Human Biology Chapter on Cell Membranes & Fluids
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Questions and Answers

Which of the following is NOT a function of the cell membrane?

  • To regulate the movement of substances in and out of the cell
  • To produce energy for the cell (correct)
  • To provide structural support and shape to the cell
  • To act as a barrier between the cell and its environment

    • What is the primary mechanism by which water moves across cell membranes?

  • Active transport
  • Passive diffusion (correct)
  • Exocytosis
  • Endocytosis

    • Which of the following is NOT a type of active transport?

  • Endocytosis
  • Facilitated diffusion (correct)
  • Sodium-potassium pump
  • Proton pump

    • What is the difference between intracellular and extracellular fluid?

    <p>All of the above (D)</p> Signup and view all the answers

    Why is it important to maintain proper fluid and electrolyte balance?

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following is NOT a primary function of the kidneys related to fluid balance?

    <p>Producing hormones such as aldosterone and antidiuretic hormone (ADH) (D)</p> Signup and view all the answers

    Which of the following statements is TRUE regarding the distribution of electrolytes in the body?

    <p>Magnesium is primarily found in the bones (C)</p> Signup and view all the answers

    What is the primary mechanism that distributes extracellular fluid (ECF) between the vascular and interstitial compartments?

    <p>Hydrostatic and colloid osmotic pressure (C)</p> Signup and view all the answers

    Which of the following is a TRUE statement regarding osmolarity/osmolality?

    <p>Osmolality is a measure of the number of dissolved solute particles in a given weight of solution. (B)</p> Signup and view all the answers

    Which of the following hormones is primarily responsible for moving calcium out of bone?

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

    What is the primary route of fluid intake in the body?

    <p>Food and fluids we eat and drink (B)</p> Signup and view all the answers

    Which of the following is an example of a mandatory fluid output route?

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

    What are the two primary hormones involved in regulating renal fluid output?

    <p>Aldosterone and antidiuretic hormone (ADH) (C)</p> Signup and view all the answers

    What is the primary driver of thirst?

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

    What is the typical range for normal serum osmolality?

    <p>275-295 mOsm/Kg H2O (D)</p> Signup and view all the answers

    Which of the following conditions is characterized by a decrease in serum osmolality?

    <p>Syndrome of Inappropriate ADH secretion (SIADH) (A)</p> Signup and view all the answers

    Which of the following conditions is most likely to cause hypernatremia?

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

    Which of the following is an example of an isotonic fluid?

    <p>0.9% sodium chloride (D)</p> Signup and view all the answers

    Which of the following forces promotes fluid movement from the capillaries into the interstitial space?

    <p>Capillary filtration pressure (C)</p> Signup and view all the answers

    Which of the following factors contributes to edema by decreasing capillary colloidal osmotic pressure?

    <p>Decreased serum protein levels (C)</p> Signup and view all the answers

    Which of the following forces opposes the movement of fluid from capillaries into the interstitial space?

    <p>Interstitial hydrostatic pressure (B)</p> Signup and view all the answers

    Which of these conditions can lead to a decreased urine output?

    <p>Acute renal insufficiency (B), Glomerulonephritis (C)</p> Signup and view all the answers

    Which of these conditions is NOT a factor leading to increased capillary filtration pressure?

    <p>Decreased serum protein levels (C)</p> Signup and view all the answers

    Which of the conditions listed causes an increase in serum osmolality?

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

    What type of fluid is necessary to treat dehydration caused by hypernatremia?

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

    Which of these is a primary mechanism of thirst?

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

    What is the primary role of the renin-angiotensin-aldosterone system (RAAS)?

    <p>Regulation of blood pressure and volume (A)</p> Signup and view all the answers

    How does the sympathetic nervous system contribute to sodium balance?

    <p>By constricting blood vessels and increasing blood pressure (B)</p> Signup and view all the answers

    Which of these statements about fluid volume excess is correct?

    <p>Fluid volume excess can lead to hyponatremia. (D)</p> Signup and view all the answers

    Regarding the relationship between body water and age, which of these statements is true?

    <p>Adolescents have a higher total body water percentage compared to infants. (C)</p> Signup and view all the answers

    What is the primary cause of intracellular thirst?

    <p>Increased ECF osmolality (C)</p> Signup and view all the answers

    Which of the following is a manifestation of fluid volume excess?

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

    What is the primary difference between diabetes insipidus and SIADH?

