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MT-MLS 207 [HISTO LAB] > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

1
Q

What are muscle cells also commonly referred to as?

A

Muscle fibers

Muscle cells are long in structure, leading to this alternative nomenclature.

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2
Q

What is the greatest degree of contractility observed in?

A

Muscle cells (myocytes)

Myocytes are specialized cells that exhibit significant ability to contract.

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3
Q

What is the function of the sarcolemma?

A

Cell membrane of muscle cells

It encloses the muscle cell and regulates the entry and exit of substances.

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4
Q

What does sarcoplasm refer to?

A

Cytoplasm of muscle cells

It contains the organelles and is the site of metabolic processes.

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5
Q

What is the role of the sarcoplasmic reticulum?

A

Smooth endoplasmic reticulum in muscle cells

It is involved in the storage and release of calcium ions, crucial for muscle contraction.

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6
Q

What are sarcosomes?

A

Mitochondria in muscle cells

They are responsible for energy production through ATP synthesis.

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7
Q

What do muscle cells form when they group together?

A

Muscle tissue

These cells are bound by intracellular substances to create functional units.

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8
Q

What type of muscle is almost similar to cardiac muscle?

A

Skeletal muscle

Skeletal muscle shares some structural characteristics with cardiac muscle.

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9
Q

What are the characteristics of skeletal muscle fibers?

A

Very long, cylindrical, unbranched

These fibers give skeletal muscle its unique shape and structure.

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10
Q

Is skeletal muscle striated or non-striated?

A

Striated

The striations are due to the arrangement of actin and myosin filaments.

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11
Q

Is skeletal muscle voluntary or involuntary?

A

Voluntary

Skeletal muscle can be consciously controlled.

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12
Q

What is the nucleation characteristic of skeletal muscle?

A

Multinucleated, periphery

This means that each muscle fiber contains multiple nuclei located at the edges.

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13
Q

What are bundles of skeletal muscle fibers called?

A

Fascicles

Fascicles are groups of muscle fibers that are bundled together.

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14
Q

What is the outer layer that encloses bundles of fascicles called?

A

Epimysium

The epimysium is made of dense irregular connective tissue.

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15
Q

What is the function of the perimysium in skeletal muscle?

A

Encloses bundles of fascicles

The perimysium consists of thin connective tissue layers, similar to but thinner than the epimysium.

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16
Q

What does the endomysium enclose?

A

Inner layer of the fascicle or muscle fibers

The endomysium consists of reticular fibers with scattered fibroblasts.

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17
Q

What is a sarcomere?

A

The basic unit of muscle contraction, consisting of repetitive small contractile units from one Z disc to another Z disc.

Sarcomeres are found in striated muscle and are essential for muscle contraction.

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18
Q

What does the A-band represent in a sarcomere?

A

Darker bands due to thick filaments, which also overlap with thin filaments.

The A-band is critical for understanding the structure of muscle fibers.

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19
Q

What is found in the H-zone of a sarcomere?

A

Thick filaments ONLY, appearing as a lighter zone in the center of the A-band.

The H-zone is important for distinguishing between thick and thin filaments.

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20
Q

What is the M-line in a sarcomere?

A

A thin dark stripe that bisects the H-zone.

The M-line helps maintain the alignment of thick filaments.

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21
Q

What does the I-band represent in a sarcomere?

A

Lighter bands due to the presence of thin filaments ONLY.

The I-band changes in width during muscle contraction.

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22
Q

What is the function of the Z-disc?

A

It bisects the I-band and serves as an anchor point for thin filaments.

Z-discs are crucial for the structural integrity of sarcomeres.

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23
Q

What are thick filaments primarily composed of?

A

Myosin, which is made up of 6 polypeptide chains: 2 heavy chains and 4 light chains.

Myosin is essential for muscle contraction.

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24
Q

What is F-actin?

A

Long filamentous polymers that are anchored on the Z-disc.

F-actin is a crucial component of the thin filament structure.

