BIOL125 Lecture Notes - Lecture 9: Carotid Sinus, Thermoreceptor, Calcium Channel

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jadeoyster197

27 Jun 2018

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BIOL week 9 LB  Control of Cardiac Output

Blood pressure (BP) terminology

- SBP = systolic blood pressure

- DBP = diastolic blood pressure

- PP = pulse pressure

oDifference between systolic and diastolic pressure

- MAP = mean arterial blood pressure

- TPR = total peripheral resistance

oResistance to blood flow

- CO = cardiac output

- HR = heart rate

- SV = stroke volume

Cardiac Output (CO) and reserve

- Cardiac output is the amount of blood pumped by each ventricle in one minute 

typically talk about left ventricle because its pumping blood for the systemic

circulation

oCO is the product of heart rate (HR) and stroke volume (SV)

HR is the number of heart beats per minute

SV is the amount of blood pumped out by a ventricle with each beat

- Cardiac reserve is the difference between resting and maximal CO

Cardiac Output

- Eg. If HR = 75 beats/min and SV = 70 mL/beat

-CO (mL/min) = HR (75 beats/min) x SV (70 mL/beat)

- CO = 5250 mL/min (5.25 L/min)

Blood Pressure (BP)

- BP  the hydrostatic pressure in the arterial system that pushes blood towards

capillary bed

- Hydrostatic pressure  pressure exerted by a liquid in response to an applied force

- As volume decreases, pressure increases

- Blood pressure is lowest in the veins

- Pressure decreases as blood moves away from the heart

- Blood pressure is an important aspect of our body physiology

- Without having optimum/normal BP, the nutrients, oxygen and proteins cannot

travel from the arterial side of the body to the tissue or to venous side

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- Transports metabolic wastes and CO2 to lungs and kidneys to be excreted

- Adequate profusion of blood is important to prevent ischemia, hypoxia, necrosis

Factors Affecting BP

-Blood pressure = Cardiac Output x TPR (Ie. CO x Total Peripheral Resistance)

Average = 75 cycles per minute ie. Bpm

- If you know lumen size of vessels, you can work out resistance with a formula (small

changes in lumen size significantly changes blood flow and pressure)

Factors Affecting Cardiac Output

Cardiodynamics

- Factors affecting Cardiac Output

oCardiac output

Adjusted by the body making changes in heart rate or stroke volume

oHeart rate

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Adjusted extrinsically by autonomic nervous system or hormones

oStroke volume

Adjusted by changing EDV (end diastolic volume) or ESV (end systolic

volume)

Regulation of stroke volume (SV)

- SV = end diastolic volume (EDV) minus end systolic volume (ESV)

SV = EDV - ESV

oEDV = amount of blood collected in a ventricle during diastole

oESV = amount of blood remaining in a ventricle after contraction

Factors affecting stroke volume

- Preload = amount ventricles are stretched by contained blood  more blood = more

stretch

oDependent on venous return

oAmount of blood entering the ventricle per diastole

oTo reduce preload (in angina patients for eg.), use vasodilation drugs

- Contractility = cardiac cell contractile force due to factors other than EDV

- Afterload = back pressure exerted by blood in the large arteries leaving the heart

oThe pressure that a ventricle needs to work against

oResistance to ventricular rejection

oIf blood vessels remain restricted, then that offers more resistance

oIf blood vessels can be dilated (vasodilated), that will ease the work of the

heart

oMost important determinant is TPR

Preload and Afterload

- The more cardiac muscle is stretched, within physiological limits, the more forcibly it

will contract

- Increased EDV through more venous return  increased SV and CO

- Increased EDV increases sarcomere length of heart cell causing more forcible

contraction

- Mechanism to prevent pooling of blood in the ventricles

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Document Summary

Biol week 9 lb control of cardiac output. Pp = pulse pressure: difference between systolic and diastolic pressure. Tpr = total peripheral resistance: resistance to blood flow. Hr is the number of heart beats per minute. Sv is the amount of blood pumped out by a ventricle with each beat. Cardiac reserve is the difference between resting and maximal co. If hr = 75 beats/min and sv = 70 ml/beat. Co (ml/min) = hr (75 beats/min) x sv (70 ml/beat) Bp the hydrostatic pressure in the arterial system that pushes blood towards capillary bed. Hydrostatic pressure pressure exerted by a liquid in response to an applied force. Pressure decreases as blood moves away from the heart. Blood pressure is an important aspect of our body physiology. Without having optimum/normal bp, the nutrients, oxygen and proteins cannot travel from the arterial side of the body to the tissue or to venous side.

Related Questions

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. 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

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. 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

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

BIOL125 Lecture Notes - Lecture 9: Carotid Sinus, Thermoreceptor, Calcium Channel

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