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AP1 > Ch6-Muscles > Flashcards

Ch6-Muscles Flashcards

1
Q

3 Types of Muscle Tissue

A

1 - Skeletal
2 - Cardiac
3 - Smooth

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2
Q

Skeletal Muscle Characteristics

Body Location ?

A

Attached to Bones (some facial muscles to skin)

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3
Q

Skeletal Muscle Characteristics

Cell Shape & Appearance ?

A

Single, very long, cylindrical, multinucleate cells with very obvious striations.

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4
Q

Skeletal Muscle Characteristics

Connective Tissue Component?

A

Epimysium, perimysium, and endomysium

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5
Q

Skeletal Muscle Characteristics

Regulation of Contraction?

A

Voluntary via nervous system controls

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6
Q

Skeletal Muscle Characteristics

Speed of Contraction?

A

Slow to Fast.

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7
Q

Skeletal Muscle Characteristics

Rhythmic Contraction?

A

No

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8
Q

Cardiac Muscle Characteristics

Body Location?

A

Walls of the Heart

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9
Q

Cardiac Muscle Characteristics

Cell Shape & Appearance?

A

Branching chains of cells; single nucleus (uninucleate): intercalated discs.

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10
Q

Cardiac Muscle Characteristics

Connective Tissue Components ?

A

Endomysium attached to the fibrous skeleton of the heart.

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11
Q

Cardiac Muscle Characteristics

Regulation of Contraction?

A

Involuntary; the hear has a pacemaker; also nervous system controls; hormones.

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12
Q

Cardiac Muscle Characteristics

Speed of Contraction

A

Slow

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13
Q

Cardiac Muscle Characteristics

Rhythmic Contraction ?

A

Yes

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14
Q

Smooth Muscle Characteristics

Body Location ?

A

Mostly in the walls of hollow visceral organs (other than the heart).

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15
Q

Smooth Muscle Characteristics

Cell Shape & Appearance ?

A

Single, fusiform, uninecleate; no striations.

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16
Q

Smooth Muscle Characteristics

Connective Tissue Components ?

A

Endomysium

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17
Q

Smooth Muscle Characteristics

Regulation of Contraction ?

A

Involuntary; nervous system controls; hormones; chemicals, stretch.

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18
Q

Smooth Muscle Characteristics

Speed of Contraction ?

A

Very Slow

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19
Q

Smooth Muscle Characteristics

Rhythmic Contractions ?

A

Yes, in some.

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20
Q

Muscle Tissue General

Skeletal Muscle’s Function ?

A

1 - Body Movements
2 - Stabilize body position
3 - Produce heat ( Shivering is Involuntary contraction of skeletal muscle.)

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21
Q

Muscle Tissue General

Smooth Muscle’s Function ?

A

1 - Regulating Organ Volumes - via sphincters

2 - Movement of substances w/in body => Blood, urine, air, food, sperm.

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22
Q

Muscle Tissue Properties

ECCEE

A

Excitability - response to chems released from nerve cells.
Conductivity - ability to propagate electrical signals over membrane.
Contractibility - ability to shorten & generate force.
Extensibility - ability to be stretched w/out damaging tissue.
Elasticity - ability to return to original shape after being stretched.

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23
Q

Skeletal Muscles

Connective Tissue Fundamentals

A

1 - Superficial fascia - loose connective under the skin.
2 - Deep fascia - dense irregular connective tissue around muscle.
3 - Connective tissue components - epimysium - perimysium - endomysium
4 - All extend beyond belly of muscle to form tendons.

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24
Q

Connective Tissue Components
Membrane Names
E P E

A

1 - Epimysium - covers the whole muscle belly & blends into tissue that separates muscles.
2 - Perimysium - slightly thicker layer of connective tissue. Surrounds a bundle of cells called fascicle
3 - Endomysium - thin layer of areolar tissue surrounding each cell. Allows room for capillaries and nerve fibers.