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25
What is the relationship between G-actin and F-actin?
G-actin units form bundles to create F-actin. ## Footnote G-actin is the globular form of actin, whereas F-actin is filamentous.
26
What is the role of tropomyosin in muscle fibers?
It regulates the interaction between actin and myosin, consisting of 3 troponin subunits. ## Footnote Tropomyosin is vital for muscle contraction regulation.
27
What are the three subunits of troponin?
* TnT (tropomyosin) * TnC (calcium ions) * Tnl (inhibit actin-myosin interaction) ## Footnote Each subunit of troponin has a specific role in muscle contraction.
28
Fill in the blank: The H-zone is lighter because it contains _______.
[thick filaments ONLY]
29
True or False: The I-band contains both thick and thin filaments.
False ## Footnote The I-band contains only thin filaments.
30
What is the junction formed between a motor neuron and a muscle fiber called?
NEUROMUSCULAR JUNCTION or SYNAPSE
31
What is the enlarged axon terminal resting in indentations of the muscle fiber's cell membrane called?
PRE-SYNAPTIC TERMINAL
32
What is the space between the Pre-synaptic Terminal and the muscle fiber membrane called?
SYNAPTIC CLEFT
33
What does the muscle fiber membrane that the Pre-synaptic Terminal is on referred to as?
POST-SYNAPTIC MEMBRANE
34
What neurotransmitter is released into the synaptic cleft during muscle contraction?
acetylcholine
35
What process releases acetylcholine from the vesicles in the axon terminal?
exocytosis
36
Where does acetylcholine bind after being released in the synaptic cleft?
folded sarcolemma located in the post-synaptic membrane
37
What does the binding of acetylcholine to the post-synaptic membrane trigger in the muscle fiber?
action potential
38
Fill in the blank: The space between the pre-synaptic terminal and the muscle fiber membrane is called the _______.
SYNAPTIC CLEFT
39
True or False: The post-synaptic membrane is the same as the muscle fiber membrane.
True
40
What triggers the action potential in muscle contraction?
It is triggered once the action potential goes through T-tubule.
41
What is released from the sarcoplasmic reticulum during muscle contraction?
Calcium.
42
What does calcium bind to in the muscle fiber?
Troponin C.
43
What is the role of tropomyosin during muscle contraction?
It opens to expose the Troponin binding site.
44
What happens when a muscle contracts according to the sliding filament model?
The SARCOMERES shorten.
45
What causes the thick and thin filaments to slide past each other?
The interaction of the actin and myosin molecules.
46
Fill in the blank: The sliding filament model states that when a muscle contracts, the _______ shortens.
SARCOMERES
47
True or False: The sliding filament model explains that the thick and thin filaments remain stationary during muscle contraction.
False
48
What binds to the Myosin-binding site during muscle contraction?
Myosin heads ## Footnote The Myosin-binding site is present in the F-actin.
49
What causes tropomyosin to flip or rotate?
Calcium binding ## Footnote This exposes the Myosin-binding site for binding with Myosin heads.
50
What molecules are bound to the head of each myosin unit before contraction?
ADP and phosphate ## Footnote These remain from the previous muscular contraction.
51
What do myosin heads do after binding to actin myofilaments?
Release phosphates ## Footnote They then bind to the actin myofilaments via the newly exposed myosin binding sites.
52
What propels the sliding motion of myofilaments?
Head-first movement of the myosin units powered by chemical energy ## Footnote This energy is stored in the myosin heads.
53
What happens to ADP molecules during the sliding motion?
They are released ## Footnote This occurs as the myosin units move.
54
What halts the gliding/sliding motion of myofilaments?
ATP binding to myosin heads ## Footnote This severes the bond between myosin and actin.
55
What do ATP molecules decompose into?
ADP and phosphate ## Footnote The energy released is stored in the myosin heads for the next cycle.
56
What happens to the myosin heads after ATP decomposition?
They resume their starting positions along the actin myofilament ## Footnote This allows them to begin a new sequence of actin binding.
57
What triggers a new cycle of muscle contraction?
Further calcium ions ## Footnote This is essential for the continuation of the sliding filament process.
58
Fill in the blank: The process described is called _______.
