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20 Cards in this Set
- Front
- Back
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What area of circulation has the highest resistance in the cardiovascular system and why
Where is the pressure the highest? |
arterioles, which are the smallest branches of the arteries
highest pressure- aorta |
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What is the way to find flow when you know the velocity and cross sectional area?
What is the most important factor in changing resistance to flow? |
Flow= velocity x cross sectional area
F= Q Q= (P1-P2)/R R= Rfactor= 8nl/r4(pi) r= radius n= viscosity Radius of vessel (2x radius= 16x flow) |
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Describe the difference between adding parallel and series resistances
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Resistance in parallel:
more parallel circuits decrease resistance: (seen in pregnant women- placenta acts as parallel circuit which makes resistance lower) Series resistance- sum of the individual resistances: Rtotal= Rartery + Rarterioles + R capillaries |
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Describe the difference between laminar and turbulent flow and the effect on resistance
- If I increased blood velocity what affect would that have on tubulence? - If I decreased viscosity? - narrowed a vessel? - anemic patient with lowered hematocrit |
Laminar flow reduces resistance and turbulent flow produces increased resistance
- Increasing velocity happens when a vessel is narrowed and therefore raises turbulence - Decreased blood viscosity happens with anemia and therefore increases turbulent flow |
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Give 4 factors which influence the tendency towards turbulent vs. laminar flow
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Major causes of turbulence include:
1. High velocity 2. Vessel irregularities including branching to series over parallel resistance, plaques etc. 3. Stenosis 4. decrease radius |
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Describe the relationship between arterial compliance, stroke volume and blood pressure
For example if you increased the pressure on a vein but the volume did not increase... what does this do to compliance and stroke volume? |
Compliance is a measure of flexibility of the blood vessels. More compliant = less elastance (stiffness)
- C = V/P Volume/ pressure - vein has higher compliance and therefore is less elastic than arterial If you increased pressure it would decrease compliance and therefore lead to an increase in stroke volume |
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1. What is pulse pressure in relation to diastolic and systolic
2. If diastolic and and systolic both increase in HTN would indicate? |
1.
- it is the difference between systolic and diastolic - usually increased with decreased vascular compliance (systolic goes up and diastolic goes down) This would indicate a decrease in compliance and... Also an accompaning Resistance as well as a decrease in compliance |
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Give the equation describing cardiac output.
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CO= BP/TRP
CO= HR x SV SV= End-diastolic - End systolic stroke volume and ejection fraction are funciton fo cardiac contractibility BP = P (mean arterial pressure - venous pressure) TPR= total peripheral resistance |
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Define the following terms...
1. stroke volum 2. end diastolic volume 3. end systolic volume 4. ejection fraction |
1. Stroke volume is a function of the inotropic condition of the heart and preload... is the volume of blood pumped from one ventricle of the heart with each beat. subtracting the volume of the blood in the ventricle at the end of a beat (called end-systolic volume) from the volume of blood just prior to the beat (called end-diastolic volume).
2. preload- pre load just prior to beat volume in ventricle 3. post load- volume in heart at end of a beat 4. • Ejection fraction is the ratio or percentage of blood pumped out of the ventricular chamber with each beat. It is influenced by several factors including the inotropic condition of the heart. Ejection fraction= (Stroke Volume)/(end diastolic volume) (may be 100/150 or 67%) |
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Define preload and afterload how does it affect the heart and CO?
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Afterload-- in the clinic, the term "end-systolic pressure" is usually more appropriate, although not equivalent. afterload is used to measure the tension produced by a chamber of the heart in order to contract
Preload- "end-diastolic volume"- when venous return increases, end-diastolic volume increases and stretches or lengthens the ventricular muscle fibers |
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Describe autonomic innervation and its influence on the heart. Include neurotransmitter, receptor type and effect.
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symp- B1 norepi increases HR
para- musc- Ach relaxes heart |
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The sympathetic stimulation stimulates which receptors, with which neurotransmitter, and which phase/ affect does it have?
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B1, norepinephrine, phase 4 increase rate of depolarization of SA node (positive chronotripic effect),
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Describe how the baroreceptors react to changes in BP to alter cardiac function
What happens to Barorectors if there is a chronic BP problem? |
location in carotid sinus and aortic arch allows them to sense changes in BP and changes "firiing rate" which makes the sympathetic output go down (lowering BP)
- Chronic BP changes causes Baroreceptors to lose function |
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Describe respiratory sinus arrhythmia.
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Respiratory sinus arrhythmia is spill over from the respiratory center to the vasomotor center such that during inspiration HR increases and increases force and
during expiration HR decreases. |
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Describe the Frank-Starling law of the heart using pre- and afterload
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- used to describe increase in stroke volume and cardiac output that occur in response to an increase in venous return or pre-load.
- The idea is based on length-tension relationship in ventricle. - increase volume leads to increase lenght which increases tension (pressure) |
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What would a Frank-Starling curve graph look like... x/y axis labels?
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Graph of stroke volume/cardiac output vs. pressure
greater the positive inotropic effect moves line to the left (sympathetic stimulation of B1) Ach or parasympathic stimulation would cause negative inotropic effect (moves line low and to the right) |
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After running for awhile
Why did the subject feel dizzy? |
When going from running to standing still makes blood stand in legs, decreases pre-load, decreases contractivity, decreases
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Describe the relationship between pulse pressure, arterial compliance and stroke volume
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Pulse pressure is most importantly dependent on stroke volume. A decrease in Compliance usually causes an increase in stroke volume. If there is a decrease in arterial compliance pulse pressure goes up.
This is important because we know diastolic pressure will remain unchanged during or decrease during ventricular systole (therefore pulse pressure increases to the same extent that systolic does) |
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If resistance increases what will most likely happen to systolic, diastolic, and pulse pressures?
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Increase both diastolic and systolic and therefore pulse pressure will remain the same
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If there were increased "after load" aka aortic pressure, what would be the effect on the stroke volume?
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since the ventricle must eject blood against a higher pressure, it will result in a lower stroke volume
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