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Unit 2 > BIOMED 10/23c Hemodynamics > Flashcards

BIOMED 10/23c Hemodynamics Flashcards

1
Q

total body water

A

50-70% of body weight

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2
Q

total body water composition

A

○ 2/3: intracellular fluid

1/3: extracellular fluid

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3
Q

What composes extracellular fluid

A

(1/3 of total body water)
contains:
1. plasma
2. interstitial fluid

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4
Q

what is plasma?

A

it has a lot of soluble proteins (free and have a negative charge) - albumin
the proteins are too large to diffuse along the capillary membrane

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5
Q

what is interstitial fluid?

A

everything that is part of tissues that is outside the cells and the blood vessels

  • ultra filtrate of plasma
  • ion composition is similar to plasma
  • difference: capillary wall
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6
Q

why does plasma have more proteins than interstitial fluid?

A

proteins are too large to diffuse along the capillary membrane, whereas the solutes are gases are able to

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7
Q

what separates plasma from interstitial fluid?

A

cell membrane

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8
Q

where are the gases, fluids, and solutes exchanged?

A

microcirculation!
Arterioles > capillaries (1 single endothelial layer thick) > venules > veins > heart > arteries

AND lymphatic network

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9
Q

what is the importance of the lymphatic network

A

fluid balance maintenance

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10
Q

how are gases and solutes exchanged?

A

DIFFUSION
SOLUTES:
– Lipid soluble substances (O2, CO2) diffuse through the endothelial cells
– Water-soluble substances (ions, glucose, amino acids) diffuse through
pores
– Plasma proteins are too large to diffuse

GASES:
through endothelial cells

Vesicular transport is minimal

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11
Q

what is flow determined by?

A
  1. resistance to flow
  2. pressure gradient between capillary and interstitium
  3. fluid exchange along the capillary
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12
Q

what determines a fluid’s resistance to flow?

A
  1. diameter of vessels

2. permeability of capillary wall

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13
Q

what is the major vessel that determines the overall impact of the diameter on the resistance?

A

arterioles! they are the most dynamic to change in diameter

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14
Q

What is the permeability of the capillary wall a function of?

A

Pore Size!

Capillaries in different tissues have different pore sizes

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15
Q

what are the different capillary pore sizes for different tissues?

A

– Cerebral = tight junctions between endothelial cells; capillary is NOT leak; K is low; pores are very small; Blood brain barrier
– Muscular = larger, INTERMEDIATE; K is intermediate (permeability constant)
– Glomerular = LARGE; very leaky capillaries in kidney to filter blood and make urine

– Bone marrow = VERY LARGE

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16
Q

what determines the pressure gradient between the capillary and the interstitium?

A

starling forces

  • hydrostatic pressure
  • osmotic/oncotic pressure
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17
Q

what is hydrostatic pressure?

A

blood pressure inside the vessel walls
Pc = capillary hydrostatic pressure (~30mmHg)
Pi = interstitial hydrostatic pressure (~-1)

PUSHES FLUID OUT OF CAPILLARY for FILTRATION

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18
Q

what is osmotic pressure?

A

due to negatively charged proteins that are too big to diffuse out of the capillary
Pic = capillary oncotic pressure (-26mmHg)
Pii = interstitial oncotic pressure (close to 0)

PULLS WATER INTO THE CAPILLARY for ABSORPTION

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19
Q

what is the difference between osmosis, osmotic pressure, and osmotic force?

A

– Membrane permeable to fluid, but not to solutes
– Osmosis = flow of fluid due to differences in concentration of solute in a membrane
** Diffusion is when the ion/solute moves through membrane
– Osmotic pressure = amount of pressure required to stop the flow of fluid from low to high concentration (from chamber 2 to 1)

– Osmotic force = pulls water into the capillary

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20
Q

what defines the fluid exchange between interstitium and capillary?

A

the balance between the osmotic pressure and the hydrostatic pressure

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21
Q

what determines the fluid exchange along the capillary?

A

changes in osmotic and hydrostatic pressure

arteriolar: delta P > delta Pi
- net filtration OUT of vasculature (3ml/min)

venous: delta P < delta Pi
- net absorption INTO the vasculature (2.7ml/min)

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22
Q

why don’t we get swelling even though net movement out of vessel is more than what is inside?

A

10% of what isn’t reabsorbed is picked up by the lymphatic vessels and finds its way back to the vasculature

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23
Q

what causes edema?

