Fluid and Electrolytes: Normal Physiology

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Questions and Answers

What percentage of body weight does water constitute in an older adult?

40%

45% (correct)

50%

60%

Which fluid compartment refers to body water located within cells?

Extracellular fluid

Intracellular fluid (correct)

Interstitial fluid

Intravascular fluid

What is the fluid portion of blood that is classified as an extracellular fluid?

Transcellular fluid

Intracellular fluid

Interstitial fluid

Intravascular fluid (correct)

What risk is increased in older adults due to decreased water content in their bodies?

Higher risk for dehydration Signup and view all the answers

Approximately what fraction of body water is contained within the intracellular fluid compartment?

Two thirds Signup and view all the answers

What type of fluid is classified as transcellular fluid?

Cerebrospinal fluid Signup and view all the answers

What role do electrolytes play in body fluids?

Maintain electroneutrality Signup and view all the answers

What happens to fluid balance when fluid is lost due to diarrhea or vomiting?

Serious fluid and electrolyte imbalances Signup and view all the answers

What percentage of body weight is typically associated with water content in adults?

50% to 60% Signup and view all the answers

How does body fat content relate to water content in the body?

Higher fat content results in lower water content. Signup and view all the answers

Which population is at a higher risk for fluid imbalances due to lower water content?

Older adults Signup and view all the answers

What is the primary role of body fluids and electrolytes in maintaining homeostasis?

They transport nutrients and waste products. Signup and view all the answers

What happens to the water content in the body as one ages?

It decreases. Signup and view all the answers

Why is it crucial for nurses to monitor fluid and electrolyte balance?

Disease processes can affect fluid and electrolyte balance. Signup and view all the answers

Which physiological mechanism is essential for maintaining fluid balance in the body?

Adaptive responses Signup and view all the answers

What is the main reason men typically have a higher percentage of water compared to women?

Men have leaner muscle mass than women. Signup and view all the answers

Which of the following is a cation?

Sodium (Na+) Signup and view all the answers

What is the primary function of cations and anions in body fluids?

To maintain electroneutrality Signup and view all the answers

Which process requires a protein carrier in the cell membrane?

Facilitated diffusion Signup and view all the answers

Which of the following correctly describes diffusion?

Movement continues until concentrations are equal on both sides of a membrane Signup and view all the answers

Which of the following ions is an example of an anion?

Chloride (Cl–) Signup and view all the answers

What stops the process of diffusion?

When the concentrations are equal on both sides of the membrane Signup and view all the answers

Which of the following is NOT a mechanism for electrolyte movement?

Endocytosis Signup and view all the answers

Which statement about facilitated diffusion is true?

It requires a carrier protein for molecules to enter the cell Signup and view all the answers

What triggers the release of antidiuretic hormone (ADH) from the pituitary gland?

Fluid deficit or increase in plasma osmolality Signup and view all the answers

What is the primary function of the kidneys in regulating water balance?

Adjust urine volume and reabsorb water and electrolytes Signup and view all the answers

How much urine does the average adult produce in a day?

1.5 L Signup and view all the answers

What effect does excessive water intake have on ADH secretion?

Suppresses ADH release Signup and view all the answers

What role do osmoreceptors in the hypothalamus play in water regulation?

Sense fluid deficits or increases in plasma osmolality Signup and view all the answers

What happens in the kidneys with severely impaired renal function?

Inability to maintain fluid and electrolyte balance Signup and view all the answers

Which hormone is responsible for sodium retention and potassium excretion?

Aldosterone Signup and view all the answers

What factor is essential for preventing the development of hyperosmolality?

Intact thirst mechanism Signup and view all the answers

What is the primary function of mineralocorticoids like aldosterone?

Cause sodium retention and potassium excretion Signup and view all the answers

Which factor directly activates the renin-angiotensin-aldosterone system (RAAS)?

Decreased renal perfusion to the distal renal tubule Signup and view all the answers

What can cause insensible water loss?

