Body Fluid Compartments and Homeostasis
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Questions and Answers

What is the primary function of osmosis in biological systems?

  • To create an electrical gradient by moving ions across cell membranes.
  • To allow the flow of water from lower to higher solute concentration.
  • To diffuse water across a semi-permeable membrane from higher to lower water concentration. (correct)
  • To facilitate the movement of solutes from high to low concentration.

Which fluid compartment in the body contains approximately 60% of the total water content?

  • Extracellular fluid
  • Interstitial fluid
  • Plasma
  • Intracellular fluid (correct)

What would happen to cells if there was too much water in the body?

  • Cells would become more effective at regulating solute concentrations.
  • Cells would gain a higher concentration of solutes.
  • Cells could potentially burst due to low solute concentration. (correct)
  • Cells would undergo plasmolysis.

In plasma, which ion demonstrates the highest concentration among the specified ions?

<p>Sodium (Na+) (A)</p> Signup and view all the answers

How is the electrochemical impact of ions quantified in a solution?

<p>Using the formula mmol/L X valency = mEq/L. (C)</p> Signup and view all the answers

What occurs in the body when an ionic charge imbalance is present?

<p>Electrical neutrality may be compromised. (C)</p> Signup and view all the answers

Which of the following ions is predominantly found in intracellular fluid?

<p>Potassium (K+) (D)</p> Signup and view all the answers

Which type of fluid is classified as interstitial fluid?

<p>Fluid surrounding cells that is not in blood vessels. (B)</p> Signup and view all the answers

What is the primary action of parathyroid hormone (PTH) in regulating calcium levels?

<p>It promotes the breakdown of bone matrix to release calcium. (C)</p> Signup and view all the answers

How does calcitonin respond to elevated calcium levels in the blood?

<p>By increasing the activity of osteoblasts to incorporate calcium into bone. (C)</p> Signup and view all the answers

What role does dihydroxyvitamin D (calcitriol) play in calcium regulation?

<p>It aids in the intestinal absorption of dietary calcium. (A)</p> Signup and view all the answers

What effect does parathyroid hormone (PTH) have on phosphate levels?

<p>It increases phosphate excretion through the kidneys. (A)</p> Signup and view all the answers

The release of which hormone is triggered by a decrease in blood calcium levels?

<p>Parathyroid hormone (PTH) (B)</p> Signup and view all the answers

What is the main function of the sodium-potassium pump?

<p>To maintain ion balance across the cell membrane (B)</p> Signup and view all the answers

Which statement correctly describes hydrostatic pressure in the kidneys?

<p>It is the pressure exerted by blood against blood vessel walls (C)</p> Signup and view all the answers

Dehydration affects the osmotic gradient by primarily causing:

<p>Water to move from the extracellular fluid to the intracellular fluid (B)</p> Signup and view all the answers

What role do baroreceptors play in blood pressure regulation?

<p>Detect changes in blood pressure linked to blood volume (A)</p> Signup and view all the answers

What is the primary effect of the renin-angiotensin system?

<p>To decrease urine output and stimulate thirst (C)</p> Signup and view all the answers

What is the relationship between osmolarity and hydration status?

<p>Higher osmolarity indicates lower hydration status (C)</p> Signup and view all the answers

During significant dehydration, what happens within the kidneys?

<p>Less nitrogenous waste is removed due to impaired function (C)</p> Signup and view all the answers

What is the minimum daily urine production required for proper bodily functions?

<p>0.47 litres (C)</p> Signup and view all the answers

Which statement accurately characterizes active transport?

<p>Utilizes energy to move solutes against their concentration gradient (B)</p> Signup and view all the answers

What is the typical effect of antidiuretic hormone (ADH) on the kidneys?

<p>Controls the amount of water reabsorbed, reducing urine output (C)</p> Signup and view all the answers

What is the primary consequence of hyperkalemia on cardiac function?

<p>Inability of the heart to relax after contraction (C)</p> Signup and view all the answers

Which condition is characterized by a lower than normal concentration of chloride in the blood?

<p>Hypochloremia (A)</p> Signup and view all the answers

Which substance primarily helps maintain the body's acid-base balance through buffer systems?

<p>Bicarbonate (A)</p> Signup and view all the answers

What is the effect of aldosterone on sodium and potassium regulation in the kidneys?

<p>Increases sodium reabsorption and potassium excretion (D)</p> Signup and view all the answers

What ionic form of phosphate is the most common in the body?

<p>HPO4^2- (A)</p> Signup and view all the answers

Which vitamin deficiency directly affects calcium absorption in the intestines?

