Muscle Flashcards
1
Q
What does muscle do to chemical energy?
A
Changes it into mechanical energy
2
Q
How much of the body weight does muscle form?
A
50%
3
Q
What percentage of muscle does the skeletal muscle make up?
A
80%
4
Q
What percentage of muscle does smooth and cardiac muscle make up?
A
10%
5
Q
What are the five functions of muscle?
A
- They contract…
- They generate heat
- They generate motion
- They generate force
- They provide support
6
Q
What are the three main types of muscle?
A
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
7
Q
Name the voluntary muscle
A
Skeletal muscle
8
Q
Name the involuntary muscles
A
Cardiac and smooth
9
Q
What types of muscle are skeletal and cardiac muscle?
A
Striated muscle
10
Q
What type of muscle is smooth muscle?
A
Unstriated muscle
11
Q
Is skeletal muscle strong or weak?
A
Strong
12
Q
Is cardiac muscle strong or weak?
A
Strong
13
Q
Is smooth muscle strong or weak?
A
Weaker
14
Q
What type of contractions does skeletal muscle have?
A
Short contractions
15
Q
What type of contractions does cardiac muscle have?
A
Continuous contractions
16
Q
What type of contractions does smooth muscle have?
A
Continuous contractions
17
Q
What type of nuclei does skeletal muscle have?
A
Peripheral nuclei
18
Q
What type of nuclei does cardiac muscle have?
A
Central nuclei
19
Q
What type of nuclei does smooth muscle have?
A
Central nuclei
20
Q
What is the make up of skeletal muscle?
A
Fibres, striations
21
Q
What is the make up of cardiac muscle?
A
Fibres (branching), striations
22
Q
What is the make up of smooth muscle?
A
Cells
23
Q
What is a skeletal muscle also called and why?
A
A muscle fibre because of its greater length than width
24
Q
What is the length of a muscle fibre?
A
75,000 µm or 2.5 feet
25
What is the diameter of a muscle fibre?
From 10 to 100 micrometers
26
What is the shape of a muscle fibre?
Elongated and cylindrical
27
What is the outer membrane of a muscle fibre called?
Sarcolemma
28
What is the chemical composition of muscle?
- Proteins (20%) (either as enzymes or for muscle Control)
- Lactic Acid (in muscle that has undergone fatigue)
- ATP, ADP
- Myoglobin (stores O2 & gives colour to the muscle)
29
What are all muscle fibres innervated by?
A single neuron
30
What is the innervation ratio of motor neuron to muscle fibres?
From 1:100 to 1:2000
31
What is the motor neuron of skeletal muscle cells?
Spinal motor neuron
32
Eye motor neurons ratio
1:23
33
What is the myoneural junction?
Synapse between motor neuron & muscle fiber
34
What is the motor end plate?
A specialised area of sarcolemma under axon terminal
35
What is the neurotransmitter of the myoneural junction?
Acetylcholine
36
What is the sarcolemma?
Plasmalemma of muscle cells.
37
What is external to the sarcolemma?
A well developed basement membrane
38
What is the sarcoplasm?
Cytoplasm of muscle cells excluding the myofibrils
39
What is the sarcoplasmic reticulum?
Smooth endoplasmic reticulum of muscle cells.
40
What is the epimysium?
Thick layer of collagenous connective tissue that separates large bundles of muscle
41
What is the perimysium?
Collagenous connective tissue that separates smaller bundles of muscle cells called fascicles
42
What is the fascicle?
A bundle of muscle cells bounded by perimysium
43
What is the endomysium?
A thinner layer of connective tissue that separates individual muscle cells
44
How is skeletal muscle connected to bone?
Via a tendon
45
What are each muscle cell (nuclei)?
Syncytial
46
What does syncytial mean?
Each striated muscle cell contains multiple nuclei (multinucleate)
47
What is present within the sarcoplasm?
Myofibrils
48
What are myofibrils composed of?
Repeating sacromere unit
49
What are myofibrils?
