Lecture 10: Muscle Tissue I And II Flashcards
(93 cards)
1
Q
3 types of muscle tissue
A
-skeletal
-cardiac
-smooth
2
Q
Muscle fiber definition
A
-muscle cell
-myocyte
3
Q
Functions of muscle fibers (3)
A
Produce force, movement and heat
4
Q
Muscle fibers are surrounded by
A
Connective tissue
5
Q
Sarcoplasm
A
Cytoplasm in muscle cell
6
Q
What is contraction
A
Interaction of myofilaments
7
Q
2 myofilaments in muscle fibers
A
Actin and myosin
8
Q
Actin are __________ filaments
A
Thin
9
Q
Myosin are __________ filaments
A
Thick
10
Q
How/why do actin and myosin move (general)
A
-calcium causes conformational change
-actin and myosin move relative to each other (stack)
11
Q
Which muscle tissue types are striated
A
Skeletal and cardiac
12
Q
Which muscle type is non striated
A
Smooth
13
Q
2 general Features of skeletal muscle
A
-larger cell diameter = greater force
-rich blood supply
14
Q
Is skeletal muscle mononucleated or multinucleated
A
Multi
15
Q
Skeletal muscle contains an abundance of
A
-mitochondria
-glycogen
-myoglobin
16
Q
Myoglobin vs hemoglobin
A
Myoglobin has more oxygen
17
Q
What is skeletal muscle usually attached to
A
Bone
-sometimes other muscles
18
Q
Fascia
A
Connective tissue arranged in a sheet
19
Q
Fascicle definition
A
Bundles of muscle fibers
20
Q
Muscle fiber definition
A
Myocyte (muscle cell)
21
Q
Myofibrils definition
A
Long row of myofilaments
22
Q
Organization of skeletal muscle (biggest to smallest)
A
Bone —> muscle —> fascicle —> muscle fiber —> myofibrils
23
Q
3 layers surrounding skeletal muscle
A
-epimysium
-peri my sim
-endomysium
24
Q
Epimysium
A
Surrounds entire muscle
25
Perimysium
Surround fascicles
26
Endomysium
Surrounds muscle cell/myocyte
27
Epimysium and perimysium are composed of what kind of structural protein
Type 1 collagen
28
Endomysium is composed of what structural proteins
Other types of collagen (not type 1)
29
What do striations result from in skeletal muscle
Overlapping myofilament arrangement
30
What 3 skeletal muscle striations can we see at the level of light microscopy
-A bands
-I bands
-Z disk
31
A bands appearance
Dark bands
32
I bands appearance
Light bands
33
Z disk aka
Z line
34
Z disk appearance
Dark line in I band
35
What striations get closer together in skeletal muscle during contraction
Z disks
36
What 5 skeletal muscle striations are visible at TEM
-I band
-A band
-Z disk
-H band
-M line
37
Sarcomere definition
Z disk to Z disk
38
What is the smallest contractile unit in skeletal muscle
Sarcomere
39
Sliding filament theory
Z lines brought closer together as myofilaments (actin and myosin) slide past each other
40
Do myofilaments change length
No
41
Invaginations of the sarcolemma that cause depolarization and calcium release are called
T tubules
42
Triad definition
2 terminal cisternae + 1 t tubule located at junction of the A and I bands
43
Cisternae are
Flattened membrane found in smooth ER
44
Motor unit is defined as
Motor neuron + muscle fibers it innervates
45
Terminal bouton aka
Synaptic knob
46
Skeletal muscle fiber contraction is similar to propagation of action potential in axon how?
