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CPR > Systemic Circulation and Hemodynamics > Flashcards

Systemic Circulation and Hemodynamics Flashcards

1
Q

Where is the volume of blood the greatest and cross sectional area?

A
  • Veins
  • Capillaries
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2
Q

When diameter of a vessel is halved what happens to the flow?

A
  • There is a 4th power change associated with the flow due to inverse relationship btw resistance and flow
  • For ex 16 mL per minute to 1 mL per minute
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3
Q

When diameter of a vessel is doubled what happens to flow?

A
  • If we go from diameter of 2 to 4, we will have a 44 change in flow rate
  • For example we start at diameter of 2 and flow rate of 16 mL/min and double diameter to 4 we will end with 256mL/min because of the (pi r4)
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4
Q

As viscosity goes down, resistance goes ___.

A

As viscosity goes down, resistance goes down.

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5
Q

How does an increased hematocrit impact flow (if other variables are constant)?

A

It decreases flow

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6
Q

Resistance beds in series will ____ resistance and resistance beds in parallel will ___ total resistance.

A

Resistance beds in series will increases resistance and resistance beds in parallel will decrease total resistance.

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7
Q

Where is the site of greatest control of blood flow and TPR?

A

arterioles

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8
Q

What does an increase in sympathetic stimulation cause with TPR and vessel diameter?

A
  • Vasoconstriction which reduces flow and inreases TPR
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9
Q

What is reynolds number?

A
  • prediction on whether you will move from laminar to turbulent flow
  • More than 2000 is considered to transition to turbulent
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10
Q

How does blood generally flow?

A

Laminar flow, all cells move in the same direction

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11
Q

What is turbulent flow?

A
  • Occurs when velocity is high, cross section area is large, or viscosity is low blood is likely to flow turbulent
  • RBC’s are not going in same direction
  • Leads to bruits and lesions (arteriosclerosis)
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12
Q

What is compliance?

A
  • change in volume divided by the change in pressure
  • How much the vessels can relax and hold blood and how much does pressure change
  • Veins can expand out a lot and hold a large volume of blood and does not push back (high compliance low elasticity)
  • Arteries=low compliance high elasticity,they recoil back to push blood forward, large change in pressure doesn’t change volume
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13
Q

How does aging and atherosclerosis impact compliance?

A
  • decreases it by reducing the amount that an artery can distend during systole and reducing recoil during diastole
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14
Q

What is one theory for what happens when sm mm of veins contracts?

A
  • Blood is propelled forward back to heart and venous compliance is decreased
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15
Q

Smooth muscle effect on veins?

A

Smooth muscle contracting in veins is going to redistribute blood to arteries

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16
Q

What is pulse pressure?

A
  • Systolic BP minus diastolid BP=40 mmHg
  • Directly proportional to stroke volume
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17
Q

What is MAP?

A
  • 1/3 systole BP + 2/3 diastolic BP
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18
Q

Plulse pressure is dependent on _____ a decrease in this will cause pulse presssure to ____.

A

Plulse pressure is dependent on arterial compliance, a decrease in this will cause pulse presssure to increase.

(Systolic pressure would also increase)

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19
Q

How does arteriosclerosis change blood pressure?

A
  • increases SBP, MAP and Pulse pressure
  • Diastolic doesnt usually change
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20
Q

How does aortic stenosis change blood pressure?

A
  • decreases SBP, MAP and pulse pressure
  • DBP doesn’t change
21
Q

“rules of thumb” for venous pressure?

A
  • Low pressure
  • High compliance
  • Large volume
  • Venoconstriction decreases venous compliance with little resistance change, pressure in veins increases flow back to heart
22
Q

Where does the a wave occur on an EKG?

A
  • its atrial contraction so btw mid p wave on EKG and R wave of QRS
23
Q

Where does the C wave occur on an ekg?

A
  • ventricular contraction caused by backflow of blood into atria at onset of vent contraction but mainly by bulging of AV valve backwards into atria due to increase in pressure of ventricles
24
Q

When does the V wave occur?

A
  • at end of ventricular contraction resulting from slow flow of blood into atria from veins while the atrioventricular valves are closed.
  • When AV valves open the v wave dissapears bc blood enters ventricles
25
Q

What allows for passage of ater soluble substances such as glucose and electorllytes to pass across capillary walls?

A

Clefts

  • small in brain and large in liver and gut
26
Q

What is vasomotion?

A
  • oscillating flow of blood through capillaries which flows intermittently on and off every few seconds or minutes.
  • Results from oscillating contraction of metarterioles and precapillary sphincters
27
Q

What is vasomotion largely regulated by?

