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 Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle

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مُساهمةموضوع: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الجمعة مارس 30, 2012 12:45 pm

Define: Bainbridge effect and reflex

Bainbridge effect: increased HR secondary to distension of right atrium by increased VR which stimulates directly SA node to increase its rate of discharge i.e. it is a local effect not reflex

Bainbridge reflex: reflex increased HR (tachycardia) secondary to increase in right atrial pressure





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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الجمعة مارس 30, 2012 12:49 pm

Define Frank-Starling's law


Frank-Starling's law
====================

within certain limits, increased VR (preload or EDV) increases initial cardiac muscle length with resulting increased cardiac contractility




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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الجمعة مارس 30, 2012 9:52 pm

Define Stroke volume and mention factors affecting it




Stroke volume (SV):

Definition: volume of blood pumped by each ventricle per beat.
=====

Factors controlling stroke volume:
===================

1-Preload (VR, EDV): direct relation with stroke volume (Frank-Starling's law).

2-Contractility of cardiac muscle (load): direct relation with stroke volume.

3-Afterload (systemic pressure): inverse relation with stroke volume i.e. increasing systemic pressure (as in the case of high blood pressure), increases the strain on the heart muscle and decreases stroke volume.

4-Chronic exercise training will increase an individual's stroke volume both at rest and during exercise. By slowing down the heart rate, the ventricles have more time to fill with blood, thereby increasing preload and leading to greater stroke volume.

5-Sympathetic stimulation increases cardiac contractility and stroke volume.

6-Blood volume: its increase will increase VR with increased stroke volume.

7-End systolic volume (ESV): inverse relation with stroke volume (as SV= EDV-ESV).

8-HR: marked increase in HR decreases ventricular filling and SV.







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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الأحد أبريل 01, 2012 6:04 am

Outline cardiac events occurring in the cardiac cycle?


Answer



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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الأحد أبريل 01, 2012 2:28 pm

Question

In mitral stenosis, the murmur occur corresponding which phase in cardiac cycle



Answer

During rapid and reduced ventricular filling phases and also can occur during atrial systole phase of the cardiac cycle

Explanation: as blood during these phases should pass through mitral valve from left atrium to left ventricle and as the mitral valve in this condition is stenosed, thus, turbid blood flow occurs causing a diastoled cardiac murmur




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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الثلاثاء أبريل 03, 2012 5:55 am

Question:


What is the effect of diurnal variations on blood pressure




Answer:

Blood pressure varies across the day being highest in the morning and lower towards evening and this is called the "diurnal variation." Some decrease should occur during sleep

the cause of being increased in the morning:

1-on standing from lying down, there release of some catecholamines which increase ABP
2-thinking of what should be done after awaking up causes sympathetic stimulation which increases ABP






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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الثلاثاء أبريل 03, 2012 5:57 am

Question:

What is the cause of murmur in acute rheumatic fever



Answer:



:

At 1st functional murmurs due to hyperdynamic circulation 2ry to fever

THEN, organic murmurs, 2ry to acute rheumatic carditis and the most common murmurs of which are those due to mitral and aortic regurgitation caused by valvular inflammation





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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الثلاثاء أبريل 03, 2012 9:00 am

Question

Calculate the duration of cardiac cycle when heart rate is 60 beat per minute




Answer

sixty beat per sixty sec (1min), so, each beat (cycle) duration will be 60/60= 1sec





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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الجمعة نوفمبر 29, 2013 3:51 pm

Q: Outline
1-Baroreceptor mechanism in regulation of blood pressure
2-Chemoreceptor mechanism in regulation of respiration
====
A:


homeostatic system is formed of stimulus, receptor, center and response, thus:

1-Baroreceptor mechanism in regulation of blood pressure:
Stimulus: increased arterial blood pressure.
Receptor: baroreceptors ( receptors in carotid sinus and aortic arch respond to change in arterial blood pressure).
Center: cardiovascular centers in brainstem.
Response: decreased heart rate and vasodilatation to decrease arterial blood pressure towards normal.