All or none
47
All or none principle of contraction in skeletal muscles
All will contract or none
48
Neuromuscular junctions are basically just
Synapses
49
Structures involved in skeletal muscle fiber motor innervation (3)
-axon terminal of motor neuron containing synaptic vesicles with ACh
-synaptic cleft
-sarcolemma of myocyte containing junctional folds and ACh receptors
50
2 structures involved in skeletal muscle fiber sensory innervation
-muscle spindles
-golgi tendon organ
51
Function of muscle spindles: skeletal muscle fiber sensory innervation
-non contractile
-proprioception
52
Golgi tendon organ
-sensory innervation
-monitor changes in length and tension (keep track of how much muscle is contracting)
53
Primary response of skeletal muscle to stress
Hypertrophy
54
Response to stress: hypertrophy (how it works)
-Myocytes enlarge by adding proteins
-satellite cells fuse with muscle fibers
55
What process is limited in skeletal muscle during stress response
Hyperplasia = adding new cells
56
Because hyperplasia is limited, how does stress affect skeletal muscle
Scar tissue formed
57
Rigor mortis
-after death
-lack of ATP prevents dissociation of actin and myosin
-so actin and myosin stuck in whatever position they were in (stiffness)
58
Where is cardiac muscle located
Myocardium of heart and proximal portion of pulmonary
59
Cardiac muscle features/appearance (2)
-striated
-Sarcomeres
60
How cardiac muscle contractions are modulated (what system)
Autonomic nervous system
61
How cardiac muscle contractions are propagated (by what)
Gap junctions
62
Cardiac muscle: nucleus
-mononucleated
-centrally located
63
Do cardiac muscle fibers branch
Yes
64
Intercalated disks
-unique to cardiac muscle
-where intercellular junctions occur
65
What structure allows cardiac muscle cells to stick together
Desmosomes
66
2 portions of intercalated disk
-transverse
-longitudinal
67
2 components/structures found in transverse portion of intercalated disk
-fascia adherens
-desmosomes
68
components found in longitudinal portion of intercalated disk
-gap junctions
69
Transverse vs longitudinal portion of intercalated disk (function)
-Transverse = stability
-Longitudinal = less mechanical stress
70
How t tubules and sarcoplasmic reticulum are arranged in cardiac muscle fibers (vs skeletal)
Diad
71
Where does diad occur in cardiac muscle fiber
Z disk
72
How cardiac muscle responds to stress (3)
-negligible hyperplasia
-hypertrophy
-injury leading to cell death and fibrosis (scar tissue)
73
Where is smooth muscle found
Hollow organs, blood vessels, dermis, respiratory passages
74
What does smooth muscle produce themselves
their own CT matrix
75
What kind of layers are smooth muscle often found in
Perpendicular
76
Smooth muscle shape
Fusiform
77
Smooth muscle nucleus (General)
Mononucleated, central
78
What happens to smooth muscle nucleus during contraction
Corkscrew
79
Is smooth muscle striated
No
80
Does smooth muscle have sarcomeres, actin and myosin
-kind of sarcomeres
-yes, actin and myosin
81
Does smooth muscle have t tubules
No
82
Where is most calcium found in smooth muscle cells
Extracellular
83
Caveolae
Membrane invaginations that facilitate intake of calcium
84
Of the 3 kinds of muscles, which has the slowest contractions
Smooth muscle
85
How are myofilaments arranged in smooth muscle and what is the function
-Crisscross pattern
-contraction of fusiform shape
86
3 main components/structures of smooth muscle
-myofilaments
-nucleus
-dense body
87
Dense body
-where actin is anchored
-similar function as Z lines (get closer)
-stabilized by intermediate filaments
88
2 types of smooth muscle contraction
-multi unit
-single unit (unitary)
89
Multi unit contraction: smooth muscle
-muscle functions as multiple units of cells
-each unit innervated by single ANS neuron
-no/few gap junctions
90
Example of smooth muscle multiunit contraction
Iris, vas deferens
91
Where are axon terminals located in multiunit contraction of smooth muscle
Connective tissue
92
Single unit contraction: smooth muscle
-all cells contract together
-cells linked by gap junctions
-contractions initiated by mechanical/chemical stimulated, modulated by ANS
-slow, energy efficient contractions
93
Examples of single unit contraction in smooth muscle
-uterus
-GI
-urinary tract
