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HISTOLAB MIDTERMS MUSCLE > M 1.2 > Flashcards

M 1.2 Flashcards

1
Q
  • Usually attached to bones by tendons
  • Long cylindrical fiber with many peripherally located nuclei; unbranched; striated with alternating light and dark bands seen by microscopy
  • Arise from the fusion of a hundred or more small mesodermal cells called myoblasts during embryonic development, thus, each mature skeletal muscle fiber has a hundred or more nuclei
A

Skeletal Muscle Tissue

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2
Q

Part of the myoblast population does not fuse and differentiate but remains as a group of mesenchymal cells called _____________ located on the external sur face of muscle fibers inside the developing external lamina. These proliferate and produce new muscle fibers
following muscle injury.

A

muscle satellite cells

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3
Q

Skeletal Muscle Fiber
Length: Very long, vary greatly in length, from a few centimeters in short muscles to ___________
cm in the longest muscles

A

30-40 cm

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4
Q

Skeletal Muscle Fiber
Diameter: Very large - _________ um

A

10-100 um

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5
Q

Skeletal Muscle Fiber
Structure:

A
  • Sarcolemma (Transverse (T) tubules)
  • Nuclei
  • Sarcoplasm (Glycogen, Myoglobin, Mitochondria, Sarcoplasmic reticulum, Myofibrils)
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6
Q

Skeletal Muscle Fiber
Structure ?
- Long, finger-like invaginations of the sarcolemma that penetrate into the sarcoplasm
- Aligned with each A-I band junctions
- Filled with interstitial fluid (ensures that an action potential excites all parts of the muscle fiber at essentially the same instant)

A

Transverse (T) tubules

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7
Q

Skeletal Muscle Fiber
Structure ?
- 100 or more in each skeletal muscle fiber
- Found just beneath the sarcolemma

A

Nuclei

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8
Q

Skeletal Muscle Fiber
Structure ?
- Large molecule composed of many glucose molecules
- Can be used for ATP synthesis

A

Glycogen
(Sarcoplasm)

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9
Q

Skeletal Muscle Fiber
Structure ?
- A red-colored protein, found only in muscle,
- Binds oxygen molecules that diffuse into muscle fibers from interstitial fluid and releases oxygen when it is needed by the mitochondria for ATP production

A

Myoglobin
(Sarcoplasm)

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10
Q

Skeletal Muscle Fiber
Structure ?
-Lie in rows throughout the muscle fiber, strategically close to the contractile muscle proteins that use ATP during contraction so that ATP can be produced quickly as needed

A

Mitochondria
(Sarcoplasm)

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11
Q

Skeletal Muscle Fiber
Structure ?
- A fluid-filled system of membranous sacs that encircles each myofibril
- Dilated end sacs of the SR called terminal cisterns butt against the T tubule from both sides
- Abundant in skeletal muscle fibers
- In a relaxed muscle fiber, the sarcoplasmic reticulum stores calcium ions (Ca++ ). Release of Ca++ from the terminal cisterns of the SR triggers muscle contraction

A

Sarcoplasmic Reticulum
(Sarcoplasm)

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12
Q

Skeletal Muscle Fiber
Structure ?
- The contractile organelles of skeletal muscle
- Arranged in parallel bundles
- About 2 um in diameter and extend the entire length of a muscle fiber
- Containing thin and thick filaments (myofilaments) whose overlapping organization produces staining differences that cause striations

A

Myofibrils
(Sarcoplasm)

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13
Q

Structure of Myofibril
_______________ is the basic functional contractile unit of a myofibril

A

Sarcomere

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14
Q

Components of Sarcomere:

A
  • Z discs
  • A band
  • I band
  • H zone
  • M line
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15
Q

Components of Sarcomere:
- Narrow, plate-shaped regions of dense material that separate one sarcomere from the next

A

Z discs

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16
Q

Components of Sarcomere:
- Dark, middle part of sarcomere that extends entire length of thick filaments and includes those parts of thin filaments that overlap thick filaments

A

A band

17
Q

Components of Sarcomere:
- Lighter, less dense area of sarcomere that contains remainder of thin filaments but no thick filaments. A Z disc passes through center of each of these

A

I band

18
Q

Components of Sarcomere:
- Narrow region in center of each A band that contains thick filaments but no thin filaments

A

H zone

19
Q

Components of Sarcomere:
- Region in center of H zone that contains proteins that hold thick filaments together at center of sarcomere

A

M line

20
Q

Connective Tissue Components of Skeletal Muscle
What are the three layers?

A
  • Epimysium
  • Perimysium
  • Endomysium
21
Q

Connective Tissue Components of Skeletal Muscle
What layer?
- The outer layer, encircling the entire muscle
- Consists of dense irregular connective tissue

A

Epimysium

22
Q

Connective Tissue Components of Skeletal Muscle
What layer?
- Surrounds groups of 10 to 100 or more muscle fibers, separating them into bundles called fascicles
- Consists of dense irregular collagenous connective tissue

A

Perimysium

23
Q

Connective Tissue Components of Skeletal Muscle
What layer?
- Surrounds and separates individual muscle fibers from one another
- Consists mostly of reticular fibers

A

Endomysium

HISTOLAB MIDTERMS MUSCLE (5 decks)

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