PCB 3703 Exam 1 V2 | PCB 3703 Human
Physiology | Actual Q&A with Rationale (PCB3703
Exam 1) | University of Central Florida
1. Which of the following best describes the concept of homeostasis in human physiology?
A. The maintenance of a relatively stable internal environment through compensatory
responses.
B. A state of fixed, unchanging internal conditions regardless of the environment.
C. The ability of the body to perfectly match external temperatures.
D. A process where the body allows the internal environment to fluctuate freely.
Correct Answer: A
Explanation: Homeostasis represents a dynamic state of equilibrium rather than a static,
unchanging condition. The body utilizes various control systems to maintain variables like
glucose and temperature within a narrow physiological range. This process is essential for
the survival of complex organisms in changing environments.
2. In a negative feedback loop, what is the primary role of the effector?
A. To detect the initial stimulus or change in the environment.
B. To carry out the response that opposes the initial stimulus.
C. To process information and determine the appropriate response.
D. To amplify the signal to push the variable further from the setpoint.
,Correct Answer: B
Explanation: The effector is the component of a control system that executes the command
from the integrating center. By definition, a negative feedback loop works to counteract or
oppose the original change in the system. This helps return the physiological variable back
toward its established setpoint.
3. Which of the following is an example of positive feedback?
A. Regulation of blood glucose levels by insulin.
B. The process of childbirth facilitated by oxytocin release.
C. Maintenance of body temperature through shivering.
D. Control of blood pressure via the baroreceptor reflex.
Correct Answer: B
Explanation: Positive feedback loops reinforce or amplify a stimulus rather than
decreasing it. During labor, uterine contractions trigger the release of oxytocin, which
causes even stronger contractions. This process continues until the ultimate goal, delivery
of the baby, is achieved.
4. What is the major difference between ECF and ICF?
A. The ECF has a higher concentration of potassium than the ICF.
B. The ICF contains more sodium and chloride than the ECF.
C. The ICF has a high concentration of K+ while the ECF has high Na+ and Cl-.
, D. There is no chemical disequilibrium between these two compartments.
Correct Answer: C
Explanation: The intracellular fluid (ICF) and extracellular fluid (ECF) maintain distinct
chemical compositions despite being in osmotic equilibrium. Potassium is the primary
cation inside the cell, while sodium and chloride dominate the extracellular space. This
chemical disequilibrium is vital for the generation of electrical signals in excitable tissues.
5. According to Fick’s Law of Diffusion, which factor would decrease the rate of diffusion
across a membrane?
A. An increase in the thickness of the membrane.
B. An increase in the surface area of the membrane.
C. An increase in the concentration gradient of the substance.
D. An increase in the lipid solubility of the diffusing molecule.
Correct Answer: A
Explanation: Fick’s Law states that the rate of diffusion is inversely proportional to the
thickness of the membrane. As the distance the molecule must travel increases, the time
required for diffusion increases significantly. Therefore, thicker membranes result in a
slower net rate of movement for solutes.
6. Which type of membrane transport requires energy directly from ATP hydrolysis?
A. Primary active transport.
Physiology | Actual Q&A with Rationale (PCB3703
Exam 1) | University of Central Florida
1. Which of the following best describes the concept of homeostasis in human physiology?
A. The maintenance of a relatively stable internal environment through compensatory
responses.
B. A state of fixed, unchanging internal conditions regardless of the environment.
C. The ability of the body to perfectly match external temperatures.
D. A process where the body allows the internal environment to fluctuate freely.
Correct Answer: A
Explanation: Homeostasis represents a dynamic state of equilibrium rather than a static,
unchanging condition. The body utilizes various control systems to maintain variables like
glucose and temperature within a narrow physiological range. This process is essential for
the survival of complex organisms in changing environments.
2. In a negative feedback loop, what is the primary role of the effector?
A. To detect the initial stimulus or change in the environment.
B. To carry out the response that opposes the initial stimulus.
C. To process information and determine the appropriate response.
D. To amplify the signal to push the variable further from the setpoint.
,Correct Answer: B
Explanation: The effector is the component of a control system that executes the command
from the integrating center. By definition, a negative feedback loop works to counteract or
oppose the original change in the system. This helps return the physiological variable back
toward its established setpoint.
3. Which of the following is an example of positive feedback?
A. Regulation of blood glucose levels by insulin.
B. The process of childbirth facilitated by oxytocin release.
C. Maintenance of body temperature through shivering.
D. Control of blood pressure via the baroreceptor reflex.
Correct Answer: B
Explanation: Positive feedback loops reinforce or amplify a stimulus rather than
decreasing it. During labor, uterine contractions trigger the release of oxytocin, which
causes even stronger contractions. This process continues until the ultimate goal, delivery
of the baby, is achieved.
4. What is the major difference between ECF and ICF?
A. The ECF has a higher concentration of potassium than the ICF.
B. The ICF contains more sodium and chloride than the ECF.
C. The ICF has a high concentration of K+ while the ECF has high Na+ and Cl-.
, D. There is no chemical disequilibrium between these two compartments.
Correct Answer: C
Explanation: The intracellular fluid (ICF) and extracellular fluid (ECF) maintain distinct
chemical compositions despite being in osmotic equilibrium. Potassium is the primary
cation inside the cell, while sodium and chloride dominate the extracellular space. This
chemical disequilibrium is vital for the generation of electrical signals in excitable tissues.
5. According to Fick’s Law of Diffusion, which factor would decrease the rate of diffusion
across a membrane?
A. An increase in the thickness of the membrane.
B. An increase in the surface area of the membrane.
C. An increase in the concentration gradient of the substance.
D. An increase in the lipid solubility of the diffusing molecule.
Correct Answer: A
Explanation: Fick’s Law states that the rate of diffusion is inversely proportional to the
thickness of the membrane. As the distance the molecule must travel increases, the time
required for diffusion increases significantly. Therefore, thicker membranes result in a
slower net rate of movement for solutes.
6. Which type of membrane transport requires energy directly from ATP hydrolysis?
A. Primary active transport.
