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Human Physiology PB > Test 2 Chapter 8-Muscular System > Flashcards

Test 2 Chapter 8-Muscular System Flashcards

1
Q

What is Muscle Tissue?

A

The most prominent type by weight, in the body

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2
Q

What are the 3 types of muscle

A

Skeletal muscle
Cardiac muscle
Smooth muscle

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3
Q

Skeletal Muscle characteristics

A

-Strained (light dark appearance)
-voluntary control (stimulated by somatic division of efferent)
by alpha motor neurons

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4
Q

What is a motor unit?

A

Alpha motor neurons and muscle fibers

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5
Q

Cardiac Muscle characteristics?

A

Found in heart
Properties of skeletal and smooth muscle
Striated
Involuntary regulated by ANS

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6
Q

Smooth Muscle characteristics?

  • Where is it found?
  • Location based on function?
  • Why the name?
  • Controlled by?
A

Found everywhere specifically hollow & tubular organs
Found where ever we need to move something involuntarily (besides the heart)
Named due to LACK of STRIATIONS
Involuntary control by the ANS

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7
Q

Skeletal Muscle is attached to bone via what connective tissue?

A

Tendons; and helps us to create human movement

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8
Q

What are connective tissues made of?

A
  1. Elastin
  2. Fibronectin
  3. Collagen
  4. Extracellular matrix
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9
Q

Connective tissue of the tendon continues through muscle structure what are they?

A
  1. Epimysium
  2. Perimysium
  3. Endomysium
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10
Q

Individual Muscle cell?

A

Muscle fiber

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11
Q

Connective tissue wrapping individual muscle fibers?

A

Endomysium

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12
Q

What is a bundle of muscle fibers?

A

Fasicle

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13
Q

What connective tissue wraps a fasicle?

A

PERIMYSIUM wraps a fasicle which is a bundle of muscle fibers

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14
Q

What layer surrounds the muscle?

A

Epimysium-outer most layer

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15
Q

How are muscle cells able to contract and produce force that is transmitted to bones which work through joints to create movement?

A

Muscle fibers produce force—>transmit to tendon via connective tissue layers

  1. Endomysium-Deepest
  2. Perimysium-wraps around
  3. Epimysium-wraps around the outside
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16
Q

What are the Elastic Components That are in series with muscle components?

A

Muscle produces force that is transmitted into bone via TENDONS
Series elastic component

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17
Q

What are Series Elastic Compounds

A

Series=progressively located throughout
-TENDONS
-Z-LINES
Spring like structure/effect on ends of the muscle

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18
Q

What are Parallel Elastic Components with the bone/muscle fiber?

A

Endomysium
Perimysium
Epimysium
(Wraps around end to end)

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19
Q

What is a muscle fiber?

A

Single skeletal muscle cell

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20
Q

Muscles are made up of?

A

Muscle (organ)
Fasicles (bundles of cells)
Muscle fiber (cell)
MYOFIBRIL (specialized intracellular structure
Thick & Think filaments (cytoskeleton elements)
Myofilaments (protein molecules)

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21
Q

Sarcolemma of Skeletal Muscle Cell

A

Cell Membrane

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22
Q

Sarco/Myo

A

Muscle

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23
Q

Sarcolemma is made up of

A

T-Tubules (Transverse Tubules)

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24
Q

Opening/Passageway in cell membrane (Sarcolemma) that allows passage of extracellular fluid. Goes through the fiber & goes out the other side?

A

T-TUBULES

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25
Q

Organelles?

A

Sarcoplasmic Reticulum
Nuclei
Mitochondria

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26
Q

Function of sarcoplasmic reticulum?

A

Modified function-full of calcium pumps that pump calcium into SR.

STORES CALCIUM (sequesters)

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27
Q

Sarcolemma has what in it?

A

T-Tubules

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28
Q

What stores/sequesters calcium?

A

Sarcoplasmic Reticulum

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29
Q

Central regions of sarcoplasmic reticulum associated with T-tubules

A

Lateral Sacs or terminal Cysterinae

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30
Q

What is the organization of the triad?

A

Lateral Sac
T-tubule
Lateral sac

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31
Q

Describe skeletal muscle fibes nuclei

A
  • Multinucleated
  • tiny and long
  • lots of nuclei and can add more nuclei to the cell
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32
Q

Mitchondria

A

ATP supplier

LOTS OF THEM

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33
Q

80% of muscle volume comes from?

A

MYOFIBRIL

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34
Q

What are myofibrils?

A

Bundle of proteins
100s-1000s myofibrils in an individual muscle fiber
CONTRACTILE MACHINERY allows it to form work

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35
Q

Explain the why skeletal muscle looks striated?

A

Stripes due to arrangement IN myofibrils.

-Myofibrils contain MYOFILAMENTS (Actin & Myosin)

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36
Q

Two muscle pre-fixes

A

Sarc/o=flesh

My/o=muscle

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37
Q

MYOFIBRILS

A

Made up of Myofilaments

Basic unit of contraction

38
Q

Function of Myofilaments?

