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Physiology BRS > Cardio > Flashcards

Cardio Flashcards

0
Q

Which is the site of highest resistance in the cardiovascular?

A

The arterioles

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1
Q

Flow is predicted by Reynolds number.how it is determined?

A

When Reynolds number is increased > ^tedency for turbulence >audible vibrations:bruits

Factors:
#^velocity:narrowing of the vessel>low A>^υ
(υ=Q/A)
#low viscosity :anemia>low hematocrit

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2
Q

What’s the site of largest total cross sectional and surface area?

A

The capillaries

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3
Q

What does the capillaries wall consist of?

A

A single layer of endothelial cells and a basal lamina

No muscle layer

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4
Q

Where is the unstressed volume?

A

It is the blood volume contained in the veins

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5
Q

What is the velocity of blood at the wall of the vessel?

A

Zero

Hence,shear is highest at the wall

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6
Q

Where does the largest decrease in pressure occur?

A

Across the arterioles
Paorta=100mmHg
Parteriol=50mmHg

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7
Q

How does elastic tissue affect the compliance of blood vessels?

A

They are inversely related.
Compliance=capacitance=distensibility
The greater the amount of elastic tissue ,the higher the elastance(STIFFNESS ),the lower the compliance

C=V/P. Capacitance decreases with age

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8
Q

How is pulse pressure determined?

Which is its most important determinant?

A

It is the difference between systolic an diastolic pressure
It is proportional to arterial compliance
The most important determinant of PP is stroke volume

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9
Q

Name 5cases in which we have ^pulse pressure…

A 
#hyperthyroidism
#aortic regurgitation
#obstructive sleep apnea
#aortic stiffness
#exercise
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10
Q

Name 4cases in which we have low pulse pressure…

A 
#aortic stenosis
#cardiogenic shock 
#cardiac tamponade
#HF
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11
Q

Which segment of the ECG is isoelectric?

A

The ST segment where the ventricles are Depolarized

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12
Q

What does T-wave inversion indicate?

A

Recent MI

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13
Q

What does U-wave suggest?

A

Hypokalemia

Bradycardia

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14
Q

The intrinsic rate of phase 4 depolarization is fastest in…

A

SA>AV>Hiss,Purkinje

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15
Q

The speed of conduction is highest in…

A

Purkinje > atria>ventricles>AV node

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16
Q

How is mean arterial pressure determined?

A

MAP=2/3D+1/3S

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17
Q

How is the resistance of blood vessels determined?

How does the pattern of the vessel and it’s branches affect the resistance?

A

in series:

R=8ηl/πr^4
#in parallel series:
¥the total resistance is less than any individual artery
¥in each parallel ,we have the same pressure,but only a fracture of. blood flow

¥each vessel receives the same blood flow
¥as blood flows the pressure decreases(ΔΡ=Q*R> ΔΡ ^>Ρarterioles is lower)

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18
Q

When the heart rate increases which part of the cardiac circle is preferentially shortened?

A

Diastole because there is less filling time>low CO

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19
Q

How can myocardial oxygen demand be increased?

A

C:contractility
A:afterload
R:heart rate
D:diameter of ventricle(^wall tension)

Wall tension=pressureradius/2wallthichness

20
Q

How is ejection fraction determined?

Which is approximate number?

A

EF. (Ποσοτικοποιηση του contractility)
EF=SV/EDV=EDV-ESV/EDV
It is approximately 55%

21
Q

How does HF affect EF?

A

EF is lower in systolic HF

EF is normal in diastolic HF

22
Q

In the myocardial action potential for Hiss/Purkinje/ventricles/atria which ion causes the rapid upstroke and depolarization?

A

Voltage gated Na channels open

23
Q

In the myocardial action potential for Hiss/Purkinje/ventricles/atria what is the cause of myocyte contraction?

A

At the plateau phase we have Ca influx(L-channels of dihydropyridine )
And K effluent.myocyte contraction occurs due to Ca-induced-Ca release from the SR through ryanodine receptors.

24
Q

In the pacemaker action potential of the SA and AV nodes what is the cause of spontaneous depolarization during diastole?

A

It is due to If channels (funny current),responsible for the mixed inward of K and Na at phase 4.Its slope determines HR(chronotropic effect)

25
Q

In the pacemaker action potential of the SA and AV nodes what is the cause of the upstroke?

