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BIOL 125 > Lecture 7 > Flashcards

Lecture 7 Flashcards

1
Q

What is an electrocardiogram?

A

Test for clinical abnormalities in the conduction of electrical activity in the heart.

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2
Q

Are electrocardiograms invasive?

A

No (non-invasive). Purely external measure of heart’s activity.

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3
Q

Does an ECG give any indication of physical defects?

A

No.

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4
Q

How do the electrodes detect the heart beat?

A

Body is the conductor, and the currents spread to the surface.

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5
Q

Where are electrodes most commonly placed for an ECG?

A

Left Leg, Right Arm, Left Arm.

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6
Q

What are the 6 components of an ECG, and what do they represent?

A 
P wave - atrial depolarisation.
QRS complex - ventricular depolarisation. 
T wave - ventricular repolarisation. 
PQ segment - AV nodal delay. 
QT segment - ventricular systole. 
TQ interval - ventricular diastole.
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7
Q

What are the two types of cardiac arrhythmia, and how fast is each?

A

Tachycardia - fast.

Bradycardia - slow.

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8
Q

What are cardiac arrhythmias due to?

A

Abnormal SA firing.

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9
Q

What is heart block?

A

Slowed/diminished conduction through AV node, which occurs in varying degrees.

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10
Q

What 2 types of heart block are there? And how can they be recognised on an ECG?

A

Slowed conduction through AV node - Increased PQ segment (delay between atrial and ventricular conduction).
No conduction through AV node - Absence of QRS complex and T wave.

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11
Q

What is ventricular fibrillation?

A

Loss of co-ordination of synchronised electrical activity of the heart.

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12
Q

What happens to the patient if ventricular fibrillation occurs?

A

Death in a few minutes.

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13
Q

How do you rescue a patient with ventricular fibrillation?

A

Pass a large current through chest to defibrillate ventricular muscle. (A.K.A defibrillator).

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14
Q

What is pericarditis, and what is it caused by?

A

Inflammation of pericardium, causing an accumulation of blood/pus/fluid in pericardial space.
Caused by: trauma, infections, tumours.

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15
Q

What are the symptoms of pericarditis?

A

Chest pain, breathing difficulty, fatigue.

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16
Q

How is function impaired with pericarditis?

A

Can reduce compression of the heart - reduced end diastolic volume (EDV).

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17
Q

What are 3 disorders of heart valves?

A

Rheumatic fever, mitral valve prolapse, Aortic regurgitation.

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18
Q

What is Rheumatic fever, and what effect does it have on the heart?

A

Inflammation of cardiac valves.

Slows blood flow from heart chambers.

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19
Q

What is a mitral valve prolapse (MVP), and what effect does it have on the heart?

A

Leaky mitral (bicuspid) valve.

Reduced ejection fraction.

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20
Q

What is aortic regurgitation and what effect does it have on the heart?

A

Leaky aortic semilunar valve.

Causes volume overload in LV.
LV increases contraction to overcompensate.

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21
Q

When do people most often notice symptoms relating to mitral valve prolapse (MVP)?

A

Around 20-30, but can begin at any age.

22
Q

Percentage of men and women with MVP?

A

7.6% of women, 2.5% of men.

23
Q

What happens physiologically in MVP?

A 
Abnormality of mitral valve leaflets, or supporting chords, or both.
Leaflets prolapse (buckle back) into left atrium during ventricular systole. 
Some blood leaks back into left atrium.
24
Q

What (5) symptoms can present themselves in MVP?

A

Chest pain, fatigue, palpitations, dizziness, shortness of breath etc.

25
Q

What happens in aortic regurgitation?

A

Aortic semilunar valve doesn’t close properly, leaking blood back into left ventricle.

26
Q

What is coronary artery disease caused by?

A

Thrombosis and embolism.

27
Q

What happens in coronary artery disease?

A

Blockage of coronary artery causing reduced blood flow to myocardium.

