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Physiology with pharmacology - L1 > Muscle (& epithelia) > Flashcards

Muscle (& epithelia) Flashcards

1
Q

What are the 4 basic types of tissue?

A
  • Epithelia
  • Muscular
  • Nervous
  • Connective tissue
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2
Q

Where are epithelia found (vaguely)?

A

As a boundary between controlled internal environment & uncontrolled external environment

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3
Q

What are the 3 germ layers that epithelia can develop from?

A

Endoderm - e.g. GI lining
Mesoderm - e.g. Lining of CV system
Ectoderm - e.g. epidermis

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4
Q

What is an example of an area of high abrasion where epithelia is found?

A

Skin

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5
Q

Why is the purpose of epithelia in the lungs?

A

Aids with diffusion in the lungs

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6
Q

What is the purpose of epithelia in the small intestine?

A

Aids with absorption

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7
Q

Why is epithelia described as a dynamic barrier?

A

It is able to import & expel substance, sometimes against concentration gradients.

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8
Q

What connects epithelial cells and creates very low free diffusion to occur?

A

Tight junctions

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9
Q

What effect does tight junctions have on the location on differing membrane properties & functions?

A

Leads to the apical & basolateral domains to be polarized

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10
Q

Epithelia is avascular - what does this mean?

A
  • It is entirely cellular (no blood vessels & cells)
  • it lacks extracellular fibers
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11
Q

Why do epithelial have minimal extracellular space?

A

Due to tight packing of junction

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12
Q

What property is CRITICAL to epithelial function?

A

Polarity

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13
Q

What do basement membranes separate?

A

Cells from underlying connective tissue (collagen 4)

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14
Q

What attaches epithelia to a basement membrane?

A

Epithelial cell’s basal surface attaches to a basement membrane.

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15
Q

What is the benefits for epithelia, of epithelia’s basal layer attaching to the basement membrane?

A
  • Provides mechanical support
  • Supports the growth & survival of epithelial, through controlling its nutrient, ions, proteins & oxygen.
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16
Q

What does epithelia rely on for their blood supply?

A

Capillaries in the underlying tissues.

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17
Q

Why is the basement membrane’s ability to regulate growth & division of epithelial cells so important?

A

Restricts migration of metastatic cells in the progression of cancer

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18
Q

What are the 2 components of the basement membrane?

A
  • Basal lamina
  • Reticular lamina
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19
Q

What is the function of the basal lamina?

A

Provides support by resisting stretching & tearing

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20
Q

What can the basal lamina be subdivided into?

A
  • Lamina lucida
  • Lamina densa
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21
Q

What is the function of the reticular lamina?

A

Anchors basal lamina to connective tissue

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22
Q

What type of movement does tight junction prevent?

A

Paracellular transport

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23
Q

How do claudins determine the ‘tightness’ of tight junctions?

A

Different claudins have different levels of permeability (combinations of claudins determine permeability)

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24
Q

Which is more permeable - small intestine or bladder?

A

Small intestine

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25
Q

How many claudins genes are there?

A

24

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26
Q

What type of junctions form a belt around the cell?

A

Adhering junctions

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27
Q

What type of junctions allow lateral communication between cell?

A

Gap junctions (permit small molecules to diffuse) - therefore cells are electrically coupled

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28
Q

What are desmosomes?

A

Extracellular domains that form strong adhesion points

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29
Q

What is more likely to occur when the cell experiences a hostile external environment?

A

Cell death

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30
Q

How long does it take for intestine self-renewal to occur?

A

5 days

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31
Q

How long does it take for inter-follicular epidermis self-renewal to occur?

A

4 weeks

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32
Q

How long does it take for lung epithelial self-renewal to occur?

A

6 months

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33
Q

What are the 2 ways of classifying epithelia?

A
  • Simple epithelia
  • Stratified epithelia
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34
Q

What is simple epithelia?

A

Single layer of cells

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35
Q

Where is an example of simple epithelia?

A

Lungs

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36
Q

What is stratified epithelia?

A

Many layers of cells

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37
Q

What are 2 types of non-typical epithelia classification?

A
  • pseudo-stratified (upper respiratory tract)
  • transitional (urothelium - found in bladder)
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38
Q

What are the 2 types of simple epithelia?

A
  • simple squamous epithelium
  • simple cuboidal epithelia
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39
Q

What is the role of simple squamous epithelium?

A

Facilitate rapid passage of molecules

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40
Q

Where is simple squamous epithelium found?

A

Alveoli

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41
Q

What is the difference between simple squamous epithelium and simple cuboidal epithelium?

A

Simple cuboidal epithelium has a non-motile cilium

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42
Q

What are the 2 types of columnar epithelia?

A
  • simple columnar epithelia
  • pseudostratified columnar epithelia
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43
Q

Where are 2 examples of where simple columnar epithelia can be found?