A
  • Oxygen levels in the tissue
  • As oxygen consumption increases in tissue the frequency of vasomotion and duration the sphincters remain open increases to increase flow
28
Q

What is the starling equation?

A
  • It calculates flow of water out of capillary (+ direction) or drawing it into capillary (-direction)
  • Depends on hydrostatic pressure and osmotic/oncotic pressure
29
Q

(Flow ) J= [(Pc-Pi)-(Pic-Pii)

What is Pc, where is filtration and reabsorption favored?

A
  • Capillary hydrostatic pressure (Pc): in capillaries tends to force fluid and dissolved molecuels through capillary porese into interstitial fluid. Its greater at arterial end of capillary
  • Filtration is favored at arterial end and reabsorption favored at venous
30
Q

(Flow ) J= [(Pc-Pi)-(Pic-Pii)

What is Pi p or Pic,?

A
  • coloid osmotic pressure caused by plasma protiens that draws fluid from the interstitial fluid into blood
    *
31
Q

,What is Pif?

A
  • Interstitial hydrostatic fluid pressure:
    • pressure to force fluid into capillary from interstital fluid when positive but when negative pulls fluid from the capillary
32
Q

(Flow ) J= [(Pc-Pi)-(πc-πi)

What is πif?

A
  • Interstitial osmotic pressure:
    • tends to pull fluid from capillary into interstitial fluid.
    • Even though there are more proteins found in interstitial fluid than plasma the volume of fluid is greater so the concentration is much lower
33
Q

Pc can be increased by _____.,

A

Pc​ can be increased by elevated venous pressure such as during heart failure

34
Q

Pi can be altered by ___.

A

Pi ​can be altered by restricted lymphatic flow or increased driving force out of capillary

35
Q

π can be decreased by ____.

A

π can be decreased by reduced levels of albumin,such as in starvation or liver failure, causing fluid to stay in the interstitial space

36
Q

πi can be altered by ____.

A

πi can be altered by restricteed lymph flow or inflammation

37
Q

What is acute blood flow?

A
  • Rapid changes in local vasodidlation or constriction of arterioeles metarterioles and precap sphincters
38
Q

What is autoregulation?

A
  • Rapid increase in arterial pressure will cause immediate rise in blood flow but returns to normal within a minute
    • metabolic and myogenic theories (see different card)
39
Q

What is metabolic theory of autoregulation?

A
  • When theres an increase in arterial pressure, excess flow provides too much oxygen and too many other nutrients
    • can help explain reactive hyperemiaj
40
Q

What is the myogenic theory of autoregulation

A
  • A rise in arterial pressure stretches sm mm of vessel wall and causes it to constrict resucing blood flow back to normal
  • This can occur with or without humoral or neural inputs
41
Q

What i vasodilator theory?

A
  • states that decreased oxygen availability increases formation of vasodilator substencees including adenosine, CO2 histamine potassium…
42
Q

What is oxygen demand theory?

A
  • states in absence of adequate oxygen its reasonable to assume vessels would relax
43
Q

What is metabolic control of blood flow?

A
  • Reactive hyperemia:
    • occurs after tissue blood is blocked for a short time
  • Active hyperemia
    • Occurs when tissue metabolic rate increases
44
Q

What is the most important and least important type of blood flow control in the coronary and cerebral arteries?

A
  • most: local metabolic control
  • least: sympathetic
45
Q

What are the vasoconstrictors?

A
  • Angiotensin II- acts on arterioles to increase TPR
  • Vasopressin (ADH)
  • Serotonin- constricts in response to tissue damage
46
Q

What are the vasodilators?

A
  • Bradykinin
  • Histamine
47
Q

What does Ca,K, Mg, and acetate and H ions do to blood flow?

A
  • Calcium: vasoconstriction by contracting sm mm
  • K vasodilation
  • Mg vasodilator bc it inhibits sm mm contraction
  • Increase of H causes dilation of arterioles and decrease causes constriction
  • Acetate and citrate causes vasodilation
48
Q

How is cerebral circulation controlled?

A
  • Mostly by metabolic control, PCO2, and H
  • Many vasoactive substances don’t influence cerebral blood flow
  • Iinjury to head results in vasodilation and edema
  • Pressure below 50 mmHg is critical
49
Q

Circulation of skin?

A
  • Sympathetic nervous system
  • Constriction induced by alpha 1 adrenergic
  • as body temp increases cental symp activation are inhibted to induce vasodilation of arterioles to allow warm blood to reach outer layers

CPR (18 decks)

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