2-Chemoreceptor mechanism in regulation of respiration:
Stimulus: decreased arterial O2 and increased arterial CO2.
Receptor: chemoreceptors ( receptors in carotid and aortic bodies respond to change in arterial O2 and CO2 concentrations).
Center: respiratory centers in brainstem.
Response: increased respiratory rate to increase O2 and decrease CO2 towards normal.

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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الثلاثاء يوليو 01, 2014 7:54 am

Q:

During measurement of BP:

1. Why do we tie the BP cuff at the level of the heart?

2. Palpatory method is used only to measure systolic BP, why not diastolic BP?


=======

A:

Regarding blood pressure examination:

1-We tie the BP cuff at the level of the heart to reflect the exact arterial blood pressure at the heart level as If the arm (or cuff) is lower than the heart, an erroneously high pressure will be recorded and if higher than the heart, the pressure will be erroneously low (refer to effect of gravity on BP).

2-Palpatory method is used as a rough preliminary estimation of systolic blood pressure to be confirmed by the auscultatory method to avoid the auscultatory gap, although some studies recently done to evaluate effect of palpatory method on measuring diastolic blood pressure which has some limitations as shivering, tremor, severe obesity, and moderate to severe hypotension. Shivering and tremor causes mechanical interference in measurement. In severe obese thick subcutaneous fat probably prevent thrill to transmit to surface. Elderly patient have very thin subcutaneous fat, which leads to continuous palpation of pulse throughout measurement and pose difficulty to identify thrill in pulse. Also, palpatory method need more experience and clinical sense. The final result is that in some conditions we may be obligated to estimate diastolic blood pressure using palpatory method as if stethoscope is not present, but, still estimation of systolic blood pressure by palpation (absence of pulse while increasing pressure in cuff and its reappearance with deflation) is more easy and standard than for diastolic blood pressure (absence or weakening of pulse during deflation).





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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الأحد فبراير 22, 2015 8:44 pm

Why there is bradycardia with typhoid fever?

Answer


Typhoid fever is caused by a bacteria that produce a powerful endotoxin responsible for the clinical manifestations.the endotoxin produce myocarditis as a clinical feature.when the cardiac muscle is inflamed by the toxin, autorythmic cells cannot escape inflammation.because SA node and other related structures determine the pace of the heart, the cause of relative bradycardia is inflammation of the myocardium with the autorythmic cells .






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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الأربعاء فبراير 10, 2016 11:29 pm


Q: Why in AV nodal rhythm p wave is inverted
===================

A: When AV node is the pacemaker of the heart, the direction of atrial depolarization wave will be away from the recording electrode at V5, and according to dipole law, a negative P wave will be recorded


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مُساهمةموضوع: رد: Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle   الخميس نوفمبر 10, 2016 6:37 am

Question
Fetal hearts use glucose as their primary metabolic substrate. Adult hearts use free fatty acids, which are less efficient (require more O2 to synthesize the same amount of ATP); however, during cardiac failure, the heart can switch to glucose utilization. Why doesn't it just use glucose all the time?
========
Answer
Lipids require more oxygen to burn, but also they are cheaper to store (since they have great calorific power than carbohydrates and they're hydrophobic, thus not requiring water for their storage). The body can store so much lipids that it becomes an almost everlasting energy source (A normal adult have enough energy stored as fat to allow basal metabolism for weeks to months), which cannot apply to glucose. If fat is not present, glucose would have vanished from the body long time ago. Glucose levels must be maintained at a certain level, because it's the main energy source for the brain (which cannot use lipids).

For all the previous reasons, the heart (and many other organs, like the liver) uses fat while possible. If possible just means when not starving to death and with sufficient oxygen supply. This second condition doesn't apply to heart failure. In this case, oxygen supply fails and the tissue switch to glucose just because they can use it without oxygen (glycolysis and lactic fermentation).

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Some short essay questions on CVS physiology with their answers by Dr Khaled A Abulfadle
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