    <p>Diabetes insipidus is caused by decreased ADH secretion or response while SIADH is caused by abnormal excessive ADH secretion. (D)</p> Signup and view all the answers

    Which of the following is NOT a potential manifestation of diabetes insipidus?

    <p>Fluid volume overload (B)</p> Signup and view all the answers

    What is the most likely reason why someone with SIADH may experience dilutional hyponatremia?

    <p>Retention of water due to increased ADH (B)</p> Signup and view all the answers

    What is a common manifestation of hyponatremia?

    <p>Decreased skin turgor (C)</p> Signup and view all the answers

    Which condition is characterized by a serum sodium level of 145 mEq/L?

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

    What could occur due to hyperkalemia?

    <p>Widened QRS complex (C)</p> Signup and view all the answers

    What is the effect of insulin on potassium levels when blood glucose levels are very high?

    <p>Increases cellular uptake of potassium (A)</p> Signup and view all the answers

    What is a potential cause of hypocalcemia?

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

    What is indicated by a positive Chvostek sign?

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

    Which electrolyte imbalance could lead to EKG changes such as a prolonged QT interval?

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

    What is the effect of alkalosis on calcium binding to plasma proteins?

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

    Which of the following is a common manifestation of hypermagnesemia?

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

    Which condition can cause a rapid shift of potassium from ICF to ECF, leading to hyperkalemia?

    <p>Acute renal failure (C)</p> Signup and view all the answers

    Flashcards

    Intracellular Fluid

    Fluid within cells; rich in potassium and proteins.

    Extracellular Fluid

    Fluid outside of cells; includes interstitial and blood plasma.

    Sodium Concentration Regulation

    Controlled by mechanisms like renin-angiotensin and antidiuretic hormone.

    Fluid Shifts

    Movement of fluid between vascular and interstitial compartments, affecting edema.

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    Electrolyte Imbalances

    Disruptions in normal levels of sodium, potassium, calcium, or magnesium.

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    Dehydration

    A condition resulting from excessive loss of body fluids.

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    Syndrome of Inappropriate ADH (SIADH)

    A condition where too much antidiuretic hormone causes excess water retention.

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    Diabetes insipidus

    A disorder characterized by large volumes of dilute urine due to inadequate ADH.

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    Osmolality

    The concentration of solutes in a solution, affecting fluid movement in the body.

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    Isotonic solution

    A solution with the same osmolality as body fluids, causing no net movement.

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    Hypotonic solution

    A solution with a lower osmolality than body fluids, causing cells to swell.

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    Hypertonic solution

    A solution with a higher osmolality than body fluids, causing cells to shrink.

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    Capillary filtration pressure

    The force that pushes fluid from capillaries into interstitial spaces.

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    Edema

    Swelling caused by excess fluid accumulation in interstitial spaces.

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    Capillary colloidal osmotic pressure

    The force that pulls water back into capillaries mainly due to proteins.

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    Fluid Compartments

    Three areas where body fluids are distributed: ECF, ICF, and transcellular.

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    Extracellular Fluid (ECF)

    Fluid outside the cell; accounts for 1/3 of body fluids, includes interstitial and intravascular fluids.

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    Intracellular Fluid (ICF)

    Fluid inside the cells; constitutes 2/3 of total body fluids.

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    Electrolytes

    Ions that dissociate in solution to form charged particles essential for bodily functions.

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    Major Cations in ECF

    Primary positively charged ions in ECF: Sodium, Potassium, Calcium, Magnesium.

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    Fluid Intake Sources

    Fluid is obtained through food, drinks, or intravenous administration, influenced by thirst.

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    Fluid Distribution

    Distribution of ECF via filtration and osmosis, maintaining proper balance of fluids in body compartments.

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    Output Regulation

    Fluid output is regulated via urine, sweat, and other means, influenced by hormones.

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    Hormones in Calcium Regulation

    Calcitonin moves calcium into bones; parathyroid hormone moves calcium out.

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    Histamine Release

    Increases capillary permeability during inflammation or allergic responses.

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    Antidiuretic Hormone (ADH)

    Hormone that regulates water balance by signaling kidneys to retain water.

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    Sodium Balance Regulation

    Maintained by the Renin-Angiotensin-Aldosterone System and the sympathetic nervous system.

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    Thirst Mechanisms

    Regulated by the hypothalamus; includes extracellular thirst and others.

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    Intracellular thirst

    The thirst triggered by increased extracellular fluid osmolality.

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    Fluid Volume Excess

    Expansion of the extracellular fluid compartment due to increased body sodium.

