L7-L8 Muscle Tissue I and II Flashcards
1
Q
What are 3 types of muscle?
A
- Skeletal
- Cardiac
- Smooth
2
Q
What is a muscle fiber? (=)
A
Muscle fiber = muscle cell = myocyte
3
Q
All muscle fibers are _______? * and what happens?
A
Contractile, **Muscles contract by getting shorter
4
Q
Function of muscle fibers?
A
Produce force, movement, and heat
5
Q
Where are muscle fibers located?
A
Surrounded by connective tissue matrix and are bounded by external lamina
6
Q
3 Unique terminology of muscle fibers? And what are they really in other parts (other names)?
A
- Sarcolemma: plasma membrane
- Sarcoplasm: cytoplasm
- Sarcoplasmic reticulum (SR)
7
Q
What is a contraction?
A
Interaction of cytoplasmic protein chains = myofilaments
8
Q
What are the thin and thick filaments?
A
Actin (thin) & Myosin (thick)
9
Q
____ causes conformational change of muscle fibers?
A
Ca 2+
10
Q
Striated vs Nonstriated muscle?
A
Striated: skeletal and cardiac muscle stripes
Nonstriated: smooth muscle
11
Q
What is cell diameter proportional to?
A
Force production - rich blood supply in surrounding CT
12
Q
Skeletal muscle has abundance of? (3)
A
- Mitochondria
- Glycogen (mainly store carbs for energy)
- Myoglobin (similar to hemoglobin but with more oxygen)
13
Q
Organization of skeletal muscle?
A
Tendon -> muscle -> fascicle -> muscle fiber -> myofibrils
14
Q
Definition of fascicle?
A
Bundles of muscle fibers
15
Q
Muscle fibers definition?
A
Myocyte (muscle cell)
16
Q
Myofibrils definition?
A
Long rows of myofilaments, more than 1 nucleus
17
Q
What is skeletal muscle invested by?
A
Connective tissue
18
Q
What is endomysium and where is it located?
A
Endomysium is AROUND cells; type IV, III collage (similar to basal lamina/ reticular lamina function).. stuck to muscle sarcolemma
19
Q
What is perimysium and where is it located?
A
Around fascicles; type I collagen; surrounded by epimysium
20
Q
What is epimysium and where is it located?
A
Around the whole muscle, type I collagen, smallest unit made up of muscle fiber; surrounded by endomysium
21
Q
What are two types of skeletal muscle?
A
Red muscle, white muscle
22
Q
Red muscle features?
A
Slow-twitch, type I
- Aerobic
- Abundant mitochondria & myoglobin molecules
- Slower, weaker, more fatigue resistance *
23
Q
White muscle features?
A
Fast-twitch type II
- Better capability for anaerobic glycolysis
- More glycogen
- Faster, stronger, less fatigue resistance*
24
Q
What type of fibers share categories of both?
A
Intermediate fibers
25
What are the skeletal muscle striations at LM? (3)
1. A bands: dArk band
2. I bands: LIght bands
3. Z disk: dark line in I band (also Z line looks like zipper)
26
When muscle contracts, what is it called and how is it accomplished?
Z disks come together and is called sarcomere, which is smallest contractile unit
27
What do striations result from?
Overlapping myofilament arrangement
28
Within the A band, what things are there? (2_
H band in the middle horizontally, M line in the dark line of the A band vertically
29
What is the sliding filament theory?
Z lines are brought closer together as myofilaments slide past each other (myofilaments do not change length)
30
What does the sarcoplasmic reticulum look like and what is a part of it?
Looks like tape with horizontal holepunch in cartoon figure; the terminal cisternae is part of SR that gets puffy
31
What is a terminal cisternae?
Invaginations of the sarcolemma
32
T-tubule, terminal cisternae on one side, and terminal cisternae on the other side are all called what?
Triad
33
What is the Triad? ***
2 terminal cisternae + 1 T-tubule are located at junction of A & I bands
34
In skeletal muscle, what is a motor unit?
Motor neuron + muscle fibers it innervates
35
What type of contraction principle does a motor unit follow?
"All or none"principle of contraction
36
At the end of the muscle fibers there are these rounds things- what are they called?
Terminal button
37
In the axon terminal of motor neuron, there are __?
Synaptic vesicles w/ ACh
38
There is a space between terminal button and muscle fiber.. the synaptic vessels join with neuron's plasma membrane and release ______ (steps)?
Neurotransmitter to synaptic cleft -> Sarcolemma of myocyte (junctional fold), usually ACh --> rush to T-tubule -> SR tells Z line to contract
39
What would synaptic vesicles do?
Synaptic vesicles goes to the plasma membrane
40
What is the common error students believe about the synaptic vesicles? (explain)
COMMON ERROR: students think SV cross synaptic cleft to go through muscle.. WHY wrong? bc plasma membrane is part of another cell. Instead, join (exocytosis or secretion of neurotransmitters) into synp cleft where it would be taken off by junctional folds
41
What is the function of muscle spindles and Golgi tendon organ?
Monitor changes in length & tension and also participate in stretch reflex
42
Nervous system divided into 2 directions of information?*
1. Motor: info from CNS OUT*
| 2. Sensory: info from periphery IN*
43
2 responses to stress in skeletal muscle?
