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Anatomy Exam 1 > Lecture 4: Muscles & Tissue > Flashcards

Lecture 4: Muscles & Tissue Flashcards

1
Q

Define muscle contraction

A

Response to stimuli

Not a muscle shortening because in eccentric contractions the muscle is lengthening

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2
Q

Contraction where the length of muscle does not change

A

Isometric

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3
Q

Define ‘isotonic’ contraction

A

Length of the muscle changes
Shortens or lengthens
Concentric or eccentric

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4
Q

What are the 6 characteristics that muscles can be named from?

A

Shape, origin-insertion, function, size, fiber arrangement, location

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5
Q

What are the four ways fibers can be arranged?

A

Straight - fibers run parallel
Fusiform - thick center, tapers at ends, fibers run parallel
Unipennate - feather like, one side only (pennate = feather)
Bipennate - feather with both sides
Multipennate - multiple feathers

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6
Q

Compare strength between a fusiform fiber arrangement and a pennate arrangement. Explain

A

Pennate = feather like - increase in surface area

Each cross section allows for a greater force to be created across small areas

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7
Q

How far can muscles contract compared to their resting state?

A

Half their size

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8
Q

Define agonist

A

Muscle doing the desired action, two types
Prime mover - muscle whose function is to cause that mvt or muscle that makes the strongest contribution towards the mvt
Assistant mover - muscle that causes the same mvt but it’s force is only of secondary importance

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9
Q

Define antagonist

A

Muscle that opposes the agonist, typically on the opposite side of the body
Example: biceps and triceps in a bicep curl

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10
Q

A muscle that eliminates unwanted action by the agonist

A

Synergist

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11
Q

Muscle that stabilizes base of attachment of agonist

A

Fixator - when acting as a stabilizer it is usually an isometric contraction (meaning?)

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12
Q

Define unijoint muscles

A

Muscle that crosses only one joint

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13
Q

Define multijoint muscle

A

Muscle that crosses multiple joints

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14
Q

Mulit-joint muscles are subject to what phenomenon?

A

Muscle Insufficiency

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15
Q

The inability of a multijoint muscle to contract maximally over all joints crossed, at one time

A

Muscle insufficiency

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16
Q

What are the two types of muscle insufficiency?

A

Active insufficiency —- agonist

Passive insufficiency —- antagonist

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17
Q

The diminished ability of a muscle to produce or maintain active tension

A

Active insufficiency

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18
Q

Characteristics of active insufficiency

A

The muscle is so elongated that there are no overlaps between microfilaments

When all cross bridges have been formed, the muscle is excessively shortened

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19
Q

Passive Insuficiency

A

Occurs when the antagonist muscle is at a insufficient length to allow the full force that a full ROM would produce

Mainly associated with multijoint muscles

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20
Q

Synergist muscle is also know as what?

A

Neutralizer

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21
Q

A pure neutralizer will cause….?

A

The opposite motion of the prime mover, without actually assisting with the mvt

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22
Q

What type of muscles do not allow full ROM in all joints it crosses at one time?

A

Multi-joint muscles

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23
Q

Give examples of a pure synergist vs. a helping synergist

A

Pure synergist - causes opposite motion w/o assisting in mvt
Ex. Triceps during elbow flexion, so the biceps can supinate forearm
Helping synergist - only opposes one component of mvt
Ex. Pronator teres helps in elbow flexion by biceps, it nullifies the supination component

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24
Q

Muscles that pass anterior to the axis of a joint

A

Flexors

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25
Q

Muscles that pass posterior to the axis of a joint

A

Extensors

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26
Q

Muscles that pass lateral to a joint

A

Abductors

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27
Q

Muscle tissue appearances

A

Striated or smooth

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28
Q

Muscle nuclei can be…..?

A

Multi-nucleated (syncytium) = more than 1 nucleus

Mono-nucleated

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29
Q

Voluntary vs. involuntary muscle function. Give examples

A

Voluntary = conscious control of muscle contraction
Ex. Most skeletal muscles - biceps

Involuntary = have no control over
Ex. Arrector pili muscles, heart

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30
Q

Name the types of muscle tissue

A

Skeletal/striated
Smooth
Cardiac
(4th special kind - branchiomeric muscle)

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31
Q

Skeletal muscle characteristics

A

Striated and voluntary
Attached directly or indirectly to the skeletal system
Peripheral nuclei - not in center of cell
Multi-nucleated
Conducts action potential

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32
Q

Where does the striated appearance of skeletal muscle come from?

A

When subunits are viewed under microscope they have a banded appearance

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33
Q

Smooth muscle characteristics

A

Referred to as visceral or involuntary
Not striated
Most commonly associated with viscera - especially gut tubes and hollow structures

34
Q

Groups of spindle-shape, mononucleated cells, with a centrally located nuclei

A

Smooth/visceral/involuntary muscle

35
Q

What are the most common places smooth muscle is found?

A

Viscera - gut tube and other hollow structures

36
Q

What type of muscle tissue is only found in one organ?

A

Cardiac muscle tissue

37
Q

Cardia muscle tissue shares characteristics with…..

