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BODY LOGISTICS > Muscle Tissue (Structure and Function) > Flashcards

Muscle Tissue (Structure and Function) Flashcards

1
Q

What are the 2 muscle cell types?

A

Striated and non-striated

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2
Q

What are the 2 muscle cell types further divided into?

A

Striated - skeletal muscle and cardiac muscle
Non-striated - smooth muscle

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3
Q

What is always present in striated muscle?

A

Myoglobin

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4
Q

2 ways in which cardiac and smooth muscle are similar

A
  • involuntary control
  • indirect nerve-muscle communication (cell doesn’t interact directly with cardiac/smooth muscle)
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5
Q

How do skeletal muscles communicate with nerve?

A

Direct nerve-muscle communication (nerve attaches to the muscle and stimulates it)

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6
Q

How do Cardiac Muscles Communicate with nerve

A

Indirect nerve-muscle communication

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7
Q

How do Smooth muscles communicate with nerve

A

Indirect nerve-muscle communication

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8
Q

What is myoglobin and its function?

A

An oxygen-storing molecule, providing oxygen to working striated muscles

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9
Q

What makes myoglobin good at its function?

A

Myoglobin has a higher affinity for oxygen than haemoglobin, especially at low pH, so at extremities of the body where CO2 levels are high

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10
Q

What happens when striated muscle dies or is damaged?

A

Myoglobin is released into the bloodstream and is taken up by the kidneys to be removed from the blood (myoglobinuria- tea coloured urine)

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11
Q

What is
1. muscle necrosis
2. rhabdomyolysis
3. myoglobinaemia

A
  1. When striated muscle dies (muscle necrosis)
  2. When damaged (rhabdomyolysis)
  3. `myoglobin is released into the bloodstream (myoglobinaemia)
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12
Q

How can myoglobin cause renal damage?

A

If the kidneys take up too much myoglobin it can block the glomerulus and cause renal damage

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13
Q

What is the sarcolemma?

A

The outer membrane of a muscle cell (like a plasma membrane)

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14
Q

What is the Sarcoplasm

A

cytoplasm of a muscle cell

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15
Q

What is a sarcosome

A

The mitochondrion of muscle cells

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16
Q

What is the Sacromere

A

The contraction unit in striated muscle

( z line to z line)

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17
Q

What is the Sacroplasmic reticulum

A

The Smooth Endoplasmic Reticulum of a muscle cell

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18
Q

What is a T-tubule?

A

Connects the myofibrils to the sarcolemma

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19
Q

3 connective tissue components of striated muscle

A

Endomysium
Perimysium
Epimysium

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20
Q

How do you get the striated pattern

A

Dark Band then White band layers

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21
Q

What is a striated muscle cell called

A

A striated muscle cell is called a muscle fibre

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22
Q

What is the plasmalemma of a muscle cell called

A

The plasmalemma of a muscle cell is called its sarcolemma

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23
Q

What does each cell (fibre) contain

A

Each cell (fibre) contains numerous myofibrils

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24
Q

What is thicker between myosin filament and actin filament

A

Myosin Filament = Thick
Actin Filament = Thin

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25
Q

What is the structure of Myofibrils

A

Look at lecture slide

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26
Q

Describe the endomysium?

A

Surrounding loose connective tissue of different muscle fibres within a fascicle. Contains capillaries and small nerve endings

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27
Q

Describe the perimysium

A

Connective tissue surrounding the fascicle (make up the muscle) and contains arterioles and venuoles

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28
Q

Describe the epimysium

A

Dense connective tissue layer on a muscle that is continuous with tendon

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29
Q

What is a point of origin and insertion in skeletal muscles?

A

Origin - where tendon attaches to bone - does not move during contraction
Insertion - where muscle attached to bone - does move when the muscle contracts

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30
Q

What is thicker between myosin filament and actin filament

A

Myosin Filament = Thick
Actin Filament = Thin

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31
Q

What is direction of movement dependent on?

A

Movement is always along the direction of a fascicle
(direction of the muscle fibres (cells) contraction

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32
Q

Where is movement created?

A

At the insertion point if it crosses a joint

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33
Q

Where is tension created in skeletal muscles?

A

At the origin point

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34
Q

What is the function of Skeletal muscles

A

The function is to Contract

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35
Q

What is a Fascicle

A

Each fascicle (or fasciculus) is a bundle of muscle fibers, also called myocytes, bound together via the endomysium tissue that provides pathways for the passage of blood vessels and nerves.

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36
Q

Why is Direction of movement of muscles not easy to predict

A

Lots of different muscle shapes
Movement if always along the direction of a fascicle

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37
Q

What do extrinsic muscles of the tongue do?

A

Attached to bone or cartilage and allows movement of the tongue - retract it and move side to side

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38
Q

Which muscle in the tongue permits us to stick the tongue out?

