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CV > Lymphatics, Fluid Compartments, Local Blood Flow > Flashcards

Lymphatics, Fluid Compartments, Local Blood Flow Flashcards

1
Q

What percentage of total body weight is intracellular and extracellular fluid?

A 
ICF = 40%
ECF = 20%
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2
Q

What is generally considered an isotonic solution?

A

A solution that is around 280 osmolality

Less than 280 hypotonic
Greater than 280 hypertonic

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3
Q

What factors affect of fluid movement?

A

Net driving force

  • capillary pressure vs interstitial fluid pressure
  • plasma colloid osmotic pressure vs interstitial fluid colloid osmotic pressure

Capillary filtration constant
Surface area

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4
Q

Hydrostatic forces are higher at the arteriolar or venule end?

A

Arteriolar

Tends to force fluids outwards through capillary membranes

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5
Q

Interstitial fluid hydrostatic pressure is _________. Why?

A

Negative

Due to the pumping action of the lymphatic

*usually an outward force for fluid movement. Helps pull fluid out of capillary beds

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6
Q

What generates about 70% of the oncotic pressure and tends to cause inward movement of fluid?

A

Plasma colloid osmotic pressure

Aka: plasma oncotic pressure

*albumin is the most abundant plasma protein

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7
Q

The is caused by the small amount of plasma proteins that leak into the interstitial space?

A

Interstitial fluid osmotic pressure

Aka: interstitial fluid oncotic pressure

*tends to cause outward movement of fluid

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8
Q

What is the Gibbs-Donnan Effect?

A

Albumin exerts a greater osmotic force than can be account for solely on the basis of the number of molecules dissolved in the plasma

  • Albumin has a negative charge: attracts sodium ions
  • Albumin binds a small number of chloride ions: attractors sodium ions
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9
Q

This is the sum of the hydrostatic and osmotic forces favors the new movement of water from the capillary to the interstitial space

A

Filtration

Happens on the arteriole side

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10
Q

This is the sum of the hydrostatic and osmotic forces factor the net movement of water from the interstitial space to the the capillary

A

Reabsorption

Happens on the venous side

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11
Q

Pressure in the capillary is _______ with a net driving force of ________ causing fluid to move________of the capillary

A

High
13-15mmHg
Out

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12
Q

What is the net inward force on the venous side of the capillary bed?

A

7

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13
Q

What happens to the capillary pressures when a pt is dehydrated?

A
  • decreased capillary hydrostatic pressure
  • increased oncotic pressure (on venule end)

*now the pressure gradient is smaller

  • beginning of capillary pressure gradient decreases
  • end of capillary, want to bring fluid back in at a greater lever
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14
Q

What is the lymphatic system?

A
  • Close-ended network of highly permeable lymph capillaries
  • lacking in tight junctions
  • fine filament anchors to connective tissue
  • muscular contraction: has ability to “pump” creating negative interstitial environment
  • drains back at the thoracic duct

*up to 10% of fluid filtered out of capillaries is picked up by lymphatic system

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15
Q

Plasma filtrate is returned to the circulation by? What is returned to the circulation?

A

By

  • tissue pressure
  • intermittent skeletal muscle activity
  • lymphatic vessel contraction
  • system of one-way valves

Returns

  • protein (albumin)
  • bacteria
  • fat
  • excess fluid
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16
Q

What are some causes of edema?

A

Lymphatic obstruction
Change in capillary permeability
Reduction in plasma protein
Increased capillary hydrostatic pressure

*someone at risk for decreased plasma oncotic pressure—> hypoproteinemia during malnutrition

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17
Q

How much of a 70kg adult male is fluid?

A

60% or 42L

2/3 of that is intracellular
1/3 is extracellular
-80% ECF is interstitial fluid
-20% ECF is plasma

55% for females

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18
Q

Isotonic solution

A
  • it neither shrinks nor swell cells
  • 0.9% NS
  • 5% dextrose

*will increase volume everywhere

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19
Q

Hypotonic solution

A

Solution has a lower osmolality (<282 mOsm/L)

  • water will diffuse in the cell, causing it to swell
  • solution with NaCl < 0.9% are hypotonic
  • 0.45% NS
  • D5W
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20
Q

Hypertonic solution

A

Solution that’s hyperosmolar

  • Water will flow out to the cell into the extracellular fluid concentrating the intracellular fluid and diluting the extracellular fluid
  • NaCl > 0.9% are hypertonic
21
Q

How do you know if you should give NS or LR to a pt?

A

If its a renal pt, or a pt with hyperkalemia give NS bc LR has potassium in it.

22
Q

What is the most commonly used colloid?

A

5% albumin

  • contains plasma protein fractions obtained from human plasma
  • used for volume expansion
  • moderate protein replacement
  • some j-witnesses don’t want albumin
  • considered a blood transfusion product and requires all the same nursing precautions used when administering blood products
23
Q

Describe the components of dual control regarding regulation of peripheral blood flow?

A

Extrinsic

  • primary by the nervous system
  • humorally also

Intrinsic (locally by the tissues)
-controlled by the conditions in the immediate vicinity of the blood vessels

24
Q

Name pharmacologic stimuli that cause contraction of vascular smooth muscle

A 
Catecholamines
   -epinephrine
   -norepinephrine
   -dopamine
Endothelin
Serotonin
Angiotensin II
Vasopressin
25
Q

Name pharmacologic stimuli that cause relaxation of vascular smooth muscle

A 
Histamine
Adenosine
Nitric Oxine (NO)
Carbon Dioxide
Potassium
Hydrogen ion
Prostaglandins
Acetylcholine
Bradykinin
26
Q

What is the main factor in acute control of local blood flow?