A
  • GI tract
  • Fallopian tubes
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44
Q

Which membrane are pseudostratified columnar always touching?

A

Basolateral membrane

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45
Q

What is the most common type of stratified epithelium in human body?

A

Stratified squamous epithelia

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46
Q

Which membrane are stratified squamous epithelia always touching?

A

Apical cells

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47
Q

Where are stratified cuboidal found?

A
  • Glands
  • Anus
  • Male urethra
  • Embryo
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48
Q

What is the function of transitional epithelia?

A

Facilitates shape change in distension without damaging the epithelial lining

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49
Q

What system is adopted when glands secrete through ducts?

A

Exocrine system

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50
Q

What system is adopted when glands secrete without ducts?

A

Endocrine system

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51
Q

What are the 3 substances that can be secreted from glands?

A
  • Mucus
  • Protein
  • Sebum
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52
Q

What glands secrete mucus?

A

Mucus glands

53
Q

What glands secrete protein?

A

Serous glands

54
Q

What glands secrete Sebum?

A

Sebaceous glands

55
Q

What are 2 examples of exocrine glands?

A
  • unicellular goblet cells
  • multicellular acinar
56
Q

What is the skeletal muscle responsive for?

A
  • Voluntary movement of bones that underpins locomotion
  • Control of inspiration by contraction of diaphragm
  • Skeletal-muscle pump - help with venous return to the heart
57
Q

Where does contraction take place?

A

Sarcomere

58
Q

Do skeletal muscles have striations?

A

Yes

59
Q

Describe the size of the myosin fibres & actin fibres on a skeletal muscle

A

Thick - myosin fibres
Thin - actin fibres

60
Q

What makes up the Z line in skeletal muscle structure?

A

Actinin

61
Q

Describe the structure of the actin fibres

A

Double helical structure in hexagonal shapes

62
Q

The release of what neurotransmitter at the neuromuscular junction initiates an action potential in the plasma membrane of the muscle fibre?

A

Acetylcholine

63
Q

What is an example of muscles that require fine control?

A

Movement of the eye (2-6 muscle fibres per motor neurone)

64
Q

What is an example of a muscle that doesn’t require fine control?

A

Gastrocnemius muscle (100-1000 innervated by a single motor neurone)

65
Q

Where does the wave of depolarization pass through following the sarcolemma?

A

T-tubule network

66
Q

What is the name given to the endoplasmic reticulum in skeletal muscles?

A

Sarcoplasmic reticulum

67
Q

What substance is released following depolarisation in the T-tubule network?

A

Intracellular calcium

68
Q

The T-tubule runs near 2 areas of the SR forming a what?

A

Triad

69
Q

What is the advantage of having a triad?

A

Enables efficient contraction - enables the wave of depolarisation to enter deep into the cell.

70
Q

Approximately how many myosin heads do each thick filament contain?

A

300

71
Q

What phase occurs after an interaction between the head of the myosin & actin thin filament?

A

Powerstroke phase (leading to contraction)

72
Q

Why is muscle contraction an active process?

A

It is an ATP-requiring process

73
Q

When ATP binds to the myosin head, what happens to the affinity of myosin for actin?

A

It decreases

74
Q

What occurs when the affinity of myosin for actin decreases (following the binding of ATP)?

A

The myosin will then detach from the actin.

75
Q

What conformational change occurs to the myosin head following the hydrolysis of the ATP?

A

The myosin straightens, aligning it with the next actin filament further down.

76
Q

What happens if an electrical stimulus is applied to a muscle?

A

Measurement of contraction to occur

77
Q

What happens in the latent period (of muscle contraction)?

A

This is before the release of calcium

78
Q

What happens in the contraction period (of muscle contraction)?

A

Calcium is released which leads to contraction

79
Q

What happens in the relaxation period (of muscle contraction)?

A

Calcium is removed, leading to inactivation of muscle contraction

80
Q

What is temporal summation?

A

Increased frequent stimulus - before relaxation period, another stimulus generated, leading to a bigger development of tension

81
Q

What is unfused tetanus? (think calcium level)

A

Small level of calcium drop

82
Q

What is fused tetanus? (think calcium level)

A

No calcium is removed

83
Q

What are the 3 different classes of muscle fibres?

A
  • Slow oxidative (type 1)
  • Fast oxidative (type a)
  • Fast glycolytic (type b)
84
Q

What type of ATP synthesis is slow oxidative?

A

aerobic (red)

85
Q

What type of ATP synthesis is slow oxidative?

A

aerobic (red)

86
Q

What type of ATP synthesis is fast glycolytic?

A

anaerobic (white)

87
Q

Describe the diameter of slow vs fast muscle

A

Slow fibres are half the diameter of fast fibres

88
Q

What is isometric contraction?

