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Cell and Tissue Structure > Muscle excitable tissue L2 > Flashcards

Muscle excitable tissue L2 Flashcards

(90 cards)

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1
Q

What are the 4 tissue types?

A

Epithelial, Muscle (excitable), Nervous (excitable), Connective (cells, fibres, matrix)

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2
Q

How much of the total body weight does muscle form?

A

50%: 40% skeletal muscle and 10% smooth and cardiac muscle

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3
Q

What functions do muscles preform. Hint there should be 5 functions.

A

They contract, they generate heat, they generate motion, they generate force, and they provide support

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4
Q

What type of muscle is skeletal?

A

Striated, voluntary muscle

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5
Q

What type of muscle is cardiac?

A

Striated, involuntary muscle

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6
Q

What type of muscle is smooth?

A

Unstriated, involuntary muscle

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7
Q

Where are the nuclei located on skeletal muscle?

A

Peripheral nuclei

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8
Q

Is skeletal muscle strong or weak?

A

strong

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9
Q

What type of contractions occurs with skeletal muscle?

A

Short contractions

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10
Q

What type of contractions occurs with cardiac muscle?

A

Continuous contractions

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11
Q

Where are the nuclei located on cardiac muscle?

A

Centrally

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12
Q

Is cardiac muscle strong or weak?

A

Strong

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13
Q

Is smooth muscle stronger or weaker?

A

weaker

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14
Q

What type of contractions are associated with smooth muscle?

A

Continuous contractions

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15
Q

Where are the nuclei located with smooth muscle?

A

Centrally

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16
Q

What can a single skeletal muscle cell also be called and why?

A

A single skeletal muscle cell is also called a muscle fibre because of its greater length than width

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17
Q

What is the chemical composition of skeletal muscle?

A

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)

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18
Q

What is the length of skeletal muscle cells?

A

Up to 75,000 µm or 2.5 feet

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19
Q

What is the diameter of skeletal muscle cells?

A

From 10-100 micrometres

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20
Q

What is the shape of skeletal muscle cells?

A

Elongated and cylindrical

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21
Q

Do skeletal muscle cells have an outer membrane?

A

Yes it is called sarcolemma

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22
Q

Are there nuclei and organelles in skeletal muscle cells?

A

Yes they are present. Mitochondria and E.R

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23
Q

What is the myoneural junction?

A

It is the synapse between motor neuron and muscle fibre

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24
Q

What neurotransmitter is associated with the myoneural junction?

