Podcast
Questions and Answers
The method used to measure body fluid volumes is called ______ dilution method.
The method used to measure body fluid volumes is called ______ dilution method.
indicator
Radioactive water (tritium, 3H2O) or heavy water (deuterium, 2H2O) can be used to measure total body ______.
Radioactive water (tritium, 3H2O) or heavy water (deuterium, 2H2O) can be used to measure total body ______.
water
To measure the volume of extracellular fluid, substances that disperse in the plasma and interstitial fluid but do not readily permeate the cell ______ are used.
To measure the volume of extracellular fluid, substances that disperse in the plasma and interstitial fluid but do not readily permeate the cell ______ are used.
membrane
The volume of chamber B can be calculated using the formula: Volume B = 1ml * 10 mg/ml / ______ mg/ml.
The volume of chamber B can be calculated using the formula: Volume B = 1ml * 10 mg/ml / ______ mg/ml.
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For the indicator dilution method, the substance used must be non-______ and easy to measure.
For the indicator dilution method, the substance used must be non-______ and easy to measure.
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About 80% of the total colloid osmotic pressure of the plasma results from ______.
About 80% of the total colloid osmotic pressure of the plasma results from ______.
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The process by which fluid is forced through a membrane because of pressure difference is called ______.
The process by which fluid is forced through a membrane because of pressure difference is called ______.
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At the arteriolar end, the net filtration pressure is calculated as (35-25)= +10 mmHg, indicating ______.
At the arteriolar end, the net filtration pressure is calculated as (35-25)= +10 mmHg, indicating ______.
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The capillary hydrostatic pressure (Pc) tends to force fluid ______ through the capillary membrane.
The capillary hydrostatic pressure (Pc) tends to force fluid ______ through the capillary membrane.
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Factors that can increase capillary filtration include increased capillary hydrostatic pressure and decreased plasma colloid ______.
Factors that can increase capillary filtration include increased capillary hydrostatic pressure and decreased plasma colloid ______.
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Study Notes
Measurement of Body Fluid Volumes
- Indicator Dilution Method: Measures fluid volume by injecting a substance that stays in one compartment, then calculating the volume where it distributes.
- Calculation Example: Injecting 1 ml of dye (10 mg/ml) into a chamber leads to a final concentration of 0.01 mg/ml, allowing calculation of the chamber volume as 1000 ml.
Criteria for Substance Use in Measurements
- Non-toxic, mixes evenly in the compartment, remains within the compartment, stable without metabolic changes, easy to measure, and does not affect other compartments.
Total Body Water Measurement
- Substances Used: Radioactive water (tritium, 3H2O) and heavy water (deuterium, 2H2O) rapidly mix with body water; antipyrine is also utilized due to high lipid solubility.
Measurement of Extracellular Fluid
- Estimated with substances that disperse in plasma and interstitial fluid but do not enter cells.
- Common Substances: Radioactive electrolytes such as sodium and chloride which may overestimate ECF volume.
Starling Forces
- Plasma Oncotic Pressure: Approximately 80% derived from albumin, 20% from globulins, negligible from fibrinogen.
Filtration Principles
- Filtration Process: Fluid movement across membranes due to pressure differences on either side.
- Starling Equation: Filtration = Kf × NFP, where Kf is the filtration coefficient and NFP is net filtration pressure.
Components of Filtration
- Hydrostatic Pressures: Capillary hydrostatic pressure (Pc) pushes fluid out, interstitial fluid hydrostatic pressure (Pi) pushes fluid in.
- Osmotic Pressures: Capillary plasma colloid osmotic pressure (πc) pulls fluid in, interstitial colloid osmotic pressure (πi) pulls fluid out.
Net Filtration Pressure Calculation
- Net filtration pressure is the difference between Pc and πc minus the difference between Pi and πi, with values indicating filtration at the arteriolar end (+10 mmHg) and absorption at the venous end (-10 mmHg).
Factors Increasing Capillary Filtration
- Elevated capillary filtration coefficient, increased hydrostatic pressure, or decreased plasma colloid osmotic pressure.
Interstitial Fluid Volume Dynamics
- Influenced by Starling forces, filtration coefficients, capillary activity, lymph flow, and total extracellular fluid volume.
Edema Overview
- Definition: Excess fluid accumulation in body tissues, primarily in extracellular fluid, but also in intracellular fluid.
Intracellular Edema Causes
- Hyponatremia, metabolic depression, nutrient deficiency, reduced blood flow, and inflammation can cause swelling within cells.
Extracellular Edema Causes
- Results from abnormal plasma-to-interstitial fluid leakage and lymphatic failure in fluid return.
Causes of Increased Extracellular Edema
- Increased capillary hydrostatic pressure, decreased plasma proteins, increased capillary permeability, and blockage of lymph return.
Types of Edema
- Pitting Edema: Caused by high capillary hydrostatic pressure and low oncotic pressure.
- Non-pitting Edema: Associated with increased capillary permeability and lymphatic obstruction.
Body's Potential Spaces
- Examples include pleural, pericardial, peritoneal, and synovial cavities; these areas can accumulate effusion fluid due to capillary exchange disturbances.
Autonomic Nervous System (ANS) Overview
- The ANS regulates homeostasis, innervating all organs except skeletal muscles through smooth muscle, cardiac muscle, and glands.
ANS Division Organization
- Divided into sympathetic and parasympathetic systems, with varied innervation across target organs.
Sympathetic Division Anatomy
- Originates from thoracic to lumbar segments (thoracolumbar) with neural pathways that include preganglionic and postganglionic neurons.
Paravertebral Ganglia
- Located next to thoracic and upper lumbar segments, these ganglia interconnect via preganglionic neuronal axons, extending into cervical and sacral regions.
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Description
This quiz explores the methods used to measure body fluid volumes, specifically focusing on the indicator dilution method. You'll learn how to calculate the volume of fluid distribution by analyzing the concentration of an injected substance. Understand the principles behind this important physiological measurement.