A

It is due to the opening of voltage gated Ca channels.
The amount of inward Ca molecules determines conduction velocity.in the AV node>PR interval

^inward Ca>^velocity>short PR

26
Q

How is chronotropic effect determined?

A

Rate of phase 4 depolarization->HR
proportional to the number of Ifunny channels
+:^HR-sympathetic β1
-:lowHR-parasympathetic M

27
Q

How is dromotropic effect determined?

A

It determines the conduction velocity(in the AV)->PR
It is proportional to Ca inward

+:sympathetic,β1>short PR
-:parasympathetic ,M2>long PR

28
Q

Which parts of the heart have parasympathetic Vagal innervation?

A

SA,atria,AV

29
Q

What are the low resistance paths between cells in cardiac muscle?

A

The gap junctions>rapid electrical spread

30
Q

What are three factors that increase contractility(intotropy)?

A

^HR>high rate of firing act.pot.>more Ca is stored in the SR

#sympathetic stimulation:
▶️^inward of Ca:keeps Ca channels open for more t at the
Plateau phase
▶️phosphorylation of phiospholamban>^CaATPSR
#glycocods:inhibit NaKATP>^NAi>lows efflux of Ca

31
Q

Give 5examples that decrease contractility

A 
#β1blockers(low cAMP)
#HF with systolic dysfunction
#Acidosis
#Hypoxia/hypercapnia
#Non-dihydropyridine Ca channel blocker
32
Q

Give two pharmacological examples that decrease afterload and preload

A

Nitroglycerin>venodilator>low preload

Hydralazine>vasodilato>low afterload

33
Q

Equation of stroke volume SV

A

SV=EDV-ESV

34
Q

CO equations

A

CO=SV*HR
CO=O2consumption/O2pulm.vein-O2pulm.art
CO=MAP/TPR

35
Q

Stroke work equation

A

Stroke work=Aortic pressure*SV

36
Q

Which are the Jugular venous pulse(JPV) waves?

A

α:atrial contraction
c:RV contraction(closed tricuspid valve bulging into atrium)
x:descent,atrial relaxation[absent in tricuspid regurgitation]
v:^right atrial pressure due to filling against closed tricuspid valve(billing)
ψ:descent,RA emptying into RV

37
Q

What is the Cushing reaction?

A

^intracranial pressure cause compression of the cerebral blood vessels>cerebral ischemia>^Pco2>vasomotor center increases sympathetic outflow>^perfusion pressure(hypertension)>^stretch>peri feral reflex baroreceptor induced>bradycardia

Triad
#hypertension
#bradycardia
#respiratory depression
38
Q

What are the factors that increase Pc,favoring filtration?

A 
#Arteriolar dilation
#venous constriction
#increase venous/arterial pressure
#HF
#NO
39
Q

What are the factors that increase πi favoring filtration?

A

Inadequate lymphatic function

40
Q

What are the factors that increase πc favoring absorption?

A

Dehydration

41
Q

What are the factors that decrease πc favoring filtration?

A 
#liver disease
#nephrotic syndrome
#malnutrition
42
Q

What are the factors that increase Kf favoring filtration?

A 
#burn
#infections
#toxins
#histamine(dilation of the arteries,constriction of the veins)
#cytocins
43
Q

Acts on prostaglandins in the vascular system

A

Prostacyclin. ➡️vasoconstriction
E-prostaglandin

Thromboxane A2 ➡️vasodilation
F-prostaglandin

44
Q

What are the 2causes of orthostatic hypotension?

A 
#volume depletion
#impaired baroreceptor reflex(individuals with sympatholytic agents)
45
Q

On an ECG with ventricular extrasystoles ,what is the effect on SV?whatis the effect on the next normal ventricular contraction?

A

Pulse pressure decreases(inadequate ventricular filling time)>decreased stroke volume

The next contraction will have an increased pulse pressure due to increased contractility(^Ca!!!)

46
Q

2 P waves preceding each QRS complex at the ECG indicates…

A

That the conduction velocity through the AV node must be decreased

47
Q

The greatest pressure decrease in the circulation occurs across the arterioles because…

A

They have the greatest resistance (low r>^R>^ ΔP)

48
Q

What’s the act of propranolol?

A

It is adrenergic antagonist that blocks β1 β2 receptors>low HR+contractility>lowCO

Physiology BRS (6 decks)

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