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CRAAB 3 > Nordgren- The Peripheral Vasculature > Flashcards

Nordgren- The Peripheral Vasculature Flashcards

1
Q

What is the purpose of the CV system?

A

To maintain INTERSTITIAL FLUID homeostais.

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2
Q

What is the Fisk principle?

A

Determines how substances are transported via blood bewteen the capillary bed in one location to another.

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3
Q

Where does passive diffusion often occur?

A

capillaries

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4
Q

What does diffusion depend on?

A
  1. concentration difference
  2. SA for exchange
  3. Diffusion distance
  4. permeability of capillary wall to the substance
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5
Q

Why are capillaries so efficient?

A

They maximize the area available for exchange while minimizing the distance to diffuse

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6
Q

The number of pores in the capillary depends on….

A

tissue location

ex. brain capillaries have FEW bores (tight)

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7
Q

What won’t cross a capillary wall?

A

Anything larger than 40 A (albumin)

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8
Q

Will a lipid soluble substance cross a membrane easily?

A

YES

b/c the membrane is only one cell thick

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9
Q

Net fluid OUT of a capillary =

A

filtration

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10
Q

Net fluid INTO a capillary=

A

resorption

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11
Q

Fluid flows in response to what two variables?

A
  1. Hydrostatic p (P)

2. oncotic pressure (pi)

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12
Q

What is hydrostatic pressure?

A

pressure of blood forcing fluid OUT of capillary

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13
Q

What is oncotic pressure?

A

osmotic attraction of water IN to regions of higher protein conentration

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14
Q

What is starling hypothesis?

A

Describes the relationship between opposing hydrostatic and oncotic forces on the net movment of transcapillary fluid (filtration or reabsorption)

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15
Q

What is the formula for the net filtration rate?

A

Net filtration rate = k (constant) {(hydrostatic pressure of intracapillary fluid- quantity of interstitial fluid)- (oncotic P of intracapillary fluid- quantity of intersitital fluid)}

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16
Q

What is filtration?

A

the net movement of solutes and fluid OUT of hte capillary and into the interstitial fluid

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17
Q

A POSITIVE pressure gradient is indicative of…

A

filtration

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18
Q

A NEGATIVE net pressure gradient is indicate of …

A

reabsorption

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19
Q

Why are the hydrostatic and oncotic pressures usually 0?

A

oncotic b/c very few proteins in IF

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20
Q

What occurs at the arteriole ned of a capillary?

A

filtration

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21
Q

What occurs at the venule end of a capillary?

A

reabsortpion

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22
Q

What does the release of histamine do?

A

INCREASES the capillary permeability to hte extent that proteins leak into the IF and LOWERS the oncotic pressure.

*exception to the oncotic P rule

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23
Q

What is the lymphatic system important?

A

keeps the interstitial protein concentration LOW and removes excess capillary filtrate from the tissues.

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24
Q

Why are lymphatic capillaries very porous?

A

Collect large particles and move them to lymph nodes then return fluid to the peripheral venous blood entering the right heart.

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25
Q

If vessels are in a row they are in…

A

series

26
Q

What is flow equal to?

A

Q = change in pressure/ resistance

27
Q

What is the total resistance equal to?

A

The SUM of all the individual resistances

28
Q

What vessel has the greatest impact on flow?

A

the vessel w/ the highest resistance

29
Q

What is the primary determinant for resistance of vessels in parallel?

A

not the diameter of an individual capillary, but the total cross sectional area of ALL capillaries

30
Q

What is resistance equal to for vessels in parallel?

A

R= 8Ln/πr4

31
Q

The overall effective resistance of any parallel network will always be _____ than that of any elements of that network.

A

LESS

32
Q

If flow must remain the same throughout the peripheral system, and the total cross-sectional area of vessels changes thorughout hte body, what must change to maintain the flow rate?

A

flow velocity

33
Q

What is laminar flow?

A

orderly, streamlined, low friction

34
Q

What is turbulent flow?

A

disordered, mixing, hgh friction

35
Q

What is friction?

A

shear stress, the force inside the wall of the vessels that wants to drag the inside surface along with the blood flow

36
Q

What serves as a volume reservoir in the CVS?

A

The peripheral venous system

37
Q

What is a secondary reservoir in the CVS?

A

Central venous system (great veins of the thorax and the RA)

38
Q

What happens when peripheral veins constrict?

A

Blood is displaced and enters the central venous system–> increases central venous volume, pressure, cardiac filling–> augments stroke volume (Starling!)

39
Q

What happens when blood pressure decreases across the vasculature?

A
  1. The pulsatile nature of blood pressure disappears across the arterioles
  2. Central venous pressure is about 0 mm HG
40
Q

What present a large resistance to flow?

A

arterioles

41
Q

What happens as resistance increases in arterioles?

A

The flow velocity is still high and bp must decrease to maintain flow rate

42
Q

What determines overall organ resistance?

A

Resistance in the arterioles

43
Q

What regulates resistance in the arterioles?

A

Adjustments in the diameter of the lumen

44
Q

What happens when arterioles are OPEN?

A
  1. low reservoir
  2. high flow velocity
  3. high downstream volume
45
Q

What happens when arterioles are CLOSED?

A
  1. High reservoir
  2. low flow velocity
  3. low downstream volume
46
Q

What is TPR?

A

Overall resistanct to flow thorugh the ENTIRE systemic circulation

47
Q

What will adding an organ to a system in parallel do to the TPR?

A

DECREASE the TPR

48
Q

What will decreasing the resistance in any organ do to the TPR?

A

DECREASE the TPR

49
Q

What describes the elastic properties of veins?

A

Compliancy (C)

50
Q

What is compliancy related to?

A
  1. How much volume changes in response to a change in pressure

C= change in V/ change in P

  1. Volume reservoir
51
Q

When do arteries act as a blood reservoir?

A

On a beat to beat basis.

  1. They convert the pulsatile flow coming out of the heart into a steady flow of blood through the vascular bed.
  2. Store pressure energy in walls during expansion–> pressure resrvoir
52
Q

What drives blood through peripheral vascular system during systole?

A

Arteries recoiling to shorter lengths and give up stored potential energy

53
Q

When measuring arterial pressure which sounds is systolic and which sound is diastolic?

A

first- systolic

last- diastolic

54
Q

What is MAP?

A

The average effective pressure that drives blood through the systemic organs

Pa= COxTPR

55
Q

What causes changes in MAP?

A

Changes in either CO or TPR

56
Q

What’s another way to calculate MAP?

A

PA= PD + 1/3 (Ps-Pd)

57
Q

What is arterial pulse pressure?

A

Psystolic- P diastlic

58
Q

What determines arterial pulse pressure?

A

Pp= SV/Ca

Stroke volume and arterial compliance

59
Q

Greater compliance leads to ______ pulse pressure.

A

SMaller

60
Q

The larger the volume ejected the ________the pulse pressure.

A

larger

61
Q

What causes changes in arterial compliance?

A

aging!

increased arterial volume, arterial stiffness, arterial pulse pressure, MAP

CRAAB 3 (7 decks)

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