Vaporization from lungs and skin Signup and view all the answers

What happens when cortisol is secreted in large doses?

It has both glucocorticoid and mineralocorticoid effects Signup and view all the answers

How does increased physical and psychological stress affect body functions?

Increases cortisol secretion Signup and view all the answers

What is the average amount of insensible water loss per day?

600 to 900 mL Signup and view all the answers

What condition can lead to excessive sweating?

High environmental temperatures Signup and view all the answers

What stimulates the release of aldosterone from the adrenal cortex?

Increased serum potassium and decreased serum sodium Signup and view all the answers

Study Notes

### Fluid and Electrolytes: Normal Physiology

Body fluids play a crucial role in maintaining homeostasis.
They transport nutrients, electrolytes, and oxygen to cells and carry waste products away.
Water content varies depending on age, gender, and fat content. Adults have 50-60% water content while older adults have 45-65%, making them more prone to imbalances.
Leaner muscle mass has a higher percentage of water than fat.
Maintaining fluid and electrolyte balance within narrow limits is essential.

### Body Fluids and Fluid Compartments

Intracellular fluid (ICF): Body water located within cells, making up two-thirds of total body water.
Extracellular fluid (ECF): Body water located outside the cells, making up one-third of total body water.
- Interstitial fluid: Located between cells and lymph.
- Intravascular (plasma) fluid: Fluid portion of blood.
- Transcellular fluid: Found in specialized cavities like cerebrospinal fluid, GI tract, pleural, synovial, peritoneal, intraocular, and pericardial fluid.
Transcellular fluid contributes a small amount to total body water but significant losses due to vomiting or diarrhea can lead to imbalances.

### Electrolytes

Substances whose molecules dissociate into ions, which are electrically charged particles.
Cations are positively charged ions (e.g., sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+)).
Anions are negatively charged ions (e.g., bicarbonate (HCO3–), chloride (Cl–), and phosphate (PO43–)).
Cations and anions combine to maintain electroneutrality in body fluids.

### Mechanisms of Fluid and Electrolyte Movement

Diffusion: Movement of molecules from an area of high concentration to an area of low concentration, ceasing when concentrations equalize.
Facilitated diffusion: Uses a protein carrier in the cell membrane to move molecules that cannot cross the membrane on their own, like glucose transport.

### Regulation of Water Balance

Hypothalamic-pituitary regulation:
- Osmoreceptors sense fluid deficit or increase in plasma osmolality.
- Deficit triggers thirst and Antidiuretic Hormone (ADH) release from the pituitary gland.
- Water excess suppresses ADH release.
Renal regulation:
- Kidneys are the primary regulators of fluid and electrolyte balance.
- They adjust urine volume and selectively reabsorb water and electrolytes.
- Renal tubules are the sites of action for ADH and aldosterone.
- Adults produce approximately 1.5 L of urine per day.
- Minimum 30 ml/hr of urine is essential for renal function.
- Impaired renal function can lead to edema, potassium and phosphorus retention, acidosis, and other electrolyte imbalances.
Adrenal cortical regulation:
- Adrenal cortex releases hormones to regulate water and electrolytes.
- Mineralocorticoids (e.g., aldosterone) cause sodium retention and potassium excretion, leading to water retention.
- Decreased renal perfusion activates the Renin-Angiotensin-Aldosterone System (RAAS), resulting in aldosterone secretion.
Insensible water loss:
- Invisible vaporization from lungs and skin, resulting in a loss of 600-900 mL/day.
- No electrolyte loss occurs.
- Excessive sweating (sensible perspiration) caused by exercise, fever, or high temperatures can lead to significant water and electrolyte loss.

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Description

This quiz explores the crucial role of body fluids in maintaining homeostasis and how they affect fluid and electrolyte balance. It covers the different compartments of body fluids, including intracellular and extracellular fluids, and discusses their importance in health and disease. Test your knowledge on how fluid content varies with age, gender, and body composition.