McCance & Huether’s Pathophysiology
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
Chapter 1, Cellular Communication and Signal Transduction
A researcher is studying a hormone that binds to a
transmembrane receptor, activating a G-protein. This G-protein
then directly stimulates the enzyme adenylyl cyclase to produce
the second messenger cAMP. This is an example of which type
of signaling mechanism?
A. Signal transduction through guanylyl cyclase
B. Signal transduction through ligand-gated ion channels
C. Signal transduction through calcium binding
D. Signal transduction through catalytic receptors
Correct Answer: D. Signal transduction through catalytic
receptors
Rationale for Correct Answer (D): The scenario describes a
classic G-protein-linked (metabotropic) receptor pathway. These
receptors are a major type of catalytic receptor that use G-
proteins as intermediaries to activate enzymes like adenylyl
cyclase, which then generate intracellular second messengers
like cAMP.
Rationale for Incorrect Answers:
,A: Guanylyl cyclase produces cGMP, not cAMP, and is often
directly activated by ligands (e.g., atrial natriuretic peptide), not
typically through a G-protein intermediary.
B: Ligand-gated ion channels open to allow ion flux (e.g., Na+,
K+, Ca2+) directly upon ligand binding, without involving G-
proteins or second messengers like cAMP.
C: Calcium can act as a second messenger, but its release is
often triggered by other second messengers (e.g., IP3), not
directly by the initial G-protein activation of adenylyl cyclase.
Teaching Point: G-protein-coupled receptors are catalytic
receptors that transmit signals via second messengers like
cAMP.
Item 2
Chapter 1, Cellular Metabolism
A patient with a hereditary deficiency in the pyruvate
dehydrogenase (PDH) complex would most directly impair the
cell's ability to perform which crucial metabolic step?
A. The conversion of glycogen to glucose-1-phosphate
B. The decarboxylation of pyruvate to acetyl CoA for entry into
the Krebs cycle
C. The reduction of pyruvate to lactate during anaerobic
glycolysis
D. The formation of oxaloacetate from pyruvate for
gluconeogenesis
,Correct Answer: B. The decarboxylation of pyruvate to acetyl
CoA for entry into the Krebs cycle
Rationale for Correct Answer (B): The pyruvate dehydrogenase
complex is the key enzymatic link between glycolysis and the
citric acid (Krebs) cycle. It irreversibly converts pyruvate into
acetyl CoA, which is the primary substrate for the cycle.
Rationale for Incorrect Answers:
A: This describes glycogenolysis, which is independent of the
PDH complex.
C: This is an anaerobic pathway catalyzed by lactate
dehydrogenase, which serves as an alternative fate for pyruvate
when the PDH complex is inactive (e.g., hypoxia).
D: This anaplerotic reaction is catalyzed by pyruvate
carboxylase, not the pyruvate dehydrogenase complex.
Teaching Point: PDH complex deficiency shunts pyruvate to
lactate, causing lactic acidosis and impairing aerobic ATP
production.
Item 3
Chapter 1, Structure and Function of Cellular Components
A genetic mutation disrupts the structure of the rough
endoplasmic reticulum (RER) in hepatocytes. Which synthesized
product would most likely be deficient in the bloodstream as a
direct result?
A. Glycogen
B. Cholesterol
, C. Albumin
D. ATP
Correct Answer: C. Albumin
Rationale for Correct Answer (C): The rough endoplasmic
reticulum is studded with ribosomes and is the primary site for
the synthesis and initial processing of proteins destined for
secretion from the cell (like albumin) or for insertion into
membranes.
Rationale for Incorrect Answers:
A: Glycogen is a carbohydrate polymer synthesized and stored
in the cytoplasm, not the RER.
B: Cholesterol is synthesized in the smooth endoplasmic
reticulum (SER).
D: ATP is produced primarily in the mitochondria and cytoplasm
(via glycolysis).
Teaching Point: The RER is specialized for synthesizing secretory
and membrane-bound proteins.