SLIDING FILAMENT BUNDLE ## Footnote This process leads to muscle contraction.
59
What happens to all bands in fully relaxed skeletal muscle?
All bands (parts of sarcomere) would be available in the full relaxed skeletal muscle ## Footnote This indicates that the sarcomere is at its maximum length.
60
What occurs to the diameter of the I-band when fully contracted?
Its diameter decreases in size once it is fully contracted ## Footnote The I-band represents the area of thin filaments.
61
What happens to the H-zone when the muscle is fully contracted?
The H-zone will somehow disappear once fully contracted ## Footnote The H-zone is the region where only thick filaments are present.
62
What is present in the sarcomere when it is fully relaxed?
Thick Filaments only ## Footnote This indicates that thin filaments are not overlapping in a fully relaxed state.
63
What is the configuration of filaments in a fully contracted sarcomere?
Overlapping of thick and thin filaments ## Footnote This overlap is what generates muscle contraction.
64
What is the shape of cardiac muscle cells?
Elongated and branched ## Footnote This structure allows for efficient contraction and connection between cells.
65
Are cardiac muscle cells striated or non-striated?
Striated ## Footnote This striation is due to the organized arrangement of sarcomeres.
66
Is cardiac muscle voluntary or involuntary?
Involuntary ## Footnote Cardiac muscle functions autonomously without conscious control.
67
How many nuclei do cardiac muscle cells typically have?
1 to 2 centrally located nuclei ## Footnote This is in contrast to skeletal muscle cells, which are multinucleated.
68
What are intercalated discs?
The interface between adjacent muscle cells ## Footnote Intercalated discs contain gap junctions and desmosomes, facilitating communication and strength.
69
What initiates the contraction of the entire heart?
Involvement of electrical impulse ## Footnote This electrical impulse is essential for synchronized heart contractions.
70
How are sarcomeres in cardiac muscle organized compared to skeletal muscle?
Organized and function similarly ## Footnote This similarity allows for effective contraction mechanics.
71
What are Purkinje fibers?
Modified cardiac muscle cells specialized to initiate and conduct electrical impulse ## Footnote They play a crucial role in the heart's conduction system.
72
What is the primary function of Purkinje fibers?
To receive the electrical impulse of the heart ## Footnote This allows for rapid conduction throughout the heart muscle.
73
What type of muscle is described as fusiform and unbranched?
Smooth muscle ## Footnote This muscle type is characterized by its elongated, tapering shape.
74
Is smooth muscle striated or non-striated?
Non-striated ## Footnote Smooth muscle lacks the striations seen in skeletal muscle.
75
What is the nature of the control of smooth muscle contraction?
Involuntary ## Footnote Smooth muscle contractions are not under conscious control.
76
What is the nucleation characteristic of smooth muscle cells?
Mononucleated ## Footnote Smooth muscle cells typically have a single nucleus located centrally.
77
How are myofilaments arranged in smooth muscle?
They do not form sarcomeres ## Footnote Myofilaments are scattered throughout the sarcoplasm.
78
What anchors thin filaments in smooth muscle?
Dense bodies that contain a-actinin ## Footnote Dense bodies serve as attachment points for thin filaments.
79
What type of nerves primarily regulate smooth muscle contraction?
Autonomic nerves ## Footnote The contraction of smooth muscle is primarily controlled by the autonomic nervous system.
80
What happens to smooth muscle cells upon contraction?
The entire cell gets smaller ## Footnote This contraction leads to a reduction in the overall size of the smooth muscle cell.
81
Where is smooth muscle primarily found?
In organs, especially in the digestive tract ## Footnote Smooth muscle facilitates the movement of food through the digestive system.
82
Fill in the blank: Food travels from the oral cavity up to anus via _______.
smooth muscle ## Footnote Smooth muscle contractions move food through the digestive tract.
83
How do dense regular muscles compare to smooth muscles in terms of shape?
Dense regular are more curvy, smooth muscles are straight ## Footnote This describes the structural differences between these muscle types.

MT-MLS 207 [HISTO LAB] (7 decks)

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