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Questions and Answers
What percentage of total body water is comprised of intracellular fluid (ICF)?
Which of the following is NOT a component of extracellular fluid (ECF)?
What is the most abundant cation found in intracellular fluid (ICF)?
What role do Na+/K+ pumps play in the cells?
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Which of the following factors is mentioned as affecting total body water?
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What is the most abundant cation in the intracellular fluid (ICF)?
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Which component is NOT found in cerebrospinal fluid (CSF)?
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What percentage of water is lymph primarily composed of?
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Which ion plays a crucial role in establishing the resting membrane potential in neurons?
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What is a major function of lymph in the body?
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Study Notes
Body Fluid Compartments
- Total body fluid is approximately 70% of body weight.
- Divided into two compartments: intracellular fluid (ICF) and extracellular fluid (ECF).
- ICF is inside cells and makes up 55% of total body water.
- ECF is outside cells and makes up 45% of total body water.
- ECF includes interstitial fluid, plasma, lymph, synovial fluid, cerebrospinal fluid and more.
- Interstitial fluid is between cells and makes up 80% of ECF.
- Plasma is in the blood and makes up 20% of ECF.
- Transcellular fluid is in the secretions of the body's secretory cells and cavities.
Barriers Between Compartments
- Plasma membrane separates ICF from surrounding interstitial fluid.
- Blood vessel wall separates interstitial fluid from plasma.
Composition of Body Fluids
- Organic substances include glucose, amino acids, fatty acids, hormones and enzymes.
- Inorganic substances include sodium, potassium, calcium, magnesium, chloride, phosphate and sulfate.
Differences Between ICF and ECF
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ECF:
- Most abundant cation is Na+ which plays a role in muscle contraction, impulse transmission, and fluid and electrolyte balance.
- Most abundant anion is Cl-, which regulates osmotic pressure and forms HCl in gastric acid.
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ICF:
- Most abundant cation is K+, which establishes resting membrane potential, maintains intracellular volume, helps regulate pH, and is necessary for protein biosynthesis by ribosomes.
- Abundant anions include proteins and phosphates, which regulate pH.
Factors Affecting Total Body Water
- Varies depending on body fat percentage.
- Infants have 73-80%, males have 60%, females have 40-50%, obese individuals have less, elderly have 45%, and climate and physical activity influence water content.
Potassium (K+)
- Most abundant cation in ICF.
- Establishes resting membrane potential in neurons and muscle fibers.
- Maintains normal ICF fluid volume.
- Helps regulate pH of body fluids when exchanged for H+.
- Intracellular K+ concentration is necessary for protein biosynthesis by ribosomes.
Sodium (Na+)
- Most abundant cation in ECF.
- Makes up 90% of extracellular cations.
- Plays a vital role in fluid and electrolyte balance, accounting for half of the osmolarity of ECF.
- Involved in cell membrane permeability.
Chloride (Cl-)
- Most predominant anion in ECF.
- Moves easily between ECF and ICF due to Cl- leakage channels and transporters in plasma membranes.
- Can help balance levels of anions in different fluids.
Magnesium (Mg2+)
- Found in both ICF (45%) and ECF (1%).
- Second most common intracellular cation.
- Cofactor for certain enzymes and the sodium-potassium pump.
- Essential for normal neuromuscular activity and myocardial function.
Specialized Fluids of the Body: Lymph
- Clear and colorless fluid.
- 96% water and 4% solids.
- Solids consist mostly of proteins (albumin, globulin, fibrinogen, prothrombin, clotting factors, antibodies, enzymes), lipids (chylomicrons, lipoproteins), carbohydrates (glucose), non-protein nitrogenous substances (NPN) like urea and creatinine, and electrolytes (sodium, calcium, potassium, chloride, bicarbonates).
Functions of Lymph
- Redistributes fluid.
- Removes bacteria, toxins, and other foreign bodies from tissues.
- Assists in intestinal fat absorption.
- Transports lymphocytes.
Cerebrospinal Fluid (CSF)
- Clear, colorless liquid formed within the cavities of the brain and around the spinal cord.
- Approximately 120-150ml of CSF exists at any given time.
- Completely replaced about three times a day.
Functions of CSF
- Acts as a hydraulic shock absorber.
- Regulates intracranial pressure.
- Carries nutrients to the brain and spinal cord.
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Description
Explore the different compartments of body fluids and their compositions in this quiz. Understand the percentages of intracellular and extracellular fluids, the barriers between these compartments, and the various organic and inorganic substances involved. Test your knowledge and learn more about how fluids are distributed in the body.
