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Physiology > Cardiac Muscle > Flashcards

Cardiac Muscle Flashcards

1
Q

What is the formula for cardiac output?

A

CO= HR * stroke volume

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2
Q

What is the formula for stroke volume?

A

stroke volume = end diastolic volume - end systolic volume

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3
Q

What is venous return?

A

amount of blood returning to the right atrium/min

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4
Q

What occurs when valves are closed during contraction of cardiac muscle chambers?

A

pressure develops during myocardial contraction

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5
Q

What happens hen the ventricular chamber pressure exceeds the aortic blood pressure?

A

valves open

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6
Q

What occurs when valves are open during contraction of cardiac muscle chambers?

A

the ventricular chamber pressure exceeds the aortic blood pressure

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7
Q

What are intercalated discs?

A

lay between cardiac cells and have the mechanical and electrical connections between cells

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8
Q

What is the purpose of t-tubules?

A

lie along Z line to help propagate depolarization charge

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9
Q

What is the name of the Ca reuptake pump?

A

SERCA2a

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10
Q

What is the name of the integral protein that inhibits the Ca uptake pump?

A

phospholamban

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11
Q

What is the role of depolarization in excitation-contraction coupling?

A

causes Ca entry via voltage gated Ca channels

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12
Q

Ca entry triggers Ca release from the SR via what receptor?

A

ryanodine receptors

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13
Q

Increased intracellular Ca is via what?

A
  • release from SR via Ca-induced Ca release channels
  • influx through voltage gated L-type Ca channels
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14
Q

Intracellular Ca is pumped back into SR and out of myocyte via what?

A

CaATPase pumps and Na/Ca exchanger

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15
Q

What are the steps of the ratchet mechanism?

A
  1. bound ATP causes conformation in myosin region and actin binds
  2. hydrolysis of ATP causes change in myosin region -> shortening of sarcomere
  3. ADP dissociates from myosin
  4. myosin-actin remain bound with no ATP (rigor mortis)
  5. ATP binding to myosin
  6. ATP binding causes dissociation of myosin from actin
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16
Q

Force is produced with increased what?

A

muscle length

17
Q

What is resting tension?

A
  • produced by the resting biochemical properties of the cardiac tissue
  • absence of cross-bridge cycling
18
Q

What is active tension?

A

produced by cross-bridge cycling

19
Q

What is total tension?

A

resting tension + active tension (RT + AT)

20
Q

What is Starling’s Law of the heart?

A

the force of contraction of the heart is proportional to the initial fiber length

21
Q

The length dependent increase in force following stretch may be due to what?

A
  1. decreased interfilament spacing between actin and myosin
  2. increase in the sensitivity to Ca
22
Q

What brings 2 filaments together?

A

stretching

23
Q

Stretching does what to the cardiac muscle to Ca?

A

increases the sensitivity

24
Q

What is the affect of increasing the venous return?

A
  • greater force of contraction
  • an increase in stretch
  • increase end diastolic volume
25
Q

Phosphorylating troponin causes what?

A

a contraction to occur

26
Q

When you inhibit the entire process what happens to contractions?

A

contractions decrease

27
Q

What is the role of a vagus nerve ?

A
  • innervates the heart
  • controls HR affects SA node
28
Q

What does protein kinase A do in autonomic regulation?

A

phosphorylates phoshpholamban, troponin, RyR, and Ca channel

29
Q

What is the sympathetic innervation response in autonomic regulation?

A
  1. NE being released from nerve terminals activate beta-AR
  2. beta-AR activates GS -> adenylyl cyclase - >cAMP
  3. cAMP -> regulation of protein kinase A to phosphorylate substrates
30
Q

What does downstream phosphorylation do to downstream proteins?

A
  • increase amount of Ca that can flow throguh channel
  • increase amount of Ca induced-Ca released via Ryr
  • phospholamban -> enhance rate of ATPase in Ca uptake
  • troponin I -> facilitates troponin removal to allow cycle to occur
31
Q

What is the parasympathetic innervation response in autonomic regulation?

A
  1. vagus nerve innervating and releasing Ach as neurotransmitter binds to muscarinic M2 receptor
  2. GI proteins inhibit adenylyl cyclase
  3. amount of cAMP conc. and amount of protein kinase activation is reduced
32
Q

What occurs when phospholamban has its inhibition of Ca ATPase removed?

A
  1. increase uptake of Ca by CaATPase
  2. shortened contraction and increased rate of relaxation
33
Q

What are the factors that affect EDV/preload?

A
  1. ventricular compliance
  2. filling time (heart rate): increase time= increase preload= increase EDV
  3. venous return: increase return= increase preload= increase EDV
34
Q

What is afterload?

A

forces that work against the heart to pump blood

Physiology (9 decks)

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