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Skin/Musculoskeletal Week 4 > Muscle Tissue - Sheet1 > Flashcards

Muscle Tissue - Sheet1 Flashcards

1
Q

smooth muscle

A

Functions: Contractility and Conductivity

No striations

No T-tubules

**Involuntary **

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2
Q

myofiber

A

muscle cells

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3
Q

myofibril

A

Tiny, cylindrical rods within the sarcoplasm of the muscle cell. Responsible for the appearance of cross-striations in muscle cells.

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4
Q

myofilament

A

A component of myofibrils that has three categories: 1) actin filaments (thin) 2) myosin filaments (thick) 3) Z-disk

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5
Q

sarcolemma

A

Plasma membrane. Nucleus located just inside the sarcolemma.

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6
Q

sarcoplasm;

A

cytoplasm of muscle fibers. Surrounds myofibrils and is beneath the sarcolemma

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7
Q

sarcoplasmic reticulum

A

Network of cisterns and/or membranous tubules running between and around myofibrils. Contains sarcoplasm.

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8
Q

actin

2 types…

A

G-actin (globular actin)–a globular monomer that polymerizes to form F-actin (Two helically-wound strands of polymerized G-actin)

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9
Q

myosin

A

thick, extends accross entire A-band, contains myomesin, C-protein, and others.

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10
Q

tropomyosin

A

Fibrous; arranged head to tail in a linear series.

Helically wound along grooves of F-actin helix

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11
Q

alpha-actinin

A

Component of the Z-disk

Holds actin filaments in register by binding them in parallel array

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12
Q

troponin complex

A

3 subunits:

TnT: binds entire troponin complex to tropomyosin

TnC: great affinity for Ca++

TnI: binds to actin, preventing actin-myosin interactions

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13
Q

T-tubule

A

part of the sarcolemma.

typically seen at A-I junctions.

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14
Q

triad

A

Facilitates transmission of electrical impulse from sarcolemma to interior depths of cell.

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15
Q

diad

A

Cardiac muscle? T-tubule + terminal portion of adjacent sarcoplasmic reticulum

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16
Q

nebulin

A

Long, non-elastic protein

Two molecules of nebulin wrap around each thin filament

Help anchor thin filament to Z-disk

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17
Q

titin

A

Helps position myosin filaments precisely within the sarcomere. Extends from each half of a myosin filament to the Z-disk Helps keep myosin fillaments centrally located by acting like a spring

18
Q

caveolae

A

Pinocytotic-like invaginations of sarcolemma

Probably play the role of the T-tubules found in skeletal and cardiac muscle

May work in concert with sarcoplasmic reticulum to modulate Ca++ availability

19
Q

dense bodies

A

Smooth muscle only!

Two locations: 1) Inner aspects of sarcolemma

2) Throughout cytoplasm

Comparable to Z-disks of skeletal & cardiac muscle Contain alpha-actinin

Serve as anchor sites for actin-myosin interactions as well as intermediate filaments (vimentin; desmin)

20
Q

Z-disk

A

Dense-staining; narrow.

Distance between two Z-disks = a sarcomere

21
Q

Sarcomere

A

functional unit of the myofibril. defined as that portion of a myofibril extending from Z-disk to Z-disk.

22
Q

intercalated disk

A

Complex of several types of cell-to-cell junctions:

Gap junctions (nexuses)

Desmosomes Fascia adherens (serve as anchoring points for actin filaments)

23
Q

I-band, A-band, H-band

A

I-band: narrower, light-staining band, becomes smaller; may disappear as muscle shortens.

A-band; broad, dark-staining band, represents myosin filaments, remains contant during contraction.

H-band: pale-staining and narrow, narrows and is eventually obliterated in contraction.

24
Q

Junction of A and I band = ?

A

T (transverse) tubule

25
Q

What are the three regulatory molecules in skeletal muscle?

A
  1. Troponin complex
  2. **tropomyosin **
  3. Ca++
26
Q

Ca++ as a regultory ion

A

Binds to TnC induces a conformational shift in tropomyosin, exposing previously blocked active sites on the actin filament

27
Q

In skeletal muscle, the breadth of the _____ stays the same during contraction, while the breadth of the _____ and ____ get shorter.

A

A band; I band and H band

28
Q

Endomysium

A

Sheath of fine c.t. around individual muscle fibers

Fine reticular fibers and ground substance

29
Q

Perimysium

A

Connective tissue sheath around groups of muscle fibers (fasicles)

_**Continuous with tendon fibers***_

30
Q

Epimysium

A

Outermost sheath of c.t.;

surrounds entire muscle

31
Q

Synaptic vesicles of skeletal muscle fibers

A

In axon terminals

Contain acetylcholine

32
Q

Motor end plates (structure and function)

A

form myo-neural junctions

33
Q

Golgi tendon organs (structure and function)

A

Structure: Spindle-shaped bodies comprised of collagen and enclosed by a thin capsule

Afferent (sensory) fibers penetrate between the collagen fibers

Sensitive to stretching forces on tendons (aka reflexes)

34
Q

SYNAPTIC VESSICLES CONTAINING ________ WILL RELEASE UPON ________ AND INTERACT WITH ACETYLCHOLINE RECEPTORS. ACETYLCHOLINE IS BROKEN DOWN BY ACETYLCHOLINE ESTERASE.

A

ACETYLCHOLINE; Depolarization

35
Q

describe what Purkinje fibers are and do

A

play a role in cardiac conduction system;

Contain more sarcoplasm

Nuclei more rounded

Large diameter

Lack T-tubules

More glycogen

36
Q

Muscle spindle

A

Structure: ** Internal capsule** immediately surrounds intrafusal fibers; encloses inner axial space

External capsule surrounds internal capsule and creates (periaxial space) between inner and outer capsules

37
Q

Skeletal Muscle Hypertrophy referes to what?

A

Due to increase in size of fibers, not number

38
Q

cardiac muscle– significant characteristics

A

Striated (involuntary) with lots of MITO

Single nucleus/cell; centrally located—good diagnostic tool. Have intercalated disks.

39
Q

Intercalated disks of cardiac muscle

A

Dark cross-bands; frequently appear step-like

Occur where a Z-disk should be observed

Mark spots of cell-cell attachments (i.e, at ends of cells)

40
Q

Atrial granules

A

Unique to atrial cardiac muscle cells

Contain atrial natriuretic peptide which functions to lower blood pressure

Decreases renal tubules capability to resorb (conserve) sodium and water

41
Q

Contractile mechanisms of smooth muscle

A

Ca++(probably stored in caveolae) + calmodulin form a complex –> activates myosin light chain kinase –> phosphorylates one of the two light chains associated with the myosin molecule head.

42
Q

Innervation of smooth muscle

A
  1. sympathetic innervations: synaptic vesicles contain norepinephrine
  2. parasympathetic innervation: synaptic vesicles contain acetylcholine
  3. variations in numbers of cells in a group that are innervated

Skin/Musculoskeletal Week 4 (7 decks)

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