A

Striated and smooth muscle tissues

38
Q

Cardiac muscle characteristics

A

Striated
Involuntary
Intercalated discs - special intercellular junctions

39
Q

Consists of chains of individual cells that are mononucleated and striated

A

Cardiac muscle tissue

40
Q

Muscle tissue associated with pharyngeal arches

A

Branchiomeric muscle tissue

41
Q

Characteristics of branchiomeric muscle tissue

A

A transition between smooth and striated muscle tissues

Innervated by cranial nerves

42
Q

Define origin

A

Usually the proximal attachment of muscle

43
Q

Define insertion

A

Usually the distal attachment of a muscle

44
Q

Which attachment zone is more moveable?

A

Distal = more moveable (insertion)

Proximal = fixed with regard to mvt (origin)

45
Q

Tendons

A

Attach muscle to bone
Dense collection of collagenous CT
Poorly vascularized

46
Q

Aponeuroses

A

Flat/fan-shaped tendons that turns into multiple tendons

Ex. Palm of hand

47
Q

List the hierarchical structure of skeletal muscle from outmost in

A

Muscle - fascicle - myofiber - myofibril - myofilament - sarcomere - myosin or actin filaments

48
Q

Myofilament

A

Are either thick (myosin) or thin (actin) filaments

Are organized into chains of sarcomeres

49
Q

Myofibril

A

Chain of sarcomeres

50
Q

Myofiber

A

Bundle of myofibrils
Also referred to as the muscle cell
Each fiber is formed from fused myoblasts

51
Q

Fascicle

A

Bundle of myofibers

52
Q

Muscle

A

Composed of multiple fascicles

Contains blood vessels too

53
Q

Surrounds each muscle fiber (also called?)

A

Endomysium surrounds each myofiber and lies outside the sarcolemma

54
Q

Sarcolemma

A

Name of the cell membrane for a muscle cell

55
Q

Membrane surrounding each fascicle within a muscle

A

Perimysium

56
Q

Membrane surrounding an entire muscle and continuous with tendons? What does it attach to?

A

Epimysium

Attached to the periosteum of bone

57
Q

CT provides…..what for nerves and vessels?

A

CT provides a physical support and framework for nerves and vessels

58
Q

Types of myofilaments

A

Actin & myosin

Also called thin & thick filaments

59
Q

A thin filamentous protein polymer

A

Actin

60
Q

Each actin filament is made up of…..

A

2 helically wound polymers of G-actin

61
Q

What molecules are associated with Actin?

A

Tropomyosin

Troponin

62
Q

Bundles of long molecules that form a tail + ATPase head. How is that tail attached?

A

Myosin

Tail attached via a swivel mechanism

63
Q

Myosin ATPase heads attach to ……

A

Binding sites on actin filaments

64
Q

Sliding filament theory of contraction

A

Attach-swivel release cycles

Allow myosin and actin to slide along one another in opposite directions which = a contraction

65
Q

Myosin and actin organization into myofibrils

A

Organized in cylindrical units, aligned end to end to form the myofibril

Filaments are like a round stone, and each one is stacked on top of another to create a long rod which = a myofibril

66
Q

Name the 3 main components of sarcomere structure

A

Z-lines
I-bands
A-bands

67
Q

Z-lines

A

Composed of z-actin
Separate the sarcomeres in a fibril

Z=between

68
Q

Sarcomere

A

Each cylindrical unit that when all put together forms a myofibril

Thus myofibril = chain of sarcomeres

69
Q

I-bands

A

Composed entirely of actin

Make up ends of each sarcomere = located on either side of z-line

70
Q

A-bands

A

Composed of actin and myosin

Located in middle of sarcomere

71
Q

After birth the number of myofibers….

A

Cannot be increased

72
Q

After birth the number of myofibrils…..? Relate to myofiber

A

Can be increased

Thus the mass of a myofiber can be increased === muscle increase

73
Q

What replaces lost muscle tissue

A

Scar tissue = fibrous CT

74
Q

Equivalent to the endoplasmic reticulum of regular cells

A

Sarcoplasmic reticulum

75
Q

T-tubule gross structure

A

Tubular extensions that reach from the sarcolemma into the sarcoplasm (cytoplasm)

76
Q

T-tubule function

A

Conduct action potential from sarcolemma surface to cell interior

77
Q

Cisternae

A

Sac like extensions from sarcoplasmic reticulum, that release Ca ions in responses to action potential

78
Q

What structure releases calcium ions in a sarcomere? What causes their release? What is the significance of Ca ions?

A

Cisternae release ions - extensions of sarcoplasmic reticulum

Released in response to action potential conducted by t-tubule

Ca ions trigger sliding of myosin and actin filaments = resulting in a muscle contraction

79
Q

Sliding filament theory - mechanism? Occurs inside of?

A

During a contraction, the I & H bands shorten, A band does not
Within a sarcomere/myofibril

ATPase heads of myosin attach to actin via troponin and swivel mechanism

80
Q

F-actin

A

Thin filamentous protein polymer

81
Q

G-actin

A

Globular - free monomer

Anatomy Exam 1 (10 decks)

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