28
Q

What can occur in coronary heart disease if it gets too severe?

A

Myocardial infarction - causing tissue death.

29
Q

A weak heart can lead to what? Why?

A

Reduced blood circulation due to coronary artery disease, myocardial infarction, infection.

30
Q

What does a weak heart cause, physiologically speaking?

A

Pumping pressure to systemic circulation decreases, causing increased end diastolic volume and an increase in the heart.
Swelling of legs and ankles due to water retention.
Can lead to congestion of blood in pulmonary circulation -> pulmonary oedema -> right heart failure.

31
Q

What can a weak heart cause, in terms of condition?

A

Congestive heart failure.

32
Q

What can digitalis be used to treat? And how does it work?

A

Congestive heart failure, tachycardia.

Makes heart contract harder, used when heart’s pumping function has been weakened.

33
Q

What do statins do?

A

Lower blood-cholesterol.

34
Q

What does ACE (angiotensin converting enzyme) inhibitor do?

What can they be used to control and treat?

A

Stops production of angiotensin II.

Controls high blood pressure.
Treats heart failure, where heart cannot pump enough blood to supply body’s needs.

35
Q

What is angiotensin II?

A

Hormone that constricts blood vessels.

36
Q

What are angiotensin II receptor antagonists similar to, and what do they do?

A

Work on same system as ACE inhibitors.

Prevent angiotensin II from acting on cells.

37
Q

Where is digitalis from?

A

From foxglove (digitalis purpurea).

38
Q

What is digitalis’ mechanism of action?

A

Inhibits sodium-potassium pump, causing intracellular Na+ to increase. Leads to accumulation of intracellular Ca2+ via Na+/Ca2+ exchange system, causing increased contractility of the heart via interaction of Ca2+ with troponin.

39
Q

What 5 drugs are commonly used in heart disease?

A 
Beta-blockers,
Nitroglycerine and amyl nitrate,
Calcium channel blockers,
Thrombolytic agents,
Aspirin.
40
Q

What do the beta blockers do, and what are they used for?

A

Slows heart, making it beat with less contracting force, causing drop in blood pressure.
Used for high blood pressure, angina, to prevent repeat heart attacks.

41
Q

What do nitroglycerine and amyl nitrate do?

A

Dilate coronary arteries, stopping chest pain in angina.

42
Q

What do calcium channel blockers to? And what are they used for?

A

Dilate blood vessels, can slow heart.

Used for high blood pressure and chest pain.

43
Q

What are thrombolytic agents used for?

A

During/immediately after a heart attack to break up a clot in coronary artery to restore blood flow.

44
Q

What type of patient is aspirin used upon, and why?

A

At-risk individuals of myocardial infarction, or people who’ve already had heart bypass.
Because it lowers risk of heart attack, and helps keeps arteries open.

45
Q

What do beta-blockers bind to, and what do they inhibit?

A

β-adrenergic receptors (7TM), locked in cardiac tissue.

Inhibit adrenaline and noradrenaline to these receptors.

46
Q

What do beta-blockers do to sympathetic influences that normally stimulate heart rate and contractility?

A

Reduces them. Causes a decrease in these activities.

47
Q

What do beta blockers do to the heart rate, and how?

A

Slows it down, increases delay at AV node, decreases action potential frequency at SA node, decreases contractile force of cardiac muscle.

48
Q

What effect do beta blockers have on blood pressure?

A

Lowers it.

49
Q

Are beta blockers partial antagonists? What does this mean?

A

Some are.

Provide some background of sympathetic activity, while preventing enhanced sympathetic activity.

50
Q

By which 3 methods can nitroglycerine be delivered into the body?

A

Tablets, spray, skin patch.

51
Q

What happens to nitroglycerin and amyl nitrate in the body?

A

Prodrug is converted to active metabolite NO in vascular smooth muscle.

52
Q

What does NO do in the body?

A

Relaxation of smooth muscles, vasodilation of coronary arteries.

BIOL 125 (11 decks)

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