What are the 3 Myofilaments?

A

Make up myofibrils

Actual proteins that FUNCTION to allow muscle to produce force

ACTIN
MYOSIN
TITIN (bigger than myosin)

39
Q

What is Actin?

Where does it attach?

A

Thin filament

Attaches to Z-line

40
Q

What is Myosin

A

Thick filament

41
Q

Arrangement of Actin and myosin in a myofibril?

A

Muscle—>Fasicle—>individual fibers—>myofibrils—>actin and myosin

42
Q

Z-Line (Z-disc)

Z-line to z-line is…

A

Actin filaments attaches

Boundary of the sarcomere

43
Q

What is THE FUNCTIONAL UNIT OF CONTRACTION?!

A

SARCOMERE

44
Q

A-BAND

A

Overlap of actin and myosin
Darker
(Anisotropic)

45
Q

I-Band

A

Actin (lighter)
Actin
Lighter area
(Isotropic-only 1 thing)

46
Q

Light Dark regions which make up STRIATIONS appearance

A

Light=I-Band actin only

Dark=A-band=both actin and myosin

47
Q

M-Line

A

Very center of sarcomere

Where Myosin filaments are held in place

48
Q

H-Zone

A

Center region of A band

MYOSIN ONLY

49
Q

What Structures make up the Sarcomere?

A
  1. Z-line-z-line = 1 sarcomere
    Z-line is the boundary
  2. M-Line center of sarcomere where myosin filaments are held in place
  3. I-band- contains actin (ACT-THIN) only attached to z-line
  4. H-Zone center region of A-band ONLY MYOSIN (between the ends of actin)
  5. A-BAND-is the overlap of actin and myosin
50
Q

Lateral Sac and T-Tubule are closely associated with eachother. How do they communicate? (What receptor is on the surface?)

A

T-TUbule has dihydropyradine receptors

Lateral Sacs have Ryanodine Receptors

51
Q

What receptor is on the T-Tubule?

What is it stimulated by?

A

Dihydropyradine receptors are on the surface of T-Tubules and stimulated by an electrical stimulus

52
Q

Which receptors are on the surface of lateral Sacs?

What is the function?

A

Ryanodine Receptors on the lateral sacs

RR is a calcium channel that pumps calcium into SR

53
Q

T-Tubule is an extension of what?

A

Sarcolemma (cell membrane) which is able to get electrically excited.

54
Q

Ryanodine Receptors are triggered by what?

A

Dihydropyradine receptors

55
Q

What does the Ryanodine Receptor do?

A

It is a CALCIUM CHANNEL

Pumps calcium into SR (stores calcium) and out of SR into cytosol

56
Q

MYOFILAMENTS make up what?

What are the two major Myofilaments?

A

MYOFIBRILS;

Actin and myosin

57
Q

How many proteins make up a myofilament?

A

About 300 myosin proteins make up a myosin myofilament

58
Q

The myosin molecule has what structure?

A

Long Tail section (2 wrapped around)
all tails bind up together to make up filament

Head Unit with 2 heads (project out)= functional part that forms cross bridges

59
Q

What binding sites are on the Myosin heads?

A

Actin binding site

Myosin ATPase site

60
Q

What are cross-bridges?

A

Neck and head part of myosin molecule that allows myosin to link up with other molecules

61
Q

What is the Actin Binding site?

What is the Myosin ATPase site?

A

ACTIN BINDING SITE on myosin head-BINDS ACTIN

MYOSIN ATPase-ENZYME that breaks down ATP to store energy

62
Q

How is energy stored in the Myosin molecule?

A

ATP split by myosin ATPase

ADP and Pi remain attached to myosin

Energy stored in cross bridge (ENERGY COCKS cross bridge

63
Q

Actin is what type of filament?

A

Thin

64
Q

When myosin heads split ATP putting the heads in a __ __ ___ and ___ position.

A

High Energy State and cocked position

65
Q

Takes 1 molecule of ATP to cock heads so how many molecules of ATP required to cock all myosin heads?

A

300 Myofilaments x 2 heads=600 molecules of ATP

66
Q

What is G-Actin

What is F-Actin

A

G-Actin-individual globular molecules with Myosin binding site

F-Actin-Double helical strand filament of g-actin strung together (2 strings of pearls)

67
Q

What are the 2 regulatory Proteins?

A

Tropomyosin

Troponin

68
Q

Tropomyosin

A

Thin filament protein.
Sits on surface of actin filament and COVERS MYOSIN BINDING SITES

When covered-actin and myosin do not interact

Uncovered-actin and myosin have the potential to interact

69
Q

What do the 3 subunits of Troponin attach to?

What is the function of troponin?

A

1 binds to tropomyosin
1 binds to actin
1 binds to calcium

Holds tropomyosin molecule in place

70
Q

What happens when troponin interacts with calcium?