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25
Q

Connective Tissue

Basic Characteristics

A

1 - Found between muscle fibers & bone or other attachment.
2 - Not excitable or contractible, but somewhat extensible & elastic
3 - Called ‘series-elastic’ components

26
Q

Skeletal Muscles

Locations of Fascia

A

1 - Deep Fascia - found between adjacent
muscles
2 - Superficial Fascia (hypodermis)
- Found between skin & muscles
- contains adipose tissue

27
Q

Skeletal Muscles
Muscle Attachments
D I A

A 
1 - Direct
2- Indirect
3 - Attachment to dermis
NOTE:  Stress will tear a tendon before 
            separating it from the bone or
            muscle.
28
Q

Skeletal Muscles
Muscle Attachments
Direct

A
  • Direct ‘fleshy’ attachment to bone.
  • Epimysium is continuous w/ periosteum
  • EXAMPLE: Intercostal muscles
29
Q

Skeletal Muscles
Muscle Attachments
Indirect

A
  • Epimysium continues as tendon or aponeurosis that merges into periosteum as perforating fibers.
    EXAMPLE: biceps brachii & abdominal muscles.
30
Q

Skeletal Muscles
Muscle Attachments
Attachment to Dermis

A
  • Just that
31
Q

Skeletal Muscles

Nerve & Blood Supply

A
  • Each skeletal muscle is supplied by a nerve, artery and two veins
  • Each motor neuron supplies multiple muscle cells (neurotransmitter junction).
32
Q

Skeletal Muscle

Nerve “Motor Neuron” (more)

A
  • each muscle cell is supplied by one motor neuron terminal branch & is in contact w/ one or two capillaries.
    • Nerve fibers & capillaries are found in the endomysium between individual cells.
33
Q

Muscle Cell

Basic Facts

A
  • Every mature muscle cell developed from
    100 myoblasts that fuse together in the
    fetus (multinucleated).
  • Mature muscle cells can not divide.
  • Muscle growth is a result of cellular enlargement not cell division.
  • Satellite cells retain the ability to regenerate new cells.
34
Q

Muscle Cell

Sarcolema

A
  • Muscle cell membrane

- Has tunnel-like infoldings or tranverse (T) tubules that penetrate the cell.

35
Q

Muscle Cell

Sarcomere

A

Area between two Z-lines.

36
Q

Muscle Cell

Sarcoplasm

A
  • Filled with tiny threads called myofibrils & myoglobin.
37
Q

Muscle Cell

Nuclei

A
  • Multiple flattened against inside of plasma membrane,

- There are unfused satellite cells nearby that can produce a small number of new myofibers.

38
Q

Muscle Cell

Sarcoplasm contents

A
  • Filled with myofibrils
  • Glycogen for stored energy
  • & myoglobin binding oxygen
39
Q

Muscle Cell

Sarcoplasmic Reticulum

A
  • Series of interconnected, dilated, calcium storage sacs called terminal cisternae.
  • System of tubular sacs similar to smooth ER in nonmuscle cells
  • Stores Ca+2 in a relaxed muscle
  • Release of Ca+2 triggers muscle contraction
40
Q

Muscle Cell

Tranverse (T) Tubules

A
  • Carry muscle action potentials down into the cell.

- They are invaginations of the sarcolemma into the center of the cell.

41
Q

Muscle Cell

Mitochondria

A
  • Lie in rows throughout the cell.

- Near the muscle proteins that use ATP during contractions.

42
Q

Muscle Cell

Myofibrils

A

Muscle fibers are filled with threads called myofibrils separated by SR (sarcoplasmic reticulum)

43
Q

Muscle Cell

Myofilments

A

Thick & thin filaments are the contractile proteins of muscle.