A

Geniohyoid muscle - attached to chin and base of tongue

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39
Q

Describe intrinsic muscles of the tongue and their role

A

They are not attached to bone (muscle to muscle only) and allow tongue to change shape but not position. AID IN SWALLOWING

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40
Q

Where are nuclei found in skeletal muscle histology?

A

Peripheral in transverse section of fascicles (appear as a bundle of muscle cells)
Nuclei in rows in longitudinal section

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41
Q

What accounts for the mobility of the Tongue

A

The plasticity and strength of the connective tissues
and the multidirectional orientation of the muscle fibres accounts for the mobility of the tongue

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42
Q

What is each fascicle in a skeletal muscle shown to be surrounded by in histology?

A

Perimysium (connective tissue) carrying nerves and blood vessels

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43
Q

What are the dark longitudinal streaks seen on histology of skeletal muscles?

A

Mitochondria

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44
Q

What is a muscle fibre made up of?

A

Contains numerous myofibrils

45
Q

What makes up myofibrils?

A

Sarcomeres

46
Q

What is a myofibril?

A

Make up muscle fibres which form fascicles

47
Q

What is a fascicle?

A

Bundles of muscle fibres

48
Q

A-band of a sarcomere

A

Where actin and myosin overlap - thick bands

49
Q

I-band of sarcomere

A

Only contains actin filaments - light bands

50
Q

Why would you find fibroblasts in skeletal muscle histology?

A

They lay down material for endomysium

51
Q

In a transverse section of myofibrils in histology, what are the individual dots?

A

Myosin filaments

52
Q

What are t-tubules usually associated with?

A

Mitochondrial line

53
Q

Types of muscle fibres in skeletal

A

Slow (Type 1)
fast ( Typw 2A)
intermediate (Type 2B)

54
Q

Different fibres require different amounts of blood, how does this work

A
  • Thin fibres less blood
  • Thick fibres more blood
55
Q

What are the three types of contraction speeds
What does a fascicle have

A

Three types:
Slow, fast and intermediate

Each fascicle has at least one of each

56
Q

What are red muscle fibres?

A

Slow twitch

57
Q

What are white muscle fibres?

A

Fast twitch

58
Q

Why are fast twitch muscles white

A

As they do not contain much blood

59
Q

Compare the amount of myoglobin and mitochondria in fast twitch compared to slow switch muscle fibres

A

High amount of myoglobin and mitochondria (and therefore cytochrome) in slow twitch fibres, low amounts in fast

60
Q

What is the relative diameter in fast twitch fibres compared to slows?

A

Fast have a large diameter and slow have a smaller diameter

61
Q

Example site of slow twitch muscle fibres

A

Spinal muscles

62
Q

How does myoglobin differ to haemoglobin?

A

Myoglobin can only bind to oxygen, whereas haemoglobin can also bind to CO2

63
Q

What do type 2A fibres do?

A

Type 2A fibres are sometimes called intermediate fibres because they possess characteristics that are intermediate between fast fibres and slow fibres. They produce ATP relatively quickly, more quickly than SO fibres, and thus can produce relatively high amounts of tension.

64
Q

Difference between slow and fast twitch fibres

A

LECTURE SLIDE PG 25

65
Q

What are the types of Slow twich fibres

A

Type 1 (Slow oxidative) fibres

66
Q

What are the types of fast twitch muscle fibres

A
  • Type 2A (Fast oxidative glycolytic) fibres
  • Type 2B (2X; Fast glycolytic) fibres
67
Q

Which twitch, slow or fast, requires a rich capillary supply?

A

Slow requires rich capillary supply as its aerobic, whereas fast twitch is anaerobic

68
Q

Oxidative and glycolytic muscle fibres

A

Oxidative 32 mol ATP/mol glucose - slow twitch
Glycolytic - 2 mol ATP/mol glucose - fast twitch

69
Q

What does continued muscle contraction depend on?

A

Calcium ions
Amounts of ATP

70
Q

How are cardiac cells joined to adjacent cells?

A

Using intercalated disks

71
Q

What are intercalated disks used for in cardiac muscle cells?

A

Allow electrical signals through to adjacent cells so they can’t contract together

72
Q

How and what ions pass through adjacent cardiac cells?

A

The gap junctions allow ATP and Ca2+ through as they are essential to continue muscle contraction

73
Q

What happens when the intercalated disk becomes damaged and the cardiac myocyte is broken?

A

The cell isn’t getting nutrients from adjacent cells so dies - fibroblasts fill this with connective tissue and make a scar.

74
Q

Which muscle fibres are able to branch?

A

Cardiac muscle fibres

75
Q

What two peptides are released during cardiac distension (failure)?

A

Atrial natriuretic peptide (ANP) released by atria
Brain-type natriuretic peptide (BNP) released by ventricles

76
Q

When will BNP be released by the ventricles? (2)

A

During left ventricular hypertrophy
Mitral valve disease

77
Q

What hormone is released during congestive heart failure?

