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Anatomy Module I > Lecture 3 - Muscle Histology > Flashcards

Lecture 3 - Muscle Histology Flashcards

1
Q

Three types of muscle tissue

A

Skeletal
Cardiac
Smooth

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2
Q

Sarcolemma

A

muscle cell membrane

Other cell types= plasmalemma (plasma membrane)

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3
Q

Sarcoplasm

A

Cytoplasm of the muscle Cell

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4
Q

Sarcoplasmic reticulum

A

similar to smooth endoplasmic reticulum, storage site for calcium

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5
Q

Sarcosomes

A

Term of mitochondria within a muscle cell

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6
Q

Contractile Proteins

A

actin(thin) and myosin (thick)

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7
Q

Examples of Movement of actin and myosin for each type of muscle

A

skeletal- ex. movement of limbs
cardiac- ex. movement of blood
smooth- ex. movement of bolus (involuntary)

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8
Q

Connective tissue organization

A

Epimysium
Perimysium
Endomysium
(outer to inner)

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9
Q

Epimysium (type of CT)

A

Surrounds an ENTIRE muscle; dense irregular CT

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10
Q

Perimysium (type of CT)

A

Surrounds a muscle FASCICLE; dense irregular CT, Neurovascular structures course through the perimysium

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11
Q

Endomysium (Composition)

A

surrounds a SINGLE muscle or fiber/cell; mainly comprised of reticular fibers; capillaries and nerves terminals course through endomysium

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12
Q

Muscle unit and CT

A

CT investments are continuous with the tendon

form a strong muscolotendinous unit that allows muscle contraction forces to be transmitted

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13
Q

Contraction force path

A

Muscle->tendon->bone -> movement of bone segments

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14
Q

Skeletal muscle general features

A

Each muscle fiber contains many nuclei (MULTINUCLEATED)

located peripherally, adjacent to sarcolemma

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15
Q

Myofibrils and Sarcomeres

A

each muscle fiber/cell contains many myofibrils

each myofibril contains many sarcomeres

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16
Q

Sarcomere

A

repetitive subunit of skeletal ms

Actin and myosin are two major proteins that contribute to each sarcomere

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17
Q

Sarcomere composition

A

Several proteins

  • actin (thin)
  • myosin (thick)
  • tropomyosin
  • tropo
  • titin
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18
Q

tropomyosin

A

wraps around actin

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19
Q

titin

A

stabilizes myosin at Z disc

20
Q

M-line

A

middle of sarcomere; includes myosin binding protein that holds myosin in place

21
Q

H-zone

A

corresponds to location of myosin (only)

22
Q

A-band

A

corresponds to entire length of myosin

23
Q

I band

A

corresponds to location of actin (only)

24
Q

z disc

A

each sarcomere extends from Z disc to Z disc

25
alpha actin
stabilizes actin at the z disc
26
Contractile mechanism
involves actin, myosin, tropomyosin, troponin
27
tropomyosin in relaxtion
it wraps around actin | blocks binding site on actin for myosin head
28
troponin in relaxation
holds tropomyosin in place
29
during contraction
Ca2+ binds to troponin - troponin changes conformation - tropomyosin moves away from the active site on actin - myosin binds to actin - ATP provides energy for power stroke - SHORTENS sarcomere
30
Neuromuscular Junction AP path
1. AP travels down axon to terminal 2. Opens Voltage Gated Ca2+ channels 3. Ca2+ triggers release of ACh 4. ACh traverses synaptic cleft, binds to ACh receptors on the sarcolemme (Motor end plate) 5. Na+ ion channels open, enters Na+ 6. Depolarizing potential 7. action potential initiated in muscle cell 8. AP propagated along muscle cell plasma membrane
31
How does AP reach myofibrils deep in the sarcomere?
T-tubules: invaginations of the sarcoplasm - permit AP to reach deep into muscle fiber - Surrounded on both sides by the Sarcoplasmic reticulum cistern - AP triggers release of Ca2+ from SR
32
Triad
Located in Skeletal Muscle | 2 sarcoplasmic reticulum cisterns surrounding 1 T tubule
33
Contraction vs relaxation and Ca2+
Ca release = contraction | Ca sequestered in SR = relaxation
34
Contractile mechanism summary
Action potential in motor axon -> action potential in sarcolemma travels down T-tubule and triggers Ca+2 release from SR -> Ca+2 binds to troponin -> conformational change in troponin which moves tropomyosin and uncovers the myosin binding site (on actin) ->myosin head binds to actin -> via energy release from ATP-> muscle contraction (power stroke
35
Relaxation summary
no more signal of ACh on terminal -> Ca2+ transported back into SR -> tropomyosin recovers active site on actin
36
Cardiac muscle vs Skeletal
Both Striated, Cardiac not a regular structure, Cardiac has 1 or 2 central nuclei, Cardiac has cytoplasmic cone - location of glycogen/mitochondria cardiac is small in length intercalated disc at interface of cardiac muscle cells
37
Intercalated Disc (what is it describe structure)
seen as dark lines between "ends" of cardiac muscle cells (unique to cardiac), has elevations and depression (looks like waves at the end)
38
intercalated disc components (with location)
fascia adherens - located at the end desmosomes - located at the end gap junctions - laterally located, and provide continuity for quick potentials
39
Dyads
T- Tubules that dont have flanking cisterns. There is one T tuble and one SR. This is located in Cardiac Muscle only
40
Smooth Muscle Location and Structure
No striations Seen many places, blood vessels, urinary, eye, lung spindle shaped cells taper on long axis one signel nucleus
41
Contraction of smooth muscle Shape
Contracted called corkscrew shape
42
Fiber Orientations in Smooth Muscle
Inner Circular Layer - go around muscle - so they look like long cells in cross setion Longitudinal - Organized in parllel to muscle - so look like cell circles going in to the page in a cross section
43
Dense Bodies
Located along the sarcolemma and in sarcoplasm. Similar to Z discs and bind actin
44
Dense Plaques
Aka Focal Adhesions Junctions between cells. They are dense bodies with an additional proteins connecting to adjacent cells allows for communication of neighbor cells of contraction
45
Caveolae
Slight invaginations in the smooth muscle location of calcium channels are close to the sarcoplasmic reticulum influx of calcium results in more calcium from sarcoplasmic reticulum
46
Gap Junctions in Smooth Muscle
Electrically and chemically couple the smooth muscle | for paristalsis

Anatomy Module I (9 decks)

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