McCance & Huether’s Pathophysiology
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
Chapter 1: Cellular Biology
1. Chapter 1, Cellular Communication and Signal Transduction
A researcher is studying a hormone that binds to a
transmembrane receptor, activating a G-protein. This, in turn,
activates phospholipase C, leading to the release of IP3 and an
increase in intracellular calcium. This hormone is utilizing which
primary class of signaling pathway?
A. Receptor-enzyme
B. Integrin receptor
C. Receptor-G-protein
D. Ligand-gated ion channel
Correct Answer: C. Receptor-G-protein
Rationale:
Correct (C): The description is a classic example of a receptor-G-
protein pathway. The G-protein is the key second messenger
system that, when activated, can trigger various downstream
effects, including the phospholipase C-inositol trisphosphate
(IP3) pathway described.
,Incorrect (A): Receptor-enzyme pathways (e.g., for insulin)
involve the receptor itself having enzymatic activity, such as
tyrosine kinase, which is not described here.
Incorrect (B): Integrin receptors primarily mediate cell adhesion
to the extracellular matrix and signal inwards about the cellular
environment.
Incorrect (D): Ligand-gated ion channels open directly to allow
ion flux upon ligand binding (e.g., neuronal acetylcholine
receptors), without involving a G-protein intermediary.
Teaching Point: G-protein coupled receptors are a major class
of receptors that use second messengers like IP3 to amplify
signals within the cell.
2. Chapter 1, Cellular Metabolism
A patient with a history of chronic alcohol abuse presents with
lactic acidosis. The underlying pathophysiology involves alcohol
metabolism shifting the NAD+/NADH ratio significantly toward
NADH. This impairs which crucial anaerobic metabolic pathway?
A. Glycolysis
B. Beta-oxidation
C. Gluconeogenesis
D. The citric acid cycle
Correct Answer: C. Gluconeogenesis
Rationale:
,Correct (C): Gluconeogenesis requires NAD+ as a cofactor for
the conversion of lactate to pyruvate. A high NADH/NAD+ ratio
inhibits this step, preventing lactate from being used to make
new glucose and leading to its accumulation (lactic acidosis).
Incorrect (A): Glycolysis can proceed anaerobically and is not
directly inhibited by this altered ratio; in fact, it may be
stimulated to generate ATP.
Incorrect (B): Beta-oxidation of fatty acids requires NAD+ and is
impaired by a high NADH/NAD+ ratio, but this contributes more
to fatty liver than lactic acidosis.
Incorrect (D): The citric acid cycle is an aerobic process and
would be suppressed in this scenario due to the redox state, but
it is not the direct cause of the lactic acid buildup.
Teaching Point: An altered NAD+/NADH ratio disrupts redox
potential, critically impairing gluconeogenesis and leading to
lactic acidosis.
3. Chapter 1, Structure and Function of Cellular Components
A newborn is diagnosed with Tay-Sachs disease, a lysosomal
storage disorder. The pathophysiologic defect in this disease is
the deficiency of a specific lysosomal enzyme. What is the
primary function of the organelle affected in this disease?
A. ATP production
B. Protein synthesis
, C. Detoxification of wastes
D. Intracellular digestion
Correct Answer: D. Intracellular digestion
Rationale:
Correct (D): The lysosome is the organelle responsible for
intracellular digestion of macromolecules using acid hydrolases.
A deficiency in one of these enzymes leads to substrate
accumulation.
Incorrect (A): ATP production is the primary function of
mitochondria.
Incorrect (B): Protein synthesis is the primary function of the
rough endoplasmic reticulum and ribosomes.
Incorrect (C): Detoxification is a primary function of the smooth
endoplasmic reticulum and peroxisomes.
Teaching Point: Lysosomes are the digestive system of the cell,
and enzyme deficiencies cause undigested substrates to
accumulate.
