BIOC34H3 Lecture Notes - Lecture 6: Stroke Volume, Diastole, Muscle Contraction

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cyanmarten183

24 Feb 2019

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End diastolic volume is the ventricular volume at the end of diastole - when ventricular volume is at its greatest level. Pre-load = degree of ventricle stretching at the end of diastole. Think of it as the end diastolic pressure (edp) in the ventricles. If you increase the pressure of blood in the atria and then the ventricles, the volume of blood in the ventricle (edv) is going to increase. This initial pressure (within the ventricles; prior to contraction) is referred to as preload. The ventricular pressure-volume loop shows the effects of reducing pre-load (end-diastolic pressure) on end-diastolic volume (edv) and therefore on sv. Following isovolumetric relaxation (d), volume of blood in the ventricle is the end-systolic volume (esv). Then the ventricular filling phase and the volume of the ventricle increases to edv1 at an end- diastolic pressure of edp1 sv1 = edv1 - esv. If end-diastolic pressure is reduced to edp2, then end-diastolic volume is reduced to edv2.

Related Questions

1. What is the significance of the ST segment?

a. ventricular depolarization

b. ventricular systole

c. atrial systole

d. atrial depolarization

2. Ventricular contraction is also known as ventricular __________.

3. Ventricular diastole is also known as ventricular __________.

A nurse takes your blood pressure and tells you the numbers are 110/70. What are your blood pressures?

rev: 11_20_2014_QC_55932

a. Systolic = 110 mmHg, Diastolic = 70 mmHg

b. Diastolic = 110 mmHg, Systolic = 70 mmHg

The brachial artery is the most common site of blood pressure measurement with the sphygmomanometer.

True

False

Cardiac cycle is the ____________________________.

a. The volume of blood ejected by each ventricle in one minute

b. One complete contraction and relaxation of all chambers of the heart

c. The pressure blood exerts on the wall of blood vessels

d. Depolarization and repolarization of the ventricles

coffeesalmon954

Potentially useful information: one mL = one cm³ = 10^-6 m³, one mmHg = 133.3 Pa (N/m²). SV = EDV â ESV. CO = HR X SV. Ejection Fraction = SV/EDV

Hints: calculate heart rate for each condition. Remember to calculate work for the entire volume of blood that is pressurized i.e., end diastolic volume (EDV). Therefore you will need to use the data provided to calculate the EDV to answer this question.

The work done by the heart is Pressure-Volume work. While both ventricles are doing work, in this problem you will just calculate the work done by the left (high pressure) ventricle. If both pressure and volume are expressed in SI units, their product is NÂ·m (work!) In this assignment you will calculate the work done by the left ventricle of the heart each minute to support a cardiac output of 5L/min.

B) Individuals with hypertension (high blood pressure) have a much greater resistance in their blood vessels and thus their heart not only has to produce greater pressure, it will have a much greater volume left following contractions (end systolic volume, ESV) Calculate the work the heart (for the identical cardiac output of 5L/min) in an individual with stage one hypertension for which these values apply: systolic blood pressure of 150 mmHg, an ejection fraction of 40% and a stroke volume of 60mL.

C) In this individual, how much greater is their cardiac work (@ blood pressure 150 mmHg) than a normal individual with normal blood pressure (120 mmHg)?

Please answer these questions COMPLETELY and I'll be sure to leave a "thumbs up"! Thank you!

mauveminnow262

Potentially useful information: one mL = one cm³ = 10^-6 m³, one mmHg = 133.3 Pa (N/m²). SV = EDV â ESV. CO = HR X SV. Ejection Fraction = SV/EDV

The work done by the heart is Pressure-Volume work. While both ventricles are doing work, in this problem you will just calculate the work done by the left (high pressure) ventricle. In lecture you saw that if both pressure and volume are expressed in SI units, their product is NÂ·m (work!) In this assignment you will calculate the work done by the left ventricle of the heart each minute to support a cardiac output of 5L/min.

1.)In a healthy person make the following assumptions: Stroke volume is 70mL and the Ejection Fraction is 58% (these are normal values). If systolic pressure is 120 mmHg, what is the work that the heart must perform each minute to produce a cardiac output of 5 L/min?

2.) Individuals with hypertension (high blood pressure) have a much greater resistance in their blood vessels and thus their heart not only has to produce greater pressure, it will have a much greater volume left following contractions (end systolic volume, ESV) Calculate the work the heart (for the identical cardiac output of 5L/min) in an individual with stage one hypertension for which these values apply: systolic blood pressure of 150 mmHg, an ejection fraction of 40% and a stroke volume of 60mL.

3.) 150mmHg is 25% greater than 120 mmHg. In this individual, how much greater is their cardiac work?

silverdinosaur935

BIOC34H3 Lecture Notes - Lecture 6: Stroke Volume, Diastole, Muscle Contraction

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