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    Hyponatremia

    Condition with serum sodium < 135 mEq/L, causing ECF loss & cellular dehydration.

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    Hypernatremia

    Condition with serum sodium > 145 mEq/L, causing dehydration and ECF volume loss.

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    Potassium Regulation

    Potassium levels are regulated by aldosterone and Na+/K+ pump, impacting ICF and ECF balance.

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    Hypokalemia

    Serum potassium < 3.5 mEq/L, caused by inadequate intake or excessive loss.

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    Hyperkalemia

    Serum potassium > 5.2 mEq/L, due to renal failure or rapid administration.

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    EKG Changes in Hypokalemia

    Prolonged PR interval and ST depression indicating potassium deficiency.

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    Calcium Forms in Blood

    Calcium exists in three forms: bound, complexed, and ionized, needed for functions.

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    Hypocalcemia

    Serum calcium < 8.5 mg/dL, due to renal failure or hypoparathyroidism.

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    Tetany Signs

    Symptoms of muscle spasms due to low calcium include Chvostek and Trousseau signs.

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    Magnesium Imbalances

    Disruptions in magnesium levels, with hypomagnesemia and hypermagnesemia being key conditions.

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    Study Notes

    Fluid & Electrolyte Balance

    • Lecture was given by Laura Madden, PhD, RN for NURS 3011

    Lesson Outcomes

    • Differentiate intracellular from extracellular fluid compartments in terms of water, electrolyte, and osmotically active solute distribution.
    • Describe the functions and physiologic mechanisms controlling water levels and sodium concentration. This includes effective circulating volume, sympathetic nervous system, renin-angiotensin-aldosterone system, and antidiuretic hormone.
    • Describe factors controlling fluid shifts between vascular and interstitial fluid compartments, and how these fluid shifts relate to edema and third spacing.
    • Differentiate the pathophysiology and manifestations of diabetes insipidus, syndrome of inappropriate antidiuretic hormone, fluid volume excess/deficit, hyponatremia, and hypernatremia.
    • Compare and contrast regulating factors of electrolytes, normal lab values, and the etiologies/manifestations of electrolyte imbalances related to sodium, potassium, calcium, and magnesium.

    Transport Across Cell Membranes: A Review

    • Cell membranes act as a barrier.
    • Different types of membrane transport include:
      • Simple diffusion
      • Facilitated diffusion
      • Primary active transport

    Movement Across a Membrane and Energy

    • Passive transport is easy and moves substances down a concentration gradient.
    • Active transport is hard work and moves substances against a concentration gradient.

    Active Transport

    • This is an illustration that shows how the Na+/K+ pump works.

    Fluid Compartments

    • Intracellular, extracellular, and transcellular fluid
    • ECF (1/3 of total body water) contains:
      • Intravascular (plasma) fluid: ~20% of ECF
      • Interstitial fluid: ~80% of ECF
    • ICF(2/3 of total body water): inside the cells, making up ~40% of the body weight. Potassium is the major cation.
    • Transcellular fluid: located in special spaces, such as the cerebrospinal fluid, pericardial fluid, peritoneal fluid, and pleural fluid, making up only ~1% of ECF.

    Electrolytes

    • Electrolytes are ions—charged particles.
    • Cations are positively charged.
    • Anions are negatively charged.
    • Electrolytes maintain homeostasis by balancing cations and anions at similar concentrations in intracellular and extracellular fluids.
    • Lab values are measured in mg/dL, mEq/L, or mmol/L.

    Fluid and Electrolytes

    • All body fluids contain electrolytes that are necessary for optimal function.
    • Maintaining the balance of electrolytes and body water is dynamic and involves an interplay of processes.

    Concentration of Fluid & Electrolytes

    • Osmolality is the measurement of the number of dissolved solute particles in a solution.
    • Normal serum osmolality is 275-295 mOsm/Kg H₂O.
    • Normal urine osmolality is 500-800 mOsm/kg H₂O

    Normal Physiological Processes of Fluid and Electrolytes

    • Intake and absorption
    • Can be administered intravenously or through other routes.
    • Strongly influenced by hunger and thirst (stimulated by increased osmolality)
    • Absorption or oral intake occurs in the intestines
    • Distribution of ECF occurs through filtration between the two major extracellular compartments: vascular and interstitial.
    • Hydrostatic pressure pushes fluid from capillaries into the interstitial space
    • Colloid osmotic pressure pulls fluid from interstitial space into capillaries.
    • Water moves across the semi-permeable membrane by osmosis.
    • Electrolyte movement has an energy requirement.
    • Output (excretion)
    • Regulated physiologically via renal (urine); GI tract (feces); skin (sweat); and lungs (water vapor)
    • Abnormal routes (no physiological regulatory mechanisms) include emesis, hemorrhage, drainage through tubes, etc.