Item 4
Chapter 1, Membrane Transport: Cellular Intake and Output
In the nephron, glucose is reabsorbed from the filtrate back into
the blood against its concentration gradient by coupling its
transport to the downhill movement of sodium. This process is
best described as:
A. Primary active transport
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
Chapter 1, Cellular Communication and Signal Transduction
A researcher is studying a hormone that binds to a
transmembrane receptor, activating a G-protein. This G-protein
then directly stimulates the enzyme adenylyl cyclase to produce
the second messenger cAMP. This is an example of which type
of signaling mechanism?
A. Signal transduction through guanylyl cyclase
B. Signal transduction through ligand-gated ion channels
C. Signal transduction through calcium binding
D. Signal transduction through catalytic receptors
Correct Answer: D. Signal transduction through catalytic
receptors
Rationale for Correct Answer (D): The scenario describes a
classic G-protein-linked (metabotropic) receptor pathway. These
receptors are a major type of catalytic receptor that use G-
proteins as intermediaries to activate enzymes like adenylyl
cyclase, which then generate intracellular second messengers
like cAMP.
Rationale for Incorrect Answers:
,A: Guanylyl cyclase produces cGMP, not cAMP, and is often
directly activated by ligands (e.g., atrial natriuretic peptide), not
typically through a G-protein intermediary.
B: Ligand-gated ion channels open to allow ion flux (e.g., Na+,
K+, Ca2+) directly upon ligand binding, without involving G-
proteins or second messengers like cAMP.
C: Calcium can act as a second messenger, but its release is
often triggered by other second messengers (e.g., IP3), not
directly by the initial G-protein activation of adenylyl cyclase.
Teaching Point: G-protein-coupled receptors are catalytic
receptors that transmit signals via second messengers like
cAMP.
Item 2
Chapter 1, Cellular Metabolism
A patient with a hereditary deficiency in the pyruvate
dehydrogenase (PDH) complex would most directly impair the
cell's ability to perform which crucial metabolic step?
A. The conversion of glycogen to glucose-1-phosphate
B. The decarboxylation of pyruvate to acetyl CoA for entry into
the Krebs cycle
C. The reduction of pyruvate to lactate during anaerobic
glycolysis
D. The formation of oxaloacetate from pyruvate for
gluconeogenesis
,Correct Answer: B. The decarboxylation of pyruvate to acetyl
CoA for entry into the Krebs cycle
Rationale for Correct Answer (B): The pyruvate dehydrogenase
complex is the key enzymatic link between glycolysis and the
citric acid (Krebs) cycle. It irreversibly converts pyruvate into
acetyl CoA, which is the primary substrate for the cycle.
Rationale for Incorrect Answers:
A: This describes glycogenolysis, which is independent of the
PDH complex.
C: This is an anaerobic pathway catalyzed by lactate
dehydrogenase, which serves as an alternative fate for pyruvate
when the PDH complex is inactive (e.g., hypoxia).
D: This anaplerotic reaction is catalyzed by pyruvate
carboxylase, not the pyruvate dehydrogenase complex.
Teaching Point: PDH complex deficiency shunts pyruvate to
lactate, causing lactic acidosis and impairing aerobic ATP
production.
Item 3
Chapter 1, Structure and Function of Cellular Components
A genetic mutation disrupts the structure of the rough
endoplasmic reticulum (RER) in hepatocytes. Which synthesized
product would most likely be deficient in the bloodstream as a
direct result?
A. Glycogen
B. Cholesterol
, C. Albumin
D. ATP
Correct Answer: C. Albumin
Rationale for Correct Answer (C): The rough endoplasmic
reticulum is studded with ribosomes and is the primary site for
the synthesis and initial processing of proteins destined for
secretion from the cell (like albumin) or for insertion into
membranes.
Rationale for Incorrect Answers:
A: Glycogen is a carbohydrate polymer synthesized and stored
in the cytoplasm, not the RER.
B: Cholesterol is synthesized in the smooth endoplasmic
reticulum (SER).
D: ATP is produced primarily in the mitochondria and cytoplasm
(via glycolysis).
Teaching Point: The RER is specialized for synthesizing secretory
and membrane-bound proteins.
Item 4
Chapter 1, Membrane Transport: Cellular Intake and Output
In the nephron, glucose is reabsorbed from the filtrate back into
the blood against its concentration gradient by coupling its
transport to the downhill movement of sodium. This process is
best described as:
A. Primary active transport