Linear arrays of structures known as sarcomeres that are arranged in an end to end repeating pattern.
50
What do the sarcomeres contain?
Actin and myosin
51
What do actin and myosin do?
They interact to cause contraction of the muscle cells
52
How are tendons formed?
Collagen fibres blend to form the tendon at the end muscle
53
Muscle - breakdown (large to small)
1. Muscle
2. Fascicle
3. Muscle cell/fibre
4. Myofibril
5. Myofilaments
54
What are myofibrils composed of?
Myofilaments
55
What does a myofibril display?
Alternating dark and light bands
56
What are dark bands (band type)?
A bands - thick and thin filaments
57
What are light bands (band type)?
I bands - thin filaments only
58
What (area) is the sarcomere?
The area between 2 consecutive Z discs/ lines
59
What is the functional unit of a muscle?
Sarcomere
60
What is the length of the sarcomere?
2.3 µm
61
What is the Z-disc?
Dense thin membranes made up of special lattice-like proteins present transversely
62
What is the largest known protein in the body?
Titin
63
What are dark or A-band?
Thick filaments present overlapped by the thin filaments at the ends only
64
What are light or I band?
The area present between the ends of the 2 thick filaments. It consists of thin filaments only
65
What is the H-Zone?
The lighter area in the middle of the A-band, where the thin filaments do not reach. It consists of thick filaments only
66
What is the M-line?
A line that extends vertically down the middle of the A-band in the center of the H-zone
67
What are myofilaments / sarcomeres composed of?
- Thick filament myosin
| - Thin filaments actin
68
What happens to the sarcomere during contraction?
It shortens
69
Why are striations present in myofilaments?
Due to alignment of filaments of myofibrils
70
What binds myosin and actin?
Myosin-binding protein C
71
What will G-actin form?
The thin filament
72
What is the molecular weight of G-actin?
43,000
73
What does G-actin have a prominent site for?
For cross-linkage with myosin
74
G-actin →
F-actin → thin filaments
75
What is the polymerised G-actin?
F-actin
76
How long is F-actin?
6-7nm
77
What is the structure of F-actin?
Double stranded
78
What are the two regulatory proteins of the muscles?
- Tropomyosin
| - Troponin
79
What type of protein is tropomyosin?
Rod-like protein
80
What is the molecular weight of tropomyosin?
70,000
81
How many chains does tropomyosin have and what are they?
2 - alpha and beta chains
82
What does tropomyosin do under resting conditions?
It covers the site for myosin attachment on F-actin molecule
83
What does tropomyosin form?
Forms part of thin filaments
84
What is the composition of troponin?
Globular protein complex made of 3 polypeptides
85
What does troponin form?
Part of thin filaments
86
What does troponin C do?
Binds to Ca2+
87
What is the function of troponin I?
Inhibitory in function
88
What does troponin T do?
Is attached to tropomyosin
89
What is the length of thin filaments?
1 µm
90
What is the diameter of thin filaments?
5-8 nm
91
What is the number of G-actin molecules needed in thin filaments?
300-400
92
What are two other proteins present in thin filaments?
- Nebulin
| - Titin
93
What is the function of nebulin in thin filaments?
Provides elasticity to the sacromere
94
What is the function of titin in thin filaments?
It contributes to the contraction of skeletal muscle
95
What is present on actin molecules and why?
A binding site for attachment with myosin cross bridge
96
What is the molecular weight of myosin?
480,000
97
What does the thick filament consist of?
2 symmetrical halves that are mirror images of each other
98
What is the chief constituent of thick filaments?
Myosin
99
How many ends does myosin have?
2
100
What do the ends of myosin consist of?
- A globular end having 2 heads
| - A rod-like tail
101
How many peptide chains does myosin have?
6
102
What are the 6 peptide chains? (types)
- 2 identical heavy chains (200,000 each)
| - 4 light chains (20,000 each)
103
How many binding site does myosin have?
2
104
What are the binding sites of myosin?