    Scope of Fluid & Electrolyte Balance

    • Normal ECF should have optimal effective circulating volume (ECV) and electrolyte levels.
      • Normal serum sodium (Na+): 135-145 mEq/L
      • Normal serum osmolarity: 280-300 mOsm/kg H₂O
      • Normal potassium (K+): 3.5-5.0 mEq/L

    Transport of Fluid & Electrolytes

    • Describes movement of fluids and electrolytes.

    Renin-Angiotensin-Aldosterone System (RAAS)

    • Response to decreased renal perfusion by Juxtaglomerular apparatus signals the body to increase effective circulating volume, increasing blood pressure and sodium reabsorption. This involves renin, angiotensinogen, angiotensin I, angiotensin II, and aldosterone to increase sodium reabsorption.

    Antidiuretic Hormone (ADH)

    • Released by the posterior pituitary gland.
    • ADH alters the permeability of the collecting tubules to water, allowing more water to be absorbed.
      • High ADH, causes the kidneys to reabsorb more water via the collecting ducts, producing a more concentrated urine with a higher specific gravity.
      • Low ADH, causes the kidney to excrete more water via the collecting ducts, producing a less concentrated urine with a lower specific gravity

    Aldosterone

    • Produced and released by the adrenal cortex.
    • Increases sodium and water reabsorption while increasing potassium excretion

    Concentration of Fluid & Electrolytes (Conditions increasing osmolality)

    • Serum: dehydration, sepsis, fever, sweating, burns, diabetes mellitus, diabetes insipidus, uremia, hypernatremia, ethanol, methanol, ethylene glycol ingestion, mannitol therapy
    • Urine: dehydration, syndrome of inappropriate ADH secretion, adrenal insufficiency, glycosuria, hypernatremia, high-protein diet

    Concentration of Fluid & Electrolytes (Conditions decreasing osmolality)

    • Serum: excess hydration, hyponatremia, syndrome of inappropriate ADH secretion
    • Urine: diabetes insipidus, excess fluid intake, acute renal insufficiency, glomerulonephritis

    Capillary & Interstitial Fluid Exchange

    • 4 main forces responsible for fluid transfer between capillary and interstitial spaces
      • Capillary filtration pressure
      • Capillary colloidal osmotic pressure
      • Interstitial hydrostatic pressure
      • Interstitial colloidal osmotic pressure
    • Interstitial fluid increases due to increased capillary filtration pressure, decreased capillary colloidal osmotic pressure, increased capillary permeability, and obstruction of lymphatic fluid flow.

    Edema

    • Increased interstitial fluid volume due to:
      • increased capillary filtration pressure
      • decreased capillary colloidal osmotic pressure
      • increased capillary permeability
      • obstruction of lymphatic flow

    Sodium and Water Balance

    • Regulation of water balance
      • Thirst
      • Anti-diuretic hormone (ADH) also known as vasopressin
      • Baroreceptors detect changes in blood pressure and signal pituitary
      • Osmoreceptors sense diffusion of water caused by changes in serum osmolality
    • Regulation of sodium balance
      • Sympathetic nervous system
      • Renin-Angiotensin-Aldosterone System

    Thirst

    • Regulated by the thirst center in the hypothalamus.
    • 2 primary mechanisms:
      • Extracellular thirst (decrease in blood volume)
      • Intracellular thirst (increase in ECF osmolality)
      • Angiotensin II (secondary)

    Disorders of Fluid Balance

    • Fluid Volume Excess
      • Expansion of ECF compartment, usually as a result of increased total body sodium, manifests with weight gain, edema, distended neck veins, full bounding pulse, and venous distension, and pulmonary edema (severe).
    • Isotonic Fluid Volume Deficit
      • Loss of water and electrolytes—manifest with thirst, decreased body weight, oliguria, high urine specific gravity, dry mucous membranes, and postural hypotension, tachycardia

    Disorders of Fluid Balance: ADH imbalance

    • Diabetes Insipidus - Decreased secretion or response to ADH—manifests with polyuria, polydipsia, and decreased urine specific gravity.
    • Syndrome of Inappropriate ADH secretion (SIADH)—Abnormal excessive secretion of ADH—manifests with decreased urinary output, dilutional hyponatremia, fluid volume overload, and increased urine specific gravity.