A

Tissue metabolic activity

27
Q

Metabolic mechanism

A

Any intervention that results in an inadequate O2 (nutrient) supply for the metabolic requirements of the tissues results in the formation of vasodilator substance which increase blood flow to the tissues

28
Q

This relaxes and increases flow to the capillary

A

Precapillary sphincter

29
Q

What are some of the metabolic mechanisms?

A

Hypoxia - #1

Tissue metabolites and ions

  • adenosine
  • potassium ions
  • CO2
  • hydrogen ions
  • lactic acid
  • inorganic phosphates
30
Q

What are examples of metabolic control of local blood flow?

A

Active hyperemia

Reaction hyperemia

31
Q

What is active hyperemia?

A

Something causes body to use more O2 increases flow to that area

*AKA functional hyperemia

32
Q

What is reactive hyperemia?

A

Transient increase in blood flow after blood flow to tissue has been stopped.
-tourniquet is an example. Return to flow, there is a buildup of metabolites in that limb. Causes vasodilation

-within limits, the peak blood flow and the duration of the reactive hyperemia are proportional to the duration of the occlusion

33
Q

What is autoregulation

A

-intrinsic ability of an organ to maintain a constant blood flow despite changes in perfusion pressure

  • possible explanations for autoregulation
    • myotonic mechanism
    • metabolic mechanism
34
Q

Myotonic mechanism of autoregulation

A
  • When the lumen of a blood vessel is suddenly expanded, the smooth muscles respond by contracting in order to restore the vessel diameter and resistance. The converse is also true
  • Vascular smooth muscle cells depolarize when stretched
  • proposed mechanism is stretch of vascular smooth muscles causes activation of membrane calcium channels (causes contraction)

pressure stays up, but flow goes back down to normal range

35
Q

Metabolic mechanism of autoregulation

A

When the pressure increase to a tissue, the flow increases, and excess oxygen and nutrients are provided to the tissues. These excess nutrient cause the blood vessels to constrict and the flow to return nearly to normal despite the increased pressure

36
Q

Endothelial factors of local blood control

A
  • endothelium is a source of substance that elicit contraction or relaxation of the vascular smooth muscle
  • vasoactive substances released from endothelium.
    • nitric oxide (NO)
      • endothelium-derived relaxing factor - most important!!!
    • prostacyclin
    • endothelin
    • endothelial-derived hyperpolarizing factor (EDHF)
37
Q

This is the most powerful vasodilator of endothelium

A

Nitric Oxide

38
Q

This is the most powerful vasoconstrictor of the endothelium

A

Endothelin

39
Q

Nitric Oxide

A
  • generated from amino acid L-arginine
  • generated from NO synthase
  • increased CMP concentration which produces relaxation by decreasing cytotoxic free calcium (by decreasing free calcium will allow for relaxation)
  • very short half-life (6 seconds)
    • due to rapid oxidation to nitrite and nitrate
    • also due to binding by substance such as hemoglobin
  • NO is a gas and must be lived by an inhaled delivery system
40
Q

Nitric Oxide production is stimulated by:

A 
Sheering forces acting on the endothelium
Angiotensin II
Acetylcholine 
Bradykinin
Histamine
Insulin
Substance P
41
Q

What are some important function of Nitric Oxide in the cardiovascular system?

A

Vasodilation
Inhibition of vasoconstrictor influences
Inhibition of platelet adhesion to the vascular endothelium
Inhibition of leukocyte adhesion to the vascular endothelium
Anti proliferation
Free radical scavenger

42
Q

What are systemic effects of Nitric Oxide?

A

Pulmonary vasodilation

  • decreased PVR
  • decreased pulmonary artery pressure
  • pulmonary decreases right ventricular afterload and improves right ventricular performance

Increased arterial oxygen tension

  • inhaled nitric oxide is delivered ONLY to ventilated alveoli
  • this improves V/Q relations by vasodilating capillaries and importing blood flow to areas participating in gas exchange
43
Q

Prostacyclin

A
  • Prostacyclin synthase in endothelial cells acts on cyclo-endoperoxide products to form prostacyclin
  • prostacyclin
    • strong vasodilator
    • inhibits platelet adhesion to the vascular endothelium
    • increases cAMP this mediates relaxation
44
Q

Endothelin

A
  • Synthesized by endothelium
  • Potent vasoconstrictor
  • Other actions
    • increased aldosterone section
    • increased cardiac inotropy and chronotropy
    • decreased Reynaldo blood flow and GFR
    • releases atrial natriuretc pepitde
    • in failing heard, contributes to calcium overload and hypertrophy
45
Q

Endothelin is implicated in the pathogenesis of:

A
  • hypertension
  • vasospasm
  • heart failure
  • pulmonary HTN
46
Q

What happens when damage to the endothelium occurs?

A

Damage to endothelial cells will lead to:

  • Decreased NO and prostacyclin production (2 vasodilators)
  • increased endothelin production

This will lead to:

  • vasoconstriction
  • vasospasm
  • thrombosis
47
Q

What happens with long-term blood flow regulation?

A
  • long-term regulation of blood flow is important when the metabolic demands of the tissue change.
  • over a period of hours, days and weeks, a long-term type of blood flow regulation develops in addition to acute control.
48
Q

This is a key mechanism for long-term local blood flow regulation by changing the amount of vascularity of the tissues

A

Angiogenesis - the generation of new blood vessels

49
Q

What is collateral circulation?

A
  • when an artery or a vein in blocked, a new vascular channel usually develops the blockage and allows at least partial resupply of blood to the affected tissue
  • the first stage in this process is dilation of small vascular loops that already connect the vessel above the blockage to the vessel below. Metabolic factor mediation
  • within minutes to days adequate flow restored

CV (8 decks)

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