Cardiovascular Physiology Flashcards by Reginald Richter

Endocrine functions of the cardiovascular system

Secretion of Atrial natriuretic peptide
B-Type natriuretic peptide

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What is the function of the atrial natriuretic peptide(ANP) -

promotes sodium and water excretion and also reduces vascular resistance

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What produces the Atrial natriuretic peptide

atrial myocytes

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What is the function of B-Type natriuretic peptide

decreases vascular resistance

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In what percentage of people does the Right Coronary Artery supply the AV node and the SA node

90% for AV node
55% for SA node

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Which natriuretic peptide is more potent

ANP

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Other name for the pacemakers

Central Pattern Generator

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dominant pacemaker in health

SA node

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Impulse pathway

Sinoatrial node → AV node → Bundle of His → Bundle Branches → Purkinje fibers

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Slowest conduction velocity in the cardiac conduction pathway

AV node

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What is the speed of the impulse at the AV node

About 0.05m/s

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How long does it take for an action potential to pass through the AV node?

0.1 seconds

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Where on the heart does the cardioaccelerators(sympathetic)

SA nodes
AV nodes
Cardiac muscles

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Where on the vertebrae does the cardioaccelerators originate from

T1-T4

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How long does the impulse take to travel from the SA node to the purkinje

0.22 seconds

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What is the neurotransmitter of cardioaccelerators

norepinepherine

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How does the Cardioaccelerators(sympathetic) affect the ventricular muscles

Ventricular muscles, increasing force of contraction

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WHat part of the ECG indicates conduction in the AV node

the PR interval

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How do the cardioaccelerators(sympathetic) affect the AV node SA node

Increasing Frequency of action potential firing

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How does the cardioaccelerators(sympathetic) affect the AV node

Speed of conduction at AV node

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What is Lusitropy

Myocardial relaxation

CAn is the impact of a calcu=ium

What is a positive
i)lusitropy
ii) chronotropic effect
iii) dromotropy
iv)Inotropy

i)Myocardial relaxation
ii) Increase heart rate
iii) Speed of Conduction of Action potential
iv) Increase force of contraction

SA node does not have a stable resting potential what is this called

Phase 4 ( spontaneous depolarization)

What is the impact of Ca channel blockers on the shape of the action potential in ventricular muscle?

Width of AP will be reduced Less strong ventricular contraction

What is the formula for the Stroke volume

End Diastolic Volume-End systolic volume

How does pH affect heart contractility

Acidosis decreases heart contractility

What is the normal Ejection Fraction range

55%-80%

What are cardiac glycosides

They are cubstances that increase heart contractility and heart rate

Give an example of a cardiac glycoside

Digoxin

What is the mechanism of digoxin

Digoxin inhibits the Na/K pump preventing the efflux of Na ions hence causing a shorter Phase 4 and shorter action potentials It also inhibits the Ca/Na antiporter preventing Ca from leaving the cell This increases the force of contraction since Ca accumulates in the cells

What is the end diastolic volume

120ml

What is the End systolic volume

70ml

Calculate the stroke volume

50ml

If the heart rate is 80beats/min calculate the cardiac output

80 *50

Averagely what

5L/min in a normal adult

Find the cardiac index if the if his total body surface

How is Cardiac output summarize

Dividing the cardiac output by total surface area to get the cardiac index

2.2l/min/mr

What is the normal range of reference range for cardiac index

55%-80%

What is the main factor that affects the venous return

Circulatory blood return

What is the formula for Cardiac output

Heart rate * Stroke volume

What is the impact of bradichardia

In bradichardia the heart rate reduces

What is the effect of tachichardia on cardiac output

During tachichardia -> Heart rate is high ->Heart is alway is contracting Heart spends more time in systoly(contraction) and less timein diastoly -> it is during diastoly that the ventricles are filled -> end diastolic volume reduces, stroke volume reduces and cardiac output reduces

Draw a graph showing the variation of cardiac output with heart rate

# 1.

The ventricles are mainly filled(70-75) by passive flow of blood to the atria

The remaining 25% OF ventricular filling is by atrial contraction

Cardiac Cycle

Isovolumetric relax. Passive Phase ventric. fill Atrial Kick/Systole(Active Phase of Ventric. fill.) Isoventricular contraction Ventricular Ejection

# Slide 103 old/107 new What is the end diastolic volume end systolic volume Stroke volume

# From Slide 103 old/107 new What is the ejection fraction

Stroke volume/end diastolic volume= 70/130

What are the two phases of ventricular ejectioj

Rapid Ejection 2nd??

What are the two assesments of contractility

Ejection fraction Frank-starling