Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microanatomy > Muscle > Flashcards

Muscle Flashcards

1
Q

What is the organization of skeletal muscles?

A

Fasciculus, fibers, myofibrils, myofilaments (actin and myosin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What do the CT coverings of skeletal muscle do?

A

Supply blood vessels, nerves, muscle spindles, and provide a means by which contractile forces are transmitted to other tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the CT coverings of skeletal muscle called?

A

Endomysium, perimysium and epimysium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the structure of the skeletal muscle?

A

10-110 micrometers in diameter
Up to 50 cm in length
Periphery nuclei
Many myofilaments that create light and dark bands
Striations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the functional unit of a skeletal muscle?

A

Sarcomere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Structure of the sarcomere

A

0.5- 1.00 micrometers in diameter
2.00 micrometers long
With I band, A band, H band, M line and Z line
Z line to Z line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

I band

A

Only thin (actin) filaments
White thick line next to A bands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

A band

A

Thick (myosin) and thin (actin) filaments
Thick dark line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

H band

A

Pale area in the center of the A band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

M line

A

Runs down the center of the H band
Results from attachment of adjacent myosin filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Z line

A

Dark band in the center of the I band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Skeletal muscle triad

A

T tubule in the center and SER cisterna on each side
In mammals, each sarcomere exhibits 2 triads one at each A-I band interface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of SER in the T tubule?

A

Stores calcium that is released during contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 2 types of skeletal muscle fibers?

A

Red (type 1) and white (type 2) and intermediate (shares both)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Red (type 1) skeletal muscle fiber?

A

Large amount of myoglobin, numerous mitochondria, energy from oxidative pathway, contract and fatigue slowly
Slow-twitch fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

White (type II) skeletal muscle fibers

A

Larger, fewer mitochondria, more extensive SER, energy from anaerobic glycolysis, contract and fatigue more rapidly,
Fast-twitch fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Regeneration of the skeletal muscle

A

Limited
Satellite (stem) cells present
Most injured muscle cells are replaced by CT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Motor Unit

A

A nerve fiber and the muscle cell it innervates

19
Q

Motor End Plate

A

Point of attachment of a nerve with a skeletal muscle fiber

20
Q

What are the motor end plate modifications at the distal end of axon?

A

loss of myelin sheath, presence of mitochondria and acetylcholine vesicles, dilation of axon

21
Q

What are the motor end plate modifications at the muscle fiber?

A

Folding of cell membranes enclosing sub-neural clefts
Aggregation of mitochondria
Loss of striations

22
Q

Events of Impulse Conduction

A
  1. Depolarization of axolemma
  2. Release of Ach
  3. Binding of Ach with Ach receptors present on sarcolemma
  4. Depolarization of sarcolemma
  5. Extension of depolarization wave to the T tubule and SER cisternae
  6. Release of calcium
  7. Contraction of myofilaments
  8. Inactivation of Ach by cholinesterase enzyme present in sub–neural clefts
  9. Active transport of calcium back to the SER
  10. Relaxation of myofilaments
23
Q

What are the results of contraction?

A

I band and sarcomere reduces in length
H band disappears

24
Q

Huxley’s Sliding Filament Theory

A

Thick and thin filaments maintain the same length but slide past each other during muscle contraction

25
Q

Organophosphorus Toxicity

A

Cholinesterase enzyme is phosphorylated
Results in initial stimulation followed by depression

26
Q

Botulism

A

Caused by toxins secreted by Clostridium botulinum
Blocks the release of Ach
Results in Flaccid tetraparesis

27
Q

Myasthenia Gravis

A

Caused by deficiency of Ach and/ or antibodies against Ach receptors
Results in weakness in muscles

28
Q

Structure of the cardiac muscle

A

10-15 micrometers in diameter
100 micrometers long
1 or 2 nuclei per cell, centrally located
Fibers branch
Striated
No regeneration

29
Q

What does the point of anastomosis show? (Cardiac)

A

Intercalated discs
At EM levels consist of gap junctions, desmosomes and fascia

30
Q

What happens are events of contraction in a cardiac muscle?

A

Similar to skeletal muscle except T tubules are located at the Z line and take the form of dyads rather than triads

31
Q

Purkinje Fibers

A

Impulse conducting modified cardiac fibers

32
Q

Where are purkinje fibers located?

A

Interventricular septum and beneath the endocardium

33
Q

Purkinje fibers structure compared to cardiac muscle cells

A

Occur in groups
50 micrometers
Contain fewer peripherally located myofibrils
Less developed striations
More glycogen

34
Q

Smooth muscle structure

A

Spindle-shaped
Single centrally located nucleus
5-20 micrometers in diameter
20 micrometers to 1 mm or more in length contains actin myosin filaments
Actively divides and regenerates

35
Q

What surrounds the smooth muscle?

A

Surrounded by external lamina except at sites of gap junctions

36
Q

What is present in the striated muscle?

A

Striations and troponin protein

37
Q

Myofilaments in the smooth muscle

A

Attached to dense bodies which are analogous to Z lines of striated muscle

38
Q

How do smooth muscles communicate?

A

Via gap junctions

39
Q

How does contraction in the smooth muscle differ from the skeletal muscle?

A

Occurs more slowly and lasts longer

40
Q

Steps of muscle contraction in smooth muscles

A
  1. Increase in cytosolic calcium,
  2. binding of calcium with calmodulin protein,
  3. activation of myosin kinase
  4. Phosphorylation of myosin
  5. interaction of phosphorylated myosin and actin
  6. contraction
41
Q

What leads to relaxation in the smooth muscle?

A

Desphosphorylization of myosin preventing myosin-actin interaction

42
Q

Urinary smooth muscle contraction

A

Triggered by stretching of the muscle,
Spreads from cell to cell gap junctions
Generates low level of rhythmic contraction
Increased or decreased autonomic nervous system rather than actually initiating the contraction
Ex; viscera of GI tract

43
Q

Multi-unit smooth muscle

A

Triggered by nerve impulses
Precise contractions due to autonomic innervation of each muscle cell
Lack gap junctions
ex: constrictor and dilator muscles of the iris

Microanatomy (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions