30 Questions
What percentage of total body water is composed of intracellular fluid?
2/3
Which electrolyte is the principal cation in extracellular fluid?
Sodium (Na+)
What is the approximate percentage of total body water that is distributed in the extracellular fluid?
1/3
What is the function of the cell membrane in relation to fluid compartments?
Separates intracellular and extracellular fluid
Which of the following ions is NOT a principal anion in extracellular fluid?
Sulfate (SO42-)
What is the name of the fluid compartment that includes fluid in synovial, peritoneal, and pleural cavities?
Transcellular fluid
Which of the following electrolytes is NOT a principal intracellular electrolyte?
Sodium (Na+)
What is the term for the non-cellular component of blood?
Plasma volume
Which of the following is a function of the regulation of sodium and chloride?
Regulating fluid balance
What percentage of extracellular fluid is composed of interstitial fluid?
3/4
What is a common cause of edema related to heart failure, renal failure, and pregnancy?
Hypervolemia
What is the main function of plasma proteins in the capillary?
To increase plasma osmotic pressure
What is a possible consequence of kidney disease on plasma proteins?
Decreased protein levels
What impairs protein synthesis in patients with malnutrition or liver disease?
Impaired liver function
What is the primary cause of increased capillary permeability?
Histamine release
What is a common result of increased capillary permeability?
Localized edema
What can cause localized edema due to obstruction of the lymphatic circulation?
All of the above
What happens to excess fluid and protein in the interstitium due to lymphatic obstruction?
They accumulate in the interstitium
What is a common consequence of edema due to increased hydrostatic pressure?
Increased fluid movement out of the vascular bed
What is a possible cause of decreased plasma osmotic pressure?
Decreased albumin levels
What percent of the ECF is typically made up of the transcellular compartment?
1%
What is the term for when the transcellular compartment enlarges significantly?
Third spacing
Why is fluid in the transcellular space not readily available for exchange with the rest of the ECF?
Because it is not in equilibrium with the rest of the ECF
What is edema characterized by?
An excessive amount of fluid in the interstitial compartment
What is an example of localized edema?
Facial edema
What are the four general causes of edema?
Increased capillary hydrostatic pressure, decreased capillary oncotic pressure, increased capillary permeability, and lymph obstruction
What is the result of increased capillary hydrostatic pressure on fluid movement?
Fluid is forced out of the capillaries into the tissues
What is an example of edema that can interfere with respiratory function?
Pulmonary edema
What would be the result of hypervolemia on capillary hydrostatic pressure?
Increased capillary hydrostatic pressure
What is the term for edema that is generalized throughout the body?
Anasarca
Study Notes
Water in the Body
- Water is a major component of the body, found within and outside cells, and is essential for homeostasis.
- Water is the medium for metabolic reactions and processes.
Fluid Distribution
- Total Body Water (TBW) is distributed into two compartments: Intracellular Fluid (ICF) and Extracellular Fluid (ECF).
- ICF consists of fluid inside cells, making up ~2/3 of TBW, and is separated from ECF by the cell membrane.
- ECF makes up ~1/3 of TBW and is divided into two components: plasma volume (intravascular fluid) and interstitial fluid (extravascular fluid).
Electrolytes
- Potassium (K+) is the principal cation in ICF.
- Phosphates and proteins are the principal anions in ICF.
- Sodium (Na+) is the principal cation in ECF.
- Chloride (Cl-) and bicarbonate (HCO3-) are the principal anions in ECF.
Transcellular Compartment
- The transcellular compartment is a minor subdivision of ECF, making up ~1% of ECF.
- It includes fluid in synovial, peritoneal, pleural, pericardial, intraocular, and CSF.
- This compartment can increase significantly in conditions such as ascites.
Edema
- Edema refers to an excessive amount of fluid in the interstitial compartment, causing swelling or enlargement of tissues.
- Edema can be localized or generalized throughout the body.
- There are four general causes of edema:
- Increased capillary hydrostatic pressure
- Decreased capillary oncotic pressure
- Increased capillary permeability
- Lymph obstruction
Causes of Edema
- Increased capillary hydrostatic pressure forces fluid out of capillaries into tissues, contributing to edema.
- Decreased capillary oncotic pressure due to a loss of plasma proteins (mainly albumin) allows more fluid to leave the capillary and enter the interstitium.
- Increased capillary permeability usually causes localized edema and may result from an inflammatory response or infection.
- Lymph obstruction causes localized edema by preventing excessive fluid and protein from being returned to the general circulation.
Learn about the importance of water in the human body, its distribution in compartments, and the roles of intracellular and extracellular fluids in maintaining homeostasis.
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