<p>Vitamin D (A)</p> Signup and view all the answers

What can excessive sweating lead to in terms of electrolyte balance?

<p>Loss of sodium and chloride (A)</p> Signup and view all the answers

Which condition is characterized by elevated levels of calcium in the blood?

<p>Hypercalcemia (B)</p> Signup and view all the answers

What is the primary role of calcium in the body?

<p>Muscle contraction and nerve function (C)</p> Signup and view all the answers

What condition can be caused by heavy use of antacids or alcohol withdrawal?

<p>Hypophosphatemia (A)</p> Signup and view all the answers

What physiological process does ADH primarily facilitate in the kidneys?

<p>Increases water reabsorption (C)</p> Signup and view all the answers

Which condition is characterized by low extracellular fluid volume?

<p>Hypovolemia (C)</p> Signup and view all the answers

What effect do diuretics generally have on urine output?

<p>Increase urine output (D)</p> Signup and view all the answers

What is an example of a hypertonic solution?

<p>3% NaCl (D)</p> Signup and view all the answers

What happens during hypernatremia?

<p>Hemoconcentration of blood components (A)</p> Signup and view all the answers

What is the primary effect of potassium in body cells?

<p>Establishes resting membrane potential in neurons (A)</p> Signup and view all the answers

What condition is likely to result from excessive water accumulation in the body?

<p>Hypervolemia (C)</p> Signup and view all the answers

In which situation would diuretics potentially cause hypokalemia?

<p>Prolonged fasting without supplementation (D)</p> Signup and view all the answers

What role do electrolytes play concerning water movement in the body?

<p>They maintain osmotic balance for fluid movement. (C)</p> Signup and view all the answers

Which electrolyte directly influences the excretion of sodium in the kidneys?

<p>Aldosterone (D)</p> Signup and view all the answers

Flashcards

Osmosis

The movement of water across a semi-permeable membrane from a region of higher water concentration to a region of lower water concentration.

Homeostasis

The maintenance of a stable internal environment in a living organism, even when external conditions change.

Intracellular Fluid

Fluid found within the cells, containing approximately 60% of the body's water.

Extracellular Fluid

Fluid located outside of the cells, including blood plasma and interstitial fluid.

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Plasma

The fluid portion of blood, carrying blood cells, proteins, electrolytes, nutrients, gases, and wastes.

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Interstitial Fluid

Fluid that surrounds cells and isn't in blood vessels, facilitating exchange between blood and cells.

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Equivalents (Eq)

A measure of the amount of charge an ion carries in a solution, defined as the amount of the ion supplying one mole of charge.

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Milliequivalents (mEq)

A measure of the amount of charge an ion carries in a solution, defined as the amount of the ion supplying one millimole of charge.

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Sodium-Potassium Pump

A protein in cell membranes that actively pumps sodium ions out of the cell and potassium ions into the cell, requiring energy from ATP. This creates a concentration difference essential for nerve signals, muscle contractions, and cell stability.

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Colloidal Osmotic Pressure

Pressure exerted by large molecules (colloids) in blood vessels, preventing their movement across membranes. It draws water into the vessel from outside due to the higher concentration of colloids inside.

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Hydrostatic Pressure

Force exerted by fluid against a surface, like blood pressing on blood vessel walls. It drives fluid movement between compartments.

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Hydrostatic Pressure in Kidneys

Blood pressure in kidney capillaries that drives filtration of blood to form urine. Higher pressure means more water leaves capillaries, forming more filtrate. Low pressure impairs kidney function.

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Osmotic Gradient

Difference in solute concentration across a semi-permeable membrane. Water moves from areas of high water concentration (low solute) to areas of low water concentration (high solute) to balance.

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Dehydration

State of having too little water in the body, causing increased solute concentration in tissues. Water moves from blood to dehydrated tissues, leading to further dehydration.

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Rehydration

Process of replenishing water in tissues by reversing the osmotic gradient. Water moves back from tissues to blood, restoring hydration.

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Active Transport

Movement of a substance across a membrane against its concentration gradient, requiring energy. It's like pushing a ball uphill.

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Passive Transport

Movement of a substance across a membrane along its concentration gradient, requiring no energy. It's like letting a ball roll downhill.

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Edema

Excess fluid accumulation in tissues (interstitial space). It happens when fluid leaks out of blood vessels faster than it can be drained, leading to swelling.

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ADH Role in Water Balance

Antidiuretic hormone (ADH) regulates water reabsorption in the kidneys by inserting aquaporins into the collecting duct cells, leading to increased water retention and concentrated urine.