A

ANP - reduces blood volume and therefore blood pressure

78
Q

How does ANP work to reduce blood pressure? (2)

A
  1. Increases glomerulus filtration rate in kidneys so more fluid released from bladder
  2. Decreases renin enzyme which decrease AngII and Aldo (constrict arterioles) leading to vasodilation and more fluid excreted via pee
79
Q

What is hypertrophy?

A

Cells enlarge

80
Q

What is hyperplasia?

A

multiplication of cells of same size by cell division/mitosis

81
Q

What is atrophy?

A

Decrease in cell size

82
Q

What nerve system control involuntary cardiac muscles?

A

Autonomous nervous system

83
Q

Describe how nerve signals cause atria to contract

A
  1. Signal is sent to sinoatrial node
  2. Sinoatrial node receives this signal and send it though Bachmann muddles which are around the atria
  3. Cause the atria to contract
84
Q

Describe how nerve signals can cause ventricle contraction

A
  1. Signals from sinoatrial node are sent to atrioventricular node
  2. This collects electrical signals and stores them until a threshold is reached
  3. Once reached, signals are fired down septum to Bundle of His
  4. Bundle of His divides into left and right branches which pass to Purkinje fibres
  5. Purkinje fibres make ventricles contract
85
Q

Why is the conducting system of the heart effective?

A

You can achieve coordinated control… atria contracts first followed by ventricles

86
Q

How do Purkinje fibres allow ventricles to contract in almost synchronous manner?

A

Conduct action potentials more rapidly than normal cardiac muscle fibres as the intercalated disk in Purkinje fibres becomes the outer part of the cell so multiple cells are connected

87
Q

Are Purkinje fibres striated?

A

No, as they have sparse myofibrils

88
Q

Where will you find Purkinje fibres?

A

Apex of the heart close to the endocardium lining of the ventricle

89
Q

Where are nuclei found in cardiac muscles compared to skeletal?

A

Nuclei are central in cardiac muscle ( and sometimes 2/cell) and peripheral in skeletal

90
Q

How do contractive cell types differ from cardiac to skeletal muscles?

A

Cardiac only have one type of contractive cell - cardiomyocytes
Skeletal more - fast and slow twitch fibres

91
Q

How are contraction mechanisms similar in cardiac and skeletal muscles?

A

Both have sarcomeres, but sarcomere less well developed in cardiac

92
Q

What is the shape of a smooth muscle cell?

A

Spindle shaped with a single central large nucleus

93
Q

What are smooth muscles capable of that other aren’t?

A

They can be stretched substantially and may remain contracted for hours or days as long as enough calcium and ATP

94
Q

What dopes contraction of smooth muscle cells rely on?

A

Actin-myosin interactions

95
Q

Why is contraction slower in smooth muscles?

A

There are no sarcomeres

96
Q

4 stimulus of smooth muscle cell

A

Hormones
drugs
nerve signals
blood gases

97
Q

How do ATP and calcium travel between smooth muscle cells?

A

Through gap junctions

98
Q

What structures are found running along the edge of smooth muscle? What is their function?

A

Pinocytic caveolae (cave-like invaginations) they undergo pinocytosis to sample extracellular space for drugs e.t.c

99
Q

What are dense bodies in smooth muscle cell?

A

Act as an attachment point for actin filaments for muscle contraction
Connection : Dense body -> actin -> myosin -> actin -> dense body

100
Q

What is connected to dense plaques in smooth muscle cells?

A

Associated with intermediate funk arts which hold the shape of the cell and prevent too much change in structure during contraction

101
Q

Where are smooth muscles found?

A

Contractile walls of passages or cavities like respiratory tract

102
Q

4 clinical disorders due to involuntary smooth muscle

A

Lung disease e.g asthma due to bronchi muscle spasm
Painful menstruation
Incontinence - bladder made of smooth muscle
High blood pressure

103
Q

How are most smooth muscles innervated?

A

By autonomic nervous system fibres
Release neurotransmitters from varicosities which contain synaptic vesicles into a wide synaptic cleft
Cells are stimulated at the same time
Coordinated contraction of smooth muscle cell

104
Q

Why are smooth muscle cells often damaged?

A

The cells shorten by about 80% during contraction and can hold that configuration while calcium and ATP are present, meaning its easier for them to break or tear

105
Q

To what extent are cardiac muscles capable of regeneration?

A

Incapable of regeneration- following damage, fibroblasts layer down scar tissue

106
Q

Incapable of regeneration- following damage, fibroblasts layer down scar tissue

A

They cannot divide (no mitotic ability) but can regenerate by satellite cells- hyperplasia follows muscle injury

107
Q

What are satellite cells?

A

Stem cells which can give rise to myoblasts which go on to make muscle tissue

108
Q

To what extent can smooth muscle repair itself?

A

Very good at repairing themselves as they retain their mitotic ability so can form new cells

109
Q

What special cell contacts does the intercalated disc contain in cardiac muscle?

A

Fascia adherens, desmosomes and gap junctions - gap junctions allows fast electrical conductance between mardiomyocytes

BODY LOGISTICS (16 decks)

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