10 Questions
What is the term used to describe the phenomenon where fluid can flow freely through tissue spaces because it is not in a gel form?
Free fluid
What type of edema is characterized by the ability to press the thumb against tissue and push fluid out of the area?
Pitting edema
Low tissue compliance in the negative pressure range contributes to a safety factor against edema.
True
What is the total safety factor against edema, as mentioned in the provided content?
17 mm Hg
Ascites is the term used to describe the collection of effusion fluid in the _________ cavity.
abdominal
What is the daily intake of water in the body?
Approximately 2100 ml/day from liquids and water in food, and an additional 200 ml/day is synthesized by oxidation of carbohydrates.
What makes up two-thirds of the total body water?
Potassium, magnesium, and organic phosphates
Capillary membranes separating plasma and interstitial fluid are highly permeable.
True
In hypotonic solution, a cell will _____.
swell
Match the causes of hypernatremia with their descriptions:
Hypovolemic hypernatremia = High serum Na+ with decreased extracellular volume due to fluid loss Euvolemic hypernatremia = High serum Na+ with normal extracellular volume due to pure water deficit Hypervolemic hypernatremia = High serum Na+ with increased extracellular volume from excess sodium or hypertonic water intake
Study Notes
Regulation of Body Fluids
- Daily intake of water:
- Approximately 2100 ml/day from liquids and food
- 200 ml/day synthesized in the body through oxidation of carbohydrates
- Daily loss of body water:
- Insensible water loss (700 ml/day): evaporation from respiratory tract and diffusion through skin
- Sweat loss (100 ml/day)
- Feces loss (100 ml/day)
- Kidney loss (variable)
Body Fluid Compartments
- Total body water: 60% of body mass
- Intracellular fluid (ICF): 40% of body mass, composed of potassium, magnesium, and organic phosphates
- Extracellular fluid (ECF): 20% of body mass, composed of sodium, chloride, bicarbonate, and albumin
- 75% of ECF is interstitial fluid
- 25% of ECF is plasma
- Transcellular fluid: small amount (~500 ml) found in gastrointestinal secretions, sweat, pleural fluid, etc.
Measurement of Body Fluid Compartments
- Indicator-dilution principle:
- Involves injecting a substance into a compartment and measuring its concentration after dispersion
- Can be used to measure volume of virtually any compartment
- Measurement of total body water: uses radioactive water (tritium or deuterium) or antipyrine
- Measurement of ECF volume: uses radioactive sodium, chloride, or inulin
- Measurement of plasma volume: uses labeled serum albumin or Evans blue dye
Osmolality and Tonicity
- Osmolality: concentration of impermeant solutes in a solution
- Tonicity: ability of a solution to cause a change in cell volume
- Isotonic solution: neither shrinks nor swells cells (e.g., 0.9% sodium chloride, 5% glucose)
- Hypotonic solution: causes cells to swell
- Hypertonic solution: causes cells to shrink
Hypernatremia
- Description: high serum sodium levels with decreased extracellular volume
- Causes:
- Hypovolemic hypernatremia: extrarenal and renal causes
- Euvolemic hypernatremia: pure water deficit with normal or minimal changes in extracellular volume
- Hypervolemic hypernatremia: sodium retention in excess of water
- Manifestations: altered mental status, thirst, ataxia, and hyperreflexia
Edema
- Definition: abnormal fluid accumulation in the interstitium
- Causes:
- Increased capillary pressure
- Decreased arteriolar resistance
- Increased capillary permeability
- Lymphatic obstruction
- Types:
- Peripheral edema: excess fluid in tissues perfused by the peripheral vascular system
- Intracellular edema: fluid accumulation within cells
- Pitting edema: residual indentation following application of pressure
- Nonpitting edema: no residual indentation following application of pressure
Safety Factors Against Edema
- Low tissue compliance in the negative pressure range: ~3 mm Hg
- Increased lymph flow: ~7 mm Hg
- Washdown of proteins from interstitial spaces: ~7 mm Hg
- Total safety factor against edema: ~17 mm Hg
This quiz covers the daily intake and loss of water in the human body, including the forms of water ingestion and the processes of water loss through respiration and skin diffusion.
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