1. Binding site for ACTIN
| 2. ATPase site
105
How are myosin tails arranged?
To point toward the centre of the sarcomere
106
How are myosin head arranged?
Point to the sides of the myofilament band
107
What does the epimysium blend into?
Into a connective tissue attachment
108
What are tendons?
Cord-like structures, mostly collagen fibers
109
What are aponeuroses?
Sheet-like structures
110
What is the function of aponeuroses?
Attach muscles indirectly to bones, cartilages, or connective tissue coverings
111
What do tendons do to a joint and why?
Often cross a joint due to toughness and small size
112
What are the features of cardiac muscle?
- Resistant to fatigue
| - Continuous, rhythmic activity
113
What is the function of cardiac muscle?
All-or-none (‘twitch’)
114
What controls the contraction of cardiac muscle?
Pacemaker cells
115
What type of innervation is involved in cardiac muscle?
Involuntary - the parasympathetic nervous system
116
What type of conduction occurs in cardiac innervation?
Electrical conduction (Purkinje fibres and gap junctions)
117
What are cardiocytes?
Cardiac muscle cells
118
What do cardiocytes contain?
Contain myofibrils = striated
119
Where do cells contact each other in cardiocytes?
At intercalated discs
120
What are the cells in cardiocytes bound together by?
- Gap junctions
| - Desmosomes
121
What type of nuclei is present in smooth muscle?
Central nuclei
122
Strength of smooth muscle
Weaker
123
What type of innervation is present in smooth muscle?
– Involuntary (autonomic innervation)
– Dual (stimulatory/inhibitory)
– Graded, spreading & continuous contraction
124
Describe multi-unit smooth muscle
– each cell innervated
| – variable force
125
Describe single-unit smooth muscle
– few cells directly innervated
| – synchronous contraction (myogenic)
126
Give two examples of multi-unit smooth muscle
- Airways
| - Large arteries
127
Give two examples of single-unit smooth muscle
- Gut
| - Uterus
128
What is smooth muscle composed of?
- Thick filaments
| - Thin filaments
129
Give system locations of smooth muscle
```
– cardiovascular system (vessel walls)
– respiratory system
– digestive system
– urinary system
– reproductive system
– Inside the eyes
```
130
What type of contractile apparatus is present in smooth muscle?
Little/weak contractile apparatus
131
What type of cells are present in smooth muscle?
Long, slender, spindle shaped cells
132
Is smooth muscle striated or nonstriated?
Nonstriated
133
What is the body location of skeletal muscle?
Attached to bones or, some facial muscles to skin
134
What is the body location of cardiac muscle?
Walls of the heart
135
What is the body location of smooth muscle?
Mostly in walls of hollow visceral organs (not heart)
136
What is the cell shape and appearance of skeletal muscle?
Single, very long cyclindrical multinucleate cells with very obvious striations
137
What is the cell shape and appearance of cardiac muscle?
Branching chains of cells; uninucleate, striations; intercalated discs
138
What is the cell shape and appearance of smooth muscle?
Single, fusiform, uninucleate, no striations
139
What are the connective tissue components of skeletal muscle?
Epimysium, perimysium and endomysium
140
What are the connective tissue components of cardiac muscle?
Endomysium attached to the fibrous skeleton of the heart
141
What are the connective tissue components of smooth muscle?
Endomysium
142
What is involved in the regulation of contraction in skeletal muscle?
Voluntary; via nervous system controls
143
What is involved in the regulation of contraction in cardiac muscle?
Involuntary; the heart has a pacemaker; also nervous system controls; hormones
144
What is involved in the regulation of contraction in smooth muscle?
Involuntary; nervous system controls; hormones, chemicals, stretch
145
Is there rhythmic contraction involved in skeletal muscle?
No
146
Is there rhythmic contraction involved in cardiac muscle?
Yes
147
Is there rhythmic contraction involved in smooth muscle?
Yes, in some
148
What are the cells in skeletal muscle?
Myoblast mesodermal cells
