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Muscle Flashcards

(59 cards)

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1
Q

How is force produced

A

The movement of actin fibres over myosin fibres, with the aid of a number of accessory proteins

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2
Q

4 types of contractile cells

A

Muscle cells, myoepithelial cells, myofibroblasts, and pericytes

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3
Q

Types of muscle cells

A

Skeletal, cardiac or smooth muscle cells

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4
Q

Myoepithelial cells

A

Found with secretory units of some exocrine glands. They have flattened cells and a contractile protien arrangement similar to smooth muscle

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5
Q

Myofibroblasts

A

Characteristics of both fibroblasts and smooth muscle cells. Enlarge in injury and secrete collagen to provide scaffold for repair and then contract the wound

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6
Q

Pericytes

A

Found around capillaries and venules. Can can act as stem cells but also have contractile properties

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7
Q

How are myotubules formed

A

Within the mesenchyme of the mesoderm, cells will align and eventually lose their separating cell membranes

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8
Q

Names given to skeletal muscle

A

Skeletal, voluntary and striated

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9
Q

Muscle tissue is formed from

A

Muscle cells and associated connective tissue

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10
Q

Muscles are formed from

A

Muscle fibres, blood vessels, nerves, lymphatics, connective tissue and specialised sense organs

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11
Q

Characteristics of skeletal muscle fibres

A
  • Striated
  • Multinucleated
  • Unbranched
  • Nuceli are at the periphery of the fibre, just under te cell membrane
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12
Q

What is the cell membrane in muscle fibres called

A

The sarcolemma

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13
Q

A bundle of muscle fibres

A

Fascicle

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14
Q

Connective tissue around the muscle as a whole

A

Epimysium

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15
Q

Connective tissue around the fascicle

A

Perimysuim

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16
Q

Connective tissue around a single muscle fibre

A

Endomysium

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17
Q

What is a sarcomere

A

The smallest contractile unit of a muscle cell

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18
Q

What forms a myofibril

A

Hundreds or thousands of sarcomeres placed end to end

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19
Q

Where do sarcomeres extend from/to

A

From one Z line to the next

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20
Q

What is a motor unit

A

The motor neurone and all of the muscle fibres it innervated

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21
Q

Fewer number of muscle fibres in a motor unit =

A

Finer movement of control

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22
Q

Synapse at the end of the motor neurone

A

Motor end plate

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23
Q

Muscle fibres in a motor unit are all

A

Of the same class

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24
Q

What type of junction to almost all muscle fibres have

Study These Flashcards
A

Neuromuscular junction

25
Neuromuscular junction
- Nearly all mucle fibres have one - Motor axons terminate at a motor end plate - Action potential cause the release of acetylcholine - Initiates an action potential in sarcolemma
26
Tubules within the muscle cell
T-tubules
27
T-tubules
- Extend from sarcolemma into the cell | - Ramify and surrounding each myofibril at the A-I junction of each sarcomere
28
Specialised smooth ER
Sarcoplasmic reticulum
29
Sarcoplasmic reticulum
- Very high concentrations of Ca2+ | - LIes on either sides of the T-tubules
30
T-tubule and sarcoplasmic reticulum =
Triad
31
What does an action potential at the neuromuscular jucntion cause
The release of acetylecholine which causes an action potential in the muscle cell
32
An action potential in the muscle cell travels along what
The sarcoplasmic reticulum and invades the T-tubules
33
What does the action potential in the sarcoplasmic reticulum cause
The release of Ca2+
34
The release of Ca2+ causes
The myosin fibrils to ratchet across the actin fibrils, shortening the sarcomere
35
Three types of skeletal muscle fibres
Type I, type IIa, type IIb
36
Type I muscle fibres
- Slow contracting fibres - Depend on oxidative metabolism - Have abundant mitochondira and myoglobin - Resistant to fatigue and produce less force
37
Type IIA muscle fibres
- Intermediate between the other two types - Relatively uncommon - Fast twitch but fatigue resistant
38
Type IIB muscle fibres
- Relatively fast contracting fibres - Depend on anaerobic metabolism - Fewer mitochondia and myoblogin than type I - Fatigue relatively easy and produce greater force
39
The myotendinous junctions
Where the collagen of the tendons attaches to the end of the muscle fibres
40
How is the muscle attached to collagen
Through complex interdigitations
41
Why are tendons slow to hear
They have a poor blood supply
42
Specialised sense organs within muscles
Muscle spindles
43
What do muscle spindles provide
Information of the amount of stretch and tension in the muscle
44
Special fibres within the muscle spindle
Intrafusal fibres
45
Normal contracile fibres
Extrafusual muscle fibres
46
Cardiac muscle
- Forms major part of walls of heart chambers and origins of great vessels - Has striations - Shorter than skeletal muscle fibres - Branch to form a complex network
47
Nuclei in cardiac muscle
Have a single nucleus located at the centre of the fibre
48
Dark irregular lines in cardiac muscle
Intercalated discs
49
Function of intercalated discs
Site of end-to-end attachment, maintain mechanical integrity and allow the transmission of electrical impulses
50
Dyad in cardiac muscle
T-tubule and only one branch of sarcoplasmic reticulum
51
Skeletal muscle regenerative capacity
- Has a population of myoblasts called satellite cells at the outer surface of sarcolemma - Following damage they become activated to proliferate and form new muscle fibres
52
What competes with the regeneration of tissue
Scar tissue
53
Cardiac muscle regenerative capacity
- Small population of stem cells but they play little roles in effective repair - After muscle is killed, new muscle is not regenerated
54
Smooth muscle
- No visible striations - Not under conscious control - Predominantly found in organs
55
Smooth muscle cells
Elongated, spinde-shaped cells with a single cigar shaped nucleus
56
Actin and myosin in smooth muscle
- Not as well organised as skeletal or cardiac muscle - Converge on dense bodies in cytoplasm - Converge on focal densities at periphery of the cell
57
Where is smooth muscle found
The gut, respiratory tract, blood vessels, uterus and iris of the eye
58
Contraction of smooth muscle
- Typically recieves signals for both contraction and relaxation - Smooth muscle either contracts continuously or rhythmically in absence of stimuli - Appropriate stimuli can modulate contraction either positively or negatively
59
Where does stimuli for smooth muscle originate
Nerve fibres of autonomic nervous system or a hormone

Histology (22 decks)

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