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Flashcards in Muscle Deck (67):
1

What can left ventricle failure result in? How?

Pulmonary oedema

Blood accumulation in pulmonary veins, increased blood pressure in these vessels, fluid pushed into the alveoli

2

What is left ventricle hypertrophy usually in response to?

In response to high blood pressure or another condition where the heart has to work harder

3

Which test can be used to treat for heart failure?

BNP test

4

What does BNP stand for? Are there increased or decreased levels when heart is working hard (failing)?

Brain natriuretic peptide

Increased levels

5

What is muscle hypertrophy?

The increase in size of muscle fibres in response to increased muscle work

6

What is muscle atrophy? What can cause it?

The reduction in size of muscle fibres

Muscle inactivity, malnutrition etc.

7

What are three indicators of muscle injury in the body? In which parts of the body are they found?

Creatine kinase (all muscle/brain)
Myoglobinuria (skeletal muscle)
Troponin (cardiac muscle)

8

What are the disadvantages of using creatine kinase as an indicator for myocardial infarction?

Levels can increase after intense exercise, or a fall etc. - so replaced by troponin

9

Is the quantity of troponin or creatine kinase measured proportional to the degree of damage of the muscle?

Yes - creatine kinase

No - troponin

10

Troponin will be found in increased levels during which type of scan? When should troponin levels be measured to test for muscle injury?

MRI

Within 20 hours

11

What does myalgia mean?
What does myasthenia mean?
What does myoclonus mean?

Muscle pain
Muscle weakness
Sudden spasm of the muscles

12

What does sarcolemma mean?
What does sarcoplasmic reticulum mean?
What does sarcoplasm mean?

Plasma membrane of a muscle cell
SER of a muscle cell
Cytoplasm of a muscle cell

13

What are the 3 types of muscle?

Cardiac
Smooth
Skeletal

14

Muscle can be grouped into which 2 categories? Which muscle types are in which categories?

Striated (cardiac, skeletal)
Non-striated (smooth)

15

What is the structure of skeletal muscle?

Long parallel cylinders for forceful contraction

16

Skeletal muscle fibres ________ in their diameter

Differ

17

What are the different types of skeletal muscle fibre? Order them by diameter.

Narrow RED fibres
Intermediate fibres
Wide white fibres

18

What is the difference in vascularisation and myoglobin abundance between white and red muscle fibres?

White = poor vascularisation/myoglobin

Red= rich vascularisation/myoglobin

19

Are there more mitochondria in red or white muscle fibres?

More in red fibres

20

How do red and white muscle fibres contract differently? How do they fatigue?

Red = fatigue slowly, slow repetitive contractions

White = fatigue quickly, fast strong contractions

21

Where are red muscle fibres found in high abundance?

Postural muscles of the back

22

Where are white muscle fibres found in abundance?

Finger muscles

23

Myoglobin is present in which types of muscle?

Cardiac and skeletal

24

What connects skeletal skeletal muscle to bone?

Tendons

25

Muscle fibres are grouped into bundles called _______

Fascicles

26

Bundles of fascicles make up the muscle, what surrounds these bundles of fascicles?

A muscle sheath (EPIMYSIUM)

27

What surrounds individual muscle fibres?

Endomysium

28

What surrounds individual fascicles in skeletal muscle?

Perimysium

29

Give an example of a muscle that is not connected to bone but to connective tissue?

Intrinsic muscles in the tongue

30

How can skeletal muscle be recognised on a micrograph?

Multinucleate cells, peripheral nuclei in transverse section

31

What do muscle fibres consist of?

Myofibrils

32

What do myofibrils consist of?

Thin actin filaments
Thick myosin filaments

33

Replacement of contractile proteins in muscle fibres happens every...

2 weeks

34

What are two types of atrophy? Briefly describe each?

Disuse atrophy (through muscle inactivity - decreased contractile proteins - decreased fibre diameter - loss of power)

Denervation atrophy - where the nerve to the muscle is cut

35

When does atrophy related to age begin?

30 yrs old

36

What is the cause of hypertrophy?

Increased contractile proteins, increased fibre diameter

37

How can muscle length be adjusted?

Addition (Stretching) or removal (limb in plaster) of sarcomeres

38

The ______ of sarcomeres leads to contraction

Shortening

39

Which filaments make up the A band of a sarcomere? What bands exist within the A band?

Thick myosin filaments
Dark M band, Light H band

40

Which filaments make up the I band of a sarcomere? Which bands exist in the I band?

Thin actin filaments
Dark Z line exists

41

Which is darker in appearance the A band or the I band?

A band

42

What happens in muscle contraction after the action potential travels down t tubules?

Calcium released from the SER
Calcium binds to actin filaments
Tropomyosin is removed from the active sites of actin
Myosin forms cross bridges and pulls actin to the centre of the sarcomere (using ATP)
Removal of calcium ions ---> tropomyosin blockage restored

43

What are t tubules?

Extensions of the sarcolemma that pass by every myofibril of a muscle fibre, allowing depolarisation, shortening of sarcomeres and contraction

44

What is fibrillation?

Contraction of individual muscle fibres

45

What is fasciculation? Which disease can this indicate?

Contraction of whole muscle fascicles

Motor neurone disease

46

How can cardiac muscle be recognised from a micrograph?

Centrally positioned nuclei
Branching
Intercalated discs between adjoining cells

47

Are there myofibrils in cardiac muscle fibres?

No distinct fibrils, continuous filament mass in cytoplasm

48

How are muscle fibres often connected?

Gap and tight junctions

49

What is cell hyperplasia?

Method of increasing tissue size by multiplication of the cells

50

What types of molecules are natriuretic peptides? What do they do?

Peptide hormones

Work to reduce blood pressure by reducing blood volume

51

Elevated levels of ANP are found in patients with...

Mitral valve disease
Left ventricle hypertrophy

52

ANP is released by...

Atrial myocytes

53

BNP is released by...

Ventricular myocytes and in the brain

54

pro-BNP is split into which two diagnostic markers for heart failure?

BNP and NT-pro-BNP

55

The specialised myocardial cells that carry impulses to the ventricles from the AV node are called...

Purkinje Fibres

56

What are features of purkinje fibres?

They have abundant glycogen
Sparse myofilaments
Extensive gap junctions

57

What appearance to smooth muscle cells show?

Spindle shaped with a central nucleus

58

Does smooth muscle have sarcomeres or t tubules?

No

59

How are actin and myosin filaments arranged in smooth muscle?

Arranged diagonally spiralling down intermediate filaments

60

Smooth muscle is involuntary. Does smooth muscle show fast or slow contraction?

Slow

61

What are two types of modified smooth muscle cell?

Myoepithelial cells
Myofibroblasts

62

What role do myoepithelial cells play?

Form around the secretory units of exocrine glands - contractions aids in secretion of substances into glands

63

What role do myofibroblasts play?

Found at sites of wound healing, help in wound contraction and tooth eruption

64

Smooth muscle cells are innervated by autonomic nervous system fibres. Where is neurotransmitter released from these nerve fibres?

At varicosities into a wide synaptic cleft

65

How do skeletal muscle cells repair themselves?

Cannot divide
Tissue regenerates through the division of satellite cells

66

How does cardiac muscle repair itself?

Cannot regenerate
Fibroblasts lay down scar tissue

67

How does smooth muscle repair itself?

Retains mitotic activity to form new smooth muscle when needed