4. Chapter 1, Membrane Transport: Cellular Intake and Output
Glucose is transported from the intestinal lumen into the
epithelial cell against its concentration gradient by coupling its
transport to the downhill movement of sodium ions. This
process is best described as:
A. Simple diffusion
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
Chapter 1: Cellular Biology
1. Chapter 1, Cellular Communication and Signal Transduction
A researcher is studying a hormone that binds to a
transmembrane receptor, activating a G-protein. This, in turn,
activates phospholipase C, leading to the release of IP3 and an
increase in intracellular calcium. This hormone is utilizing which
primary class of signaling pathway?
A. Receptor-enzyme
B. Integrin receptor
C. Receptor-G-protein
D. Ligand-gated ion channel
Correct Answer: C. Receptor-G-protein
Rationale:
Correct (C): The description is a classic example of a receptor-G-
protein pathway. The G-protein is the key second messenger
system that, when activated, can trigger various downstream
effects, including the phospholipase C-inositol trisphosphate
(IP3) pathway described.
,Incorrect (A): Receptor-enzyme pathways (e.g., for insulin)
involve the receptor itself having enzymatic activity, such as
tyrosine kinase, which is not described here.
Incorrect (B): Integrin receptors primarily mediate cell adhesion
to the extracellular matrix and signal inwards about the cellular
environment.
Incorrect (D): Ligand-gated ion channels open directly to allow
ion flux upon ligand binding (e.g., neuronal acetylcholine
receptors), without involving a G-protein intermediary.
Teaching Point: G-protein coupled receptors are a major class
of receptors that use second messengers like IP3 to amplify
signals within the cell.
2. Chapter 1, Cellular Metabolism
A patient with a history of chronic alcohol abuse presents with
lactic acidosis. The underlying pathophysiology involves alcohol
metabolism shifting the NAD+/NADH ratio significantly toward
NADH. This impairs which crucial anaerobic metabolic pathway?
A. Glycolysis
B. Beta-oxidation
C. Gluconeogenesis
D. The citric acid cycle
Correct Answer: C. Gluconeogenesis
Rationale:
,Correct (C): Gluconeogenesis requires NAD+ as a cofactor for
the conversion of lactate to pyruvate. A high NADH/NAD+ ratio
inhibits this step, preventing lactate from being used to make
new glucose and leading to its accumulation (lactic acidosis).
Incorrect (A): Glycolysis can proceed anaerobically and is not
directly inhibited by this altered ratio; in fact, it may be
stimulated to generate ATP.
Incorrect (B): Beta-oxidation of fatty acids requires NAD+ and is
impaired by a high NADH/NAD+ ratio, but this contributes more
to fatty liver than lactic acidosis.
Incorrect (D): The citric acid cycle is an aerobic process and
would be suppressed in this scenario due to the redox state, but
it is not the direct cause of the lactic acid buildup.
Teaching Point: An altered NAD+/NADH ratio disrupts redox
potential, critically impairing gluconeogenesis and leading to
lactic acidosis.
3. Chapter 1, Structure and Function of Cellular Components
A newborn is diagnosed with Tay-Sachs disease, a lysosomal
storage disorder. The pathophysiologic defect in this disease is
the deficiency of a specific lysosomal enzyme. What is the
primary function of the organelle affected in this disease?
A. ATP production
B. Protein synthesis
, C. Detoxification of wastes
D. Intracellular digestion
Correct Answer: D. Intracellular digestion
Rationale:
Correct (D): The lysosome is the organelle responsible for
intracellular digestion of macromolecules using acid hydrolases.
A deficiency in one of these enzymes leads to substrate
accumulation.
Incorrect (A): ATP production is the primary function of
mitochondria.
Incorrect (B): Protein synthesis is the primary function of the
rough endoplasmic reticulum and ribosomes.
Incorrect (C): Detoxification is a primary function of the smooth
endoplasmic reticulum and peroxisomes.
Teaching Point: Lysosomes are the digestive system of the cell,
and enzyme deficiencies cause undigested substrates to
accumulate.
4. Chapter 1, Membrane Transport: Cellular Intake and Output
Glucose is transported from the intestinal lumen into the
epithelial cell against its concentration gradient by coupling its
transport to the downhill movement of sodium ions. This
process is best described as:
A. Simple diffusion
