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BMS10 > Histology Of Muscle > Flashcards

Histology Of Muscle Flashcards

1
Q

What non-muscle cell is present in muscle connective tissue?

A

Fibroblasts

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2
Q

What non-muscle cell is present in myoepithelia?

A

Exocrine epithelia

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3
Q

Name one place where myoepithelia may be found

A

Salivary glands

Mammary glands

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4
Q

What are the precursor cells of muscle cells?

A

Myoblasts

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5
Q

What are the origins of myogenic precursors?

A

Somite

Mesenchyme of pharangeal arches

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6
Q

What are the two lips of the dermamyotome, where do they migrate and what do they form? (Development)

A

Dorsal-medial lip cells migrate ventrolaterally to form myotome muscles/epaxial deep back muscles

Ventral-lateral lip cells migrate to limbs, hypaxial myotome and ventral body wall muscles

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7
Q

Name the connective tissues in muscle in ascending density

A

Endomysium

Perimysium

Epimysium

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8
Q

Where does the muscle connective tissue merge with the tendon?

A

Myotendinous junction

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9
Q

What are myofibres grouped into? Describe the connective tissue involved in this structure

A

Fascicles - myofibres individually wrapped in endomysium and the fascicle is surrounded by perimysium

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10
Q

Where are the nuclei in skeletal muscle cells?

A

Periphery of cell

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11
Q

What does the A band consist of?

A

Thick myosin filaments overlapping actin

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12
Q

What does the I band consist of?

A

Thin actin filaments

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13
Q

What does the H zone consist of?

A

Thick myosin filaments (no overlap)

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14
Q

What does the M line consist of?

A

Myosin cross-linking proteins

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15
Q

What does the Z line consist of?

A

Actin cross-linking proteins

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16
Q

What part of the sarcomeres demarcate a single sarcomere?

A

Z lines

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17
Q

What do costameres do?

A

Link myofibrils to sarcolemma at Z lines

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18
Q

What links adjacent myofibrils together?

A

Desmin (intermediate filament) with plectin at Z lines

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19
Q

What is the motor end plate?

A

Specialised area on muscle fibre membrane where a nerve axon contacts to form a synapse

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20
Q

What is a motor unit?

A

One motor neuron and all the muscle fibres it innervates

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21
Q

Where are the motor units smaller?

A

Hand muscles

Eye muscles

22
Q

Where are fast myosin isoforms found?

A

White muscle fibres

23
Q

How much myoglobin do fast myosin isoforms have?

A

Small amount

24
Q

Describe the activity of fast myosin isoforms

A

Contract rapidly but quickly become fatigued

25
Q

Where are slow myosin isoforms found?

A

Red muscle fibres

26
Q

How much myoglobin do slow myosin isoforms have?

A

Lots

27
Q

Describe the function of slow myosin isoforms

A

Contract slowly but keep going for a long time (endurance)

28
Q

Are most muscles just one type of myosin fibre?

A

No, often mixtures of different types

29
Q

What type of myosin isoform do posture muscles in your back consist of?

A

Slow

30
Q

What type of myosin isoform do the muscles in your eyes consist of?

A

Fast

31
Q

Why do we have a tubular system in muscles?

A

Allows propagation of action potential throughout the muscle

32
Q

What do triads consist of?

A

2 outer = sarcoplasmic reticulum (terminal cisternae)

Inner = T-tubule

33
Q

What does the sarcoplasmic reticulum have in its membrane (activated during depolarisation)?

A

Voltage-gated calcium ion channels

34
Q

Where are the triads located?

A

Each sarcomere has a pair of triads at the A-I borders

35
Q

What are muscle satellite cells?

A

Resident adult muscle stem cells

36
Q

What do muscle satellite cells become when activated?

A

Myoblasts

37
Q

What can satellite cells do for the muscle?

A

Produce new myonuclei for existing myofibres

Fuse together to form new myofibres

38
Q

Where does cardiac muscle develop from?

A

Front end of embryo - cardiogenic mesoderm

39
Q

What are heart muscle cells called?

A

Cardio myocytes

40
Q

Where is the nucleus in a cardiac muscle cell?

A

Central

41
Q

What types of muscle are striated?

A

Skeletal and cardiac

42
Q

How are cardiac muscle cells connected?

A

Intercalated discs

43
Q

What are intercalated discs and what do they do?

A

Modified Z-lines

Form a functional syncytium

44
Q

What are intercalated discs comprised of and why?

A

Desmosomes - hold cells together (intermediate filaments)

Gap junctions - allows Ca2+ flow between cells

Fascia adherens - hold cells together (actin)

45
Q

Why can the heart not regenerate after injury?

A

No satellite cells

46
Q

How does the heart contract? Where do the contractions originate from?

A

Atria - top-down

Ventricles - bottom-up

SAN

47
Q

How big are smooth muscle cells?

A

~5 microns/micrometres dia.

20-500 microns/micrometres in length

48
Q

What is the shape of a smooth muscle cell?

A

Spindle-shaped

49
Q

How are the actin and myosin filaments arranged in a smooth muscle cell?

A

Actin and myosin mesh work fills cytoplasm

Actin tethered to cell surface by junctional complexes

50
Q

How do smooth muscle cells contract?

A

Twist and shorten like wringing out a flannel

51
Q

What are gap junctions for?

A

Allow electrical excitation to spread from cell to cell

52
Q

What are smooth muscle cells controlled by?

A

Hormones

Sympathetic/parasympathetic innervation

Histamines (allergic reactions)

BMS10 (13 decks)

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