Thirst Mechanism and Kidney Function
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Questions and Answers

Which of the following best describes the primary functions of potassium within a cell?

  • Influencing nerve impulse transmission and muscle contraction (correct)
  • Facilitating DNA replication and protein degradation
  • Regulating cellular carbohydrate storage and fat metabolism
  • Controlling calcium excretion and regulating digestive enzymes
  • What is the most significant method of potassium excretion in the body?

  • Respiration
  • Feces
  • Perspiration
  • Urine (correct)
  • Which condition is NOT a clinical manifestation of potassium deficiency?

  • Cardiac arrest
  • Hypotension (correct)
  • Muscle weakness
  • Confusion
  • Which of the following patients is MOST at risk for potassium deficiency?

    <p>A patient with severe anorexia due to chemotherapy</p> Signup and view all the answers

    What underlying factor can lead to increased potassium loss during stress?

    <p>Increased production of cortisol</p> Signup and view all the answers

    Which of the following is a common cause of potassium deficiency related to gastrointestinal losses?

    <p>Diarrhea</p> Signup and view all the answers

    Which of these options describe a plausible consequence of potassium deficiency?

    <p>Paralytic ileus</p> Signup and view all the answers

    What role does potassium play in maintaining heart function?

    <p>Supports normal cardiac rhythm and excitability</p> Signup and view all the answers

    What is an early sign of fluid volume excess?

    <p>Crackles in breath sounds</p> Signup and view all the answers

    Which of the following interventions is essential for managing fluid volume excess?

    <p>Perform daily weight checks</p> Signup and view all the answers

    What is the approximate daily water output for an adult, considering all loss mechanisms?

    <p>2500 ml</p> Signup and view all the answers

    What function does sodium primarily serve in the body?

    <p>Promote neuromuscular irritability</p> Signup and view all the answers

    Which of the following symptoms is NOT indicative of fluid volume deficit?

    <p>Increased urine output</p> Signup and view all the answers

    What condition can result from sodium deficiency?

    <p>Hypotension</p> Signup and view all the answers

    Which statement correctly describes a major source of sodium in the diet?

    <p>Table salt</p> Signup and view all the answers

    Which of the following is considered a late sign of fluid volume deficit?

    <p>Hypotension with tachycardia</p> Signup and view all the answers

    What physiological role does aldosterone play in sodium regulation?

    <p>Stimulates sodium reabsorption</p> Signup and view all the answers

    Which intervention is recommended for managing fluid volume deficit?

    <p>Find and correct the underlying cause</p> Signup and view all the answers

    What could a decrease in potassium and sodium indicate when monitoring lab values?

    <p>Overhydration or excessive fluid retention</p> Signup and view all the answers

    What percentage of body weight corresponds to 1 liter of fluid?

    <p>2.2% body weight</p> Signup and view all the answers

    Which condition is NOT a cause of fluid volume excess?

    <p>Tachypnea</p> Signup and view all the answers

    Which assessment finding is expected in infants under 18 months when monitoring for fluid balance?

    <p>Bulging fontanelles</p> Signup and view all the answers

    Which sign is an important indicator to monitor in infants when assessing for dehydration?

    <p>Sunken fontanelles</p> Signup and view all the answers

    What is a primary concern when administering IV fluids to a patient at risk of fluid volume excess?

    <p>Monitoring for fluid volume overload</p> Signup and view all the answers

    What is the Glomerular Filtration Rate (GFR) of nephrons filtering blood per minute?

    <p>125 mL/min</p> Signup and view all the answers

    What triggers the secretion of antidiuretic hormone (ADH)?

    <p>Decreased water levels</p> Signup and view all the answers

    What is the main function of aldosterone in the body?

    <p>Decrease water excretion</p> Signup and view all the answers

    What mechanism describes the movement of water from an area of lesser concentration to an area of higher concentration?

    <p>Osmosis</p> Signup and view all the answers

    What does the renal secretion of renin affect?

    <p>Triggers the release of aldosterone</p> Signup and view all the answers

    Which process requires cellular energy to move substances?

    <p>Active transport</p> Signup and view all the answers

    What role do the lungs play in the regulation of fluid balance?

    <p>Regulate CO2 levels and water vapors</p> Signup and view all the answers

    Which statement accurately describes passive transport?

    <p>It does not require energy and moves from high to low concentration.</p> Signup and view all the answers

    What is a primary cause of respiratory alkalosis?

    <p>Hyperventilation</p> Signup and view all the answers

    Which condition could result in respiratory acidosis due to impaired CO2 release?

    <p>Pneumonia</p> Signup and view all the answers

    What compensatory mechanism do the kidneys employ in response to an increase in pH?

