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63 Cards in this Set
- Front
- Back
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How much of the adult body weight is water? |
60% |
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How much of the adult body weight is ICF? |
40% |
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How much of the adult body weight is ECF? |
20% |
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What is the function of the extracellular fluid? |
To contain all of the ions and nutrients needed to support life |
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What ions are found in large amounts in the ECF? |
Sodium, chloride, bicarbonate |
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What non-ion molecules are found in the ECF? |
Oxygen, glucose, fatty acids, amino acids, CO2, cellular wastes |
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What ions are found in large amounts in the ICF? |
Potassium, magnesium, phospate |
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What does homeostasis mean? |
Maintenance of nearly constant conditions in the internal environment |
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How much of the adult body weight is interstitial ECF? |
15% |
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How much of the adult body weight is intravascular ECF (plasma)? |
5% |
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How much water does adipose tissue contain? |
Almost none |
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If a person's hematocrit is 40%, how much of their blood is intracellular fluid? |
40% |
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If a patient is bleeding heavily, how does fluid shift in the body? |
From interstitial to intravascular, then intracellular to interstitial |
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What is osmolarity? |
Total amt of solute reactivity in moles/volume |
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How do plasma proteins impact blood osmolarity? |
Cause higher osmolarity in intravascular space than in interstitial space (cannot diffuse outside of vessels) |
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How much osmotic pressure (in mmHg) does each 1 mOsm difference create? |
19 mmHg |
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What happens if you introduce pure water into the bloodstream? |
Fluid shifts into RBCs to attempt to correct osmolarity difference and they lyse |
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What is the osmolarity of dextran? |
280 mOsm |
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What is the osmolarity of blood? |
290 mOsm |
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Why does dextran not cause cell lysis? |
Although the dextrose metabolizes out of the blood, leaving water, it happens so slowly that the cells can adjust |
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What is the relative osmolarity of normal saline to blood and why is it advantageous? |
Slightly hyperosmotic so no chance of cell lysis |
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What governs the size of arterioles in mammals? |
Physics; largest and smallest animals have same size arterioles |
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What do the arterioles govern? |
The pressure (flow) into capillary beds via constriction and relaxation |
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What are the sizes of veins and arteries relative to each other? |
Veins are bigger |
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What % of the blood is in the veins at any given time? |
60% |
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How thick are vein walls compared to arteries? |
Much thinner |
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What is the effect of venous constriction? |
Increased venous return Increased preload Increased cardiac output Increased O2 demand on heart |
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What is the effect of venous relaxation? |
Decreased venous return Decreased preload Decreased cardiac output Decreased O2 demand on heart (NTG) |
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What is the normal arterial capillary hydrostatic pressure? |
37mmHg |
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What is the normal oncotic pressure in the capillary bed? |
25 mmHg |
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What creates the oncotic pressure in the capillary bed? |
Colloidal solutes such as albumin |
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What is the equation for osmotic pressure? |
Π = M * R * T M = molar concentration R = universal gas constant T = temp |
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What is oncotic pressure? |
Colloidal osmotic pressure |
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What is the typical interstitial hydrostatic pressure in the capillary bed? |
2-3 mmHg |
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What is the normal venous capillary hydrostatic pressure? |
20 mmHg |
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How does hypoalbuminemia cause edema? |
Low albumin decreases oncotic pressure, so hydrostatic pressure drives fluid out of the vasculature |
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What causes hypoalbuminemia? |
Liver disease Malnutrition Kidney failure |
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How much of the body's albumin does the liver replace daily? |
25% |
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How do RHF and portal hypertension cause edema? |
Congestion/backup means venous hydrostatic pressure is increased beyond osmotic pressure, driving fluid into the tissues |
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How does fluid overload cause edema? |
Increased volume increases venous pressure, which tips hydrostatic pressure over oncotic and drives fluid into the tissues |
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How do anaphylaxis and sepsis cause edema? |
Endothelial retraction from inflammation allows plasma proteins to leak out; equalization of oncotic pressure in the interstitial space means massive fluid shifts into the tissues |
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Why won't albumin fix sepsis? |
The proteins will just leak out of the vasculature again |
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Why won't cortisol fix sepsis? |
Because the inflammatory cascade has already begun;
HOWEVER - it may prevent a second episode. |
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Why do pregnant women get edema? |
Baby blocks venous return via the femoral veins and IVC; increased venous pressure leads to fluid shifts into tissues |
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Why do women post-mastectomy get edema? |
Obstruction of lymphatic tracts means the ~20% of fluid that does not get returned via the venous system cannot leave the tissues effectively |
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How much of the fluid brought into the tissues by the arteries leaves through the veins? |
About 80%; the rest becomes lymph |
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How does erectile tissue become edematous? |
Relaxation of the arterial system increases hydrostatic pressure and drives fluids out of the vessels into the tissues |
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What do renal juxtaglomerular cells do? |
They sense a decrease in BP and release renin |
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What does renin do? |
Activates angiotensinogen into angiotensin I |
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What produces angiotensinogen? |
The liver |
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What is the limiting factor in the conversion of angiotensinogen into angiotensin I? |
Renin |
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What converts angiotensin I to angiotensin II? |
Angiotensin-converting enzyme (ACE) |
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Where does angiotensin-converting enzyme work? |
In the lungs |
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What does angiotensin II do? |
Promotes vasoconstriction and stimulates aldosterone secretion |
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Where is aldosterone secreted from? |
The adrenal cortex |
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What does aldosterone do? |
Tells the kidney to conserve sodium and water, resulting in increased blood volume and pressure |
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What condition stimulates the release of ADH? |
Increased plasma osmolarity (mostly due to increased sodium concentration) |
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How do ADH release and thirst relate? |
They are caused by the same part of the brain, but do not cause each other |
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Where is ANP released from and when? |
From the right atrium, when it is stretched (increased preload) |
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What part of the body does ANP work on? |
The kidney |
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What is negative feedback? |
When one condition triggers a mechanism to reduce or reverse that condition |
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Is CO2 retention an example of positive or negative feedback? |
Negative; when CO2 increases, the body increases respiratory drive to lower it |
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What is the negative feedback associated with blood loss? |
The body shifts fluid into the vascular space in order to reverse the volume loss |