A

Muscle at fixed length, tension generated but no change in length.

89
Q

What is isotonic contraction?

A

Muscle stimulation causes a change in length

90
Q

What molecule enters the cell, when the nerve terminal becomes depolarised?

A

Calcium

91
Q

What is triggered when extracellular calcium moves into the cell (synapse)?

A

Acetylcholine-containing vesicles exocytose into the synaptic cleft.

92
Q

What does the acetylcholine molecules that are released into the synaptic cleft bind to?

A

Acetylcholine receptor channels.

93
Q

What occurs when the acetylcholine receptors on the sarcoplasmic membrane are stimulated?

A

The channels are opened, leading to a depolarisation of the sarcolemma.

94
Q

What breaks down the acetylcholine to inhibit stimulation of the acetylcholine receptors?

A

Acetylcholinesterase

95
Q

How does the presynaptic neurone become repolarised?

A

Potassium leave through the voltage-gated potassium channels, down its electrochemical gradient. This will lead to the repolarisation of the membrane potential.

96
Q

What does the inhibitor tetrodotoxin do?

A

Inhibits sodium channel - prevents the release of acetylcholine.

97
Q

What does the inhibitor dendrotoxin do?

A

Inhibits potassium channel - prevents membrane repolarization.

98
Q

What do the inhibitors Tetanus toxin & Botulinum toxin do?

A

Prevent the release of acetylcholine

99
Q

What does the inhibitor conotoxin do?

A

Can affect calcium channels - affects the release of acetylcholine

100
Q

What does the inhibitor bungarotoxin do?

A

Inhibits acetylcholine receptor - prevents transmission of the action potential into the muscle cell

101
Q

What does the inhibitor physostigmine do?

A

Inhibits acetylcholinesterase

102
Q

What does the inhibitor saxitoxin do?

A

Inhibit sodium channel - prevents transmission of the polarisation in the muscle membrane

103
Q

What is the physiological consequence of botulinum toxin?

A

Muscle paralysis

104
Q

How does Botulinum Toxin impact on SNARES?

A

V&T snares are cut up, preventing the formation of the V snare & T snare complex and therefore the release of acetylcholine

105
Q

What does the V&T SNARE complex formation allow for?

A

The release of acetylcholine

106
Q

What is a clinical use of botulinum toxin?

A

Blepharophasm - uncontrolled eyelid movement
Cosmetic treatments - even may help treat migraines

107
Q

What 2 types of muscle is striated?

A

Skeletal muscle & cardiac muscle

108
Q

Describe the structural differences between cardiac myocytes & skeletal muscle

A

Cardiac myocytes are shorter and more branched as well as being joined at the intercalated disk

109
Q

What type of junction allows electrical coupling between adjacent myocytes at the intercalated disk?

A

Gap junction

110
Q

What type of muscle is non-striated?

A

Smooth muscle

111
Q

What is the primary pacemaker in the heart that can overrule other pacemakers?

A

Sino-atrial node

112
Q

What 2 processes can cause smooth muscle to contract?

A
  • presence of an action potential
  • change in membrane potential
113
Q

What is an example of where smooth muscle is present in a physiological system?

A

Digestive, urinary & reproductive system

114
Q

What ligand can lead to the contraction of smooth muscle?

A

Hormones & histamines

115
Q

What are the 2 classes of smooth muscle?

A

Multiunit & unitary

116
Q

What type of calcium channels are in the T-tubule membrane?

A

L-type Ca2+ channels

117
Q

What causes a mechanical tethering between L-type Ca2+ channels in the T-tubule & Ca2+ release channels (ryanodine receptors) in skeletal muscles.

A

An influx of calcium into the T-tubules

118
Q

What removes Calcium from the cytoplasm?

A

Plasma Membrane Calcium ATPase (PMCA)

119
Q

What does smooth muscle have because it lacks T-tubules?

A

Shallow invaginations - caveolae

120
Q

What 4 proteins wrap around the actin?

A

Tropomyosin - (wraps round actin)
Troponin complex - TnC, TnT, TnI

121
Q

What is the role of Troponin C?

A

Calcium binding protein

122
Q

What is the role of Troponin T?

A

Interacts with tropomyosin, binding protein

123
Q

What is the role of Troponin I?

A

Inhibitory protein, prevents the binding of myosin to actin

124
Q

What is the role of the Troponin complex?

A

Prevents the binding of actin & myosin

125
Q

What binds to the Troponin complex which causes a conformational change, revealing actin fibres?

A

Calcium

126
Q

Is there Troponin in smooth muscle?

A

No

127
Q

What is the replacement for Troponin in smooth muscle?

A

Calponin

128
Q

What happens when the myosin light chain kinase is activated?

A

It phosphorylates MLC (myosin light chain)

Physiology with pharmacology - L1 (17 decks)

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