    <p>Retention of HCO3</p> Signup and view all the answers

    What symptom is NOT typically associated with respiratory alkalosis?

    <p>Bradycardia</p> Signup and view all the answers

    What would indicate a carbonic acid deficit in a patient?

    <p>Serum pH &gt; 7.45</p> Signup and view all the answers

    Which treatment is recommended for managing acute respiratory alkalosis?

    <p>Breathing into a paper bag</p> Signup and view all the answers

    What pH level typically identifies respiratory acidosis?

    <p>pH &lt; 7.35</p> Signup and view all the answers

    Which of the following is a sign of hyperventilation?

    <p>Decreased urine pH</p> Signup and view all the answers

    Study Notes

    Thirst Mechanism

    • Regulated by the kidneys, lungs, skin, and hormones.
    • The thirst mechanism is triggered by a decrease in blood volume or an increase in blood osmolarity.

    Kidneys

    • Filter out excess water and electrolytes.
    • Secrete renin - an enzyme that triggers the release of aldosterone.
    • Glomerular Filtration Rate (GFR) is the rate at which nephrons filter blood - approximately 125 mL/min or 180 L/day.
    • The body must excrete a minimum of 400-500 mL/day of urine to eliminate waste.

    Lungs

    • Regulate CO2 levels and water vapor.

    Skin

    • Regulates fluid losses through sweat.

    Hormones

    • Antidiuretic Hormone (ADH)
      • Secreted by the posterior pituitary gland.
      • Secreted when water levels decrease, blood pressure drops, or sodium levels increase.
      • Stimulates the kidneys to reabsorb water, decreasing urine output.
    • Aldosterone
      • Secreted by the adrenal cortex.
      • Target organ is the kidneys, decreasing the excretion of sodium and water.

    Transport

    • Passive transport does not require energy.
      • Diffusion: Particles move from an area of higher concentration to an area of lower concentration, resulting in equal distribution.
      • Filtration: Fluids and electrolytes move from an area of higher pressure to an area of lower pressure. The pumping force of the heart provides the hydrostatic pressure needed.
      • Osmosis: Water moves from an area of lesser concentration to an area of higher concentration, resulting in equal distribution.
    • Active transport requires cellular energy.
      • Requires ATP (adenosine triphosphate) and moves substances from an area of low concentration to an area of higher concentration, regardless of positive or negative charges.
      • Examples of substances actively transported include sodium, potassium, calcium, iron, hydrogen, amino acids, and glucose.

    Intake and Output

    • All intake includes enteral and parenteral routes.
    • All output includes urine, diarrhea, vomitus, NG suction, chest tube drainage, and wound drains.
    • Insensible losses include lung vapor, sweat, and water loss in stool.
    • The daily water intake and output is approximately 2500 ml (fluid leaves via kidneys, lungs, skin, GI).
    • Daily weights: 1 L of fluid = 2.2 lb, 500 mL = 1.1 lb.

    Documenting Fluid Balance

    • Flow sheets, nurse's notes, and end-of-shift reports.

    Fluid Volume Deficit (Hypovolemia/Dehydration)

    • Causes
      • Diarrhea, vomiting, sweating, high fever, increased urine output (diuretics), tachypnea, insufficient IV replacement.
    • Signs and Symptoms (Clinical Manifestations)
      • Decreased urination, significant weight loss, dry mucous membranes, thirst, cool hands and feet, decreased pulse pressure, depressed fontanelles in infants.
      • Late signs: hypotension with tachycardia, tachypnea.
    • Key Points
      • Infants and elderly are at a greater risk of dehydration.
    • Interventions
      • Find and correct the cause (diarrhea, vomiting).
      • Oral fluid replacement, unless contraindicated.
      • IV fluids if oral fluids are contraindicated.
      • Daily weighings.
      • I&O monitoring.
      • Monitor skin turgor, oral mucous membranes, and urine characteristics (specific gravity).
      • Monitor fontanelles in infants under 18 months.
      • Protect perianal skin if the client has diarrhea.
      • Provide oral hygiene if the client has vomiting.
      • Monitor for fluid volume excess when replacing fluids.

