Physiology Flashcards by Chelsea Mitchell

What does blood vessel resistance equal (long eqn)?

R=8nL/(pi*r^4). n=viscosity

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What is Poiselle’s equation for flow (use resistance equation and other short equation with flow and pressure)?

Flow=Q= (Ppir^4)/(8nL)

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Short equation for flow?

VA=Q (VAQcum). Velocity*Area=Q A vacuum has a high flow of particles.

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What is Laplace’s law for wall stress?

(P*r)/thickness = Wall stress. In Star Wars there are the walls closing in and causing stress. That is PRime/time for action.

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Eqn for total peripheral resistance (long)?

TPR = (MAP - CVP)/CO.

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Eqn for total peripheral resistance (short, easy)?

TPR=R=P/Q or delta P/ delta Q.

V=IR
Pressure=Flow*Resistance
Resistance=Pressure/Flow

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Eqn for MAP (including TPR, CO)

MAP=TPR(CO) + CVP. (The +CVP part is optional)

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How does the sympathetic system change resistance, and therefore impact MAP?

It acts on alpha-1 receptors and constricts arteries in the GI tract/mucosa and skin. This increases TPR, and thus increases MAP.

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How does the sympathetic system change CO, and therefore impact MAP?

Sympathetic receptors (beta-1) increase the heart rate and contractility (force of contraction). This increases stroke volume and CO. Increased CO means increased MAP.

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What is the equation for blood pressure (use the TPR equation and derive it)

BP=TPR*CO

TPR=(MAP-CVP)/CO.
BP=MAP-CVP
TPR=BP/CO
BP=TPR*CO

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Pulse pressure equation

Pulse pressure=SBP-DBP=systolic blood pressure-diastolic blood pressure.

I.e. 120-80=40 normal

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Eqn for MAP regarding blood pressure?

MAP=DBP + 1/3(pulse pressure)

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CO?

HRSV. Remember the units make sense. (beats/minvolume/beat)

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Average CO?

5.6L/min. 10-20% less for women.

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Stroke volume?

EDV-ESV

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Average stroke volume?

70-80mL (not that much!). (Similar to heart rate, which is 80bpm)

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CO related to consumption and pulmonary vessels?

CO= O2 consumed / (Conc. O2 in pulmonary vein - Conc. O2 in pulm artery)

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Ejection fraction?

(End Diastolic volume - End Systolic Volume)/ End Diastolic Volume

(EDV-ESV)/EDV

SV/EDV

Blood pumped out/Blood you started with in the ventricle

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How many cusps are in each of the valves?

Mitral=2, tricuspid=3, pulmonary=3, aortic=3

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If you have partial heart block, what will you see on the ECG?

Second P wave. This is second degree heart block. Think 2nd, you will have a 2nd P-wave.

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If you have complete heart block,, what will you see on the ECG?

You will see a “dissociation” bw the P and QRS. So, they are not associated with one another. Separated.

Normal HR?

80-100bpm

What is Bainbridge Reflex responding to? What is the result?

Responds to an increase in RIGHT ATRIAL PRESSURE (there is an increased volume of fluid in the right atrium). It increases the HEART RATE.

How long does a cardiac cycle last?

0.8 s. (think, 80bpm, 80mL stroke volume)

How can you tell ventricular systole has started? Diastole?

You hear "lub". You hear "dub".

Which valve closes first, the aortic or the pulmonary?

Aortic (you get "splitting" of "dub")

Where is the AV bundle? What does it do?

It is after the AV node. It is divided. one side goes to th left ventricle, and one side goes to the right ventricle.

What is the "isoelectric" portion of the ECG when the ventricles are depolarized?

S-T segment

What is the period between atrial depolarization and repolarization? Ventricular?

P-R; Q-T

Venous return

Blood/min back to heart. Opposite is CO, which is blood/min away from heart.

Frank Starling

An increase in ventricular filling (greater preload) leads to an increase in fiber length. This increases the strength of contraction of the ventricle.

What is the most important factor for determining preload?

Venous return

What determines the afterload of the left ventricle? Right ventricle?

Aorta, pulmonary arch

Does increased HR ALWAYS mean increased CO?

No, at very high rates there will not be enough time for filling, so it will not directly correlate.

How does sympathetic activation affect the heart?

increases rate, conduction velocity, contractility (force)

Flow equation with pressure and resistance. How do you measure pressure?

Flow=(INITIAL PRESSURE-FINAL PRESSURE)/ Resistance. initial pressure=at start of vessel

Metabolites that cause local vasodilation are what?

CO2, NO2, H+, K+, lactate, adenosine

What do histamine and bradykinin do?

In inflammation, you want more blood flow, so they dilate arteries and constrict veins.

What does serotonin do?

Arterial constriction. Stored by blood platelets. When the platelets bind to a clot, they release serotonin, where it serves as a vasoconstrictor and helps to regulate hemostasis and blood clotting. (Think, Sara has a cut at Thanksgiving, she needs to stop the bleeding.)

What will sympathetic activation of veins do?

Cause vasoconstriction. You want blood to go back to the heart.

If you have resistance in the vena cava, how will that affect venous return?

It will decrease venous return. The vessels won't be able to pump blood as easily from the veins to the vena cava.

When you have exercising muscle, what metabolites will increase? What do they cause?

Adenosine, K+, lactate. Vasodilation!

What happens to arterial pressure in response to exercise?

Increases! The increase in cardiac output is GREATER THAN the decrease in TPR, so you will have increased arterial pressure overall.

How does parasympathetic efferent stimulation change in the heart in response to exercise?

Decreases. Parasympathetic causes vagal tone (X) which decreases the heart rate. So you want to decrease this so you can increase the hr.

What causes an anxious dental patient to have increased systolic BP?

Decreased arterial compliance (?)

What molecule is relevant with sympathetic stimulation of the heart?

Norepinephrine

What is the mechanism by which sympathetics act on the heart, causing increase force of contraction?

They cause increased intracellular calcium.

what part of the heart has the highest conduction velocity? lowest?

purkinje, AV

Rankings of automaticity of regions of heart?

SA>AV>Purkinje (?) ddidnt know this could beat on its own

What are the numbers for the bpm of the nodal regions?

SA: 80-100, AV: 40-60, His: 30-40

Which side of the bundle of His is thicker, and perforates the interventricular septum? How does it continue and split?

Left. It continues and splits into a thin anterior division and a thick posterior division.

How long does it take the conduction to go from Bundle of His to muscle?

.03 to .04s