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Physiology I > SCT II - Circulation > Flashcards

SCT II - Circulation Flashcards

1
Q

Equation of Mean Arterial Pressure

A

Mean Arterial Pressure = Cardiac Output x Total Peripheral Resistance

CO = HR x SV

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2
Q

What other way could we calculate Mean Arterial Pressure?

A

MAP (Mean Arterial Pressure) = DP (Diastolic Pressure) + 1/3 PP (Pulse Pressure)

PP (Pulse Pressure) = SP (Systolic Pressure) - DP (Diastolic Pressure)

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3
Q

How do you calculate TPR?

A

Resistance = 8/π * Lƞ/r^4

L - Length of vascular system
ƞ - Viscosity of blood
r - Radius of vessel

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4
Q

How different is the viscosity of blood in vivo and in vitro?

A

In vivo, blood is 1.25x more viscous than water

In vitro, blood is 2.5x more viscous than water

RBC tend to be in the center of the flow, in tubes there is no flow

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5
Q

How can the equation of MAP be converted to adapt to a single organ?

A

ΔP (Pressure of Organ) = Φ (Flow of Organ) x R (Resistance of Organ)

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6
Q

Poiseuille Law

A

ΔP = (8 x L x ƞ x Φ) / π x r^4

ΔP - Pressure Gradient
L - Length of Vascular System
ƞ - Viscosity of Blood
Φ - Flow of Blood
r - Radius of Vessel

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7
Q

Reynold’s Number

A

Re = (v x D x ρ) / ƞ

v - Velocity of Flow
D - Diameter of Vessel
ρ - Density of Blood
ƞ - Viscosity of Blood

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8
Q

What is special about the diameter in the equation of Reynold’s Number?

A

Diameter has a negative correlation with Reynold’s Number due to its effect on Velocity (4-fold)

Think of pressing onto the exit of a hose to increase water velocity

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9
Q

What are Korotkoff Sounds?

A

Sounds heard during the measurement of blood pressure; compressing the vessel to decrease the diameter, increasing the velocity, increasing Reynold’s number, and hence making the flow turbulent and easy to listen to

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10
Q

What are the two types of turbulent flow that can be helpful in diagnostics?

A
  1. Korotkoff Sounds
  2. Murmurs (heart, valves, etc.)
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11
Q

What is compliance?

A

Ability to stretch

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12
Q

How do you calculate compliance?

A

C =ΔV / ΔP

C - Compliance
V - Volume
P - Pressure

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13
Q

Explain compliance vs Distensibility

A

Compliance = Distensibility x Volume

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14
Q

How much more compliance do veins have? And why?

A

Veins have 24x compliance than arteries

8x more Distensible
3x more Volume (capacity)

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15
Q

In the central pulse wave, what is the name and cause of the little notch after systolic pressure?

A

Incisura
Closure of aortic valve

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16
Q

What type of wave is the central pulse wave? Why is it like that?

A

Dicrotic wave
1. Anacrotic limb (ascending pressure)
2. Catacrotic limb (descending pressure)

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17
Q

What qualities should you check for a pulse?

A

Rhythm
- Rhythmic or arhythmic?

Frequency
- Frequent or rare?

Amplitude
- Low or high?

Rate of Rise
- Slow or fast rise?

Compressibility
- Hard or soft?

Equality
- Equal or unequal on both arms

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18
Q

What happens during aortic stenosis?

A

SV DECREASES
SP DECREASES
DP UNCHANGED
PP DECREASES

Ejection becomes turbulent, resulting in a SYSTOLIC MURMUR

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19
Q

What is aortic regurgitation (insufficiency)?

A

The aortic valve fails to close and therefore there is backflow of blood

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20
Q

What happens during aortic insufficiency?

A

DP DECREASES
EDV INCREASES
SV INCREASES
SP INCREASES
PP INCREASES
Rate of Ejection INCREASES

Backflow is turbulent, resulting in a DIASTOLIC MURMUR

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21
Q

What happens during atherosclerosis?

A

Hardening of artery

COMPLIANCE DECREASES
DP INCREASES
SP SUPER-INCREASES
PP INCREASES
Rate of Rise INCREASES

Similar to aortic insufficiency

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22
Q

Describe the relationship between velocity and surface area

A

Velocity ~ 1/Surface Area

23
Q

Explain continuous, fenestrated, and discontinuous capillaries

A

Continuous: Tight cells, rigid basement membrane

Fenestrated: Spaced cells, rigid basement membrane

Discontinuous: Spaced cells, spaced basement membrane

24
Q

How do large amounts of material move in bulk flow?

