Textbook Question
A drop in pH below 4.5 in the duodenum stimulates the secretion of
(a) Secretin
(b) Cholecystokinin
(c) Gastrin
(d) All of these
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Ch. 24 The Digestive System
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011
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Table of contents
- Ch. 1 An Introduction to Anatomy and Physiology25
- Ch. 2 The Chemical Level of Organization34
- Ch. 3 The Cellular Level of Organization29
- Ch. 4 The Tissue Level of Organization24
- Ch. 5 The Integumentary System17
- Ch. 6 Bones and Bone Structure33
- 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 Senses15
- Ch. 18 The Endocrine System21
- Ch. 19 Blood31
- Ch. 20 The Heart31
- Ch. 21 Blood Vessels and Circulation26
- Ch. 22 The Lymphatic System and Immunity25
- Ch. 23 The Respiratory System4
- Ch. 24 The Digestive System18
- Ch. 26 The Urinary System31
- Ch. 27 Fluids & Electrolytes30
- Ch. 28 The Reproductive System12
- Ch. 29 Development and Inheritance17
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
Chapter 24, Problem 28
Nutritionists have found that after a heavy meal, the pH of blood increases slightly, especially in the veins that carry blood away from the stomach. What causes this increase in blood pH?
Verified step by step guidance1
Step 1: Understand that pH is a measure of hydrogen ion concentration, where an increase in pH means the blood is becoming more alkaline (fewer hydrogen ions).
Step 2: Recall that after a heavy meal, the stomach produces more gastric acid (HCl) to aid digestion, which increases acidity in the stomach lumen but does not directly acidify the blood.
Step 3: Recognize that the blood leaving the stomach (via the veins) carries absorbed nutrients and metabolic byproducts, including bicarbonate ions (HCO₃⁻) released from the pancreas to neutralize stomach acid in the small intestine.
Step 4: Understand that the release of bicarbonate into the bloodstream raises the blood's pH by neutralizing hydrogen ions, causing the slight increase in blood pH observed after a meal.
Step 5: Summarize that the increase in blood pH after a heavy meal is primarily due to the influx of bicarbonate ions into the blood from the pancreas, which neutralizes acid and makes the blood more alkaline.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Blood pH and Acid-Base Balance
Blood pH measures how acidic or basic the blood is, normally maintained around 7.35-7.45. The body regulates this balance through buffers, respiration, and kidney function to keep enzymes and metabolic processes functioning properly.
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01:29
Acids and Bases
Digestion and Metabolic Byproducts
During digestion, food is broken down into nutrients, producing metabolic byproducts like carbon dioxide and acids. After a heavy meal, increased metabolism and nutrient absorption can alter the concentration of these substances, influencing blood pH.
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02:17Introduction to Metabolism
Role of Carbon Dioxide in Blood pH
Carbon dioxide (CO2) dissolves in blood forming carbonic acid, which lowers pH. After eating, blood leaving the stomach may have reduced CO2 due to increased oxygen use and metabolic changes, causing a slight rise in blood pH (more alkaline).
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04:19Carbon
Related Practice
Textbook Question
Increased parasympathetic stimulation of the intestine would result in
(a) Decreased motility
(b) Decreased secretion
(c) Decreased sensitivity of local reflexes
(d) Decreased segmentation
(e) None of these
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Textbook Question
Recently, more people have turned to surgery to help them lose weight. One form of weight control surgery involves stapling a portion of the stomach shut, creating a smaller volume. How would such a surgery result in weight loss?
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Textbook Question
How does each of the three phases of gastric secretion promote and facilitate gastric control?
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Textbook Question
Some people with gallstones develop pancreatitis. How could this occur?
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