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Body Logistics > Muscle Tissue > Flashcards

Muscle Tissue Flashcards

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1
Q

What are the two categories of muscle?
Categorise the three types of muscle

A

Striated - cardiac and skeletal

Non-striated - smooth

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2
Q

What causes striations?

A

Repeating bands of the proteins actin and myosin
Present along the length of the myofibrils

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3
Q

For each type of muscle state:
- whether myoglobin is present
- type of control
- type of nerve-muscle communication

A

S - present, voluntary, direct

C - present, involuntary, indirect

M - absent, involuntary, indirect

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4
Q

What type of molecule is myoglobin?
What does it supply? To what?

A

Red protein

O2 to working striated muscles

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5
Q

What condition particularly does haemoglobin give O2 to myoglobin?

A

Low pH

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6
Q

When striated muscle dies or is damaged what happens?
What can this lead to?

A

Myoglobin is released into the bloodstream

Renal damage

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7
Q

What removes myoglobin from the blood?
What clinical observation does this lead to?

A

Kidneys

Tea-coloured urine

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8
Q

What is the outer membrane of a muscle cell called?

A

Sarcolemma

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9
Q

What is the cytoplasm of a muscle cell called?

A

Sarcoplasm

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10
Q

What is a sarcomere?

A

The contraction unit in a striated muscle

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11
Q

What are the thick and thin myofilaments?

A

Thin - actin

Thick - myosin

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12
Q

What is the epimysium?

A

Dense fibrous connective tissue surrounding muscle tissue

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13
Q

What are the sections of muscle tissue called?

A

Fascicles

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14
Q

What type of connective tissue surround fascicles?

A

Perimysium

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15
Q

What type of loose tissue surrounds muscle fibres?

A

Endomysium

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16
Q

What is underneath the endomysium?

A

Sarcolemma

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17
Q

What are the sections in a fascicle called?

A

Muscle fibres

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18
Q

What are the sections in a muscle fibre called?

A

Myofibril

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19
Q

What is the main function of skeletal muscle?

A

Contraction

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20
Q

What direction is movement?

A

Along the direction of a fascicle

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21
Q

What is created at the origin and insertion point?
Are they proximal or distal?
Give a rough example of each

A

Origin - tension, proximal
Shoulder

Insertion - movement, distal
Elbow

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22
Q

What do distal and proximal mean?

A

Distal - further away from the centre

(Proximal is the opposite)

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23
Q

What does the perimysium contain? (2)