    Syndrome of Inappropriate ADH (SIADH) Versus Diabetes Insipidus

    • Compare and contrast symptoms of SIADH and Diabetes Insipidous

    Sodium Imbalances - Hyponatremia

    • Hyponatremia - serum sodium less than 135 mEq/L
      • Types of hyponatremia
        • Hypertonic hyponatremia
        • Hypotonic (dilutional) hyponatremia
          • Hypovolemic: loss of water and sodium due to excessive water loss.
          • Euvolemic: most common—water retention (ADH)
          • Hypervolemic: Failure of the body to detect hypervolemia—increased ADH
      • Manifestations of hyponatremia
        • Muscle cramps, weakness, headache, apprehension, stupor or coma, nausea, vomiting, and diarrhea

    Sodium Imbalances - Hypernatremia

    • Hypernatremia - serum sodium greater than 145 mEq/L
      • Etiology - net water loss or net sodium gain
      • Manifestations - ECF loss, cellular dehydration, decreased skin turgor, CNS manifestations (headache, agitation, decreased reflexes, seizures, coma), CV manifestations (tachycardia, weak pulses, hypotension, vascular collapse)

    Potassium Regulation

    • Dietary intake
    • Renal regulation of K+ (aldosterone- increases secretion)
    • K+/H+ exchange
    • Shifts between ICF and ECF
    • Na+/K+-ATPase pump
    • Insulin & beta-adrenergics- increase cellular uptake

    Potassium Imbalances

    • Hypokalemia- serum potassium less than 3.5 mEq/L, causes include inadequate intake, excessive loss, and redistribution
    • Hyperkalemia - serum potassium greater than 5.3 mEq/L, causes include decreased excretion and rapid rate of administration.

    EKG Changes with Potassium Imbalances

    • Provides illustrations demonstrating EKG changes associated with Potassium Imbalances.

    Calcium

    • 99% found in bone; 3 forms of extra-cellular calcium
    • 40% bound to plasma proteins (albumin)
    • 1% decrease in albumin equates to 0.8% decrease in calcium
    • pH affects binding (acidosis less binding; alkalosis more binding); 10% is complexed
    • 50% is not bound and is ionized – used by cells for enzymatic functions

    Calcium Imbalances

    • Hypocalcemia- serum calcium less than 8.29 mg/dL
      • Etiology—renal failure, hypoparathyroidism, various medications
      • Manifestations—positive Chvostek sign, tetany, hypotension, prolonged QT interval
    • Hypercalcemia- serum calcium greater than 10.5 mg/dL
      • Etiology—increased bone resorption, neoplasms, hyperparathyroidism
      • Manifestations—crisis, polyuria, excessive thirst, volume deficit, fever, altered LOC, azotemia, short QT interval, AV block

    Magnesium Imbalances

    • Hypomagnesemia - serum magnesium <1.3 mg/dL
      • Etiology - insufficient intake, increased loss
      • Manifestations - tetany, tachycardia, hypertension, arrhythmias
    • Hypermagnesemia - serum magnesium > 2.2 mg/dL
      • Etiology - renal insufficiency
      • Manifestations - hyporeflexia, hypotension, cardiac arrest

    Phosphorus Imbalances

    • Hypophosphatemia -
      • Etiology - respiratory alkalosis, hyperglycemia, Vitamin D deficiency, chronic diarrhea, inadequate phosphate in diet, various issues affecting bone or blood.
      • Manifestations - weakness, CNS dysfunction, hypotension, cardiac failure, various hematologic disorders.
    • Hyperphosphatemia - -Etiology - renal insufficiency, hypoparathyroidism, respiratory acidosis, cow's milk. -Manifestations - hypocalcemia, oliguria, poor appetite, calcifications in organs.

    Key Things to Remember About Electrolytes

    • Sodium (Na+)
    • Potassium (K+)
    • Calcium (Ca+)
    • Magnesium (Mg+)

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    Fluid & Electrolyte Balance - NURS 3011 PowerPoint PDF

    Description

    Test your knowledge on the functions of cell membranes, fluid balance, and kidney roles in maintaining electrolytes. This quiz covers key concepts related to intracellular and extracellular fluids, transport mechanisms, and hormonal regulation. Perfect for students studying human biology or physiology.

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