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Body Logistics > Muscle Tissue - Function and Disease > Flashcards

Muscle Tissue - Function and Disease Flashcards

1
Q

State 2 similarities between cardiac and smooth muscle

A
  • Central nuclei
  • One contractile cell type
  • Act as a syncytium
  • Cells communicate through gap junctions
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2
Q

State 2 differences between cardiac and smooth muscle

A
  • Smooth muscle has no sarcomeres
  • Cardiac muscle has specialised conduction
  • Smooth muscle has no troponins
  • Cardiac muscle has intercalated discs
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3
Q

What are the parasympathetic and sympathetic types of cardiac innervation

A

Parasympathetic - Cardiac plexus receives signals from the vagus nerve
Sympathetic - Composed or sympathetic trunk fibres

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4
Q

Name one effect of parasympathetic and sympathetic cardiac innervation

A

Parasympathetic - Reduces heart rate, vasoconstriction of coronary arteries
Sympathetic - Increases heart rate, fight or flight response

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5
Q

What elements are involved in cardiac contraction? Name 2

A
  • T-tubules
  • Calcium ions
  • Troponin complex
  • Actin
  • Myosin
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6
Q

What happens between myosin and actin in cardiac contraction?

A

Myosin head binds to ATP and pulls actin filaments causing contraction

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7
Q

What type of nerve fibres supply smooth muscles and what specialised organelle do they contain?

A
  • Autonomic nerve fibres

- Synaptic vesicles full of neurotransmitters

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8
Q

Which enzyme is involved in smooth muscle contraction and what is it activated by?

A
  • Myosin chain kinase

- Activated by Calcium-Calmodulin complex

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9
Q

Name 2 characteristics of smooth muscle cell ultrastructure

A
  • Dense body with bundles of thick and thin filaments
  • Each contractile unit have 3 subunits
  • Actin passes through gap junctions
  • Fibres line up prior to contraction
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10
Q

What is contained in the axon vesicles of skeletal muscle fibres?

A

Acetylcholine

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11
Q

What does Acetylcholine bind to in skeletal muscle cells and what is its effect?

A
  • Binds to sarcolemma receptors

- Initiates an action potential

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12
Q

How to nerve fibres correlate to fine motor control?

A

Small amount of fibres per motor unit allows fine motor control

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13
Q

Where does skeletal muscle contraction occur?

A

Neuromuscular junction

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14
Q

What 2 ions are involved in skeletal muscle contraction?

A

Na+ and Ca2+

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15
Q

Where does depolarisation spread to after the sarcolemma?

A

T-tubules

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16
Q

What does Ca2+ bind to in skeletal muscle to start the contraction cycle?

A

Troponin complex

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17
Q

What is the effect of antibodies in Myasthenia Gravis? What does this result in?

A
  • They block Ach receptors
  • Results in reduced synaptic transmission
  • Sufferers have intermittent muscle weakness
18
Q

Name 2 myofilament proteins in sliding filament theory

A
  • Titin

- Tropomyosin

19
Q

Describe the structure of myosin

A
  • Rod-like structure with 2 heads

- Heads protrude at opposite ends of the filament

20
Q

What are the 2 protein components of Actin?

A
  • F-Actin fibres

- G-Actin globules

21
Q

What complex sits on top of Actin binding sites?

A

Tropomyosin-Troponin complex

22
Q

How many Troponin complexes are there in each Actin twist?

A

2

23
Q

What joins together in the functional contraction unit to cause contraction?

A

Myosin heads and actin filaments

24
Q

Where are myosin heads not present in the functional contraction unit?

A

M region (middle of the sarcomere)

25
Q

In terms of contractile unit structure, what stays the same and what changes during contraction?

A
  • Length of actin and myosin filaments remains the same

- Sarcomeres shorten and Z-lines move closer together

26
Q

What molecule causes detachment of myosin and actin?

A

ATP

27
Q

What are the 5 muscle roles in movement?

A
  • Agonist
  • Antagonist
  • Synergist
  • Neutraliser
  • Fixator
28
Q

What is the mechanism of first, second and third class levers?

A

First - “see-saw”
Second - “wheelbarrow”
Third - “fishing rod”

29
Q

What is compartment syndrome? What are the symptoms and how is it treated?

A
  • Trauma Results in high pressure in one of the fascia compartments
    Symptoms - prolonged cap refill, shiny/swollen skin
    Treatment - Fasciotomy and skin graft
30
Q

Define muscle strength and muscle tone

A

Muscle Strength - Muscle’s ability to contract and create force in response to resistance
Muscle Tone - Tension in a muscle at rest

31
Q

What is muscle atrophy and muscle hypertrophy?

A

Muscle Atrophy - Destruction > Replacement

Muscle Hypertrophy - Replacement > Destruction

32
Q

Name 2 characteristics of muscle hypertrophy

A
  • A and I bands are overstretched
  • New muscle fibrils and sarcomeres produced
  • Muscle fibres arise from mesenchymal cells
33
Q

Name 3 causes of muscle atrophy

A
  • Muscle disuse
  • Surgery
  • Disease
34
Q

Describe the mechanism of Duchenne Muscular Dystrophy

A
  • Dystrophin gene mutation affects membrane material movement
  • Excess calcium and water enter muscle cells
  • Muscle cells burst and are replaced by adipose tissue
35
Q

What levels are high in the blood in Duchene Muscular Dystrophy?

A
  • CK

- Myoglobin

36
Q

What is Creatinine Kinase and when is it released into the blood?

A
  • Enzyme found in metabolically active tissue

- Released into the blood when skeletal muscle is damaged

37
Q

What is the mechanism and effect of Botox?

A
  • Blocks neurotransmitter release at the motor end plate

- Causes non-contractile state of skeletal muscle

38
Q

What does Organophosphate Poisoning inhibit and what is the effect of this?

A
  • Inhibits the normal function of Ach esterase

- Active site is blocked and muscle is continuously stimulated

39
Q

What are the muscarinic symptoms of Organophosphate Poisoning?

A 
Salivation
Lacrimation
Urination
Defecation
GI cramping
Emesis 
“SLUDGE”
40
Q

What are the nicotinic symptoms of Organophosphate Poisoning?

A 
Muscle cramps
Tachycardia
Weakness
Twitching
Fascicultations
“Monday - Friday”

Body Logistics (22 decks)

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