A

Capillaries and nerves

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24
Q

What do skeletal muscle have a lot of - that you can look for in pictures

A

Mitochondria - dark

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25
Why don’t Z lines line up in some pictures?
When the cell is activated The middle section contracts first
26
What are the three types of muscle contraction speeds?
Slow Fast Intermediate
27
What are the two types of twitch fibres? What colour are they?
Slow - red Fast - white
28
What two things is continued muscle contraction dependent on?
Ca2+ ATP
29
What do cardiac muscles specifically have?
Intercalated discs
30
What types of granule do cardiac muscles have? What are they released by? When are they released?
ANP - atria BNP - ventricles Heart failure
31
How do you reduce arterial pressure? (2)
Decrease blood volume Decrease systemic vascular resistance
32
What is hypertrophy?
Enlargement of individual cells
33
What is hyperplasia?
Multiplication of cells
34
What are three key features of purkinje fibres?
- abundant glycogen - sparse myofibrils - extensive gap junctions
35
Describe the function of purkinje fibres
- rapidly conduct action potentials - enabling ventricles to contract in a synchronous manner
36
Where are nuclei in cardiac muscle?
Central
37
Where are nuclei in skeletal muscle
Peripheral
38
Describe the nucleus in smooth muscle cells
Single large central
39
What three things do smooth muscle cells not have?
Striations Sarcomeres T tubules
40
How does smooth muscle contraction compare with skeletal and cardiac? (3)
- slower - more sustained - requires less ATP
41
How do skeletal muscle repair?
- they cannot divide - regenerate by mitotic activity of satellite cells (hyperplasia) - satellite cells can fuse with existing muscle cells (hypertrophy)
42
What cells are responsible for repair in skeletal muscle?
Satellite
43
What type of muscle is incapable of repair? What happens instead?
Cardiac Fibroblasts invade and divide Laying down scar tissue
44
How do smooth muscle repair?
- they retain their mitotic activity
45
What is the central line in a myofibril? What does it not have?
M line Myosin heads
46
What is the zigzagged line in a myofibril?
The z line
47
What does an A band include?
End to end of myosin
48
What is the light band in a myofibril?
I
49
What is the dark band in a myofibril?
A
50
What does the H band include?
The M line, not including the myosin
51
In white and red muscle compare: Amount of myoglobin and mitochondria Fibre diameter Amount of cytochrome
White - lower White - larger White - lower
52
How do myocytes communicate in cardiac and smooth muscle?
Through ago junctions
53
Name two types of myofilaments
Actin and myosin
54
Describe the general structure of myosin
Two heads Protrude at opposite ends
55
What are the two protein components of actin?
F actin fibres G actin globules
56
What two molecules are associated with actin? Describe them
Troponin - attach to each tropomyosin molecule Tropomyosin - coil around the actin helix - reinforcing it
57
Describe how components of myofibrils change shape Erin contraction
- actin and myosin remain the same - Sarcomeres shorten - z lines come close together
58
What does the innveration of muscles mean?
A single motor neurone is able to innveration multiple muscle fibres Causing fibres to contract at the same time
59
In neuromuscular junction transmission what is released into the synaptic cleft?
Ach
60
What does Ach bind to? What does this cause? What does this cause?
Ach receptors Depolarisation of sarcolemma Ca2+ released from gated Ca2+ ion release channels, into the sarcoplasm
61
What does Ca2+ bind to? What does this lead to?
TnC subunit of troponin Tropomyosin dissociates from troponin
62
Where do are Ca2+ returned to at the end?
Terminal cisternae of sarcoplasmic reticulum
63
What causes myasthenia gravis?
1. Antibodies directed against Ach receptor 2. Blocking the receptor 3. Reduction in receptor number 4. Reduced synaptic transmission
64
Symptoms of myasthenia gravis
Ptosis - drooping of one eyelid Slurred speech Difficulty holding head up Choking on food
65
What are the five steps of the sliding filament theory?
1. Myosin head forms a cross bridge with the actin filament 2. The head pulls on the actin filament through a form of relaxation (passive) 3. ATP attaches to the myosin head - breaking the bond with the actin filament 4. ATP hydrolyses and cocks the myosin head back to the starting point (active) 5. The myosin filaments slide along the actin - causing the band to shrink
66
Describe botulism toxin and Botox?
- clostridium botulinum produces botulism toxin - it blocks neurotransmitter release at motor end plate - skeletal muscles are in a non-contractile state
67
What is the botulism toxin used for?
- treat muscle spasms - treat wrinkles
68
Describe organophosphate poisoning
- it inhibits function of Ach esterase - Ach cavities at neuromuscular junction is increased
69
Name some symptoms of organophosphate poisoning
- Salivation - muscle cramps - urination
70
What type of mutation is duchenne muscular dystrophy?
C linked recessive of dystrophin gene
71
What causes duchenne muscular dystrophy?
1. Absence of dystrophin 2. Excess Ca2+ enters muscle cells 3. Ca2+ taken up by mitochondria 4. Water taken up into mitochondria 5. Mitochondria and muscle cells burst 6. Creatine kinase and myoglobin levels are high in the blood 7. Muscle cells replaced by adipose tissue
72
What would show in a blood test for people with duchenne muscular dystrophy?
Creatine kinase Myoglobin
73
What are some symptoms of duchenne muscular dystrophy?
- poor balance - belly sticks out - tight heel cord - arms and shoulder back when moving
74
What is an agonist?
Primer movers (main muscle for a movement)
75
What is an antagonist?
Oppose agonists
76
What is a synergist?
The assist agonists
77
What is a neutraliser?
Prevent unwanted action that an agonist can perform
78
What is a fixator?
Act to hold a body part immobile whilst another part is moving
79
What is a first class lever?
Effort at one end Load at the other Fulcrum in middle
80
What is a second class lever?
Effort at one end Fulcrum at other Load in middle
81
What is a third class lever?
Load at one end Fulcrum at other Effort in middle
82
How are muscles organised? Surrounded by what?
Grouped into compartments with similar actions Thick dense fascia
83
What causes compartment syndrome?
1. Trauma in one compartment 2. Internal bleeding 3. Exerts pressure on blood vessels and nerves
84
Name some symptoms of compartment syndrome
- deep poorly localised pain - paresthesia (pins and needles) - swollen shiny skin
85
How is compartment syndrome treated?
Fasciotomy Covered by skin graft
86
Define muscle tone
The tension in a muscle at rest
87
Define muscle strength
The muscles ability to contract and create force in response to resistance
88
What is muscle tone regulated by?
- gravity - use - muscle elasticity - motor neuron acitvity
89
Muscles retain tension and stiffness What does this cause?
- muscles ready to react - never fully relaxed - improves with exercise
90
What causes atrophy? Define it simply
The destruction is more than replacement: - disuse - surgery - disease Muscles wasting away
91
What is the opposite of atrophy? What is the mechanism?
Hypertrophy 1. New muscle fibrils produced 2. New Sarcomeres added in the middle of existing ones 3. New muscles fibres arise from mesenchymal cells
92
What is used to diagnose heart attacks? What is used now?
Creatine kinase levels in blood Troponin I assay
93
What leads to a rise in plasma creatine kinase levels?
- intramuscular injection - vigorous physical exercise - a fall - acute kidney injury
94
How is troponin assay used as a marker for myocardial infarction? What must you note?
- released from ischaemic cardiac muscle (Not necessarily proportional to degree of muscle damage)
95
What causes malignant hyperthermia? (2)
- Severe reaction to certain drugs used for anaesthesia - massive contractile fasciculation (involuntary movement)

Body Logistics (9 decks)

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