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Term 1 MD > Cardiac Muscle Physiology > Flashcards

Cardiac Muscle Physiology Flashcards

1
Q

Pacemaker activity of the heart is generally regarded as:

A

Automaticity

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2
Q

How does the heart regulate force of contraction?

A

Titrating Calcium levels via inotropism

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3
Q

What is a syncytium?

A

Arrangement of muscle fibers in which the fibers fuse to form an interconnected mass of fibers. Gap junctions within the heart.

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4
Q

Fast channels within the heart:

A

Voltage activated sodium channels

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5
Q

Slow channels within the heart

A

Voltage activated calcium channels

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6
Q

In cardiac muscle the sarcoplastic reticulum forms a Diad or Triad?

A

Diad: for communication between two cardiomyocytes

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7
Q

Which ion is essential to cardiac muscle contraction?

A

Calcium

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8
Q

Inotropism

A

The ability of the myocardial cells to change the force/strength at the level of the cell and this modification can occur independently of any change in force caused by alterations in preload or afterload on the heart

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9
Q

Anrep Effect

A

Abrupt increase in afterload produces modest increase in inotropy

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10
Q

Bowditch effect

A

Increase in heart rate produces a small (+) inotropic effect

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11
Q

Factors that increase inotropy in the cardiomyocyte tissue

A
  1. Parasympathetic inhibition
  2. Sympathetic Activation
  3. Circulating catecholamines
  4. Heart rate (Bowditch Effect)
  5. Afterload (Anrep Effect)
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12
Q

(+) Inotropic Drugs

A

Digoxin
Beta Agonists: Gs-Protein linked receptors:
1. Dopamine
2. Dobutamine
3. Epinephrine
Phosphodiesterase inhibitors: increase cAMP: Milrinone

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13
Q

Which drug inhibits Na+/K+ ATPase, which decreases the gradient of Na+ and therefore indirectly inhibits Na+/Ca2+ exchanger?

A

Digoxin

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14
Q

What is digoxin used for clinically?

A

Cardiac glycoside: Systolic Heart Failure

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15
Q

Calcium channel blockers inhibit

A

Voltage dependent L-type calcium channels, which decrease muscle contractility

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16
Q

Dihydropyridine

A

Calcium channel blocker that acts on vascular smooth muscle

17
Q

Calcium Channel Blockers

A
  1. Amplodipine
  2. Clevidipine
  3. Nicardipine
  4. Nifedipine
  5. Nimodipine
18
Q

Clinical use for calcium channel blockers:

A

Hypertension, prevention of cerebral vasospasm

19
Q

Drugs that are non-dihydropyrine Calcium channel blockers and clinical use

A
  1. Dilitiazem
  2. Verapamil
    Clinical Use: Atrial Fibrillation
20
Q

Verapamil use

A

Atrial fibrillation treatment

21
Q

Drugs used to treat bronchial asthma

A

Albuterol, levalbuterol, salmeterol, salbutamol (inhalation)
*Beta-2 agonists (2 lungs mnemonic)

22
Q

Drugs used to induced uterine smooth muscle relaxation in pregnant women

A

Terbutaline: tocolysis
-Premature labor

23
Q

What is milrinone used for?

A

Short-term use in acute decompensated heart failure

24
Q

Milrinone is what type of drug?

A

Selective PDE-3 inhibitor (increases inotropy, chronotropy, general vasodilation in vascular smooth muscle)

25
Q

MOA of milrinone:

A

Increase cAMP in cardiomyocytes which increases calcium influx.
-In vascular smooth muscle, increases cAMP, inhibits MLCK activity (myosin light chain kinase)

26
Q

What are nitrates used for?

A

Increase in vascular smooth muscle, dilates veins and decrease the preload

27
Q

Nitroglycerin, isosorbine denitrate, isosorbide mononitrate are examples of what kind of drug and used for which clinical condition?

A

Nitrates
-Clinical use: angina acute coronary syndrome

28
Q

Hydralazine

A

increases cGMP (vascular smooth muscle relaxation)
-Dilates arterioles
-Clinical use: severe hypertension (acute treatment)

29
Q

Nitroprusside

A

Increases cGMP: vascular smooth muscle relaxation

30
Q

Pharmacomechanical coupling of Calcium channel receptor called

A

Ligand-gated Calcium channels

31
Q

Electromechanical coupling of calcium channel receptor called

A

Voltage gated calcium channels

32
Q

Myogenic regulation in the arterioles calcium channel receptor called

A

Leak calcium channels

33
Q

Mechanical stretch promotes inward of calcium

A

Stretch-activated calcium channels

34
Q

Which of the following is the most important difference between the myosin II filaments of the smooth and striated muscles:

A

Actomyosin ATPase activity is much slower in smooth muscle

Term 1 MD (54 decks)

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