    Fluid Volume Excess (Hypervolemia/Fluid Overload)

    • Causes
      • CHF, excess fluid intake (usually associated with psychiatric disorders), excessive sodium intake, compromised regulatory system, excessive IV fluids, decreased kidney function, and cirrhosis.
    • Signs and Symptoms (Clinical Manifestations)
      • Significant weight gain, leg or ankle edema (pitting or non-pitting), wheeze/dry cough, periorbital edema, headache, crackles, muscle cramps (cramping, weakness, hypotension).
      • Late signs: HTN (hypertension), pulmonary edema (rales), wet cough, frothy sputum, increased ICP (intracranial pressure), breathlessness, tachypnea, tachycardia, JVD (jugular vein distention).
    • Interventions
      • Monitor sodium intake.
      • I&O monitoring.
      • Monitor peripheral and pulmonary edema, including breath sounds.
      • Daily weight monitoring.
      • Fluid restriction.
      • Monitor for fluid volume deficit.
      • Monitor urine specific gravity.
      • Monitor lab values (hematocrit will decrease, potassium and sodium will decrease).
      • Monitor fontanelles in those under 18 months.

    Electrolytes

    • Functions:

      • Promote neuromuscular irritability
      • Maintain fluid volume
      • Regulate acid-base balance
    • Sodium

      • Key Points - Recommended daily amount (RDA): 1.5 g. - Major cation in the extracellular fluid compartment. - Often bound with Chloride to maintain water distribution.
      • Functions - Water balance, muscle contraction, heart contraction, transmission of nerve impulses, kidney urine concentration, and fluid volume maintenance.
      • Sources - Table salt, but found everywhere.
      • Regulation - Aldosterone
      • Deficiency: - Hyponatremia - Causes: sodium loss or water excess, excess sweating, urination, or diarrhea, nausea and vomiting, NG tube suction, diuretics, adrenal insufficiency.
    • Potassium (K+)

      • Key Points
        • Major intracellular cation.
      • Functions - Regulation of water and electrolyte content within the cell, acid-base balance, nerve impulse transmission, regulate heartbeat, insulin release, protein synthesis, use and storage of glucose, maintenance of excitability of cellular membranes in the heart and nervous system, muscle contraction.
      • Sources - Fruits and vegetables, tea, raisins, meat
      • Excretion: - Kidneys (80%), feces, perspiration
      • Deficiency
        • Hyperkalemia
          • Causes: renal excretion without conservation, excessive GI losses (suctioning or vomiting), diuretics (without K+ supplements), steroids, Lanoxin (digoxin), loss from cells with burns or trauma.
          • Symptoms (Clinical Manifestations): Muscle weakness, cardiac arrhythmias, cardiac arrest, hyporeflexia or areflexia, paresthesia, paralytic ileus, polyuria, fatigue, vertigo, ECG changes, anorexia, weak pulse, respiratory paralysis, lethargy, confusion.
          • Patients at Risk for K+ Deficit
            • Using diuretics (especially loop or thiazide)
            • Unable to take anything by mouth (NPO)
            • Severe anorexia (chemotherapy)
            • Unable to chew or swallow
            • Gastric suction applied
            • Severe diarrhea
            • Stress (activates aldosterone - saves sodium and water and gets rid of potassium)

    Acid-Base Balance

    • pH (potential of hydrogen) is a measure of acidity or alkalinity.
    • The normal blood pH is 7.35 - 7.45. Values below 7.35 are considered acidic, while values above 7.45 are considered alkaline.

    Acidosis

    • A state in which the body fluids have an excess of acid.
    • Types
      • Respiratory Acidosis: Caused by an increase in PaCO2.
        • Causes: Conditions that interfere with the release of CO2 from the lungs (pulmonary edema, pneumonia, sedatives, brain trauma, paralysis of respiratory muscles, upper airway obstruction, COPD, lung infection).
        • Symptoms: Decreased pH, increased PaCO2, and decreased bicarbonate.
      • Metabolic Acidosis: Caused by a decrease in bicarbonate.
        • Causes: Diabetes, renal failure, diarrhea, starvation, sepsis.
        • Symptoms: Decreased pH, decreased bicarbonate, normal or decreased PaCO2.

    Alkalosis

    • A state in which the body fluid has an excess of alkalinity.
    • Types
      • Respiratory Alkalosis: Caused by a decrease in PaCO2.
        • Causes: Hyperventilation (blowing off CO2), anxiety, pain, fever, high altitude.
        • Symptoms: Increased pH, decreased PaCO2, increased bicarbonate.
      • Metabolic Alkalosis: Caused by an increase in bicarbonate.
        • Causes: Vomiting, overuse of antacids, diuretics, excessive use of bicarbonate.
        • Symptoms: Increased pH, increased bicarbonate, normal or increased PaCO2.

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    Fluid & Electrolytes PDF

    Description

    Explore the intricate mechanisms of thirst regulation and kidney function. This quiz delves into how the kidneys, lungs, skin, and hormones interact to maintain fluid balance in the body. Test your knowledge on essential concepts like Glomerular Filtration Rate and the roles of ADH and aldosterone.

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