15 Questions
What is the main function of body water?
Constitutes the medium for solute dissolution and metabolic reactions
Where is the average water content of the human body distributed?
Intravascular extracellular fluid and interstitial cell fluid
What does osmolality measure in a solution?
Concentration of solutes per kilogram of solvent
What is the response to increased blood osmolality?
Aldosterone release via the RAA system to promote retention of sodium and excretion of potassium
What occurs in dehydration with pure water loss or deficit?
Increased ECF osmolality and recruitment of water from the ICF
Which of the following best describes the distribution of water in the human body?
40-75% in intracellular fluid and 25-60% in extracellular fluid
What is the response of the hypothalamus to changes in blood osmolality?
Release of aldosterone via renin-angiotensin-aldosterone system
What is the main effect of dehydration with pure water loss or deficit?
Increased extracellular fluid osmolality
What is the parameter to which the hypothalamus responds in relation to blood osmolality?
Concentration of solutes per kilogram of solvent
In response to increased blood osmolality, what is the main function of aldosterone?
Promote retention of sodium and excretion of potassium
What is the normal plasma water content as a percentage of the total plasma composition?
93%
In response to changes in blood osmolality, which hormone is responsible for promoting the retention of sodium and excretion of potassium?
Aldosterone
What is the main effect of pure water loss or deficit in dehydration?
Decreased ECF osmolality
What physical property of a solution is based on the concentration of solutes per kilogram of solvent?
Osmolality
How does the hypothalamus respond to changes in blood osmolality?
By regulating thirst and ADH secretion
Study Notes
Body Water and Osmolality
- The main function of body water is to regulate various bodily functions, including temperature, metabolism, and cellular processes.
Distribution of Body Water
- The average water content of the human body is distributed as follows:
- 55-60% of body weight is water, with 40% being intracellular fluid and 20% being extracellular fluid.
- 28% of the total body water is found in blood plasma.
Osmolality
- Osmolality measures the concentration of solutes in a solution, specifically the number of osmoles of solute per kilogram of solvent.
Response to Changes in Blood Osmolality
- When blood osmolality increases, the hypothalamus responds by stimulating thirst and increasing the production of antidiuretic hormone (ADH) to conserve water.
- The response to increased blood osmolality also involves the release of aldosterone, which promotes the retention of sodium and excretion of potassium.
Dehydration
- In dehydration with pure water loss or deficit, the main effect is a decrease in blood volume, leading to a decrease in blood pressure.
- Dehydration can cause intravascular dehydration, where there is a loss of blood volume, leading to decreased blood pressure.
Regulation of Blood Osmolality
- The hypothalamus responds to changes in blood osmolality by regulating the sensation of thirst and the production of ADH.
- The parameter to which the hypothalamus responds is the osmolality of the blood.
Hormonal Regulation
- Aldosterone promotes the retention of sodium and excretion of potassium in response to increased blood osmolality.
- ADH promotes water retention in response to increased blood osmolality.
Plasma Composition
- The normal plasma water content is approximately 92% of the total plasma composition.
Learn about the composition and distribution of body water and electrolytes in the human body, including the intracellular and extracellular fluid compartments. Understand the role of water as a medium for metabolic reactions and the average water content of the human body.
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