A

accumulation of fluid in interstitial space

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24
Q

what is non-inflammatory edema

A
  1. lymph system malfunction

2. disruption/altering in starling forces

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25
Q

what happens when lymph system malfunctions?

A

fluid is transudate (low protein concentration) and we get pitting edemas

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26
Q

what are the reasons for lymph edema?

A

◊ Primary = congenital
◊ Secondary = most common, resulting from trauma or surgery; UE swelling -> resection of lymph nodes following a mastectomy
Generally unilateral, unless bilateral mastectomy

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27
Q

how do you fix the symptoms of lymph edema?

A

compression wraps increase hyrdostatic pressure in the interstitium and decreases the pressure gradient and decreases fluid filtration of out the capillaries

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28
Q

what happens when the starling forces are altered?

A

edema occurs when there is an increase in hydrostatic pressure and a decrease in oncotic pressure

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29
Q

what kind of inflammation is a malfunction of the lymph system

A

non-inflammatory

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30
Q

why do we get increased hydrostatic pressure in capillary?

A

decreased flow through venous system; increased venous resistance caused by some sort of mechanical blockage

31
Q

what happens after hydrostatic pressure in the capillary rises?

A
  1. increased filtration

2. increased fluid accumulation and edema

32
Q

what are causes of increased capillary hyrdostatic pressure?

A
  1. DVT

2. Heart Failure

33
Q

what is the edema response to a DVT?

A
  • Unilateral edema distal (due to increased filtration)
  • Redness
  • Inflammatory response in the vein itself -> painful, hot swollen limbs - phlebitis
34
Q

what causes edema when there is heart failure?

A
  1. left sided heart failure:
    - Right ventricular output exceeds left ventricular output
    - Pressure Backs up in pulmonary vasculature
    - Fluid accumulates in the PULMONARY tissue
    - Interstitial accumulation
    - Fluid in alveoli and interferes with gas exchange
  2. right sided heart failure:
    - output of left ventricle exceeds right ventricular output
    - Peripheral edema (bilateral LE)
    - most edema in the bilateral dependent position
35
Q

what is the impact of decreased oncotic pressure on edema?

A

when plasma protein concentration is decreased -> oncotic pressure decreases -> absorption decreases -> fluid accumulates -> edema

36
Q

what is the most common plasma protein that drives oncotic pressure?

A

albumin
50-60% of plasma protein
normal concentration = 3.5-5.5 g/dL
Oncotic pressure is normally 25 mmHg

37
Q

what happens in hypoalbuminemia

A

plasma protein concentration is decreased and it leads to decreased oncotic pressure this absoroption decreases and fluid accumulates as edema

38
Q

where can hypoalbuminemia stem from?

A
  • Liver
  • Nephrotic disease
  • Burns
  • Protein-calorie malnutrition
39
Q

what happens when there is protein calorie malnutrition?

A

Yields to gut edema and protein continues to spiral downward

can also seen petally and pre-tibially

40
Q

how do you treat hypoalbuminemia from protein calorie malnutrition?

A
  • Treatment: IV line to inject nutrition mixture to raise protein levels
  • Total parenteral (right into the veins)
41
Q

what is inflammatory edema?

A
  • not pitting

- accompanied by redness, heat, and pain

42
Q

how does inflammatory edema occur?

A

Leaky capillaries (increase in capillary permeability) - INFLAMMATORY (mechanism differs from the lymph and starling forces) - fluid is exodate and has a high protein content - pores are getting bigger so proteins can squeeze out

43
Q

what is the process of inflammatory edema?

A

Mast cells release histamine -> diffuses to endothelial cells -> retract and increase pore size -> receptors are expressed for rolling, adhering, and migrating

44
Q

define effusion

A

Accumulation of fluid in enclosed space

-joint or pleural

45
Q

define depended edema

A

edema in the lowermost region

46
Q

define anasarca

A

generalized edema

47
Q

define ascites

A 
accumulation of
fluid in peritoneal
cavity, causing
abdominal
swelling
48
Q

compartment syndrome

A

Limb-threatening ↑ in pressure in
fascial compartment due to
bleeding or swelling of tissue in that
compartment

49
Q

early signs and symptoms of compartment syndrome

A 
– Numbness, paresthesias along
cutaneous distribution of nerves in
that compartment
– Severe, progressive pain, worse
with stretch or squeezing of
affected muscles
– Taut, shiny skin
50
Q

late signs and symptoms of compartment syndrome

A

– Paralysis

– Diminished pulses

51
Q

overall, edema results from?

