Textbook Question
Exercise physiologists recommend that adequate amounts of fluid be ingested before, during, and after exercise. Why is fluid replacement during extensive sweating important?
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Ch. 27 Fluids & Electrolytes
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology26
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization30
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure36
- Ch. 7 The Axial Skeleton11
- Ch. 8 The Appendicular Skeleton17
- Ch. 9 Joints13
- Ch. 10 Muscle Tissue12
- Ch. 11 The Muscular System28
- Ch. 12 Nervous Tissue18
- Ch. 13 The Spinal Cord, Spinal Nerves, and Spinal Reflexes22
- Ch. 14 The Brain and Cranial Nerves20
- Ch. 15 Sensory Pathways and the Somatic Nervous System17
- Ch. 16 The Autonomic Nervous System and Higher-Order Functions30
- Ch. 17 The Special Senses16
- Ch. 18 The Endocrine System20
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation29
- Ch. 22 The Lymphatic System and Immunity31
- Ch. 23 The Respiratory System12
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes32
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance23
Martini, Nath, Bartholomew11th EditionFundamentals of Anatomy & PhysiologyISBN: 9780136874089Not the one you use?Change textbook
Chapter 26, Problem 27
Dan has been lost in the desert for 2 days with very little water. As a result of this exposure, you would expect to observe which of the following?
(a) Increased ADH levels
(b) Decreased blood osmolarity
(c) Normal urine production
(d) Increased blood volume
(e) Cells enlarged with fluid
Verified step by step guidance1
Step 1: Understand the physiological context. Dan has been without much water for 2 days, which means his body is likely experiencing dehydration.
Step 2: Recall the role of Antidiuretic Hormone (ADH). ADH is released by the posterior pituitary gland in response to increased blood osmolarity (concentration of solutes in the blood) to conserve water by reducing urine output.
Step 3: Analyze the expected changes in blood osmolarity. With dehydration, water loss exceeds solute loss, so blood osmolarity increases rather than decreases.
Step 4: Consider urine production. Due to increased ADH, the kidneys will conserve water, leading to decreased urine volume, not normal urine production.
Step 5: Evaluate blood volume and cell size. Dehydration causes blood volume to decrease and cells to shrink as water moves out of cells to balance osmolarity, so cells would not enlarge with fluid.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Antidiuretic Hormone (ADH) Function
ADH is a hormone that helps the body conserve water by reducing urine output. When the body is dehydrated, ADH levels increase to promote water reabsorption in the kidneys, concentrating the urine and maintaining blood volume.
Recommended video:
Guided course
13:06
Review of Major Hormones
Blood Osmolarity and Hydration Status
Blood osmolarity measures the concentration of solutes in the blood. Dehydration increases blood osmolarity because of water loss, signaling the body to retain water and restore balance through mechanisms like ADH release.
Recommended video:
07:59Osmosis and Osmolarity
Cellular Fluid Balance During Dehydration
In dehydration, extracellular fluid becomes more concentrated, causing water to move out of cells by osmosis. This results in cell shrinkage rather than enlargement, as cells lose water to balance osmotic pressure.
Recommended video:
07:16Osmoregulation and Nitrogenous Waste
Related Practice
Textbook Question
Mary, a nursing student, has been caring for burn patients. She notices that they consistently show elevated levels of potassium in their urine and wonders why. What would you tell her?
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Textbook Question
Yuka is dehydrated, so her physician prescribes intravenous fluids. The attending nurse becomes distracted and erroneously gives Yuka a hypertonic glucose solution instead of normal saline. What effect will this mistake have on Yuka’s plasma ADH levels and urine volume?
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Textbook Question
After falling into an abandoned stone quarry filled with water and nearly drowning, a young boy is rescued. In assessing his condition, rescuers find that his body fluids have high PCO₂ and lactate levels and low PO₂ levels. Identify the underlying problem and recommend the necessary treatment to restore homeostatic conditions.
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Textbook Question
The most recent advice from medical and nutritional experts is to monitor one’s intake of salt so that it does not exceed the amount needed to maintain a constant ECF volume. What effect does excessive salt ingestion have on blood pressure?
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Textbook Question
While visiting a foreign country, Milly inadvertently drinks some water, even though she had been advised not to. She contracts an intestinal disease that causes severe diarrhea. How would you expect her condition to affect her blood pH, urine pH, and pattern of ventilation?
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