Body Water and Electrolytes

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Questions and Answers

What is the main function of body water?

Acts as a site for energy production

Forms the structural framework of the body

Facilitates hormone secretion

Constitutes the medium for solute dissolution and metabolic reactions (correct)

Where is the average water content of the human body distributed?

Extracellular fluid only

Intravascular extracellular fluid and intracellular fluid

Intracellular fluid only

Intravascular extracellular fluid and interstitial cell fluid (correct)

What does osmolality measure in a solution?

Pressure exerted by solutes on the solvent

Volume of solutes per liter of solvent

Mass of solutes per unit volume of solvent

Concentration of solutes per kilogram of solvent (correct)

What is the response to increased blood osmolality?

Aldosterone release via the RAA system to promote retention of sodium and excretion of potassium Signup and view all the answers

What occurs in dehydration with pure water loss or deficit?

Increased ECF osmolality and recruitment of water from the ICF Signup and view all the answers

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 Signup and view all the answers

What is the response of the hypothalamus to changes in blood osmolality?

Release of aldosterone via renin-angiotensin-aldosterone system Signup and view all the answers

What is the main effect of dehydration with pure water loss or deficit?

Increased extracellular fluid osmolality Signup and view all the answers

What is the parameter to which the hypothalamus responds in relation to blood osmolality?

Concentration of solutes per kilogram of solvent Signup and view all the answers

In response to increased blood osmolality, what is the main function of aldosterone?

Promote retention of sodium and excretion of potassium Signup and view all the answers

What is the normal plasma water content as a percentage of the total plasma composition?

93% Signup and view all the answers

In response to changes in blood osmolality, which hormone is responsible for promoting the retention of sodium and excretion of potassium?

Aldosterone Signup and view all the answers

What is the main effect of pure water loss or deficit in dehydration?

Decreased ECF osmolality Signup and view all the answers

What physical property of a solution is based on the concentration of solutes per kilogram of solvent?

Osmolality Signup and view all the answers

How does the hypothalamus respond to changes in blood osmolality?

By regulating thirst and ADH secretion Signup and view all the answers

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.

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Description

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.