1. Limited hyperplasia (adding cells)
| 2. Primary response is hypertrophy
44
Features of limited hyperplasia? (2)
- No mitosis
- Satellite cells may give rise to myoblasts (make muscle cells) if external lamina is intact - otherwise, scar tissue is formed
45
Features of primary response of stress? (2)
Hypertrophy
- Myocytes enlarge by addition of proteins
- Satellite cells fuse with muscle fibers
46
Clinical correlation- rigor mortis and how it works?*
Occurs following death because lack of ATP which prevents the disassociation of actin and myosin (stiffness b/c no energy to unlink them.. until it degrades and becomes relaxed again)
NO MEANS OF RETAINING CALCIUM*
47
What are muscle tissue?
Major cells in body which contract and produce movement
48
What is the difference between muscle and cardiac?
Cardiac muscle has ONE nucleus
49
Where is the cardiac muscle located?
In myocardium of the heart & proximal portion of pulmory vv
50
Cardiac muscle features? ___ ___
Striated, sarcomeres
51
What are autorhythmic contractions and what do they do?
- Modulated by autonomic neurons
| - Propagated by gap junctions
52
What are striated muscles under control of?
Somatic nervous system
53
What are autonomic neurons?
Part of nervous system where we do not have conscious control over
54
What do cardiac muscles have a tendency to do?
Branch and end in squiggly lines- like puzzle
55
What are intercalated disks?
Dark-staining line where intercellular junctions occur
56
In a EM of intercalated disks, what are the two important portions you need to know (and 2 anatomy parts of each)?
- Transverse portion: Fascia adherens (FA), Desmosomes (D)
| - Longitudinal portion: Gap junctions (N), less mechanical stress
57
What is an important not about intercalated disks?
Abundant mitochondria & glycogen inclusions
58
What keeps the intercalated disks together?
Nexus
59
What are some features of cardiac muscle FIBERS? (4)
- Can be branched, arranged in layers (laminae)
- Mononucleated, central nucleus
- Mitochondria and myoglobin in very high quantity
- Intercalated discs with gap junctions
60
What are connexons part of ____ _____ ?
Gap junction
61
4 features cardiac muscle fibers?
- T-tubules large, SR sparse, primarily extracellular
- Calcium source
- Diad at the Z disc
- Sarcomeres and myofibrils
62
What are Purkinje fibers?
They are specialized cardiac cells that can depolarize rapidly
63
What occurs when cardiac muscles respond to stress? (3)
- Hyperplasia is negligible (very limited cardiomyocyte mitosis)
- Hypertrophy in response to mechanical stress (addition of proteins, but no satellite cells)
- Injury typically leads to cell death & fibrosis (scar tissue)
64
What is hyperplasia?
Increased cell prod in a normal tissue or organ
65
What is hypertrophy?
In response to mechanical stress (addition of proteins, but no satellite cells)
66
What are satellite cells?
Cells that aid in production of new skeletal muscle cells
67
What is fibrosis (scar tissue)?
Created by surrounding connective tissue
68
Of three types of muscle, which muscles look most disorganized?
Smooth muscle
69
Where is smooth muscle found?
- Found in hollow organs, blood vessels, dermis, respiratory passages
70
Where are smooth muscles most often found in?
Perpendicular layers
71
What do smooth muscles produce?
Their own "CT"matrix
72
What are 3 characteristics of smooth muscle?
1. Fusiform shape
2. Single, central nucleus
3. Not striated
73
What are sarcomeres?
When 2 Z-disks come together
74
Smooth muscles have NO ___?
T-tubules
75
Sarcoplasmic reticulum is very sparse- what is the source and what is important about it?
Ca2+ source is mainly extracellular
76
What are caveolae and what do they do?
Membrane invaginations that facilitate intake of Ca2+/ bring Ca from the ECM (slowest contractions .. milliseconds)
77
What are smooth muscles and what do they do?
Crisscross patterns of myofilaments that facilitate contraction of fusiform shape
78
What is anchored at the dense bodies?
Actin
79
Actin has (2) features?
- Similar function as Z lines
| - Stabilized by intermediate filaments
80
Myofilament have a ____ shape? What is exclusive about them?
Hook shape, they still need to contract but changes position and NOT size
81
What is a focal adhesion?
Telling cells to stick together (spot wells but instead of associated with intermediate filament, it is associated with actin)
82
Why are there rough ER proteins on smooth muscle and not the cardiac/ striated?**
Because makes OWN connective tissue
83
Smooth muscle- what happens when the cell is relaxed versus contracted?***
When the cell is relaxed, the nucleus is oval-shaped
| When the dense bodies physically move closer, it is corkscrew shape!
84
What is a multiunit contraction? (3)
- Muscle functions as multiple units of cells
- Each unit innervated by a single ANS neruon
- No/few gap junctions
85
What are examples of the multiunit contraction?
Iris, vas deferens
86
WHERE ARE TWO PLACES WHERE WE FIND MOST SMOOTH MUSCLE? ****
blood vessels and gut
87
What is significant about the axon terminals in CT?
No direct junction with muscle cells
88
What is single-unit (unitary) contraction?
All cells contract together as a single unit b/c cells linked by gap junctions
89
What are the single-unit contractions initiated by?
Mechanical/ chemical stimuli and modulated by ANS
90
How are the contractions efficient?
Slow, energy efficient
91
What are examples of single-unit contractions?
Uterus, GI & Urinary tracts
