front 101

What is I band?

Back 101

Contains thin filaments because it's lighter in color

Front 102

What are Z discs?

Back 102

Separate one sarcomere from the next

Front 103

What is H zone?

Back 103

Area of only thick filaments

Front 104

What is M line?

Back 104

Supporting proteins that hold thick filaments together in H zone

Front 105

What is the function of sarcoplasmic reticulum?

Back 105

Stores and release Ca2+ into sarcoplasmic after nervous stimulation

Front 106

Gross contracture of sarcomeres are a cause of

Back 106

Lack of ATP