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ADH Release Trigger

The hypothalamus releases ADH in response to increased blood plasma concentration (dehydration), prompting the posterior pituitary to release ADH into the bloodstream.

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ADH Effects on Blood Flow

ADH constricts arterioles, reducing peripheral blood flow and redirecting blood towards the core of the body, maintaining core temperature.

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Diuretic Effect

Diuretics increase urine output, reducing the body's water retention. They are used to treat conditions like hypertension and heart failure by removing excess fluid.

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Alcohol and Caffeine Impact

Alcohol and caffeine inhibit ADH release, promoting increased urination and potential dehydration.

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Hypovolemia: Definition

Hypovolemia is a condition of low extracellular fluid volume, often due to loss of sodium and water.

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Hypovolemia Causes

Hypovolemia arises from various factors, including osmotic diuresis, vomiting, diarrhea, and fluid shifts due to burns or trauma.

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Hypovolemia Symptoms

Hypovolemia presents with symptoms like weakness, fatigue, dizziness, thirst, and decreased skin turgor due to low fluid levels.

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Hypervolemia: Definition

Hypervolemia is an excess of extracellular fluid volume, leading to fluid overload in the body.

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Hypervolemia Causes

Hypervolemia can be caused by conditions affecting the heart, liver, kidneys, and even hormonal imbalances.

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Parathyroid hormone (PTH) function

PTH is released when blood calcium is low. It stimulates osteoclasts to break down bone, releasing calcium into the blood. It also increases calcium absorption in the gut and reduces calcium loss in the kidneys.

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Vitamin D's role in calcium regulation

Vitamin D is converted into calcitriol, the active form, which helps the intestines absorb dietary calcium. PTH promotes this conversion.

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Calcitonin's role in calcium regulation

Calcitonin is released when blood calcium is high. It stimulates osteoblasts, which build bone and remove calcium from the blood, lowering blood calcium levels.

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How does PTH affect phosphate?

PTH increases phosphate loss in the kidneys, reducing blood phosphate levels.

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Calcium and phosphate relationship

Calcium and phosphate levels in the blood are tightly regulated by the hormones PTH and calcitriol. PTH raises blood calcium and lowers blood phosphate, while calcitriol increases calcium absorption.

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What happens to the heart during hyperkalemia?

Hyperkalemia causes the heart to contract without relaxing, leading to a seizure and cessation of blood pumping, resulting in death within minutes.

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What are the primary functions of Chloride?

Chloride (Cl-) is the main extracellular anion. It contributes to osmotic pressure, maintains hydration, balances cations in the extracellular fluid, and ensures electrical neutrality.

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What is the main role of Bicarbonate?

Bicarbonate (HCO3-) is vital for regulating the body's acid-base balance, acting as a buffer.

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How is Carbon Dioxide (CO2) converted into Bicarbonate?

Through enzymatic reactions, CO2 combines with water to form bicarbonate in the cytoplasm of red blood cells.

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What are the key roles of Calcium (Ca2+)?

Calcium ions are essential for muscle contraction, enzyme activity, blood clotting, cell membrane stabilization, and neurotransmitter/hormone release.

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How is Hypocalcemia related to Hypoparathyroidism?

Hypoparathyroidism, often occurring after thyroid removal, leads to decreased parathyroid hormone production, resulting in decreased calcium absorption and hypocalcemia.

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What is the most common form of Phosphate in the body?

The most common form of Phosphate is HPO4 ^2-, also known as hydrogen phosphate.

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How is Phosphate depletion linked to Hypophosphatemia?

Excessive use of antacids, alcohol withdrawal, and malnutrition contribute to decreased phosphate absorption, leading to Hypophosphatemia.

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Where does Ion loss mainly occur?

Ions are primarily lost through the kidneys, with smaller amounts lost in sweat and feces.

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How do Aldosterone and Angiotensin II regulate Potassium and Sodium?

These hormones regulate the exchange of Potassium and Sodium in the renal collecting tubule, primarily by influencing their reabsorption and excretion.

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Study Notes

Body Fluid Compartments and Homeostasis

  • Body Water Content: Adults are primarily water, with 50-60% of body mass being water.

Fluid Compartments

  • Intracellular Fluid (ICF): Fluid within cells, making up approximately 60% of total body water. Contains high levels of potassium, hydrogen phosphate, magnesium, and protein.

  • Extracellular Fluid (ECF): Fluid outside cells, including plasma and interstitial fluid. Makes up approximately 1/3 of total body water. Contains high levels of chloride and bicarbonate. Plasma, within blood vessels, carries blood cells, proteins, electrolytes, nutrients, gases, and wastes, while interstitial fluid surrounds cells.

