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(I) Symposium: Science Underpinning Practice, High Yield > Cardiovascular Physiology > Flashcards

Cardiovascular Physiology Flashcards

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1
Q

What effect does the SNS system have on the heart and on what receptors

A

The SNS affects the automaticity of the heart and also the contractlity by binding to beta-1 receptors found on the nodal cells and also on the myocardium. Beta receptors on the nodal cells increases the L-type calcium channels expressed by phosphorylation more channels. Whereas in the myocardium there is an increased entry of calcium increase the number of cross links this increasing contractility.

Tachycardia

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2
Q

What effect does the PNS system have on the heart and what receptors are implicated?

A

The PNS system: Ach binds to the M2 receptors found only on the nodal cell reducing the rate of action potentials sent through so it is a negative chronotrope.
Bradycardia.

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3
Q

What is a chronotrope?

A

Chronotropic effects are those that change the heart rate. Chronotropic drugs may change the heart rate and rhythm by affecting the electrical conduction system of the heart and the nerves that influence it, such as by changing the rhythm produced by the sinoatrial node.

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4
Q

What is an ionotrope ?

A

Inotropic factors are factors that affect the amount of force that the cardiac fibers contract with

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5
Q

Cardiac output equation

A

CO= HR x SV

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6
Q

What area of the heart’s electrical conduction is known as the “pacemaker” of the heart?
?
a. SA node
b. AV node
c. Purkinje Fibers
d. Bundle of His

A

A

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7
Q

What area of the heart is responsible for the delay of
conduction between the atrium and ventricles?
a. AV node
b. Bundle of His
c. Bachmann’s Bundle
d. Right bundle branch

A

A

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8
Q

True or False: Depolarization of the heart muscle is
when the muscle contracts and repolarization is
when the heart muscle rests.
a. True
b. False

A

A

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9
Q

The SA node fires at a rate of?
a. 80-90 bpm
b. 40-60 bpm
c. 60-100 bpm
d. 60-80 bpm

A

d

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10
Q

On an EKG the P-wave represents what area of the
heart? (You may choose more than one)
a. Left bundle branch
b. AV node
c. Bachmann’s Bundle
d. SA node
e. Atrial myocardium

A

D/E

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11
Q

What is a consequence of hypokalemia?…

A

More [K+] will leave the cell to go to the concentration of low [K+] resulting in activation of Na+ channel more readily at nodal cell; this will lead to arrythmia that could be potentially fatal.

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12
Q

What is consequence of hyperkalemia ?

A

↑K+ ECF–> ↓ K+ leaving cell–> K+ accumulates in the cell–> cell +++–> Na+ voltage gated channels remain inactivated —> don’t return to resting state—> cardiac arrest.

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13
Q

What drugs cause hyperkalaemia

A

ACE-Inhibitors
Potassium supplements
Spironolactone, amiloride
Heparins

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14
Q

What drugs cause hypokalaemia

A

Diuretics
Beta agonist
Insulin
Corticosteroids
lithium

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15
Q

What drugs cause hypernatraemia

A

Corticosteroids
IV antibiotics with sodium
Oral contraceptive
Sodium bicarbonate

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16
Q

What drugs cause hyponatremia

A

Antidepressant
Desmopressin
Carbamazepine
Diuretics
Lithium

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17
Q

What drugs out of this list is not renally cleared?
A. Diuretics
B. Beta blocker
C. Calcium channel blocker
D. Ramipril

A

D. Ramipril excreted by the bile.

18
Q

What happens to aldosterone during dehydration?

A

Aldosterone and ADH secretion increased following dehydration. It is suggested that the ADH. besides its water reabsorptive functions in the kidney, initiates aldosterone secretion. The aldosterone then works primarily on the distal and collecting ducts causing absorption of salt and water.

19
Q

What is automaticity.

A

The heart’s intrinsic ability to depolarize and generate action potential free of autonomic innervation.

20
Q

Describe ECG starting from P-wave all the way to T wave.

A

ECG: At the start of the P wave the sino-atrial node depolarizesà P-wave: Depolarization of the atriaà QRS-Complex: depolarization of the ventricular myocardiumà T-wave: Repolarization of the ventricular myocardium

21
Q

Describe the conduction pathway.

A

Sino-atrial node —> AV node (0.1s wait before the bundle of His is innervated to allow for the atria to contract). —> Bundle of His —> Purkinje Fibers: Contraction of the ventricles

22
Q

Describe briefly the channels involved in SA nodes depolarisation occurring

A

Funny Na+ channels are open at rest and there is a slow movement of Na+ making the cell positive moving it to -55 mV where T-type calcium channels are stimulated.
T-type calcium channels allow for more Ca2+ move into the cell and at -40 mV the L-type Ca2+ open.
L-type Ca2+ channels allow for explosion of Ca2+ influx causing the nodal cells to depolarise into adjacent contractile myocardial cells via intercalated discs.

23
Q

Describe briefly the contraction of myocardium

A

L-type Ca2++ channels open allowing Ca2+ enter and rise in intracellular Ca2+ allows for myosin to bind actin forming cross bridges.

24
Q

The more cross-bridges formed the stronger the …. Of the heart

A

Contraction

25
Q

In order of Na+ voltage gated channels to be activated what must happen.

A

After depolarisation voltage gated K+ channels open allowing for K+ to leave the cell, making the cell increasingly negative.

26
Q

What drugs cause QT prolongation.

A

Antiarrthymics: amiodarone, sotalol, quinidine
Macrolides: erytromycin, clarithromycin
Fluoroquinolones: Levofloxacin, Moxifloxacin
Antifungal drugs: ketoconazole, fluconazole
Antimalarial: chloroquine
Psychoactive drugs: SSRI, antipsychotics
Antiretroviral: Saquinavir.

27
Q

Where are Beta1-receptors located.

A

On the heart.
Nodal cells
Myocardium

28
Q

If SNS binds to beta-1 receptors what effect are initiated.

A

Increase phosphorylation of L-type Ca2+ channels= increasing HR and Contractility.

29
Q

Name a positive inotropes and negative chronotrope drug and its mechanism of action.

A

Digoxin is a positive inotrope because it increases intracellular calcium in the muscle by inhibiting the Na+/K+ ATPase pump increasing the sodium in the cell which in turn increases calcium entry. Causing increase in cross bridge formation=increased contractility.

On the AV node digoxin stimulates parasympathetic nervous system, slowing electrical conduction in the AV node therefore decreasing heart rate.

30
Q

Beta-blockers are negative inotropes.
(a) True
(b) False

A

(a) true

31
Q

Alpha-1-receptors are located…

A

Post junctional receptors on most vessels.

32
Q

What are the effects if noradrenaline binds to alpha-1 receptor.

A

Vasoconstriction

33
Q

What drugs antagonise noradrenaline effects on alpha-1 receptors.

A

Doxazosin.

34
Q

Alpha-2 receptors are located on…

A

Auto receptors in skin vessels and muscle of distal arterioles.

35
Q

Beta-2 receptors are located on.

A

Arterioles of the heart, skeletal muscle, liver

36
Q

What are the effects of beta-2 receptors

A

Dilation.

37
Q

Increase in end. Diastolic volume results in increase in…

A

Preload

38
Q

Increase in after load will result in

A

Diastolic hypertension

39
Q

What hormones can also affect the contractility of the heart.

A

Thyroid hormone: T3 and T4

40
Q

Describe renin-angiotensin-aldosterone system

A

(I) Symposium: Science Underpinning Practice, High Yield (12 decks)

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