BIOC34H3 Lecture 1: Lecture 1 Notes

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cyanmarten183

24 Feb 2019

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Cardiac output = amount of blood pumped out of the heart per unit of time. It is a function of heart rate, and stroke volume = volume of blood pumped per beat. All of the cardiovascular regulatory systems have one critical function to prevent blood pressure from falling too low. High blood pressure will kill, but will take years; low blood pressure will kill in minutes because organs are critically sensitive to low oxygen levels. We can calculate blood pressure by multiplying cardiac output by peripheral resistance: the resistance to blood flow within the circulatory system. This resistance occurs primarily in small vessels, particularly small arteries called arterioles. All adjustments that occur in the cardiovascular system can affect one or more of three variables (hr, sv, pr) with the goal of keeping blood pressure levels up. Blood volume (bv) is a fourth variable that can affect blood pressure.

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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

Rest activity

min volume 19700ml air/min 43400 ml air /min

breathing rate 13breat/min 21

heartrate 72beats/min 112 beats/min

blood pressure 118/70 158/88

% O2 inhaled air 20.94% (.)2094ml O2/ml air) same

% O2 exhaled air 18.94% (.1894 ml O2/ml air) same

a) claculate Tidal volume [ml air/breath]
b) calculate Oxygen consumption (VO2) [ ml O2 consumed/min] -
c) calculate Oxygen content of arterial blood (CO2a) [ml O2/mlblood] -
d) calculate Oxygen content of venous blood (CO2v) [ml O2/ml blood]-
You need to know that there is 13.3 g hemoglobin/100 ml blood, and1.3
ml O2 binds to each gram of hemoglobin. Assume arterial blood is100%
saturated with oxygen, whereas mixed venous blood is 60%saturated
when the subject is resting.
e) caluclate Cardiac Output (CO) [ ml blood/min ] -
f) caulculate Stroke Volume (SV) [ ml blood/beat] -

g) Tidal volume [ml air/breath]
h) Oxygen consumption (VO2) [ ml O2 consumed/min]
i) Stroke Volume (SV) [ ml blood/beat]
Assume change in stroke volume is the same as the change inpulse
pressure when going from rest to exercise - s
j) Cardiac Output (CO) [ ml blood/min ] -
k) Oxygen content of arterial blood (CO2a) [ml O2/ml blood] = sameas when resting
l) Oxygen content of venous blood (CO2v) [ml O2/ml blood] -

Now answer these questions:

1. By what multiplication factor (e.g. 2 times, 3 times, etc.)did oxygen consumption
increase over resting when the person exercised?
2. a. Did minute volume increase by the same factor that oxygenconsumption
increased? If not, what made up the difference?
b. Did cardiac output increase by the same factor that oxygenconsumption
increased? If not, what made up the difference?
3. What was most responsible for the change in minute volume? i.e.compare the
factorial change in breathing rate with that of tidal volume.
4. What was most responsible for the change in cardiac output? i.e.compare the
factorial change in heart rate with that of stroke volume.
5. Calculate total peripheral resistance during rest and exercise(see pg 21). What
physiological changes led to the change in peripheral resistance?In what part of the
body did they occur, and why is this adaptive?

ivorymuskrat878

BIOC34H3 Lecture 1: Lecture 1 Notes

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