A

Move in response to pressure (area of high pressure to low pressure)

Faster than diffusion/osmosis

Important for the regulation of extracellular fluid

25
Q

Explain oncotic pressure

A

Pressure due to proteins - proteins pull substances towards them

26
Q

Explain hydrostatic pressure

A

Pressure due to fluids - higher intensity of flow, higher the pressure

27
Q

What’s the primary role of Starling forces?

A

Forces decide which way the fluid will move (secretion/absorption)

28
Q

Which starling forces are in favor of filtration?

A

Interstitial Fluid Colloid (Osmotic Pressure) + Capillary (Pressure)

29
Q

Which Starling forces are in favor of absorption?

A

Interstitial Fluid (Pressure) + Plasma Colloid (Osmotic Pressure)

30
Q

Which path does Pnet take?

A

Pnet = Pc - Pif

Pnet - Total hydrostatic pressure
Pc - Capillary hydrostatic pressure
Pif - Interstitial fluid pressure

Pnet <3 Pc - Favors FILTRATION

31
Q

Which path does πnet take?

A

πnet = πc - πif

πnet - Total oncotic pressure
πc - Capillary oncotic pressure
πif - Interstitial fluid pressure

πnet <3 πif - Favors ABSORPTION

32
Q

What is the equation of effective filtration pressure?

A

Peff = Pnet - πnet

Peff - Effective filtration pressure
Pnet - Net hydrostatic pressure
πnet - Net oncotic pressure

If Peff > 0 - Filtration
If Peff < 0 - Absorption

33
Q

Along the length of a capillary, what happens to Pc and πc?

A

Pc decreases (> 2/3 – <1/3)
πc stays the same (< 2/3 – >1/3)

34
Q

Why does πc stay the same throughout the capillary?

A

Proteins cannot move through the compartments, staying constant throughout the length of the capillary

35
Q

What can cause edema?

A

Two things:
1. Either filtration&raquo_space;»» absorption
2. Lymphatic passage problems

36
Q

What could cause filtration&raquo_space;»> absorption

A
  1. Pnet increase
  2. πnet decrease
37
Q

What can increase Pnet?

A

Vasodilation
1. Extremely high temp (arteries dilate to lose heat)
2. Sympathetic tone damage (inhibits vasoconstriction)
3. Vasodilating drugs
4. Beri-Beri (B1-Thiamine Deff.)

38
Q

What can increase πnet?

A

Venous end
1. Compression of veins
2. Blockage of veins
3. Right/Left Ventricular Failure, Systemic & Pulmonary (respectively)

39
Q

What can decrease πnet?

A

Hypoproteinaemia
1. Bad diet; malnutrition
2. Liver diseases; produces proteins
3. Nephrotic syndrome; proteins are filtered into piss… not good

40
Q

How can venous tone increase venous return?

A

Sympathetic tone causes vasoconstriction, blood depots are activated, increasing VR, increasing EDV

41
Q

What is the physiologic CVP (Central Venous Pressure)?

A

-2 - 6 mmHg

42
Q

Reduced CVP risk

A

Risk of shock and hemorrhage

43
Q

Increased CVP risk

A

Risk of right ventricular failure

44
Q

What regulates the vascular tone?

A

Resting Vasoconstriction
1. Basal tone (myogenic)
Spontaneous contractility of smooth muscle cells of the vessel

  1. Resting vasoconstrictor tone (neurogenic)
    SNS innervation
45
Q

What happens during reflex vasoconstriction?

A

Increase in the action potentials through the sympathetic nerves causes increase in contraction (consitrctions)

46
Q

What causes vasodilation?

A
  1. Base tone DECREASES
  2. Resting vasoconstrictor tone DECREASES
  3. Vasodilator nerves are ACTIVATED
47
Q

What causes vasoconsitrction?

A
  1. Base tone INCREASES
  2. Reflex vasoconstrictor ACTIVATED/INCREASED
48
Q

What regulates the basal tone?

A

It’s myogenic, so the smooth muscle regulates itself

49
Q

At what locations does the SNS provide vasoconstrictor nerves?

A
  1. Arteries
  2. Arterioles
  3. Most organs
  4. Veins
50
Q

At what locations does the SNS provide vasodilation nerves?

A
  1. Skeletal muscle
  2. Certain glands
51
Q

Explain redistribution of blood during fight-or-flight

A

Cardiac output is redistributed to mainly supply the muscles:

Kidney: vasoconstrict = less blood
Liver: vasoconstrict = less blood
Skin: vasoconstrict = less blood
Muscles: vasodilate = more blood

52
Q

Which locations are you able to find PNS vasodilator nerves?

A
  1. Erectile tissue
  2. Pia mater (meninges)
53
Q

What happens during axon reflex?

A

Injury triggers axon to release histamine and substance-p, which activate vasodilation to increase blood flow to the wound for quicker repair

Physiology I (16 decks)

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