A 
– Disruption of lymphatic system
– ↑ Hydrostatic pressure
• Deep vein thrombosis
– ↓ in oncotic pressure
• Protein calorie malnutrition
– ↑ Capillary permeability
• Acute inflammation
52
Q

treatment for compartment syndrome

A

fasciotomy - cut open fascia to relieve the pressure

53
Q

in the absence of compensatory mechanisms, hemorrhage triggers:

A

Venous Return Drops -> Decreased Stroke Volume -> Decreased CO -> Decreased BP

54
Q

what is pulse pressure?

A

systolic - diastolic

when pulse pressure drops, SV drops

55
Q

what are compensations for hemorrhage?

A
  1. elevated HR
  2. cool, pale skin
  3. decreased urine output
56
Q

why do we get elevated HR during hemorrhage?

A

in response to fall in BP, baroreceptors and carotid sinus send signal to medulla where we get the increase in firing; Decrease in Parasymp; Increase in Symp activity to HR and BVs;

Yields increased HR, Contractility, TPR, and venoconstriction

57
Q

why do we get cool pale skin in response to hemorrhage?

A

Peripheral
vasoconstriction
– ↓ blood flow to
skin→ cool, pale skin

58
Q

why do we get decreased urine output during hemorrhage?

A

Renin-angiotensin-aldosterone system

  • Increased BP yields increase in angiotensin II that augments vasoconstriction
  • > Yields increased thirst, sodium reabsorption, and water!
  • Aldosterone also yields increased fluid volume and decreased fluid output
↑ Blood pressure by
– ↑ Total peripheral
resistance
• Peripheral vasoconstriction
→ ↓ blood flow to skin→
cool, pale skin

– ↑ Fluid volume
• ↑ Na+ and H2O resorption
→ ↓ Urine output

59
Q

when there is a ___ in ____ pressure we get retention of fluid in blood volume that yields ____ _____ pressure

A

decrease
capillary hydrostatic pressure
increased
arteriolar pressure

60
Q

what does circulatory shock result from?

A

• failure of compensatory mechanisms
• Results from hypoperfusion of tissues
– Cellular hypoxia → Anaerobic metabolism →
Metabolic acidosis → Cell injury or death

61
Q

what are signs/symptoms of shock

A 
– Weak, rapid pulse
– Hypotension
– Low urine output
– Altered mental status
• Anxiety → Confusion → Loss of consciousness
62
Q

what are the main stages of shock?

A
  1. initial
  2. compensatory
  3. progressive
  4. refractory
63
Q

what is initial stage of shock?

A

– Cellular hypoxia → reliance on anaerobic metabolism

-high likelihood to come back from

64
Q

what is compensatory stage of shock

A

– Hypercapnia and Acidosis → Hyperventilation
– Activation of baroreceptor reflex and renin-angiotensin
system to increase BP

-mid likelihood to come back from shock

65
Q

what is progressive stage of shock?

A

– If compensatory mechanism fail, ↑metabolic acidosis
• General vasodilation → ↓ peripheral resistance
• Histamine release → fluid leakage, edema

-less likely to come back from this

66
Q

what is refractory shock?

A

– Irreversible damage to cells → Organ failure → Death

-most often leads to death

67
Q

what are different types/causes of shock?

A
  1. hypovolemic
  2. cardiogenic
  3. obstructive
  4. distributive
68
Q

what is hypovolemic shock?

A

– Fluid loss due to hemorrhage, burns,

vomiting/diarrhea

69
Q

what is cardiogenic shock?

A

– Failure of cardiac pump

70
Q

what is obstructive shock?

A

– Obstruction of blood flow due to tamponade, aortic

stenosis, pulmonary embolism

71
Q

what is distributive shock?

A

– Septic, anaphylactic, neurogenic

72
Q

what does hemorrhage yield?

A

• Hemorrhage → ↓ Venous Return → ↓ CO

73
Q

what are the responses to hemorrhage summarized?

A 
– Baroreceptor Reflex
• ↑ SNS activity → ↑ HR, ↑ Contractility, ↑ TPR → ↑
BP
– Renin – Angiotensin – Aldosterone
• ↑ TPR, ↑ Fluid Retention → ↑ BP

Unit 2 (31 decks)

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