  • Other Water-Based Fluids: Cerebrospinal fluid, lymph, synovial fluid, pleural fluid, pericardial fluid, and aqueous humor are also part of the body’s fluid systems.

Electrolytes

  • Electrolyte Balance: Body fluids are electrically neutral; cations and anions are balanced. The body strives for electrical homeostasis (electrical neutrality)

  • Equivalents (mEq): Measures the electrochemical impact of ions. Reflects ionic charge, not just concentration. Calculated as mmol/L x valency = mEq/L.

  • Example: Na+ (140 mmol/L) = 140 mEq/L; Ca2+ (2.5 mmol/L) = 5 mEq/L

Sodium-Potassium Pump

  • Function: Found in cell membranes, maintains Na+ and K+ balance. For every three Na+ ions pumped out, two K+ are pumped in.

  • Importance: Creates ion concentration differences across the membrane, crucial for nerve signals, muscle contractions, and cell stability. This process uses energy (ATP).

Fluid Movement

  • Osmosis: Water moves from high to low concentration across a semi-permeable membrane. Does not require energy.

  • Osmotic Gradient: Difference in solute concentration across a membrane. Drives water movement between compartments.

  • Hydrostatic Pressure: Force exerted by fluid against a wall, influencing fluid movement between compartments.

  • Colloidal Osmotic Pressure: Pressure exerted by large molecules (colloids) in blood vessels. Draws water into vessels.

Fluid Balance & Regulation

  • Dehydration/Rehydration: Water loss (e.g., sweating) increases solute concentration. Water moves from blood to other tissues until equilibrium is reached. Rehydration involves water moving in the opposite direction.

  • Renal Considerations (Hydrostatic): Kidney function requires sufficient hydrostatic pressure to ensure proper water and waste filtration. Reduced pressure can impair kidney function.

  • Plasma Osmolality: Ratio of solutes to water in blood plasma (275-295 mmol/kg). Maintained through water intake and output.

  • Osmoreceptors and Baroreceptors: Detect changes in osmolality and blood pressure, triggering responses (e.g., thirst, increased heart rate/contraction).

  • Renin-Angiotensin System (RAS): Helps control blood pressure and fluid balance through vasoconstriction, water/sodium retention, and increased thirst. Angiotensin II and aldosterone are key players.

  • Antidiuretic Hormone (ADH): Released by the posterior pituitary, controlling water reabsorption by the kidneys. Regulates water balance in response to changes in blood osmolality.

  • Diuresis: Excessive urine production in response to fluid intake.

  • Diuretics: Compounds increasing urine output and reducing water retention (e.g., alcohol, caffeine).

Fluid Imbalances

  • Hypovolemia: Low extracellular fluid volume (often due to sodium and water loss from e.g., vomiting, diarrhea).

  • Hypervolemia: Increased extracellular fluid volume (e.g., heart failure, kidney failure).

  • Types of IV Fluids: Classified by tonicity (relative solute concentration compared to blood plasma).

  • Crystalloids: Simple salt solutions used to replenish fluids (e.g., normal saline).

  • Colloids: Larger molecules stay in the bloodstream longer (e.g., albumin).

  • Isotonic: Similar solute concentration to blood plasma.

  • Hypotonic: Lower solute concentration than blood plasma.

  • Hypertonic: Higher solute concentration than blood plasma.

Key Electrolytes

  • Sodium (Na+): Major extracellular cation, crucial for osmotic pressure and nerve function.

  • Potassium (K+): Major intracellular cation, essential for nerve and muscle function.

  • Chloride (Cl-): Predominant extracellular anion, important for hydration and electrical neutrality in ECF

  • Bicarbonate (HCO3-): Maintains acid-base balance, critical in buffering and transporting CO2.

  • Calcium (Ca2+): Essential for muscle contraction, enzyme activity, and blood clotting.

  • Phosphate: Important in bone composition, cell membranes, and energy processes.

Other Considerations

  • Ion Loss: Ions are primarily lost through urine, but also in sweat and feces.

  • Electrolyte Regulation: Kidneys play a crucial role in regulating ion levels in the extracellular fluid, alongside hormones like aldosterone.

  • Calcium and Phosphate Regulation: Calcitonin, parathyroid hormone (PTH), and vitamin D (in its active form, calcitriol) all regulate calcium and phosphate levels.

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Description

Explore the complex world of body fluids and their role in homeostasis. This quiz covers the distribution of intracellular and extracellular fluids, as well as the significance of electrolytes within the body. Test your knowledge on how these components maintain balance and support bodily functions.

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