A

Acetylcholine

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25
What is a motor unit?
It is all the muscle fibres innervated by a single neuron
26
What is the innervation ratio of motor neuron : muscle fibres?
1:100 to 1:2000
27
What are the innervation ratios of eye motor neurons and gastrocnemius?
Eye motor neurons 1:23, Gastrocnemius 1:1000
28
What is the motor end plate of the myoneural junction?
It is a specialised area of sarcolemma under the axon terminal
29
What is the sarcolemma?
The plasmalemma of muscle cells. External to this cell membrane is a well developed basement membrane
30
What is the sarcoplasm?
It is the cytoplasm of muscle cells excluding the myofibrils.
31
What is the epimysium?
A thick layer of collagenous connective tissue that separates large bundles of muscle.
32
What is the perimysium?
A collagenous connective tissue that separates smaller bundles of muscle cells called fascicles.
33
What is a fasicle?
It is a bundle of muscle cells bounded by perimysium.
34
What is the endomysium?
It is a thinner layer of connective tissue that separates individual muscle cells.
35
How do muscle fibers develop?
They develop through the fusion of mesodermal cells called myoblasts
36
What do collagen fibres do in skeletal muscle organisation?
They blend to form tendon at end muscle
37
What do tendons do in skeletal muscle organisation?
Tendons attaches skeletal muscle to bone
38
What type of muscle are muscle fibres found?
In skeletal and cardiac muscle
39
What are muscle cells. Hint Fibres
Muscle cells make individual muscle fibers which are cells that are large and elongated and have multiple peripheral nuclei that produce voluntary contractions
40
What are myofibril's made up of?
Myofilaments
41
What are myofilaments/sarcomeres composed of?
Thick filament called myosin and thin filaments called actin
42
Why are striations formed?
Due to alignment of filaments of myofibrils
43
What happens during contraction?
The sarcomere shortens and myosin binding protein C binds myosin and actin
44
What is G-actin?
G-actin is the monomer which will form the thin filament (actin). It is a protein with a molecular weight of 43 KDa. It has a prominent site for cross-linkage with myosin.
45
How are actin - thin filaments formed?
G-actin goes to F-actin which is a long polymerised G-actin that is 6-7nm long and double stranded in structure and that goes to thin filaments.
46
What are 2 regulatory proteins of the muscles?
Tropomyosin and Troponin
47
What is troponin?
It is a globular protein complex that is made up of 3 polypeptides: Troponin C,I,T which forms part of thin filaments.
48
What does troponin C do?
Binds to Ca^2+
49
What is the function of troponin I?
It is inhibitory in function
50
What is Troponin T?
It is attached to tropomyosin
51
What is tropomyosin?
A rod like protein with a molecular weight of 70kDa. It has 2 chains of alpha and beta chains. It forms part of thin filaments of muscle
52
What does tropomyosin do under resting conditions?
It covers the site for myosin attachment on F-actin molecule
53
What does the protein Nebulin do in regards to thin filaments?
Nebulin provides elasticity to the sarcomere
54
What does the protein Titin do in regards to thin filaments?
Titin is the largest known protein in the body. It contributes to the contraction of skeletal muscle
55
What length are thin filaments?
1 µm
56
What is the diameter of thin filaments?
5-8nm
57
What is the number of G-actin mol?
300-400
58
What are thick filaments consistent of?
2 symmetrical halves that are mirror images of each other. The chief constituent is myosin.
59
What is the molecular weight of myosin?
480 KDa
60
Describe the molecule myosin?
Its molecule has 2 ends, a globular end having 2 heads and a rod like tail. It has 6 peptide chains: 2 identical heavy chains with 200 KDa each and 4 light chains with 20 KDa each
61
What are the 2 binding sites on the myosin molecule?
Binding site for actin and ATPase site
62
3 things about the innervation of cardiac muscle?
The innervation is involuntary, the pacemaker cells coordinate contraction of tissue and there is electrical conduction (Purkinje fibres and gap junctions)
63
Is cardiac muscle resistant to fatigue?
Yes
64
Does cardiac muscle have an all or none feature?
Yes ("twitch")
65
What is the name for cardiac muscle cells?
Cardiocytes
66
What do cardiocytes contain?
Myofibrils which are striated
67
Where do cardiocytes cells contact each other?
At intercalated disks
68
What do cardiocytes cells bind together by?
Gap junctions and desmosomes
69
Where is the body location of skeletal muscle?
Attached to bones or, for some facial muscles to skin
70
What is the cell shape and appearance of skeletal muscle?
Single, very long, cylindrical, multinucleate cells with very obvious striations
71
Where is the body location of cardiac muscle?
Walls of the heart
72
Where is the body location of smooth muscle?
Mostly in walls of hollow visceral organs (other than the heart)
73
What is the cell shape and appearance of cardiac muscle?
Branching chains of cells; uninucleate, striations; intercalated disks
74
What is the cell shape and appearance of smooth muscle?
Single, fusiform, uninucleate; no striations
75
Is the innervation of smooth muscle involuntary?
Yes, autonomic innervation
76
Is the innervation of smooth muscle stimulatory or inhibitory?
It is dual, both stimulatory and inhibitory
77
Is the smooth muscle innervation graded?
Yes it is graded and spreading and continuous contraction
78
Describe multi-units of smooth muscle:
Each cell is innervated with variable force for example in the airways, and large arteries
79
Describe single-units of smooth muscle:
Very few cells are innervated. There is synchronous contraction which is myogenic. For example in the gut and uterus
80
Smooth muscle is located in the organs of....
Cardiovascular system (vessel walls), respiratory system, digestive system, urinary system, reproductive system and inside the eyes
81
What are the function and features of smooth muscle?
Little/weak contractile apparatus, long, slender, spindle shaped cells with single central nucleus and is nonstriated
82
What is the speed of contraction of skeletal muscle?
Slow to fast
83
What is the regulation of contraction in skeletal muscle?
Voluntary via nervous system controls
84
What is the regulation of contraction in cardiac muscle?
Involuntary, the heart has a pacemaker and also nervous system controls and hormones
85
What is the speed contraction of cardiac muscle?
slow
86
What is the regulation of contraction in smooth muscle?
Involuntary with nervous system controls, hormones, chemicals, stretch
87
What is the speed of contraction like in smooth muscle?
Very slow
88
What are the connective tissue components of skeletal muscle?
Epimysium, perimysium and endomysium
89
What are the connective tissue components of smooth muscle?
Endomysium
90
What are the connective tissue components of cardiac muscle?
Endomysium attached to the fibrous skeleton of the heart

Cell and Tissue Structure (8 decks)

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