Questions and Answers
What is the primary purpose of the gastrointestinal system?
What percentage of body weight is primarily composed of water in an average healthy adult male?
In multicellular organisms, groups of similar cells form what biological structure?
Which of the following ions is NOT abundant in the extracellular fluid compartment?
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What is the estimated number of cells in the human body?
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Which statement regarding the percentage of body water in human beings is true?
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What distinguishes the extracellular fluid from intracellular fluid?
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Which of the following substances can be used to measure total body water?
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Which of the following systems is not involved in the gas exchange process?
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What is the correct statement about the extracellular fluid volume?
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Which of the following best describes the role of the urinary system?
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Which of the following can be used to measure plasma volume?
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What is required to describe the distribution of total body fluids?
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Which factors are known to affect total body water?
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How are organs functioning together classified?
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How much does blood volume typically form of total body weight?
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Which ion is present in higher concentration in intracellular fluid (ICF) compared to extracellular fluid (ECF)?
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What is the approximate ratio of protein concentration between intracellular fluid (ICF) and plasma?
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Which cation has the lowest concentration in the intracellular fluid (ICF)?
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Which of the following correctly describes the composition of extracellular fluid (ECF) compared to intracellular fluid (ICF)?
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Which of these is NOT a component of the extracellular fluid (ECF)?
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What is the total body water (TBW) approximately as a percentage of body weight?
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Which method can be used to measure the volume of a fluid compartment in the body?
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What is the osmolarity of both intracellular fluid (ICF) and extracellular fluid (ECF)?
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What percentage of total body water (TBW) is found in the intracellular fluid compartment (ICF)?
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Which of the following statements about extracellular fluid (ECF) distribution is correct?
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How much intravascular fluid (IVF) is typically found in a 70 kg male?
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What method is used to determine the volume of a fluid compartment in the body?
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What proportion of total body water (TBW) is represented by interstitial fluid (ISF) in a 70 kg male?
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What is the main purpose of the Fick's indicator-dilution method?
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Which of the following is the approximate total blood volume as a percentage of body weight in a 70 kg male?
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Why is interstitial fluid (ISF) important in the body?
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Which method accurately calculates total blood volume using hematocrit?
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What substance is commonly used to label red blood cells for blood volume measurement?
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Which of the following components primarily distinguishes plasma from interstitial fluid?
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The intracellular fluid (ICF) is primarily separated from extracellular fluid (ECF) by what?
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What is the characteristic of the cell membrane regarding permeability?
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Which ions are present in larger quantities in the extracellular fluid (ECF)?
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What method is used for estimating blood volume through radioactivity?
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What quantity in interstitial fluid is generally lower compared to plasma?
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Study Notes
Body Fluid Compartments
- Total body water (TBW) represents about 60% of body weight.
- TBW is divided into two main compartments:
- Intracellular fluid (ICF): comprises 2/3 of TBW (40% of body weight) or about 28 L in a 70 kg male.
- Extracellular fluid (ECF): comprises 1/3 of TBW (20% of body weight) or about 14 L in a 70 kg male.
Subdivisions of Extracellular Fluid
- ECF is further divided into:
- Intravascular fluid (IVF): 5% or 3.5 L (plasma within circulatory vessels).
- Interstitial fluid (ISF): 15% or 10.5 L (fluid bathing the cells).
- Total blood volume is approximately 8% of body weight, including plasma and cellular elements.
Measurement of Fluid Volumes
- Fluid compartment volumes can be measured using the Fick’s indicator-dilution method.
- This involves injecting an indicator substance, allowing dispersion, and analyzing dilution.
- Blood volume can also be calculated with hematocrit values using the equation:
- Total blood volume = RBC volume x 100 / hematocrit.
Ionic Composition of Fluids
- ICF is rich in potassium and phosphate ions, with high protein content (4 times more than plasma).
- ECF contains high levels of sodium, chloride, and bicarbonate ions, but low potassium, calcium, and other electrolytes.
- Plasma has higher protein concentration compared to interstitial fluid due to low permeability of capillary membranes to proteins.
Key Differences in Ionic Composition
- Cation concentrations in ICF and ECF:
- Sodium: ICF 10 mmol/L, ECF 145 mmol/L
- Potassium: ICF 155 mmol/L, ECF 4.5 mmol/L
- Calcium: ICF 0.001 mmol/L, ECF 2.5 mmol/L
- Magnesium: ICF 13 mmol/L, ECF 1.0 mmol/L
- Anion concentrations reveal distinct differences, particularly higher phosphate levels in ICF.
Summary of Key Concepts
- TBW is distributed between ICF and ECF; ECF is made up of IVF and ISF.
- The ECF’s ionic composition is dominated by sodium, while ICF contains more potassium and protein.
- The measurement of fluid compartments plays a crucial role in understanding body hydration and electrolyte balance.
Knowledge Check Questions
- Percentage of body weight formed by water in an average adult male is approximately 60%.
- Aging typically results in a decrease in the percentage of body weight made of water.
- Healthy neonates have a water composition of around 70%.
- Inulin is effective in measuring total body water, while different isotopes can measure plasma volume.
Ion Identification
- Abundant ions in ECF: sodium, chloride.
- Abundant ions in ICF: potassium, phosphate.
Measurement Techniques
- Substances used to measure total body water: inulin, deuterium.
- Substances for measuring ECF: sodium, mannitol.
Factors Affecting Total Body Water
- Age, gender, body composition.
- Illness and hydration status.
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Description
Test your knowledge on body fluid compartments, including total body water and its subdivisions. This quiz covers important concepts such as intracellular and extracellular fluids, as well as measurement techniques for fluid volumes. Perfect for students in physiology or healthcare fields.