A

Troponin has a conformational change

Since attached to tropomyosin, tropomyosin will have a conformational change

71
Q

Sliding Filament Theory?

A

Suggests filaments slide over each other in the way they interact in muscle contraction

72
Q

3 Phases of Sliding Filament Theory?

A
  1. Excitation
  2. Coupling
  3. Contraction
    (Excitation, contraction coupling–>doesn’t like this as much)
73
Q

Excitation (Sliding Filament Theory 1st Stage)

A
  1. stimulate muscle fiber (produce AP in NMJ due to End plate potential that reaches threshold)–>action potential on sarcolemma
  2. AP propagates over surface of sarcolemma (muscle fiber not myelinated so contiguous conduction)
  3. Also Propagates through the muscle via T-TUBULES
  4. AP stimulates Dihydropyradine receptors on T-Tubule
  5. RYANODINE RECEPTORS ARE STIMULATED( DHP receptors are next to lateral sacs w/ Ryanodine Receptors )
  6. Ryanodine Receptors on Calcium channels–>allows calcium channels to open
  7. Calcium diffuses out of Sarcoplasmic Reticulum (SR) into sarcoplasm (cytplasm of muscle fiber)
  8. Ca binds to troponin causing a conformational change
  9. Troponin changes shape–>moves tropomyosin –> exposes myosin binding sites on actin filaments
74
Q

Coupling (2nd stage of Sliding Filament Theory)

A

Calcium binds to troponin

Troponin changes shape moving tropomyosin out of the way

Exposes Myosin binding sites

Allowing Actin and myosin to bind to each other (COUPLE)

75
Q

Contraction (3rd Stage Sliding Filament Theory)

A

Begin to see shortening occur.

CONTRACTION= POWER STROKE
1. Power Stroke (1st event) 1% shortening of sarcomere

  1. Happens over and over (40%)
  2. Need new ATP molecule to add to ATPase (on each of the myosin heads)
  3. Allows for detaching of actin and myosin= THEY SEPARATE
  4. take ATP and reload myosin back to high energy state
76
Q

What are the Events at an NMJ?

A
  1. AP propagates down myelinated alpha motor neuron via saltatory conduction
  2. Reaches Terminal Button
  3. TB Has Calcium Ion channels which open up
  4. Increase permeability of calcium
  5. Influx of Ca –> stimulates exocytosis of vesicles
  6. vesicles fuse & release NT (Ach into the cleft)
  7. ACh diffuses across cleft and binds CHOLINERGIC NICOTINIC receptors on motor end plate
  8. Produces changes in Na/K ion channels
  9. Produce a graded potential but it ALWAYS REACHES THRESHOLD
  10. Action Potential moves out of motor end plate
  11. AP Stimulates normal channels on sarcolemma
  12. Opens up Na/K channels resulting in an AP
  13. Cholinesterase removes Acetylcholine
77
Q

When calcium diffuses into sarcoplasm what does it bind to and do?

A

Calcium binds to troponin

Troponin conformational change–>Tromomyosin conformational change–> myosin binding sites on actin filament are exposed

78
Q

Coupling step is 1 step…what happens?

A

form actomyosin cross bridge. Actin and myosin are linked together. Heads of MYOSIN MOLECULES FORM CROSS BRIDGE

79
Q

Cross bridge is formed via what?

A

Myosin heads form cross bridge (link to actin filament) Currently Myosin is in its high energy state

End of coupling

80
Q

What is the trigger of the myosin molecule?

A

-Coupling. At the actomyosin cross bridge formation it drops down to low energy (POWERSTROKE)

81
Q

What is Power Stroke?

A

1st event of contraction

Myosin molecule drops into low energy state

82
Q

What happens to Z line during power stroke?

A

sarcomere pulls into itself (shortens) about 1%

83
Q

What is the functional unit of contraction?

A

sarcomere

84
Q

how much can muscle shorten?

A

40% of resting length

85
Q

Excitation involves the

A

neuromuscular junction

86
Q

Coupling involves

A

Actomyosin cross bridge formation

Cross bridge cycle

87
Q

Contraction involves what?

A

POWER STROKE

88
Q

In Muscle Relaxation what happens?

A

-Getting the cross bridge cycled stopped.

**1. Pumping Calcium back into sarcoplasmic reticulum

  1. Troponin regains normal shape–causing tropomyosin covers myosin binding site
  2. Actin and myosin can’t interact any more so muscle relaxes
89
Q

Relaxation requires what?

A

pumping calcium back into the sarcoplasmic reticulum

90
Q

When contraction ends what state is myosin in?

A

myosin is in cock loaded high energy state (stays ready)

91
Q

What is Rigor Mortis?

A

when someone dies muscle gets stiff

92
Q

Why does Rigor Mortis happen?

A
  • metabolism stops, can’t make atp to run calcium pumps
  • power stroke occurs but need atp to release power stroke
  • muscle is stuck actin and myosin is stuck together

Human Physiology PB (9 decks)

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