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Cardiovascular System Module > Lecture 9 > Flashcards

Lecture 9 Flashcards

1
Q

How does excitation contraction coupling occur at the cellular level?

A

The cell depolarises the cell membrane from -80mV to +10mV where it excites the contractions for the cell

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2
Q

What does electrolyte excitation elevate?

A

Cytoplasmic ca2+ in the cell, interacts with the myofilament proteins of the cell to give the resulting contraction

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3
Q

What does the structure of the ventricular cardiomyocytes mean?

A

Proves the function - ca2+ contraction

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4
Q

What type of muscle are heart muscles?

A

Striated heart muscle

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5
Q

What is found in striated heart muscle?

A

Lots of mitochondria

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6
Q

Why are heart muscles called striated muscles?

A

Because they have alternative light and dark banding

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7
Q

What are the light and dark bands?

A

Sarcomeric structures - striated parents of the cardiomyocytes

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8
Q

Why do striations occur?

A

Because of the rigid arrangements of the thick and thin filaments of the sarcomere structures

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9
Q

What are sarcomeres defined by?

A

Defined by the boundary of the Z lines

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10
Q

How far apart are the Z lines?

A

2 microns apart

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11
Q

What are Z lines?

A

Scaffolding structures that hold in place the thin filaments

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12
Q

What do you see in the middling portions?

A

Much more myofilament activity as this is where the invaginations of the thick and thin filaments are

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13
Q

What are sacromeric structures?

A

The individual contractile units within the cell - control with electrical excitation contraction

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14
Q

What is in the middle of the H zone?

A

The N line

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15
Q

What does the H zone do?

A

Holds the thick filament in place

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16
Q

What happens if the sarcomere shortens?

A

The whole cell shortens

17
Q

What shape does the plasma Lamar make?

A

A cube - as it has right angle convolutions

18
Q

Where do the T-tubular invaginations of the plasma lemma occur at?

A

Z lines

19
Q

What do the 90 degree convolutions of the plasma lemma allow?

A

Allows the electrical citation to get deeper into teh cell to get closer to the sarcomeric units

20
Q

What do the cardiomyocytes occur in?

A

They occur in unison, they occur in close proximity to the Z lines

21
Q

What are the two structural specialisations of the cardiomycoyte?

A

Convolutions of the plasma lemma and the facilitation of CICR

22
Q

Describe the facilitation of CICR in the cardiomyocytes?

A

Close positioning of the SR next to the t-tubule

23
Q

What are the transverse T -tubules part of?

A

The Extracellualr part of the matrix

24
Q

What is the double membrane system?

A

Developing from the T tubule cavity and SR

25
Q

What determines the whole cell responsiveness?

A

Local spatiotemporal ca2+ dynamics

26
Q

What does the local spatiotemporal ca2+ dynamics determine?

A

The whole cell cytosolic ca2+, nanometers localisation of CICR

27
Q

Why do calcium sparks arise?

A

When the SR recognises that the ryanodine receptor 2 channels recognise the amount of ca2+ is too much, the ca2+ opens the channels and produces a ca2+ spark

28
Q

What needs to happen in order for ca2+ to be released for the SR?

A

Dynamic equilibrium - is never 0 to is just at a lower level

29
Q

How do Ca2+ sparks arise?

A

From spontaneous openings of protein channels on the SR membrane

30
Q

How are ca2+ sparks at rest?

A

They occur spontaneously at rest

31
Q

What are ryanodine receptors 2 sensitive to?

A

Sensitive to cytoplasmic ca2+ elevations and increases in SR luminal Ca2+

32
Q

What techniques can look at ion currents?

A

Patch clamps experiments and configurations which can control the membrane potentials of the cell

33
Q

Look up voltage L-type Ca current

A
34
Q

What does an increase in frequency of ca2+ sparks mean?

A

More green, more spark, summation of ca2+ signals

35
Q

What is the type of feedback loop of CICR?

A

Positive feedback loop and occurs at every t-tubule invagination at every Z line

36
Q

What does each electrical action potential arriving at a cardiomyocytes lead to?

A

A rapid ca2+ rise across all individual sarcomeric units

37
Q

What are the two main processes for return of ca2+ to rest?

A

Plasma lemma extrusion by Na+/Ca2+ exchange, re uptake to the SR by a ca2+ ATPase (SERCA)

38
Q

What is SERCA regulated by?

A

By an accessory protein phospholamban

Cardiovascular System Module (18 decks)

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