Textbook Question
What do you think has happened to Elise's ECF volume and osmolarity over the past 3 days? Will this lead to a change in the volume of water in the cytosol of her cells? Explain.
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Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis
Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomic Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Metabolism and Nutrition7
- Ch. 24 The Urinary System39
- Ch. 25 Fluid, Electrolyte, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Chapter 25, Problem L3.3
Ms. Johanssen is a patient in the hospital. The nurse examines her laboratory reports and notices that she has developed hyperkalemia and acidosis over the past several days. On closer examination of her medical chart, the nurse also sees that her physician recently doubled her dose of spironolactone, an aldosterone-blocking diuretic. How does this explain her laboratory findings?
Verified step by step guidance1
Understand the role of aldosterone: Aldosterone is a hormone that promotes sodium reabsorption and potassium excretion in the kidneys. It also helps regulate acid-base balance by promoting hydrogen ion excretion. Spironolactone, as an aldosterone-blocking diuretic, inhibits these processes.
Explain hyperkalemia: By blocking aldosterone, spironolactone reduces potassium excretion in the kidneys. This leads to an accumulation of potassium in the blood, a condition known as hyperkalemia.
Explain acidosis: Aldosterone also promotes the excretion of hydrogen ions in the kidneys. When aldosterone is blocked by spironolactone, hydrogen ions are retained, leading to a decrease in blood pH, which is referred to as acidosis.
Connect the findings to the medication dose: The doubling of the spironolactone dose would amplify its aldosterone-blocking effects, further reducing potassium and hydrogen ion excretion. This explains the worsening hyperkalemia and acidosis observed in Ms. Johanssen's laboratory reports.
Summarize the physiological impact: The combination of hyperkalemia and acidosis is a direct result of the increased spironolactone dose, which disrupts the normal balance of potassium and hydrogen ions regulated by aldosterone in the kidneys.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hyperkalemia
Hyperkalemia refers to an elevated level of potassium in the blood, which can lead to serious cardiac and muscular complications. It often occurs when the kidneys are unable to excrete sufficient potassium, or when potassium intake exceeds the body's ability to eliminate it. In the context of diuretics, certain medications, like spironolactone, can cause potassium retention, contributing to hyperkalemia.
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Acidosis
Acidosis is a condition characterized by an excess of acid in the body fluids, leading to a decrease in blood pH. It can result from various factors, including respiratory issues or metabolic disturbances. In patients with hyperkalemia, acidosis can occur as potassium ions shift from the intracellular to the extracellular space, causing hydrogen ions to move into cells, thus increasing acidity in the blood.
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Guided course
03:46Homeostasis Example 1
Spironolactone
Spironolactone is a potassium-sparing diuretic that works by blocking the action of aldosterone, a hormone that promotes sodium retention and potassium excretion. By inhibiting aldosterone, spironolactone leads to increased sodium excretion while retaining potassium. This mechanism can explain the patient's hyperkalemia, especially after the recent increase in her medication dosage, which may have exacerbated her potassium levels.
Related Practice
Textbook Question
As a percentage of body weight, the total body water tends to be higher in ________ and lower in ________ .
a. infants; men
b. women; men
c. men; infants
d. infants; women
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Textbook Question
A laboratory printout of arterial blood gases indicates that a patient has an increased Pco₂ , decreased pH, and normal bicarbonate ion concentration. Is this patient in acidosis or alkalosis? Is the pH disturbance respiratory or metabolic in nature? Explain your reasoning. How long do you think the patient has had this pH disturbance? (Hint: Look at the bicarbonate ion concentration. What system controls the concentration of bicarbonate ions, and how quickly does it compensate for pH disturbances?)
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Textbook Question
A cell in a/an ________ fluid will lose water, and a cell in a/an ________ fluid will gain water.
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Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
a. The thirst mechanism is mediated by osmoreceptors located in the cerebral cortex.
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Textbook Question
What happens to the concentration of sodium ions in the ECF if you consume a large amount of salt without consuming any water? How will this affect the osmotic pressure of the ECF? Why could this lead to an elevation in blood pressure?
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