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40 Cards in this Set
- Front
- Back
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What is insensible water loss?
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Water loss that we are not consciously aware of (sweat, exhalation)
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What is the extracellular fluid compartment?
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any fluid that is not within a cell; tissue fluid (interstitial fluid) or blood plasma
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What is the intracellular fluid compartment?
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any fluid that is contained within a cell's plasma membrane (RBCs are an example of an intracellular fluid compartment within an extracellular fluid compartment, the blood vessel)
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What is transcellular fluid?
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fluid within distinct cavities (synovial fluid, pericardial fluid, CSF)
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Who has more body fat? Women or men?
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women; more body fat = less % of weight is water
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Men have a lower body fat than women. Do they have more or less % body water?
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men have more % body water since there is less fat. body fat and body water are inversely proportional
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What is hematocrit?
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packed RBC volume; % of RBCs in the total blood
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In a normal person, what is the difference between the ionic composition of the interstitial fluid (tissue fluid) and the plasma?
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they are very similar, but there is a slight positive charge in the plasma since albumin (negative) repels negative charges form the plasma
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What is the Donnan Effect?
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theoretically, the ionic composition between tissue fluid and plasma is equal, but large negative proteins like albumin in the plasma repel - charges and attract + charges into the plasma. so the plasma is slightly more positive than the tissue fluid
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Where is there a higher concentration of negative ions? Tissue fluid or plasma?
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tissue fluid; albumin and other negative proteins in plasma repel them
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Where is there a higher concentration of positive ions? Tissue fluid or plasma?
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plasma; negative proteins like albumin attract them into plasma
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How can we detect whether or not there is a movement between fluid compartments?
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indicator-dilution method; inject a known concentration of substance, allow it to disperse, detect the concentration in the compartment, it should be the same if there is no movement between compartments. can also be used to determine volume of the compartment, if there is no movement between compartments
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If we know plasma volume and hematocrit, how can we determine total blood volume?
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(plasma volume)/(1-hematocrit)
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What is the difference between moles and osmoles?
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osmoles refers to all particles found in the solution participating in osmotic pressure. moles is just one type of molecule (but there are many different particles diffusing in/out of blood so osmoles is better a unit)
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What is osmolarity vs. osmolality?
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osmolarity is osmoles/Liter; osmolality is osmoles/Kg
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What does it mean if a solution is 0.9% NaCl?
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0.9 grams NaCl/100mL of water = 9 grams/Liter
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A cell placed into a hypertonic solution will ... (swell or shrink)?
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shrink; water moves out to dilute the high concentration in the solution
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A cell placed into a hypotonic solution will ... (swell or shrink)?
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swell; the concentration of particles inside the cell is higher = water moves in to dilute it
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Why are most IV solutions 0.9% NaCl?
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that is the same osmolarity as blood = no swelling or shrinking of RBCs or dehydration/overhydration
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If a solution of high concentrated saline was given to a patient through IV, what would happen?
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high concentration of salt in the plasma = water moves out of the cells to dilute the plasma and cells shrink
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If a solution of pure water (no salt) was given to a patient through IV, what would happen?
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it would be hypo-osmotic to the plasma and water would move into the cells to equilibrate the osmotic pressure = cell swelling
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When a large dose of concentrated saline solution is put into the blood vessels via IV (into extracellular compartment), what happens to the solute concentrations in the intercellular and extracellular compartments?
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initially there is a large increase in just the plasma, but eventually there is an equilibrium where both levels have increased from the initial concentrations
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What is hyponatremia?
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low sodium in blood
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Why does diarrhea lead to dehydration hyponatremia?
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salt and water are both lost in the feces
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Why can overhydration lead to hyponatremia?
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too much water can dilute the sodium concentration
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If there was no ADH (diabetes insipidus), why would we expect hypernatremia?
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no ADH = extreme water loss in the urine from blood = sodium in the blood is getting more concentrated
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If there was primary aldosteronism, why would we expect overhydration hypernatremia
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high aldosterone = more sodium reabsorption = more water reabsorption also
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What happens to cells when there is hyponatremia? Swell or shrink?
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low sodium in the blood = more sodium in the cells = water moves into the cells = swelling
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What happens to cells when there is hypernatremia? Swell or shrink?
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more sodium in the plasma = water from cells will move into the plasma to dilute it = water out of cells = shrinking
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Increased capillary hydrostatic pressure has what effect on edema?
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promotes edema by increasing capillary filtration rate
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Decreases colloid osmotic pressure has what effect on edema?
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promotes edema by increasing capillary filtration rate
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What is lymphedema?
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lymphatic failure/blockage leading to accumulation of fluid in tissue = edema
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Why does heart failure lead to edema?
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no pumping of blood = pooling of blood = increased hydrostatic pressure = increased capillary filtration rate; also low BP from low output = lower GFR = renin = more water reabsorption = edema
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Why does liver cirrhosis cause edema?
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plasma proteins are made in the liver. poor liver function = low proteins = low colloid pressure = water doesn't move into the capillaries = stays in tissue fluid
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3 safety factors against edema
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negative pressure = low compliance of tissues = less space to accumulate fluid; lymphatics can increase greatly; remove proteins from the tissue fluid so water leaves tissue fluid
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Why is the interstitial gel important?
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resists water movement into tissue fluid; helps keep the tissue non-compliant
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What causes pitting edema?
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free fluid in the tissue spaces that can move through the proteoglycan gel. normally the proteoglycans hold the water tightly in place, but if there is excess fluid, it won't all be attached to proteoglycan and can move freely
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What causes non-pitting edema?
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fluid in the tissue fluid that has fibrinogen so it cannot move; associated with lymphatic failure
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If edema is forming, how are proteins removed from the tissue fluid to act as a safety factor?
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lymphatics are able to remove proteins easily; as lymph flow increases to help prevent edema, it takes proteins with it and slows the flow of water into the tissue fluid
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What is effusion?
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edema in a potential space (pleural effusion, pericardial effusion)
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