44
Q

Muscle Cell

Filaments & Sarcomere

A
  • Thick and thin filaments overlap each other in a pattern that creates striations (light I bands and dark A bands)
  • The I band region contains only thin filaments.
  • They are arranged in compartments called sarcomeres, separated by Z discs.
  • In the overlap region, six thin filaments surround each thick filament
45
Q

Muscle Cell

Thick & Thin Filaments’ Proteins

A
  • Supporting proteins: M line, titin and Z disc help anchor the thick and thin filaments in place.
46
Q

Muscle Cell

3 types of Muscle Proteins

A

Myofibrils are built of 3 kinds of protein:
1 - contractile proteins
- myosin and actin
2 - regulatory proteins which turn

contraction on & off
- troponin and tropomyosin
3 - structural proteins which provide proper alignment, elasticity and extensibility
- titin, myomesin, nebulin and dystrophin

47
Q 
Muscle Cell 
Thick Filaments (Myosin)
A
  • Made of 200 to 500 myosin molecules
    - 2 entwined polypeptides (golf clubs)
  • Arranged in a bundle with heads (cross bridges) directed outward in a spiral array around the bundled tails
    central area is a bare zone with no heads
48
Q 
Muscle Cell 
Tin Filaments (Actin)
A
  • Two intertwined strands of fibrous (F) actin
    - each subunit is a globular (G) actin
    with an active site
  • Groove holds tropomyosin molecules,
    each blocking the active sites of 6 or 7 G
    actins
     One small, calcium-binding troponin molecule stuck to each tropomyosin molecule
49
Q

Muscle Cell
Regulatory & Contractile Proteins
Myosin & Actin

A 
Contactile Proteins
(They do the work)
50
Q

Muscle Cell
Regulatory & Contractile Proteins
Tropomyosin & troponin

A

Regulatory Proteins

  • Act like a switch that starts & stops shortening of muscle cell
  • the release of calcium into sarcoplasm and its binding to troponin, activates contraction
  • troponin moves the tropomyosin off the actin active sites
51
Q

Muscle Cell
Other Structural Proteins
Myomesin

A

The M line connects to titin and adjacent thick filaments

52
Q

Muscle Cell
Other Structural Proteins
Nebulin

A
  • An inelastic protein helps align the thin filaments.
53
Q

Muscle Cell
Other Structural Proteins
Dystrophin

A

Links thin filaments to sarcolemma and transmits the tension generated to the tendon.

54
Q

Muscle Cell

Striations: Organization of Filaments

A
  • Dark A bands (regions) alternating with lighter I bands (regions)
    • anisotrophic (A) and isotropic (I) stand
      for the way these regions affect
      polarized light
  • A band is thick filament region
    • lighter, central H band area contains
      no thin filaments
  • I band is thin filament region
    • bisected by Z disc protein called
      connectin, anchoring elastic & thin
      filaments
    • from one Z disc (Z line) to the next is a
      sarcomere
55
Q

Muscle Cell

Relaxed versus Contracted Sarcomere

A 
- Muscle cells shorten because their  
    individual sarcomeres shorten
       - pulling Z discs closer together
       - pulls on sarcolemma
 - Notice neither thick nor thick filaments 
    change length during shortening
 - Their overlap changes as sarcomeres 
    shorten
56
Q

Muscle Cell

Nerve Muscle Relationships

A
  • Skeletal muscle must be stimulated by a nerve or it will not contract (paralyzed)
  • Cell bodies of somatic motor neurons are in brainstem or spinal cord
  • Axons of somatic motor neurons are called somatic motor fibers
    - each branches, on average, into 200
    terminal branches that supply one
    muscle fiber each
  • Each motor neuron and all the muscle fibers it innervates are called a motor unit
57
Q

Muscle Cell
Motor Units
A Motor Neuron & the Muscle Fibers it Innervates

A
  • Dispersed throughout the muscle
  • When contract together causes weak contraction over wide area
  • Provides ability to sustain long-term contraction as motor units take turns resting (postural control)
58
Q

Muscle Cell
Motor Units
Fine Control

A
  • Small motor units contain as few as 20 muscle fibers per nerve fiber
  • Eye muscles
59
Q

Muscle Cell
Motor Units
Strength Control

A
  • Gastrocnemius muscle has 1000 fibers per nerve fiber
60
Q

Muscle Cell

A

h

AP1 (2 decks)

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